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DETECTION OF DRUG USE DURING PREGNANCY
SUBSTANCE ABUSE IN PREGNANCY
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DETECTION OF DRUG USE DURING PREGNANCY Tai C. Kwong, PhD, and Douglas Shearer, PhD, MD
Drug users who are pregnant jeopardize not only their own health and well-being but that of the fetuses they carry. As illicit drugs become more available to all segments of society?O it is increasingly urgent to address the consequences. The medical complications arising from cocaine and other drug use during pregnancy include premature onset of labor and rupture of fetal membranes, spontaneous abortion, abruptio placentae, premature births, stillbirth, and increased fetal mortality and &aturity.14, 32, 51, 60, 62, 67, 72. 82 Medical and developmental problems in the neonate include small head circumference? 11, 13, 32, 71, 72, 93 smallfor-gestational-age, and an increased incidence of sudden infant death ~yndrome.2~. 52 Studies on cocaine abuse indicate that cocaine use during pregnancy is the best indicator of an increased incidence of abortion, high maternal gravidity, and poor prenatal care.28, Furthermore, cocaine is the best indicator of preterm birth and lower birth weight. It is therefore imperative that every attempt be made to identify women who use drugs during pregnancy to avoid, or at least minimize, the risks of complications to both the pregnant woman and fetus. Early identification of these women (and any drug-exposed neonates) permits the initiation of appropriate interventional care, as well as the formulation of plans for follow-up care and management. No precise data describe the prevalence of illicit drug use among pregnant women. Estimates of prevalence have been based on maternal
From the Department of Pathology and Laboratory Medicine, University of Rochester School of Medicine and Dentistry (TCK, DS); Regional Toxicology Laboratory, University of Rochester Medical Center (TCK); and the Monroe County Medical Examiner’s Office (DS), Rochester, New York
OBSTETRICS AND GYNECOLOGY CLINICS OF NORTH AMERICA VOLUME 25 NUMBER 1 MARCH 1998
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self-reporting by interview or questionnaire and urine drug testing. Selfreporting underestimates the prevalence, because many women (24% to 63%)deny any cocaine use despite a positive drug test, probably because of feelings of guilt and the fear of legal consequences.12,29, 30, 65, 93 The results of urine testing can be negative even though the patient admits to current use, because of the short time during which a drug test is 9D Thus, a combination of structured questionnaire and urine acc~rate.’~, toxicologic screen identifies more current users than either technique alone. URINE TESTING FOR DRUGS OF ABUSE Urine is the most readily accessible sample for toxicologic analysis in the clinical laboratory. Drug or drug metabolite concentrations in urine specimens can be lower than the detection limits of thin-layer chromatography and high-performance liquid chromatography (HPLC), the analytical methods most used in clinical laboratories for detecting the relatively high drug concentrations found in suspected drug overdose cases. The testing of urine specimens in pregnant patients for drug-of-abuse exposure requires more sensitive assays; the nonisotopic immunoassays are generally used. Commercial nonisotopic enzyme immunoassays or fluorescence polarization immunoassays do not have the sensitivity of radioimmunoassay but have the advantage of being homogeneous methods that are more easily adapted to automated instruments for rapid analysis and turnaround time. Moreover, they are the basis for an increasing number of single-use, hand-held, on-site testing devices that can be used at the bedside or in the physician’s office. Presumptive Versus Confirmed Positive Results The immunospecificity of immunoassays is generally directed toward a group of structurally closely related drugs or metabolites and not a specific drug. For example, the opiate assays detect morphine and codeine as well as many of the semisynthetic narcotics such as hydromorphone and oxycodone, and the amphetamine assays do not distinguish between amphetamine or methamphetamine and the sympathomimetic amines. In other instances, immunoassays are triggered by structurally unrelated drugs. Cannabinoid and benzodiazepine assays are triggered by nonsteroidal anti-inflammatory and opiate assays by ofloxaciIP (Appendix I). Therefore, a positive immunoassay result must be considered as presumptive-positive for a group of drug compounds and should be subjected to confirmation testing for definitive identification of individual analytes. Most confirmation methodologies, if properly performed, can accurately distinguish the interfering substances from the drugs of abuse of interest. These are false-positive
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results only because no confirmation testing was done to show that what was detected was an interfering drug and not the drug of interest. The standard of practice in analytical toxicology is to perform confirmation testing on a fresh aliquot using a technique that is based on an analytical principle different from that of the initial test, and one that is more specific and at least equally sensitive.55The laboratory should communicate to the clinician the specificity of both initial and confirmation assays and whether medications, including those administered during the birthing process, can cause false-positive results.61 The confirmed presence of a drug of abuse in urine (i.e., an analytical true-positive) is not necessarily an indication of drug abuse.27There may be a legitimate explanation for the positive result. The patient many have been exposed to marihuana or crack cocaine passively or may have ingested hemp seed or contaminated poppy seeds. Alternatively, the patient may be taking medications that either contain the drug (e.g., codeine) itself or metabolize to it (e.g., methamphetamine and amphetamine from selegiline, benzphetamine, and famprofazone).These results may be considered as clinical (as opposed to analytical) falsepositives (Appendix 11). Therefore, it is important to question the patient carefully on the circumstances that may contribute to a positive result. Interpretation of an Opiate-Positive Result
The presence of morphine in urine, even if it has been confirmed by chromatographic analysis, is not necessarily an indication of heroin use. Morphine in urine also could have originated from codeine use or in the ingestion of poppy seeds (Fig. 1). A positive morphine result owing to the ingestion of contaminated poppy seeds is not a laboratory error, because the contaminant is morphine. Interpretation of a codeine and morphine result to determine the source of morphine is complex and must be done with caution.26,27 The ingestion of poppy seeds alone cannot explain the positive test under the following circumstances: high urine morphine concentration greater than 1000 ng/mL with no detectable codeine (<25 ng/mL); high codeine concentration greater than 300 ng/mL with a morphine-to-codeine ratio of less than 2; and the presence of 6-mono-acetylmorphine (6-MAM).The extent of contamination varies
Diacetylmorphine (Heroin)
I Monoacetylmorphine (6-MAM) Codeine
-. I
Morphine+
Poppy seeds
Figure 1. Possible sources for morphine in urine.
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with the batch of poppy seeds ingested, but it is advisable for patients to refrain from consuming food containing poppy seeds for at least 48 hours before testing.
Passive Inhalation and Exposure
During the smoking of marihuana or crack cocaine, a significant amount of the drug is released into air as side-stream smoke, which can be inhaled by individuals in the immediate vicinity. The amount of drug absorbed passively depends on the concentration of the drug in the air and on environmental factors. It is indisputable that detectable amounts acid (THC-COOH) of 11-nor-delta-9-tetrahydrocannabinoid-9-carboxylic and benzoylecgonine are present in the urine of individuals following passive exposure to marijuana.27In a carefully designed study of human subjects exposed to the simultaneous smoking of 4 or 16 marijuana cigarettes over several days in a small poorly ventilated room, none of the urine collected was positive when the 100 ng/mL cutoff was ~ s e d . 'Use ~ , ~of~the 20 ng/mL cutoff gave positive tests in a few urine samples (the 50 ng/mL cutoff was not tested because it was not in general use when the study was carried out). The extreme exposure conditions of the 16-cigarette experiment (subjects wore goggles because of eye irritation by the smoke) caused all of the subjects to test positive; the last positive specimen was collected 55.1 k 15.1 (mean k SE) hours after exposure. In the 4-cigarette experiment, some of the urine collected immediately following exposure tested positive; the last positive collection being 4.4 t 2.2 (mean 2 SE) hours after exposure. Thus, the passive inhalation of marihuana smoke may result in absorption of a small amount of cannabinoids in the body and may give a positive drug test shortly after exposure if the low cutoff of 20 ng/mL is used by the laboratory. This can be eliminated by using a higher cutoff value of 50 ng/mL. Passive exposure under realistic social conditions cannot result in urine THC-COOH concentrations exceeding 15 ng/mL using gas chromatography-mass spectrometry (GC-MS) as the confirmation techniq~e.~' Urinary concentrations of benzoylecgonine following exposure to crack cocaine smoke were less than 10 ng/mL, far below the standard 300 ng/mL cutoff and assay detection limits (typically, in the range of 30 to 50 ng/mL).23The amount of cocaine inhaled from passive exposure was estimated to be 0.25 mg, whereas the amount of intravenously introduced cocaine that was able to cause a positive test was 1 mgZ3 Thus, an individual would have to be exposed to extreme conditions to test positive at the standard 300 ng/mL cutoff. Passive exposure via dermal absorption has been do~umented:~but casual exposure is insufficient to produce a benzoylecgonine concentration that can trigger a positive drug test at 300 ng/mL.
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Time Window of Detection Urine drug concentration and the time following exposure when a urine specimen can test positive are dependent on a host of factors. Among them are dose, the time since exposure, the volume of distribution and elimination half-life of the drug, the urine flow or volume (directly dependent on the hydration status of the patient), urine pH, assay cutoff, and the specificity of the assay A drug with a short elimination half-life can be detected in urine only for a short time. Cocaine is rapidly inactivated with a half-life of 1.5 hours, whereas its major metabolite, benzoylecgonine, has a relatively long half-life of 4 to 7 hours.', 17, 48 Therefore, cocaine is rarely detectable in urine, and urine testing for cocaine is targeted toward benzoylecgonine. In the majority of cases, urine benzoylecgonine levels rapidly decline to below the usual 300 ng/mL cutoff within 48 to 72 hours of the last exposure,2l but detection after 10 to 22 days has been reported for longterm, high-dose cocaine abusers.88The volume of distribution of THC is large (4 to 14 L/kg).46With such a large tissue store, an individual with a history of heavy marijuana use can continue to test positive for THCCOOH at the 20 ng/mL cutoff for weeks after cessation of use.25 The degree of hydration affects test results by changing the concentration of the drug relative to the assay cutoff; the same amount of drug can have higher or lower concentration depending on the volume of urine it is in. This is particularly true when the concentration of drug is near the cutoff. For example, the first void in the morning (concentrated) may test positive, whereas the collection following substantial fluid intake may be negative. Water-loading before a drug test is performed in an attempt to produce dilute urine specimens with drug concentration below the cutoff. The laboratory could analyze these urine specimens for specific gravity and creatinine; a specific gravity of less than 1.003 or a creatinine level of less than 20 mg/dL suggests dilution.63A positive test following a series of negative results is not necessarily an indication of renewed drug use, because the second urine specimen could have been more concentrated. Normalizing drug concentration to that of urinary creatinine can be helpful in interpreting the results of serially collected sample^.^' Urinary pH can affect the degree of ionization of a drug. In the acidic medium of urine, most drugs of abuse, because they are basic, are in the ionized form, which does not favor renal tubular reabsorption, leading to increased excretion. This pH effect on urine clearance can be dramatic; the percentage of a methamphetamine dose excreted unchanged into urine drops from 76% in acid urine to 2% in alkaline urine.6 The assay cutoff chosen determines the sensitivity of a urine drug test. The convention is to designate a result positive if it is equal to or greater than the cutoff and to designate it negative if it is less. There are no recommended thresholds for testing maternal urine for drugs of abuse. Most clinical laboratories have chosen the cutoff values used in
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workplace drug testing programs (Table 1).Some of these cutoffs have been shown to be too high for clinical testing, the consequence being underestimation of drug exposure in many instances. Choosing lower thresholds for benzoylecgonine, phencyclidine, and cannabinoids (80, 15, and 20 ng/mL instead of 300, 75, and 25 ng/mL, respectively) yielded higher detection rates for a pediatric outpatient population ranging in age from 3 days to 18 years.38Casanova and co-workers,1° using 5 ng/mL as their cutoff for benzoylecgonine, reported that if the customary forensic urine drug screening threshold of 300 ng/mL for benzoylecgonine had been used, 19% of the benzoylecgonine-positive mothers in their study would have been designated negative. The false-negative rate was still 15% when the cutoff was 150 ng/mL. In the same study, 27% of the benzoylecgonine-positiveinfants would have been missed by the 300 ng/mL cutoff. The duration of testing positive can vary with the specificity of the immunoassay. This is best illustrated by the effect of improved specificity of the cannabinoid metabolites assay on detection time.&,45 Antibody in this assay cross-reacts with the target analyte, THC-COOH, as well as numerous other metabolites, and the measured apparent THC-COOH concentration is the sum of the cross-reactive metabolites. The use of antibody of improved specificity for THC-COOH in recent years has resulted in lower apparent concentration. In a recent human study, the duration for a positive marijuana test after a single exposure was 1 to 2 days, which is significantly shorter than the common assumption of a week or 10nger.4~ On-site Testing
Several hand-held testing devices have been approved by the Food and Drug Administration for the testing of drugs of abuse in urine at the bedside or in physician offices? All hand-held devices use some form of immunochromatography immunoassay, and most have been designed to test for the five drug classes of the Federal Drug Testing Program plus benzodiazepines using the standard workplace drug-test-
Table 1. TYPICAL INITIAL AND CONFIRMATION TEST THRESHOLDS Substance
Amphetamines Cannabinoids Cocaine metabolites Opiates Phencyclidine
Initial Test (ng/mL)
Confirmation Test (ng/mL)
1000
Amphetamine, 500 Methamphetamine, 500 THC-COOH, 15 Benzoylecgonine, 150 Codeine, 300 Morphine, 300 Phencyclidine, 25
50 300 300 25
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ing The advantages of these hand-held devices include the short turnaround time (in minutes), eliminating the delay in patient disposition while waiting for a laboratory report. Several issues regarding on-site testing must be considered. First, acceptable quality control procedures for these single-use devices are actively being debated. A second issue is the proper training of nonlaboratory personnel to administer the test and evaluate the results, which are determined by visual inspection of the formation or disappearance of a color band. Third, if the result is positive, there is the risk of making major clinical decisions based on an unconfirmed result of a nonspecific immunoreaction.
HAIR TESTING Analysis of the hair of drug users has demonstrated the presence of drugs.5*69 Systemic drug exposure leads to incorporation of the drug into the hair shaft during hair growth in amounts that remain until the hair is replaced, thus hair testing offers a window of detection much wider than possible with urine.53Several issues in regards to hair testing for drugs of abuse challenge the scientific validity of hair testing and the ability to perform a rational interpretation of hair drug concentration. These include the mechanism(s) by which drug gets into hair; the effect of environmental contamination and chemical treatment of hair, biases resulting from hair type, gender, and race; and analytical diffi~ulties.~~ The mechanisms by which drugs are incorporated into hair are not understood and are an area of active research.76One proposed mechanism assumes that drugs simply enter hair roots by a diffusion process from vascular channels into hair-forming cells in the hair follicle and then are incorporated as part of the protein structure found in the hair matrix. However, other possibilities include the deposition of drug into the hair via secretion into sebum and sweat, where it can come into contact with the hair shaft, or via the external contamination of hair.76,87 Although hair has the ability to metabolize drugs, it is considerably less able to do so in comparison with most other organs. Therefore, parent drug compounds are present in higher concentrations than are the metabolites (e.g., THC > THC-COOH, nicotine > cotinine). Both heroin and 6MAM can be detected in the hair of the heroin abuser when these compounds are difficult to detect in blood because of their short in urine is detectable for only approxielimination h a l f - l i ~ e s6MAM .~~ mately 8 hours.16The concentration of 6MAM in the hair of heroin users is 3.5 times greater than that of morphine and five times greater than that of c0deine.3~The amount of cocaine detected in hair predominates over benzoylecgonine and ecgonine methyl ester by a factor of five to ten fold,z and the benzoylecgonine detected in hair is derived from cocaine hydrolysis in the hair shaft.70 One of the most serious concerns is the difficulty in discriminating the presence of drug in hair as the result of active use versus external 87 Therefore, the presapplication such as environmental contamination.a*
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KWONG & SHEARER
ence of cocaine in hair should not be interpreted necessarily as evidence of drug use. Various approaches to distinguish the source of exposure have been proposed. Baumgartner and co-workers3, have suggested that because extensive washing of hair will remove only externally applied drug but not that incorporated into hair after systemic exposure, the ratio of drug concentration in washings to that in hair extract can distinguish between active or passive exposure. There is concern, however, that the washing protocol cannot completely remove externally applied drug8,87 Moreover, this approach is applicable to freshly contaminated hair only, because bathing and shampooing of hair can remove most but not all of an externally applied cocaine sample. Thus, analysis of environmentally contaminated hair from which the bulk of the surface-contaminated drug has been washed off by bathing and shampooing can produce positive results that are indistinguishable from those obtained from the hair of active drug users.8*87 Detection of benzoylecgonine in hair has been proposed to be a marker of active cocaine but cocaine hydrolysis to benzoylecgonine in hair does take place, and unless careful precautions are taken to control assay conditions, particularly the pH during the extraction process, hydrolytic production of benzoylecgonine will occur and lead to a false-positive result.87 Pigmentation is an important factor affecting incorporation of drug into hair.76Hair pigmentation results from the incorporation of melanin into hair shaft structures, and the color of hair is correlated with the amount of melanin. Basic drugs, cationic at physiologic pH, will bind to melanin, which is polyanionic. In experiments performed in Long-Evans rats, which have differently pigmented hair in different parts of the body, the mean concentration of codeine in pigmented hair was 46 times that in nonpigmented In vitro cocaine-binding studies show that specific binding to Africoid black hair is 157 times greater than binding to Caucasoid blond hair.50Pigmentation influencing drug concentration in hair has been described for codeine and its metabolite^;^ nicotine;’ and phencyclidine.81 Treatment of hair with chemicals such as hydrogen peroxide, alkaline wave-setting solutions, or shampoo can reduce drug concentrations in hair.88When realistic treatment conditions were used, the hair samples retained approximately 20% to 40% of the original cocaine content after 30 treatments. Similar results were found by Joseph and co-workers,5° who concluded that bleaching of most hair specimens resulted in significant decreases in specific binding of cocaine when compared with untreated hair. The concept of segmental hair analysis to chronicle drug use during pregnancy was first suggested by Graham and c o - ~ o r k e r sand ~ ~ was based on the premise that drug use results in drug deposition into hair, which grows at a fairly constant rate. Therefore, analysis of segments of a drug user’s hair can yield a profile of drug usage during pregnancy. Several segmental analysis studies to test for drug abuse over varying lengths of time have obtained useful information on the history of drug use over a wide The results of segmental analysis should be
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interpreted with caution, however, and should take into consideration many variables, including hair length, hair washing, cosmetic treatments, and whether drug use occurred only in the last few days of pregnancy, in which case there would be insufficient time for the drug to enter the hair shaft. Moreover, hair growth is irregular enough to negate ascribing exact quantitative values to levels of cocaine exposure at a specific point in the pregnancy.78At best, hair segmental analysis may detect trends in the concentration of drug along the various sections of hair without pinpointing the exact time of drug use or dose consumed. Testing of newborn hair to document drug exposure in utero is an appropriate clinical application of hair testing.53,56 Newborn hair grows during the third trimester, and detection of drug at birth reflects maternal drug use during the last 3 months of pregnancy.35,53 The quantity of benzoylecgonine in newborn hair correlates best with that in the proximal segment of the mother’s hair, which represents maternal hair growth in the 12 weeks or so before delivery9 The timing of hair collection is not critical, because hair collected even a few weeks after birth still offers the opportunity for confirming gestational drug exposure. Newborns who test negative in their urine because their mothers abstained from drug use only a few days before delivery may test positive if hair analysis is performed. Environmental contamination is not an issue if the newborn is tested during the immediate postdelivery period while still in the hospital and not after the newborn has been discharged home with the mother who is suspected of drug abuse. The literature on newborn hair testing is, for the most part, related to cocaine exposure, although amphetamines, opiates, and methadone have been found in adult hair testing? Hair analysis is technically more involved than urine or meconium testing. Hair samples must first be decontaminated by washing with a variety of agents, including methanol, ethanol, dichloromethane, acetone, detergent, or warm water.56Drug is then extracted from hair by incubation with methanol, ethanol, acid, and proteinase or pronase. The low drug concentrations in hair are detectable by radioimmunoassay only For confirmation of cocaine and opiates by GC-MS assays with data acquisition in selected ion-monitoring mode, as little as 5 to 10 mg of adult hair is a d e q ~ a t e , 787~ whereas ,~~, a sophisticated research protocol based on negative-ion chemical ionization mass spectrometry is needed for the detection of THC and metabolite^.^^ GC-MS procedures requiring 50 to 100 mg of hair are more suitable for testing adult hair, because most newborns do not have that much hair, and their mothers probably will object to extensive shaving of their babies for drug testing. Because hair analysis is technically demanding, its availability is limited to a few specialized laboratories. MECONIUM TESTING
Meconium has been proposed as an alternative matrix to urine for drug testing, because it contains a high concentration of drugs to which
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KWONG & SHEARER
the fetus has been exposed during pregnancy.59,66, 73, Meconium is thought to form initially at the end of the first Because meconium is not excreted by the fetus, it serves as a reservoir of drugs to which the fetus has been exposed and as a cumulative record of prior exposure over the last two trimesters of pregnancy, a detection time frame that is impossible to attain by urine testing. Most of the published reports involving meconium have described the detection of cocaine. Studies detailing the detection of other drugs (opiates, amphetamines, 73, 74 have reported the abuse of cocaine to be the and ~annabinoids)~~, most prevalent. The higher sensitivity of meconium testing in comparison with urine testing for identifying cocaine-, opiate-, and cannabinoid-exposed newborns was first reported by Ostrea and co-workers.” Some patients continued to have positive test results for as long as 3 days postdelivery, whereas 37% of those same neonates revealed a positive urine screen.74A much larger study on meconium testing for the detection of intrauterine cocaine exposure involved 1201 mother-infant pairs (from a total of 1237 live births recorded during the study period).77 Meconium testing yielded an additional 25% of infants exposed to cocaine who were labeled negative by urine testing, whereas no newborn with urinepositive results had negative results in the corresponding meconium. The difference in the detection rates in meconium versus urine assays can be attributed to the methods used (i.e., enzyme immunoassay versus fluorescence polarization immunoassay for urine screening and radioimmunoassay or GC/MS for meconium analysis) rather than to the type of specimen used (urine versus meconium). When equivalent assay methods are used and when lower cutoff values are employed, the detection rates of urine testing are equivalent to those of meconium lo analy~is.~, Advantages of using meconium specimens are the ease of sample collection, the fact that sample amount is usually of sufficient quantity for complete analysis, the relatively high drug concentration, and the longer detection window. Disadvantages include missed collection owing to late passage of meconium in some premature newborns,%technical difficulties with analysis, longer turnaround time, and much higher cost in comparison with urine testing.56 AMNIOTIC FLUID Amniotic fluid specimens have been examined for drugs of abuse.47 Fluids were collected from both known drug users and nonusers transvaginally either at the time of birth when rupture of membranes occurred or at the time of amniocentesis. Cocaine or benzoylecgonine was detected by HPLC in 74%of amniotic fluid samples from known abusers in comparison with 61% and 35% of maternal and newborn urine samples, respectively. As is true in urine, amniotic fluid contains a higher concentration of benzoylecgonine than cocaine. Because the assay cutoff
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values in the study mentioned previously were not mentioned, it is impossible to determine whether the lower sensitivity of testing maternal urine was the result of the use of a higher cutoff. Availability of amniotic fluid is an issue in patients who have premature rupture of membranes or rapidly advancing labor. Currently, amniotic fluid testing does not offer any real advantage over more conventional urine screening. Furthermore, its clinical value as an indicator of long-term drug exposure has not been studied.
SUMMARY
Several methods of drug testing are efficacious in identifying and monitoring drug use during pregnancy. Urine screening remains the most commonly used method despite the limited period during which drugs can be detected. Hair has been recognized as a possible alternate test specimen, but wider acceptance of hair testing must await better understanding of drug disposition in hair, answers to the issues relating to interpretation, and the development of less demanding laboratory techniques. Regardless of the matrix used, proper interpretation of the results of drug testing requires familiarity with the sensitivity, specificity, and limitations of the laboratory methodologies employed. Moreover, unconfirmed positive results may actually be false-positives and must be interpreted with caution, particularly if they are the basis for major clinical decisions.
References 1. Ambre 3: The urinary excretion of cocaine and metabolites in humans: A kinetic analysis of published data. J Anal Toxic01 9241, 1985 2. Ambruster DA: On-site drug testing. Med Lab Observer 29:40, 1997 3. Baumgartner WA, Hill V A Hair analysis for drugs of abuse: Decontamination issues. In Sunshine I (ed): Recent Developments in Therapeutic Drug Monitoring and Clinical Toxicology. New York, Marcel Dekker, 1992, p 577 4. Baumgartner WA, Hill VA Sample preparation techniques. Forensic Sci Int 63:121,1993 5. Baumgartner WA, Hill VA, Blahd WH. Hair analysis for drugs of abuse. J Forensic Sci M1433, 1989 6. Beckett AH, Rowland M: Urinary excretion kinetics of methamphetamine in man. J Pharm Pharmacol 171095, 1965 7. Bingo1 N, Fuchs M, Diaz V Teratology of cocaine in humans. J Pediatr 11093, 1987 8. Blank DL, Kidwell DA: Decontamination procedures for drugs of abuse in hair: Are they sufficient? Forensic Sci Int 70:13, 1995 9. Callahan CM, Grant TM, Phipps P: Measurement of gestational cocaine exposure: Sensitivity of infants’ hair, meconium, and urine. J Pediatr 120763,1992 10. Casanova OQ,Lombardero N, Behnke M: Detection of cocaine exposure in the neonate. Arch Pathol Lab Med 119:988, 1994 11. Chasnoff IJ, Griffith D, Freier C: Cocaine/polydrug use in pregnancy: Two-year followup. Pediatrics 89:284, 1992
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12. Chasnoff IJ, Griffith DR Cocaine: Clinical studies of pregnancy and the newborn. Ann NY Acad Sci 562260, 1989 13. Cherukuri R, Minkoff H, Feldman J: A cohort study of alkaloidal cocaine ("crack) in pregnancy. Obstet Gynecol72:147, 1988 14. Chouteau M, Namerow PB, Leppert P: The effect of cocaine abuse on birth weight and gestational age. Obstet Gynecol 72:351, 1988 15. Christmas JT, Knisely JS, Dawson K S Comparison of questionnaire screening and urine toxicology for detection of pregnancy complicated by substance use. Obstet Gynecol 80:750, 1992 16. Cone E, Welch P, Paul BD: Forensic drug testing for opiates. I. Detection of 6-acetylmorphine in urine as an indicator of recent heroin exposure: Drug and assay considerations and detection times. J Anal Toxicol 151, 1991 17. Cone EJ: Pharmacokinetics and pharmacodynamics of cocaine. J Anal Toxicol 19:459, 1995 18. Cone EJ, Huestis MA: Relating blood concentrations of tetrahydrocannabinol and metabolites to pharmacologic effects and time of marijuana usage. Ther Drug Monit 15:527, 1993 19. Cone EJ, Johnson RE: Contact highs and urinary cannabinoid excretion after passive exposure to marijuana smoke. Clin Pharmacol Ther 40:247, 1986 20. Cone EJ, Johnson RE, Darwin W D Passive inhalation of marijuana smoke: Urinalysis and room air levels of delta-9-tetrahydrocannabinol. J Anal Toxicol 11:89, 1987 21. Cone EJ, Menchen SL, Paul BD Validity testing of commercial urine cocaine metabolite assays. I. Assay detection times, individual excretion patterns, and kinetics after cocaine administration to humans. J Forensic Sci 34:15, 1989 22. Cone EJ, Yousefnejad D, Darwin W D Testing human hair for drugs of abuse. 11. Identification of unique cocaine metabolites in hair of drug abusers and evaluation of decontamination procedures. J Anal Toxicol 15:250, 1991 23. Cone EJ, Yousefnejad D, Hillsgrove MJ: Passive inhalation of cocaine. J Anal Toxicol 19:399, 1995 24. Davidson-Ward SL, Bautista D, Chan L Sudden infant death syndrome in infants of substance-abusing mothers. J Pediatr 117876, 1992 25. Ellis GM Jr, Mann MA, Judson BA: Excretion pattern of cannabinoid metabolites after last use in a group of chronic users. Clin Pharmacol Ther 38:572, 1985 26. Elsohly MA, Jones A B Morphine and codeine in biological fluids: Approaches to source differentiation. Forensic Sci Rev 1:13, 1989 27. Elsohly MA, Jones AB: Drug testing in the workplace: Could a positive test for one of the mandated drugs be reasons for other than illicit use of the drug? J Anal Toxicol 19:450, 1995 28. Feldman JG, Minkoff HL, McCalla S A cohort study of the impact of perinatal drug use on prematurity in an inner-city population. Am J Public Health 82:726, 1992 29. Frank D, Zuckerman CS, Amaro H Cocaine use during pregnancy: Prevalence and correlates. Pediatrics 82888, 1988 30. Garcia DC, Romero A, Garcia GC: Gastric fluid analysis for determining gestational cocaine exposure. Pediatrics 98:291, 1996 31. Gerstenberg B, Schepers G, Voncken P: Nicotine and cotinine accumulation in pigmented and unpigmented rat hair. Drug Metab Dispos 23:143, 1995 32. Gillogley KM, Evans AT, Hansen RL: The perinatal impact of cocaine, amphetamine, and opiate use detected by universal intraparturn screening. Am J Obstet Gynecol 163:1535, 1990 33. Goldberger B, Caplan Y, Maguire T Testing human hair for drugs of abuse. 111. Identification of heroin and 6-acetylmorphine as indicators of heroin use. J Anal Toxicol 15:226, 1991 34. Goldberger BA, Loewenthal B, Darwin WD: Intrasubject variation of creatinine and specific gravity measurements in consecutive urine specimens of heroin users. Clin Chem 41:116, 1995 35. Graham K, Koren G, Klein J: Determination of gestational cocaine exposure of hair analysis. JAMA 262:3328, 1989
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36. Grant T, Brown Z, Callahan C: Cocaine exposure during pregnancy: Improving assessment with radioimmunoassay of maternal hair. Obstet Gynecol 83:524,1994 37. Gygi SP, Josephe RE, Cone EJ: Incorporation of codeine and metabolites into hair: Role of pigmentation. Drug Metab Dispos 24495, 1996 38. Hicks JM, Morales A, Soldm SJ: Drugs of abuse in a pediatric outpatient population. Clin Chem 36:1256, 1990 39. Huestis MA: Judicial acceptance of hair tests for substances of abuse in the United States courts: Scientific, forensic, and ethical aspects. Ther Drug Monit 18:456, 1996 40. Huestis MA, Mitchell JM, Cone EJ: Urinary excretion profiles of 11-nor-9-carboxy-delta 9-tetrahydrocannabinol in humans after single smoked doses of marijuana. J Anal Toxicol 20:441, 1996 41. Huestis MA, Cone EJ: Predicting new marijuana use from creatinine normalized 11nor-9-carboxy-T9-tetrahydrocannabinol(THCCOOH) concentrations: Criteria development and validation [abstract]. J Anal Toxicol 21:82, 1997 42. Huestis MA, Henningfield JE, Cone EJ: Blood cannabinoids. I. Absorption of THC and formation of 11-OH-THC and THCCOOH during and after smoking marijuana. J Anal Toxicol 16276,1992 43. Huestis MA, Henningfield JE, Cone EJ: Blood cannabinoids. 11. Models for the prediction of time of marijuana exposure from plasma concentrations of delta 9-tetrahydrocannabinol (THC) and 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (THCCOOH). J Anal Toxicol 16283, 1992 44.Huestis MA, Mitchell JM, Cone EJ: Lowering the federally mandated cannabinoid immunoassay cutoff increases true-positive results. Clin Chem 40:729, 1994 45. Huestis MA, Mitchell JM, Cone EJ: Detection times of marijuana metabolites in urine by immunoassay and GC-MS. J Anal Toxicol 19:443, 1995 46. Hunt CA, Jones RT: Tolerance and disposition of tetrahydrocannabinol in man. J Pharmacol Exp Ther 215:35, 1980 47. Jain L, Meyer W, Moore C: Detection of fetal cocaine exposure by analysis of amniotic fluid. Obstet Gynecol 81:787, 1993 48. Jeffcoat AR, Perez-Reyes M, Hill JM: Cocaine disposition in humans after intravenous injection, nasal insufflation (snorting), or smoking. Drug Metab Dispos 17153, 1989 49. Joseph R, Dickerson S, Willis R Interference by nonsteroidal anti-inflammatory drugs in EMIT and TDx assays for drugs of abuse. J Anal Toxicol 19:13, 1995 50. Joseph R, Su T-P, Cone EJ: In vitro binding studies of drugs to hair: Influence of melanin and lipids on cocaine binding to Caucasoid and Africoid hair. J Anal Toxicol 20:338, 1996 51. Kain ZN, Rimar S, Barash PG: Cocaine abuse in the parturient and effects on the fetus and neonate. Anesth Analg 77835, 1993 52. Kandall SR, Gaines J, Habel L: Relationship of maternal substance abuse to subsequent sudden infant death syndrome in offspring. J Pediatr 123:120, 1993 53. Koren G: Measurement of drugs in neonatal hair: A window to fetal exposure. Forensic Sci Int 70:77, 1995 54. Koren G, Klein J, Forman R Hair analysis of cocaine: Differentiation between systemic exposure and external contamination. J Clin Pharmacol32671,1992 55. Kwong TC: Toxicology. In McClatchey KP (ed): Clinical Laboratory Medicine. Baltimore, Williams and Wilkins, 1994, p 445 56. Kwong TC, Ryan RM: Detection of intrauterine illicit drug exposure by newborn drug testing. Clin Chem 43235, 1997 57. Le SD, Taylor RW, Vidal D: Occupational exposure to cocaine involving crime lab personnel. J Forensic Sci 37959, 1992 58. Lewis D, Moore C, Leikin J B Multiple birth concordance of street drug assays of meconium analysis. Vet Hum Toxicol 37318, 1995 59. Lewis DE, Moore CM, Leikin JB: Meconium analysis for cocaine: A validation study and comparison with paired urine analysis. J Anal Toxicol 19:148, 1995 60. Lipshultz S, Frassica J, Orav J: Cardiovascular abnormalities in infants prenatally exposed to cocaine. J Pediatr 11844,1991 61. Liu RH: Evaluation of commercial immunoassay kits for effective workplace drug
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testing. In Liu RH, Goldberger A (eds): Handbook of Workplace Drug Testing. Washington, DC, AACC Press, 1995, p 67 62. Mack G, Thomas D, Giles W: Methadone levels and neonatal withdrawal. J Pediatr Child Health 2796, 1991 63. Mandatory guidelines for federal workplace drug testing programs. Federal Register 5929908, 1994 64. Manno JE: Interpretation of urinalysis results. NIDA Res Monogr 7354, 1987 65. Matera C, Warren WB, Moomjy M Prevalence of use of cocaine and other substances in an obstetric population. Am J Obstet Gynecol 163:797,1990 66. Maynard EC, Amoruso LB, Oh W. Meconium for drug testing. Am J Dis Child 145650, 1991 67. McCalla S, Minkoff HL, Feldman J: Predictors of cocaine use in pregnancy. Obstet Gynecol 79641, 1992 68. Meatherall R, Dai J: False-positive EMIT I1 opiates from ofloxacin. Ther Drug Monit 1998, 1997 69. Moeller MR, Fey P: Simultaneous determination of drugs of abuse (opiates, cocaine and amphetamine) in human hair by GC/MS and its application to a methadone treatment program. Forensic Sci Int 63:185,1993 70. Nakahara Y, Kikura R Hair analysis for drugs of abuse. VII. The incorporation rates of cocaine, benzoylecgonine and ecgonine methyl ester into rat hair and hydrolysis of cocaine in rat hair. Arch Toxicol 681:54, 1994 71. Neerhof M, MacGregor SN, Retzky S S Cocaine abuse during pregnancy: Peripartum prevalence and perinatal outcome. Am J Obstet Gynecol 161:633, 1989 72. Or0 AS, Dixon S D Perinatal cocaine and methamphetamine exposure: Maternal and neonatal correlates. J Pediatr 111:571, 1987 73. Ostrea EM Jr, Brady MJ, Parks I'M: Drug screening of meconium in infants of drugdependent mothers: An alternative to urine testing. J Pediatr 115:474, 1989 74. Ostrea EM, Brady M, Gause S Drug screening of newborns by meconium analysis: A large-scale prospective, epidemiologic study. Pediatrics 89:107, 1992 75. Rollins DE, Jennison TA, Jones G: Investigation of interference by non-steroidal antiinflammatory drugs in urine tests for abused drugs. Clin Chem 36:602, 1990 76. Rollins DE, Wilkins DG, Gygi SP: Testing for drugs of abuse in hair-experimental observations and indications for future research. Forensic Sci Rev 9:1997 77. Ryan RM, Wagner CL, Schulz J M Meconium analysis improves identification of intrauterine cocaine exposed infants. J Pediatr 88825, 1991 78. Sachs H Theoretical limits of the evaluation of drug concentrations in hair due to irregular hair growth. Forensic Sci Int 70:53, 1995 79. Selavka CM, Rieders F The determination of cocaine in hair: A review. Forensic Sci Int 70:155, 1995 80. Singer L, Arendt R, Song LY Direct and indirect interactions of cocaine with childbirth outcomes. Arch Pediatr Adolesc Med 148:959, 1994 81. Slawson MH, Garcia K, Wilkins DG: Mechanisms of xenobiotic incorporation into hair: Phencyclidine. Toxicologist 30:36, 1996 82. Spence MR, Williams R, Digregorio GJ: The relationship between cocaine use and pregnancy outcome. Obstet Gynecol 78:326, 1991 83. Staub C: Analytical procedures for determination of opiates in hair: A review. Forensic Sci Int 70111, 1995 84. Strano-Rossi S, Bermejo-Barrera A, Chiarotti M: Segmental hair analysis for cocaine and heroin abuse determination. Forensic Sci Int 70:211, 1995 85. Struempler RE, Nelson G, Urry F M A positive cannabinoids workplace drug test following the ingestion of commercially available hemp seed oil. J Anal Toxicol 21:283, 1997 86. Verna A, Dhanireddy R Time of first stool in extremely low birth weight ( 4 0 0 0 gm) infants. J Pediatr 122:626, 1992 87. Wang WL, Cone EJ: Testing human hair for drugs of abuse. IV. Environmental cocaine contamination and washing effects. Forensic Sci Int 7039, 1995 88. Weiss RD, Gawin F H Protracted elimination of cocaine metabolites in long-term, lightdose cocaine abusers. Am J Med 85:879, 1988
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89. Welch MJ, Sniegoski LT, Allgood CC, et al: Hair analysis for drugs of abuse: Evaluation of analytical methods, environmental issues, and development of reference materials. J Anal Toxicol 17389, 1993 90. Wiemann CM, Berenson AB, San Miguel W. Tobacco, alcohol and illicit drug use among pregnant women: Age and racial/ethnic differences. J Reprod Med 39:769,1994 91. Wilkins DG, Haughey HM, Cone E Quantitative analysis of THC, 11-OH-THC, and THCCOOH in human hair by negative-ion chemical ionization mass spectrometry. J Anal Toxicol 19:483, 1995 92. Woods JR Jr, Dolkart LA: Significance of amniotic fluid meconium. In Creasy RK, Resnik R (eds): Maternal-Fetal Medicine: Principles and Practice, ed 2. Philadelphia, WB Saunders, 1989, p 404 93. Zuckerman B, Frank DA, Hingson R Effects of maternal marijuana and cocaine use on fetal growth. N Engl J Med 320762, 1989
Address reprint requests to Tai C. Kwong, PhD University of Rochester Medical Center Box 608 601 Elmwood Ave Rochester, NY 14642
APPENDIX I
Substances That Give False-Positive Results by Both Initial and Confirmatory Testing"
The following medications and substances give a positive result by both initial immunoassay and confirmatory gas chromatography/ mass spectrometry test. These are analytical true-positives. Therefore, the findings must be interpreted with caution. AMPHETAMINES (METHAMPHETAMINE AND AMPHETAMINE)
Prescription medications that contain either D-amphetamine or racemic D,L-amphetamine (i.e., equal amounts of D- and L-amphetamine) include the following: Adderall Benzedrine Biphenamine Dexedrine Durophet Obetrol Prescription medications that contain D-methamphetamine include Desoxyn (Gradumet). Substances known to be metabolized to methamphetamine (and amphetamine) include benzphetamine (Didrex), dimethylamphetamine, and famprofazone, fencamine, furfenorex, selegiline (deprenyl, Elde-
P'Yb
Substances known to be metabolized to amphetamine include Anphetaminil Clobenzorex (Dinintel, Finedal) Ethylamphetamine Fenethylline (Captagon) Fenproporex (Tegisec) Mefenorex (Pondinil) Mesocarb Phenylamine
*From the Medical Review Officer Manual for Federal Workplace Drug Testing Programs, CSAP Technical Report, Division of Workplace Programs, Center for Substance Abuse Prevention (CSAP), Substance Abuse and Mental Health Services Administration, US Department of Health and Human Services, DHHS Publication, 1997.
59
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KWONG & SHEARER
Nonprescription medications that contain L-methamphetamine include Vicks Inhaler. COCAINE
There are no prescription medications that contain cocaine. The combination of tetracaine, epinephrine, and cocaine (TAC) is frequently used in emergency departments. Cocaine hydrochloride is used for ear, nose, and throat procedures. Other topical analgesics, such as Novocain, Xylocaine (lidocaine), and benzocaine bear no structural similarity to cocaine or its metabolite (benzoylecgonine)and will not test positive. MARIHUANA
Prescription medications that contain delta-9-tetrahydrocannabinol (THC) include dronabinol (Marinol). A food item that contains THC is hemp seeds. OPIATES (HEROIN, MORPHINE, CODEINE)
Prescription medications that contain morphine include the following: Astramorph PF Duramorph MSIR MS Contin tablets Infumorph Oramorph Prescription medications that contain codeine include Actifed with Codeine Cough syrup Codimal PH Deconsal Dimetane-DC Cough syrup Empirin with Codeine Fiorinal with Codeine Phenaphen with Codeine Phenergan Robitussin A-C Triaminic Expectorant with Codeine Tylenol with Codeine (1,2, 3, or 4) Tussar-2 A substance that metabolizes to morphine is heroin. A food item that contains morphine is poppy seeds.
DETECTION OF DRUG USE DURING PREGNANCY
61
PHENCYCLIDINE
There are no prescription medications that contain phencyclidine (PCP). There are no legal medical uses of PCP or any other substance that can be misidentified as PCP.
APPENDIX I1
Substances That Give False-Positive Results by Initial Testing The following medications and substances may trigger a positive response by the initial immunoassay test. This presumptive positive result becomes a false-positive if it is reported without a confirmatory test. Different immunoassay kits have different specificities. The physician should contact the laboratory for details.
AMPHETAMINES (METHAMPHETAMINE AND AMPHETAMINE)
Ephedrine Phentermine (Fastin, Adipex-P) Phenylpropanolamine Pseudoephedrine Fenfluramine (Pondimin) Dexfenfluramine (Redux)
COCAINE
None
MARIHUANA (THC)
Nonsteroidal anti-inflammatory drugs (after high dose and rare)
OPIATES (HEROIN, MORPHINE, CODEINE)
Dihydrocodeine (paracodin) Hydrocodone (Hycodan) Hydromorphone (Dilaudid) Ofloxacin (Floxin) Oxycodone (Percodan) Oxymorphone (Numorphan) Levorphanol (Levo-Dromoran) 63
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PHENCYCLIDINE (PCP)
Dextromethorphan BENZODIAZEPINES
Oxaprozin (Daypro)
0889-8545/98 $8.00
+ .OO
DETECTION OF DRUG USE DURING PREGNANCY Tai C. Kwong, PhD, and Douglas Shearer, PhD, MD
Drug users who are pregnant jeopardize not only their own health and well-being but that of the fetuses they carry. As illicit drugs become more available to all segments of society?O it is increasingly urgent to address the consequences. The medical complications arising from cocaine and other drug use during pregnancy include premature onset of labor and rupture of fetal membranes, spontaneous abortion, abruptio placentae, premature births, stillbirth, and increased fetal mortality and &aturity.14, 32, 51, 60, 62, 67, 72. 82 Medical and developmental problems in the neonate include small head circumference? 11, 13, 32, 71, 72, 93 smallfor-gestational-age, and an increased incidence of sudden infant death ~yndrome.2~. 52 Studies on cocaine abuse indicate that cocaine use during pregnancy is the best indicator of an increased incidence of abortion, high maternal gravidity, and poor prenatal care.28, Furthermore, cocaine is the best indicator of preterm birth and lower birth weight. It is therefore imperative that every attempt be made to identify women who use drugs during pregnancy to avoid, or at least minimize, the risks of complications to both the pregnant woman and fetus. Early identification of these women (and any drug-exposed neonates) permits the initiation of appropriate interventional care, as well as the formulation of plans for follow-up care and management. No precise data describe the prevalence of illicit drug use among pregnant women. Estimates of prevalence have been based on maternal
From the Department of Pathology and Laboratory Medicine, University of Rochester School of Medicine and Dentistry (TCK, DS); Regional Toxicology Laboratory, University of Rochester Medical Center (TCK); and the Monroe County Medical Examiner’s Office (DS), Rochester, New York
OBSTETRICS AND GYNECOLOGY CLINICS OF NORTH AMERICA VOLUME 25 NUMBER 1 MARCH 1998
43
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KWONG & SHEARER
self-reporting by interview or questionnaire and urine drug testing. Selfreporting underestimates the prevalence, because many women (24% to 63%)deny any cocaine use despite a positive drug test, probably because of feelings of guilt and the fear of legal consequences.12,29, 30, 65, 93 The results of urine testing can be negative even though the patient admits to current use, because of the short time during which a drug test is 9D Thus, a combination of structured questionnaire and urine acc~rate.’~, toxicologic screen identifies more current users than either technique alone. URINE TESTING FOR DRUGS OF ABUSE Urine is the most readily accessible sample for toxicologic analysis in the clinical laboratory. Drug or drug metabolite concentrations in urine specimens can be lower than the detection limits of thin-layer chromatography and high-performance liquid chromatography (HPLC), the analytical methods most used in clinical laboratories for detecting the relatively high drug concentrations found in suspected drug overdose cases. The testing of urine specimens in pregnant patients for drug-of-abuse exposure requires more sensitive assays; the nonisotopic immunoassays are generally used. Commercial nonisotopic enzyme immunoassays or fluorescence polarization immunoassays do not have the sensitivity of radioimmunoassay but have the advantage of being homogeneous methods that are more easily adapted to automated instruments for rapid analysis and turnaround time. Moreover, they are the basis for an increasing number of single-use, hand-held, on-site testing devices that can be used at the bedside or in the physician’s office. Presumptive Versus Confirmed Positive Results The immunospecificity of immunoassays is generally directed toward a group of structurally closely related drugs or metabolites and not a specific drug. For example, the opiate assays detect morphine and codeine as well as many of the semisynthetic narcotics such as hydromorphone and oxycodone, and the amphetamine assays do not distinguish between amphetamine or methamphetamine and the sympathomimetic amines. In other instances, immunoassays are triggered by structurally unrelated drugs. Cannabinoid and benzodiazepine assays are triggered by nonsteroidal anti-inflammatory and opiate assays by ofloxaciIP (Appendix I). Therefore, a positive immunoassay result must be considered as presumptive-positive for a group of drug compounds and should be subjected to confirmation testing for definitive identification of individual analytes. Most confirmation methodologies, if properly performed, can accurately distinguish the interfering substances from the drugs of abuse of interest. These are false-positive
DETECTION OF DRUG USE DURWG PREGNANCY
45
results only because no confirmation testing was done to show that what was detected was an interfering drug and not the drug of interest. The standard of practice in analytical toxicology is to perform confirmation testing on a fresh aliquot using a technique that is based on an analytical principle different from that of the initial test, and one that is more specific and at least equally sensitive.55The laboratory should communicate to the clinician the specificity of both initial and confirmation assays and whether medications, including those administered during the birthing process, can cause false-positive results.61 The confirmed presence of a drug of abuse in urine (i.e., an analytical true-positive) is not necessarily an indication of drug abuse.27There may be a legitimate explanation for the positive result. The patient many have been exposed to marihuana or crack cocaine passively or may have ingested hemp seed or contaminated poppy seeds. Alternatively, the patient may be taking medications that either contain the drug (e.g., codeine) itself or metabolize to it (e.g., methamphetamine and amphetamine from selegiline, benzphetamine, and famprofazone).These results may be considered as clinical (as opposed to analytical) falsepositives (Appendix 11). Therefore, it is important to question the patient carefully on the circumstances that may contribute to a positive result. Interpretation of an Opiate-Positive Result
The presence of morphine in urine, even if it has been confirmed by chromatographic analysis, is not necessarily an indication of heroin use. Morphine in urine also could have originated from codeine use or in the ingestion of poppy seeds (Fig. 1). A positive morphine result owing to the ingestion of contaminated poppy seeds is not a laboratory error, because the contaminant is morphine. Interpretation of a codeine and morphine result to determine the source of morphine is complex and must be done with caution.26,27 The ingestion of poppy seeds alone cannot explain the positive test under the following circumstances: high urine morphine concentration greater than 1000 ng/mL with no detectable codeine (<25 ng/mL); high codeine concentration greater than 300 ng/mL with a morphine-to-codeine ratio of less than 2; and the presence of 6-mono-acetylmorphine (6-MAM).The extent of contamination varies
Diacetylmorphine (Heroin)
I Monoacetylmorphine (6-MAM) Codeine
-. I
Morphine+
Poppy seeds
Figure 1. Possible sources for morphine in urine.
46
KWONG & SHEARER
with the batch of poppy seeds ingested, but it is advisable for patients to refrain from consuming food containing poppy seeds for at least 48 hours before testing.
Passive Inhalation and Exposure
During the smoking of marihuana or crack cocaine, a significant amount of the drug is released into air as side-stream smoke, which can be inhaled by individuals in the immediate vicinity. The amount of drug absorbed passively depends on the concentration of the drug in the air and on environmental factors. It is indisputable that detectable amounts acid (THC-COOH) of 11-nor-delta-9-tetrahydrocannabinoid-9-carboxylic and benzoylecgonine are present in the urine of individuals following passive exposure to marijuana.27In a carefully designed study of human subjects exposed to the simultaneous smoking of 4 or 16 marijuana cigarettes over several days in a small poorly ventilated room, none of the urine collected was positive when the 100 ng/mL cutoff was ~ s e d . 'Use ~ , ~of~the 20 ng/mL cutoff gave positive tests in a few urine samples (the 50 ng/mL cutoff was not tested because it was not in general use when the study was carried out). The extreme exposure conditions of the 16-cigarette experiment (subjects wore goggles because of eye irritation by the smoke) caused all of the subjects to test positive; the last positive specimen was collected 55.1 k 15.1 (mean k SE) hours after exposure. In the 4-cigarette experiment, some of the urine collected immediately following exposure tested positive; the last positive collection being 4.4 t 2.2 (mean 2 SE) hours after exposure. Thus, the passive inhalation of marihuana smoke may result in absorption of a small amount of cannabinoids in the body and may give a positive drug test shortly after exposure if the low cutoff of 20 ng/mL is used by the laboratory. This can be eliminated by using a higher cutoff value of 50 ng/mL. Passive exposure under realistic social conditions cannot result in urine THC-COOH concentrations exceeding 15 ng/mL using gas chromatography-mass spectrometry (GC-MS) as the confirmation techniq~e.~' Urinary concentrations of benzoylecgonine following exposure to crack cocaine smoke were less than 10 ng/mL, far below the standard 300 ng/mL cutoff and assay detection limits (typically, in the range of 30 to 50 ng/mL).23The amount of cocaine inhaled from passive exposure was estimated to be 0.25 mg, whereas the amount of intravenously introduced cocaine that was able to cause a positive test was 1 mgZ3 Thus, an individual would have to be exposed to extreme conditions to test positive at the standard 300 ng/mL cutoff. Passive exposure via dermal absorption has been do~umented:~but casual exposure is insufficient to produce a benzoylecgonine concentration that can trigger a positive drug test at 300 ng/mL.
DETECTION OF DRUG USE DURING PREGNANCY
47
Time Window of Detection Urine drug concentration and the time following exposure when a urine specimen can test positive are dependent on a host of factors. Among them are dose, the time since exposure, the volume of distribution and elimination half-life of the drug, the urine flow or volume (directly dependent on the hydration status of the patient), urine pH, assay cutoff, and the specificity of the assay A drug with a short elimination half-life can be detected in urine only for a short time. Cocaine is rapidly inactivated with a half-life of 1.5 hours, whereas its major metabolite, benzoylecgonine, has a relatively long half-life of 4 to 7 hours.', 17, 48 Therefore, cocaine is rarely detectable in urine, and urine testing for cocaine is targeted toward benzoylecgonine. In the majority of cases, urine benzoylecgonine levels rapidly decline to below the usual 300 ng/mL cutoff within 48 to 72 hours of the last exposure,2l but detection after 10 to 22 days has been reported for longterm, high-dose cocaine abusers.88The volume of distribution of THC is large (4 to 14 L/kg).46With such a large tissue store, an individual with a history of heavy marijuana use can continue to test positive for THCCOOH at the 20 ng/mL cutoff for weeks after cessation of use.25 The degree of hydration affects test results by changing the concentration of the drug relative to the assay cutoff; the same amount of drug can have higher or lower concentration depending on the volume of urine it is in. This is particularly true when the concentration of drug is near the cutoff. For example, the first void in the morning (concentrated) may test positive, whereas the collection following substantial fluid intake may be negative. Water-loading before a drug test is performed in an attempt to produce dilute urine specimens with drug concentration below the cutoff. The laboratory could analyze these urine specimens for specific gravity and creatinine; a specific gravity of less than 1.003 or a creatinine level of less than 20 mg/dL suggests dilution.63A positive test following a series of negative results is not necessarily an indication of renewed drug use, because the second urine specimen could have been more concentrated. Normalizing drug concentration to that of urinary creatinine can be helpful in interpreting the results of serially collected sample^.^' Urinary pH can affect the degree of ionization of a drug. In the acidic medium of urine, most drugs of abuse, because they are basic, are in the ionized form, which does not favor renal tubular reabsorption, leading to increased excretion. This pH effect on urine clearance can be dramatic; the percentage of a methamphetamine dose excreted unchanged into urine drops from 76% in acid urine to 2% in alkaline urine.6 The assay cutoff chosen determines the sensitivity of a urine drug test. The convention is to designate a result positive if it is equal to or greater than the cutoff and to designate it negative if it is less. There are no recommended thresholds for testing maternal urine for drugs of abuse. Most clinical laboratories have chosen the cutoff values used in
48
KWONG & SHEARER
workplace drug testing programs (Table 1).Some of these cutoffs have been shown to be too high for clinical testing, the consequence being underestimation of drug exposure in many instances. Choosing lower thresholds for benzoylecgonine, phencyclidine, and cannabinoids (80, 15, and 20 ng/mL instead of 300, 75, and 25 ng/mL, respectively) yielded higher detection rates for a pediatric outpatient population ranging in age from 3 days to 18 years.38Casanova and co-workers,1° using 5 ng/mL as their cutoff for benzoylecgonine, reported that if the customary forensic urine drug screening threshold of 300 ng/mL for benzoylecgonine had been used, 19% of the benzoylecgonine-positive mothers in their study would have been designated negative. The false-negative rate was still 15% when the cutoff was 150 ng/mL. In the same study, 27% of the benzoylecgonine-positiveinfants would have been missed by the 300 ng/mL cutoff. The duration of testing positive can vary with the specificity of the immunoassay. This is best illustrated by the effect of improved specificity of the cannabinoid metabolites assay on detection time.&,45 Antibody in this assay cross-reacts with the target analyte, THC-COOH, as well as numerous other metabolites, and the measured apparent THC-COOH concentration is the sum of the cross-reactive metabolites. The use of antibody of improved specificity for THC-COOH in recent years has resulted in lower apparent concentration. In a recent human study, the duration for a positive marijuana test after a single exposure was 1 to 2 days, which is significantly shorter than the common assumption of a week or 10nger.4~ On-site Testing
Several hand-held testing devices have been approved by the Food and Drug Administration for the testing of drugs of abuse in urine at the bedside or in physician offices? All hand-held devices use some form of immunochromatography immunoassay, and most have been designed to test for the five drug classes of the Federal Drug Testing Program plus benzodiazepines using the standard workplace drug-test-
Table 1. TYPICAL INITIAL AND CONFIRMATION TEST THRESHOLDS Substance
Amphetamines Cannabinoids Cocaine metabolites Opiates Phencyclidine
Initial Test (ng/mL)
Confirmation Test (ng/mL)
1000
Amphetamine, 500 Methamphetamine, 500 THC-COOH, 15 Benzoylecgonine, 150 Codeine, 300 Morphine, 300 Phencyclidine, 25
50 300 300 25
DETECTION OF DRUG USE DURING PREGNANCY
49
ing The advantages of these hand-held devices include the short turnaround time (in minutes), eliminating the delay in patient disposition while waiting for a laboratory report. Several issues regarding on-site testing must be considered. First, acceptable quality control procedures for these single-use devices are actively being debated. A second issue is the proper training of nonlaboratory personnel to administer the test and evaluate the results, which are determined by visual inspection of the formation or disappearance of a color band. Third, if the result is positive, there is the risk of making major clinical decisions based on an unconfirmed result of a nonspecific immunoreaction.
HAIR TESTING Analysis of the hair of drug users has demonstrated the presence of drugs.5*69 Systemic drug exposure leads to incorporation of the drug into the hair shaft during hair growth in amounts that remain until the hair is replaced, thus hair testing offers a window of detection much wider than possible with urine.53Several issues in regards to hair testing for drugs of abuse challenge the scientific validity of hair testing and the ability to perform a rational interpretation of hair drug concentration. These include the mechanism(s) by which drug gets into hair; the effect of environmental contamination and chemical treatment of hair, biases resulting from hair type, gender, and race; and analytical diffi~ulties.~~ The mechanisms by which drugs are incorporated into hair are not understood and are an area of active research.76One proposed mechanism assumes that drugs simply enter hair roots by a diffusion process from vascular channels into hair-forming cells in the hair follicle and then are incorporated as part of the protein structure found in the hair matrix. However, other possibilities include the deposition of drug into the hair via secretion into sebum and sweat, where it can come into contact with the hair shaft, or via the external contamination of hair.76,87 Although hair has the ability to metabolize drugs, it is considerably less able to do so in comparison with most other organs. Therefore, parent drug compounds are present in higher concentrations than are the metabolites (e.g., THC > THC-COOH, nicotine > cotinine). Both heroin and 6MAM can be detected in the hair of the heroin abuser when these compounds are difficult to detect in blood because of their short in urine is detectable for only approxielimination h a l f - l i ~ e s6MAM .~~ mately 8 hours.16The concentration of 6MAM in the hair of heroin users is 3.5 times greater than that of morphine and five times greater than that of c0deine.3~The amount of cocaine detected in hair predominates over benzoylecgonine and ecgonine methyl ester by a factor of five to ten fold,z and the benzoylecgonine detected in hair is derived from cocaine hydrolysis in the hair shaft.70 One of the most serious concerns is the difficulty in discriminating the presence of drug in hair as the result of active use versus external 87 Therefore, the presapplication such as environmental contamination.a*
50
KWONG & SHEARER
ence of cocaine in hair should not be interpreted necessarily as evidence of drug use. Various approaches to distinguish the source of exposure have been proposed. Baumgartner and co-workers3, have suggested that because extensive washing of hair will remove only externally applied drug but not that incorporated into hair after systemic exposure, the ratio of drug concentration in washings to that in hair extract can distinguish between active or passive exposure. There is concern, however, that the washing protocol cannot completely remove externally applied drug8,87 Moreover, this approach is applicable to freshly contaminated hair only, because bathing and shampooing of hair can remove most but not all of an externally applied cocaine sample. Thus, analysis of environmentally contaminated hair from which the bulk of the surface-contaminated drug has been washed off by bathing and shampooing can produce positive results that are indistinguishable from those obtained from the hair of active drug users.8*87 Detection of benzoylecgonine in hair has been proposed to be a marker of active cocaine but cocaine hydrolysis to benzoylecgonine in hair does take place, and unless careful precautions are taken to control assay conditions, particularly the pH during the extraction process, hydrolytic production of benzoylecgonine will occur and lead to a false-positive result.87 Pigmentation is an important factor affecting incorporation of drug into hair.76Hair pigmentation results from the incorporation of melanin into hair shaft structures, and the color of hair is correlated with the amount of melanin. Basic drugs, cationic at physiologic pH, will bind to melanin, which is polyanionic. In experiments performed in Long-Evans rats, which have differently pigmented hair in different parts of the body, the mean concentration of codeine in pigmented hair was 46 times that in nonpigmented In vitro cocaine-binding studies show that specific binding to Africoid black hair is 157 times greater than binding to Caucasoid blond hair.50Pigmentation influencing drug concentration in hair has been described for codeine and its metabolite^;^ nicotine;’ and phencyclidine.81 Treatment of hair with chemicals such as hydrogen peroxide, alkaline wave-setting solutions, or shampoo can reduce drug concentrations in hair.88When realistic treatment conditions were used, the hair samples retained approximately 20% to 40% of the original cocaine content after 30 treatments. Similar results were found by Joseph and co-workers,5° who concluded that bleaching of most hair specimens resulted in significant decreases in specific binding of cocaine when compared with untreated hair. The concept of segmental hair analysis to chronicle drug use during pregnancy was first suggested by Graham and c o - ~ o r k e r sand ~ ~ was based on the premise that drug use results in drug deposition into hair, which grows at a fairly constant rate. Therefore, analysis of segments of a drug user’s hair can yield a profile of drug usage during pregnancy. Several segmental analysis studies to test for drug abuse over varying lengths of time have obtained useful information on the history of drug use over a wide The results of segmental analysis should be
DETECTION OF DRUG USE DURING PREGNANCY
51
interpreted with caution, however, and should take into consideration many variables, including hair length, hair washing, cosmetic treatments, and whether drug use occurred only in the last few days of pregnancy, in which case there would be insufficient time for the drug to enter the hair shaft. Moreover, hair growth is irregular enough to negate ascribing exact quantitative values to levels of cocaine exposure at a specific point in the pregnancy.78At best, hair segmental analysis may detect trends in the concentration of drug along the various sections of hair without pinpointing the exact time of drug use or dose consumed. Testing of newborn hair to document drug exposure in utero is an appropriate clinical application of hair testing.53,56 Newborn hair grows during the third trimester, and detection of drug at birth reflects maternal drug use during the last 3 months of pregnancy.35,53 The quantity of benzoylecgonine in newborn hair correlates best with that in the proximal segment of the mother’s hair, which represents maternal hair growth in the 12 weeks or so before delivery9 The timing of hair collection is not critical, because hair collected even a few weeks after birth still offers the opportunity for confirming gestational drug exposure. Newborns who test negative in their urine because their mothers abstained from drug use only a few days before delivery may test positive if hair analysis is performed. Environmental contamination is not an issue if the newborn is tested during the immediate postdelivery period while still in the hospital and not after the newborn has been discharged home with the mother who is suspected of drug abuse. The literature on newborn hair testing is, for the most part, related to cocaine exposure, although amphetamines, opiates, and methadone have been found in adult hair testing? Hair analysis is technically more involved than urine or meconium testing. Hair samples must first be decontaminated by washing with a variety of agents, including methanol, ethanol, dichloromethane, acetone, detergent, or warm water.56Drug is then extracted from hair by incubation with methanol, ethanol, acid, and proteinase or pronase. The low drug concentrations in hair are detectable by radioimmunoassay only For confirmation of cocaine and opiates by GC-MS assays with data acquisition in selected ion-monitoring mode, as little as 5 to 10 mg of adult hair is a d e q ~ a t e , 787~ whereas ,~~, a sophisticated research protocol based on negative-ion chemical ionization mass spectrometry is needed for the detection of THC and metabolite^.^^ GC-MS procedures requiring 50 to 100 mg of hair are more suitable for testing adult hair, because most newborns do not have that much hair, and their mothers probably will object to extensive shaving of their babies for drug testing. Because hair analysis is technically demanding, its availability is limited to a few specialized laboratories. MECONIUM TESTING
Meconium has been proposed as an alternative matrix to urine for drug testing, because it contains a high concentration of drugs to which
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KWONG & SHEARER
the fetus has been exposed during pregnancy.59,66, 73, Meconium is thought to form initially at the end of the first Because meconium is not excreted by the fetus, it serves as a reservoir of drugs to which the fetus has been exposed and as a cumulative record of prior exposure over the last two trimesters of pregnancy, a detection time frame that is impossible to attain by urine testing. Most of the published reports involving meconium have described the detection of cocaine. Studies detailing the detection of other drugs (opiates, amphetamines, 73, 74 have reported the abuse of cocaine to be the and ~annabinoids)~~, most prevalent. The higher sensitivity of meconium testing in comparison with urine testing for identifying cocaine-, opiate-, and cannabinoid-exposed newborns was first reported by Ostrea and co-workers.” Some patients continued to have positive test results for as long as 3 days postdelivery, whereas 37% of those same neonates revealed a positive urine screen.74A much larger study on meconium testing for the detection of intrauterine cocaine exposure involved 1201 mother-infant pairs (from a total of 1237 live births recorded during the study period).77 Meconium testing yielded an additional 25% of infants exposed to cocaine who were labeled negative by urine testing, whereas no newborn with urinepositive results had negative results in the corresponding meconium. The difference in the detection rates in meconium versus urine assays can be attributed to the methods used (i.e., enzyme immunoassay versus fluorescence polarization immunoassay for urine screening and radioimmunoassay or GC/MS for meconium analysis) rather than to the type of specimen used (urine versus meconium). When equivalent assay methods are used and when lower cutoff values are employed, the detection rates of urine testing are equivalent to those of meconium lo analy~is.~, Advantages of using meconium specimens are the ease of sample collection, the fact that sample amount is usually of sufficient quantity for complete analysis, the relatively high drug concentration, and the longer detection window. Disadvantages include missed collection owing to late passage of meconium in some premature newborns,%technical difficulties with analysis, longer turnaround time, and much higher cost in comparison with urine testing.56 AMNIOTIC FLUID Amniotic fluid specimens have been examined for drugs of abuse.47 Fluids were collected from both known drug users and nonusers transvaginally either at the time of birth when rupture of membranes occurred or at the time of amniocentesis. Cocaine or benzoylecgonine was detected by HPLC in 74%of amniotic fluid samples from known abusers in comparison with 61% and 35% of maternal and newborn urine samples, respectively. As is true in urine, amniotic fluid contains a higher concentration of benzoylecgonine than cocaine. Because the assay cutoff
DETECTION OF DRUG USE DURING PREGNANCY
53
values in the study mentioned previously were not mentioned, it is impossible to determine whether the lower sensitivity of testing maternal urine was the result of the use of a higher cutoff. Availability of amniotic fluid is an issue in patients who have premature rupture of membranes or rapidly advancing labor. Currently, amniotic fluid testing does not offer any real advantage over more conventional urine screening. Furthermore, its clinical value as an indicator of long-term drug exposure has not been studied.
SUMMARY
Several methods of drug testing are efficacious in identifying and monitoring drug use during pregnancy. Urine screening remains the most commonly used method despite the limited period during which drugs can be detected. Hair has been recognized as a possible alternate test specimen, but wider acceptance of hair testing must await better understanding of drug disposition in hair, answers to the issues relating to interpretation, and the development of less demanding laboratory techniques. Regardless of the matrix used, proper interpretation of the results of drug testing requires familiarity with the sensitivity, specificity, and limitations of the laboratory methodologies employed. Moreover, unconfirmed positive results may actually be false-positives and must be interpreted with caution, particularly if they are the basis for major clinical decisions.
References 1. Ambre 3: The urinary excretion of cocaine and metabolites in humans: A kinetic analysis of published data. J Anal Toxic01 9241, 1985 2. Ambruster DA: On-site drug testing. Med Lab Observer 29:40, 1997 3. Baumgartner WA, Hill V A Hair analysis for drugs of abuse: Decontamination issues. In Sunshine I (ed): Recent Developments in Therapeutic Drug Monitoring and Clinical Toxicology. New York, Marcel Dekker, 1992, p 577 4. Baumgartner WA, Hill VA Sample preparation techniques. Forensic Sci Int 63:121,1993 5. Baumgartner WA, Hill VA, Blahd WH. Hair analysis for drugs of abuse. J Forensic Sci M1433, 1989 6. Beckett AH, Rowland M: Urinary excretion kinetics of methamphetamine in man. J Pharm Pharmacol 171095, 1965 7. Bingo1 N, Fuchs M, Diaz V Teratology of cocaine in humans. J Pediatr 11093, 1987 8. Blank DL, Kidwell DA: Decontamination procedures for drugs of abuse in hair: Are they sufficient? Forensic Sci Int 70:13, 1995 9. Callahan CM, Grant TM, Phipps P: Measurement of gestational cocaine exposure: Sensitivity of infants’ hair, meconium, and urine. J Pediatr 120763,1992 10. Casanova OQ,Lombardero N, Behnke M: Detection of cocaine exposure in the neonate. Arch Pathol Lab Med 119:988, 1994 11. Chasnoff IJ, Griffith D, Freier C: Cocaine/polydrug use in pregnancy: Two-year followup. Pediatrics 89:284, 1992
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12. Chasnoff IJ, Griffith DR Cocaine: Clinical studies of pregnancy and the newborn. Ann NY Acad Sci 562260, 1989 13. Cherukuri R, Minkoff H, Feldman J: A cohort study of alkaloidal cocaine ("crack) in pregnancy. Obstet Gynecol72:147, 1988 14. Chouteau M, Namerow PB, Leppert P: The effect of cocaine abuse on birth weight and gestational age. Obstet Gynecol 72:351, 1988 15. Christmas JT, Knisely JS, Dawson K S Comparison of questionnaire screening and urine toxicology for detection of pregnancy complicated by substance use. Obstet Gynecol 80:750, 1992 16. Cone E, Welch P, Paul BD: Forensic drug testing for opiates. I. Detection of 6-acetylmorphine in urine as an indicator of recent heroin exposure: Drug and assay considerations and detection times. J Anal Toxicol 151, 1991 17. Cone EJ: Pharmacokinetics and pharmacodynamics of cocaine. J Anal Toxicol 19:459, 1995 18. Cone EJ, Huestis MA: Relating blood concentrations of tetrahydrocannabinol and metabolites to pharmacologic effects and time of marijuana usage. Ther Drug Monit 15:527, 1993 19. Cone EJ, Johnson RE: Contact highs and urinary cannabinoid excretion after passive exposure to marijuana smoke. Clin Pharmacol Ther 40:247, 1986 20. Cone EJ, Johnson RE, Darwin W D Passive inhalation of marijuana smoke: Urinalysis and room air levels of delta-9-tetrahydrocannabinol. J Anal Toxicol 11:89, 1987 21. Cone EJ, Menchen SL, Paul BD Validity testing of commercial urine cocaine metabolite assays. I. Assay detection times, individual excretion patterns, and kinetics after cocaine administration to humans. J Forensic Sci 34:15, 1989 22. Cone EJ, Yousefnejad D, Darwin W D Testing human hair for drugs of abuse. 11. Identification of unique cocaine metabolites in hair of drug abusers and evaluation of decontamination procedures. J Anal Toxicol 15:250, 1991 23. Cone EJ, Yousefnejad D, Hillsgrove MJ: Passive inhalation of cocaine. J Anal Toxicol 19:399, 1995 24. Davidson-Ward SL, Bautista D, Chan L Sudden infant death syndrome in infants of substance-abusing mothers. J Pediatr 117876, 1992 25. Ellis GM Jr, Mann MA, Judson BA: Excretion pattern of cannabinoid metabolites after last use in a group of chronic users. Clin Pharmacol Ther 38:572, 1985 26. Elsohly MA, Jones A B Morphine and codeine in biological fluids: Approaches to source differentiation. Forensic Sci Rev 1:13, 1989 27. Elsohly MA, Jones AB: Drug testing in the workplace: Could a positive test for one of the mandated drugs be reasons for other than illicit use of the drug? J Anal Toxicol 19:450, 1995 28. Feldman JG, Minkoff HL, McCalla S A cohort study of the impact of perinatal drug use on prematurity in an inner-city population. Am J Public Health 82:726, 1992 29. Frank D, Zuckerman CS, Amaro H Cocaine use during pregnancy: Prevalence and correlates. Pediatrics 82888, 1988 30. Garcia DC, Romero A, Garcia GC: Gastric fluid analysis for determining gestational cocaine exposure. Pediatrics 98:291, 1996 31. Gerstenberg B, Schepers G, Voncken P: Nicotine and cotinine accumulation in pigmented and unpigmented rat hair. Drug Metab Dispos 23:143, 1995 32. Gillogley KM, Evans AT, Hansen RL: The perinatal impact of cocaine, amphetamine, and opiate use detected by universal intraparturn screening. Am J Obstet Gynecol 163:1535, 1990 33. Goldberger B, Caplan Y, Maguire T Testing human hair for drugs of abuse. 111. Identification of heroin and 6-acetylmorphine as indicators of heroin use. J Anal Toxicol 15:226, 1991 34. Goldberger BA, Loewenthal B, Darwin WD: Intrasubject variation of creatinine and specific gravity measurements in consecutive urine specimens of heroin users. Clin Chem 41:116, 1995 35. Graham K, Koren G, Klein J: Determination of gestational cocaine exposure of hair analysis. JAMA 262:3328, 1989
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36. Grant T, Brown Z, Callahan C: Cocaine exposure during pregnancy: Improving assessment with radioimmunoassay of maternal hair. Obstet Gynecol 83:524,1994 37. Gygi SP, Josephe RE, Cone EJ: Incorporation of codeine and metabolites into hair: Role of pigmentation. Drug Metab Dispos 24495, 1996 38. Hicks JM, Morales A, Soldm SJ: Drugs of abuse in a pediatric outpatient population. Clin Chem 36:1256, 1990 39. Huestis MA: Judicial acceptance of hair tests for substances of abuse in the United States courts: Scientific, forensic, and ethical aspects. Ther Drug Monit 18:456, 1996 40. Huestis MA, Mitchell JM, Cone EJ: Urinary excretion profiles of 11-nor-9-carboxy-delta 9-tetrahydrocannabinol in humans after single smoked doses of marijuana. J Anal Toxicol 20:441, 1996 41. Huestis MA, Cone EJ: Predicting new marijuana use from creatinine normalized 11nor-9-carboxy-T9-tetrahydrocannabinol(THCCOOH) concentrations: Criteria development and validation [abstract]. J Anal Toxicol 21:82, 1997 42. Huestis MA, Henningfield JE, Cone EJ: Blood cannabinoids. I. Absorption of THC and formation of 11-OH-THC and THCCOOH during and after smoking marijuana. J Anal Toxicol 16276,1992 43. Huestis MA, Henningfield JE, Cone EJ: Blood cannabinoids. 11. Models for the prediction of time of marijuana exposure from plasma concentrations of delta 9-tetrahydrocannabinol (THC) and 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (THCCOOH). J Anal Toxicol 16283, 1992 44.Huestis MA, Mitchell JM, Cone EJ: Lowering the federally mandated cannabinoid immunoassay cutoff increases true-positive results. Clin Chem 40:729, 1994 45. Huestis MA, Mitchell JM, Cone EJ: Detection times of marijuana metabolites in urine by immunoassay and GC-MS. J Anal Toxicol 19:443, 1995 46. Hunt CA, Jones RT: Tolerance and disposition of tetrahydrocannabinol in man. J Pharmacol Exp Ther 215:35, 1980 47. Jain L, Meyer W, Moore C: Detection of fetal cocaine exposure by analysis of amniotic fluid. Obstet Gynecol 81:787, 1993 48. Jeffcoat AR, Perez-Reyes M, Hill JM: Cocaine disposition in humans after intravenous injection, nasal insufflation (snorting), or smoking. Drug Metab Dispos 17153, 1989 49. Joseph R, Dickerson S, Willis R Interference by nonsteroidal anti-inflammatory drugs in EMIT and TDx assays for drugs of abuse. J Anal Toxicol 19:13, 1995 50. Joseph R, Su T-P, Cone EJ: In vitro binding studies of drugs to hair: Influence of melanin and lipids on cocaine binding to Caucasoid and Africoid hair. J Anal Toxicol 20:338, 1996 51. Kain ZN, Rimar S, Barash PG: Cocaine abuse in the parturient and effects on the fetus and neonate. Anesth Analg 77835, 1993 52. Kandall SR, Gaines J, Habel L: Relationship of maternal substance abuse to subsequent sudden infant death syndrome in offspring. J Pediatr 123:120, 1993 53. Koren G: Measurement of drugs in neonatal hair: A window to fetal exposure. Forensic Sci Int 70:77, 1995 54. Koren G, Klein J, Forman R Hair analysis of cocaine: Differentiation between systemic exposure and external contamination. J Clin Pharmacol32671,1992 55. Kwong TC: Toxicology. In McClatchey KP (ed): Clinical Laboratory Medicine. Baltimore, Williams and Wilkins, 1994, p 445 56. Kwong TC, Ryan RM: Detection of intrauterine illicit drug exposure by newborn drug testing. Clin Chem 43235, 1997 57. Le SD, Taylor RW, Vidal D: Occupational exposure to cocaine involving crime lab personnel. J Forensic Sci 37959, 1992 58. Lewis D, Moore C, Leikin J B Multiple birth concordance of street drug assays of meconium analysis. Vet Hum Toxicol 37318, 1995 59. Lewis DE, Moore CM, Leikin JB: Meconium analysis for cocaine: A validation study and comparison with paired urine analysis. J Anal Toxicol 19:148, 1995 60. Lipshultz S, Frassica J, Orav J: Cardiovascular abnormalities in infants prenatally exposed to cocaine. J Pediatr 11844,1991 61. Liu RH: Evaluation of commercial immunoassay kits for effective workplace drug
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testing. In Liu RH, Goldberger A (eds): Handbook of Workplace Drug Testing. Washington, DC, AACC Press, 1995, p 67 62. Mack G, Thomas D, Giles W: Methadone levels and neonatal withdrawal. J Pediatr Child Health 2796, 1991 63. Mandatory guidelines for federal workplace drug testing programs. Federal Register 5929908, 1994 64. Manno JE: Interpretation of urinalysis results. NIDA Res Monogr 7354, 1987 65. Matera C, Warren WB, Moomjy M Prevalence of use of cocaine and other substances in an obstetric population. Am J Obstet Gynecol 163:797,1990 66. Maynard EC, Amoruso LB, Oh W. Meconium for drug testing. Am J Dis Child 145650, 1991 67. McCalla S, Minkoff HL, Feldman J: Predictors of cocaine use in pregnancy. Obstet Gynecol 79641, 1992 68. Meatherall R, Dai J: False-positive EMIT I1 opiates from ofloxacin. Ther Drug Monit 1998, 1997 69. Moeller MR, Fey P: Simultaneous determination of drugs of abuse (opiates, cocaine and amphetamine) in human hair by GC/MS and its application to a methadone treatment program. Forensic Sci Int 63:185,1993 70. Nakahara Y, Kikura R Hair analysis for drugs of abuse. VII. The incorporation rates of cocaine, benzoylecgonine and ecgonine methyl ester into rat hair and hydrolysis of cocaine in rat hair. Arch Toxicol 681:54, 1994 71. Neerhof M, MacGregor SN, Retzky S S Cocaine abuse during pregnancy: Peripartum prevalence and perinatal outcome. Am J Obstet Gynecol 161:633, 1989 72. Or0 AS, Dixon S D Perinatal cocaine and methamphetamine exposure: Maternal and neonatal correlates. J Pediatr 111:571, 1987 73. Ostrea EM Jr, Brady MJ, Parks I'M: Drug screening of meconium in infants of drugdependent mothers: An alternative to urine testing. J Pediatr 115:474, 1989 74. Ostrea EM, Brady M, Gause S Drug screening of newborns by meconium analysis: A large-scale prospective, epidemiologic study. Pediatrics 89:107, 1992 75. Rollins DE, Jennison TA, Jones G: Investigation of interference by non-steroidal antiinflammatory drugs in urine tests for abused drugs. Clin Chem 36:602, 1990 76. Rollins DE, Wilkins DG, Gygi SP: Testing for drugs of abuse in hair-experimental observations and indications for future research. Forensic Sci Rev 9:1997 77. Ryan RM, Wagner CL, Schulz J M Meconium analysis improves identification of intrauterine cocaine exposed infants. J Pediatr 88825, 1991 78. Sachs H Theoretical limits of the evaluation of drug concentrations in hair due to irregular hair growth. Forensic Sci Int 70:53, 1995 79. Selavka CM, Rieders F The determination of cocaine in hair: A review. Forensic Sci Int 70:155, 1995 80. Singer L, Arendt R, Song LY Direct and indirect interactions of cocaine with childbirth outcomes. Arch Pediatr Adolesc Med 148:959, 1994 81. Slawson MH, Garcia K, Wilkins DG: Mechanisms of xenobiotic incorporation into hair: Phencyclidine. Toxicologist 30:36, 1996 82. Spence MR, Williams R, Digregorio GJ: The relationship between cocaine use and pregnancy outcome. Obstet Gynecol 78:326, 1991 83. Staub C: Analytical procedures for determination of opiates in hair: A review. Forensic Sci Int 70111, 1995 84. Strano-Rossi S, Bermejo-Barrera A, Chiarotti M: Segmental hair analysis for cocaine and heroin abuse determination. Forensic Sci Int 70:211, 1995 85. Struempler RE, Nelson G, Urry F M A positive cannabinoids workplace drug test following the ingestion of commercially available hemp seed oil. J Anal Toxicol 21:283, 1997 86. Verna A, Dhanireddy R Time of first stool in extremely low birth weight ( 4 0 0 0 gm) infants. J Pediatr 122:626, 1992 87. Wang WL, Cone EJ: Testing human hair for drugs of abuse. IV. Environmental cocaine contamination and washing effects. Forensic Sci Int 7039, 1995 88. Weiss RD, Gawin F H Protracted elimination of cocaine metabolites in long-term, lightdose cocaine abusers. Am J Med 85:879, 1988
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89. Welch MJ, Sniegoski LT, Allgood CC, et al: Hair analysis for drugs of abuse: Evaluation of analytical methods, environmental issues, and development of reference materials. J Anal Toxicol 17389, 1993 90. Wiemann CM, Berenson AB, San Miguel W. Tobacco, alcohol and illicit drug use among pregnant women: Age and racial/ethnic differences. J Reprod Med 39:769,1994 91. Wilkins DG, Haughey HM, Cone E Quantitative analysis of THC, 11-OH-THC, and THCCOOH in human hair by negative-ion chemical ionization mass spectrometry. J Anal Toxicol 19:483, 1995 92. Woods JR Jr, Dolkart LA: Significance of amniotic fluid meconium. In Creasy RK, Resnik R (eds): Maternal-Fetal Medicine: Principles and Practice, ed 2. Philadelphia, WB Saunders, 1989, p 404 93. Zuckerman B, Frank DA, Hingson R Effects of maternal marijuana and cocaine use on fetal growth. N Engl J Med 320762, 1989
Address reprint requests to Tai C. Kwong, PhD University of Rochester Medical Center Box 608 601 Elmwood Ave Rochester, NY 14642
APPENDIX I
Substances That Give False-Positive Results by Both Initial and Confirmatory Testing"
The following medications and substances give a positive result by both initial immunoassay and confirmatory gas chromatography/ mass spectrometry test. These are analytical true-positives. Therefore, the findings must be interpreted with caution. AMPHETAMINES (METHAMPHETAMINE AND AMPHETAMINE)
Prescription medications that contain either D-amphetamine or racemic D,L-amphetamine (i.e., equal amounts of D- and L-amphetamine) include the following: Adderall Benzedrine Biphenamine Dexedrine Durophet Obetrol Prescription medications that contain D-methamphetamine include Desoxyn (Gradumet). Substances known to be metabolized to methamphetamine (and amphetamine) include benzphetamine (Didrex), dimethylamphetamine, and famprofazone, fencamine, furfenorex, selegiline (deprenyl, Elde-
P'Yb
Substances known to be metabolized to amphetamine include Anphetaminil Clobenzorex (Dinintel, Finedal) Ethylamphetamine Fenethylline (Captagon) Fenproporex (Tegisec) Mefenorex (Pondinil) Mesocarb Phenylamine
*From the Medical Review Officer Manual for Federal Workplace Drug Testing Programs, CSAP Technical Report, Division of Workplace Programs, Center for Substance Abuse Prevention (CSAP), Substance Abuse and Mental Health Services Administration, US Department of Health and Human Services, DHHS Publication, 1997.
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Nonprescription medications that contain L-methamphetamine include Vicks Inhaler. COCAINE
There are no prescription medications that contain cocaine. The combination of tetracaine, epinephrine, and cocaine (TAC) is frequently used in emergency departments. Cocaine hydrochloride is used for ear, nose, and throat procedures. Other topical analgesics, such as Novocain, Xylocaine (lidocaine), and benzocaine bear no structural similarity to cocaine or its metabolite (benzoylecgonine)and will not test positive. MARIHUANA
Prescription medications that contain delta-9-tetrahydrocannabinol (THC) include dronabinol (Marinol). A food item that contains THC is hemp seeds. OPIATES (HEROIN, MORPHINE, CODEINE)
Prescription medications that contain morphine include the following: Astramorph PF Duramorph MSIR MS Contin tablets Infumorph Oramorph Prescription medications that contain codeine include Actifed with Codeine Cough syrup Codimal PH Deconsal Dimetane-DC Cough syrup Empirin with Codeine Fiorinal with Codeine Phenaphen with Codeine Phenergan Robitussin A-C Triaminic Expectorant with Codeine Tylenol with Codeine (1,2, 3, or 4) Tussar-2 A substance that metabolizes to morphine is heroin. A food item that contains morphine is poppy seeds.
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PHENCYCLIDINE
There are no prescription medications that contain phencyclidine (PCP). There are no legal medical uses of PCP or any other substance that can be misidentified as PCP.
APPENDIX I1
Substances That Give False-Positive Results by Initial Testing The following medications and substances may trigger a positive response by the initial immunoassay test. This presumptive positive result becomes a false-positive if it is reported without a confirmatory test. Different immunoassay kits have different specificities. The physician should contact the laboratory for details.
AMPHETAMINES (METHAMPHETAMINE AND AMPHETAMINE)
Ephedrine Phentermine (Fastin, Adipex-P) Phenylpropanolamine Pseudoephedrine Fenfluramine (Pondimin) Dexfenfluramine (Redux)
COCAINE
None
MARIHUANA (THC)
Nonsteroidal anti-inflammatory drugs (after high dose and rare)
OPIATES (HEROIN, MORPHINE, CODEINE)
Dihydrocodeine (paracodin) Hydrocodone (Hycodan) Hydromorphone (Dilaudid) Ofloxacin (Floxin) Oxycodone (Percodan) Oxymorphone (Numorphan) Levorphanol (Levo-Dromoran) 63
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PHENCYCLIDINE (PCP)
Dextromethorphan BENZODIAZEPINES
Oxaprozin (Daypro)