Plasma Concentrations after Intravenous Administration of Phylloquinone (vitamin K1) in Preterm and Sick Neonates

Thrombosis Research 99 (2000) 467–472

ORIGINAL ARTICLE

Plasma Concentrations after Intravenous Administration of Phylloquinone (vitamin K1) in Preterm and Sick Neonates Wolfgang Raith, Gu¨nter Fauler, Gerhard Pichler and Wolfgang Muntean Department of Pediatrics, and Ludwig Boltzmann Research Institute for Pediatric Haemostasis and Thrombosis, University of Graz, Austria (Received 18 December 1999 by Editor I. Pabinger; revised/accepted 7 May 2000)

Abstract Vitamin K prophylaxis usually is administered orally or intramuscularly, but in neonatal intensive care oral administration might not be feasible and intramuscular administration is not general practice in very small infants. No data are available about plasma levels after intravenous administration of vitamin K to neonates. Therefore, we investigated plasma levels in 18 infants: 14 preterms with a birthweight of 1785⫾648 g and 4 sick newborns with a birth-weight of 3167⫾510 g after administration of a single dose of 0.3⫾0.1 mg/kg phylloquinone (vitamin K1) (Konakion MM威, Roche) intravenously after birth. Blood was collected 22.9⫾18.4 hours after intravenous administration of vitamin K1. In 10 neonates a second sample was obtained 111.8⫾49.1 hours after the first vitamin K1 administration. Gas chromatography-mass spectrometry (GC-MS) was used as the method for determination of vitamin K1. The measured plasma concentration after intravenous administration of vitamin K1 was 191.3⫾102.6 ng vitamin K in the first sample /mL in the first sample and 98.7⫾75.2 ng vitamin K1/mL in the second samples. These results are similar to those described in newborns after oral administration of 3 mg vitamin K1 and after Corresponding author: Wolfgang Muntean, Professor of Pediatrics, Department of Pediatrics, University of Graz, Auenbruggerplatz 30, A-8036 Graz, Austria. Tel:⫹43 (316) 385 2609; Fax:⫹43 (316) 385 2619; E-mail:⬍[email protected]⬎.

intramuscular administration of 1.5 mg vitamin K1. In conclusion, the recommendation of the producer to give 0.4 mg/kg of vitamin K intravenously to neonates, in whom oral or intramuscular administration is not feasible, seems to be rational.  2000 Elsevier Science Ltd. All rights reserved. Key Words: Vitamin K deficiency bleeding (VKDB); Intravenous administration of vitamin K1; Plasma levels

V

itamin K prophylaxis and the best method of administration to prevent vitamin K deficiency bleeding (VKDB) has been a matter of debate for many years [1,2,3]. Intramuscular vitamin K administration to neonates had been standard practice until 1990, but then two studies reported an increased risk of cancer in children receiving intramuscular vitamin K in the newborn period [4,5]. Even before these studies were published, the acceptance of intramuscular vitamin K by parents, midwives, and pediatricians had been declining. So intramuscular vitamin K was replaced by oral application in many countries. The correlation between cancer and intramuscular vitamin K has not been confirmed [6,7,8]. The risk, if any, attributable to the use of vitamin K cannot be large, and the possibility remains that some risk cannot be excluded [9]. Repeated oral vitamin K prophylaxis remains standard practice in many countries. Only if the oral application is not possible, vitamin K is given intramuscularly.

0049-3848/00 $–see front matter  2000 Elsevier Science Ltd. All rights reserved. PII S0049-3848(00)00280-2

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In neonatal intensive care, intramuscular application is not general practice in very small infants due to the risk of trauma and infection. In addition, the peroral route of administration cannot be used in all premature and sick neonates. There are only a few reports about plasma levels after intramuscular administration of vitamin K, and we are not aware of any reports about plasma levels after intravenous administration in infants. Therefore, we investigated vitamin K1 plasma levels in 18 preterms and/or sick neonates after giving a single dose of vitamin K1 (Konakion MM威, Roche) intravenously after birth.

1. Patients and Methods 1.1. Patients At our department all neonates admitted to the neonatal intensive care unit receive 0.2–0.4 mg vitamin K1/kg/week (Konakion MM威, Roche) intravenously, as long as oral administration is not feasible. Vitamin K1 was administered by continuos infusion over several minutes. No intramuscular vitamin K administration is given in our neonatal intensive care unit. Blood samples were collected from 18 infants, 14 preterms with a birthweight of 1785⫾ 648 g and 4 sick newborns with a birthweight of 3167⫾510 g (Table 1). Blood was collected 22.9⫾18.4 hours after intravenous administration of vitamin K1. In 10 neonates a second sample was obtained 111.8⫾49.1 hours after administration (Table 1). Samples were only taken when blood samples had to be taken for routine laboratory examinations. No additional amount of blood was taken for this study; only residual plasma was examined after all examinations necessary for routine care had been done. This study has been approved by the Ethics Committee of the Faculty of Medicine, University of Graz (NB.: 4-077 ex 94/95).

1.2. Methods Blood samples were collected by venepuncture or from arterial lines into plastic tubes containing lithium-heparin anticoagulant, and thereafter were protected from light. Plasma was separated by cen-

trifugation (3000 rpm) and 200 ␮l plasma were added to prepared deuterated vitamin K1 standard solution and the samples stored at –70⬚C until assayed. Vitamin K1(20) was obtained from Hoffmann La Roche (Basel, Switzerland). 1,4-naphtoquinone, phytol, acetic acid-d3, heptafluorobutyric anhydride and the corresponding fluorinated acid were purchased from Aldrich, Vienna. All other solvents and reagents of analytical grade were obtained from Merck, Darmstadt, Germany. Stable isotope labeled (2H3) Vitamin K1(20) was synthesized in our laboratory. The vitamin K1 assay was performed as described earlier by Fauler et al. [10,11]. Briefly: To the prepared plasma sample, as described above, were added: 0.2 ml water, 0.6 ml ethanol, and 5 ml hexane. The mixture was extracted for 15 minutes and, after centrifugation, the supernatant was decanted and the organic solvent was evaporated under a stream of nitrogen. The heptafluorobutyril derivatives were prepared by desolving the residue in a mixture of hexane, heptafluorobutyric anhydride, and heptafluorobytyric acid under reducing conditions. After 1 hour water was added; after extraction and centrifugation the supernatant was evaporated. The residue was deslolved in 50 ␮l isooctane transferred to autosampler vials and an aliquot of 10 ␮l was subjected to gas chromatography-mass spectoscopy (GC/MS). Fisons gas chromatograph coupled to a Fisons MD 800 quadrupole mass spectrometer was used. The gas chromatograph was equipped with a DB-5MS fused silica capillary column (15 m⫻0.25 mm i.d., 0.25 ␮m film thickness) from Fisons. Helium was used as carrier gas. Initial column temperature was 160⬚C and raised to 310⬚C. The transfer line between GC and MS was kept at 308⬚C. Ion source temperature was 208⬚C. Electron impact spectra were recorded with an electron energy of 70 eV and an emission current of 100 ␮A. Mass-chromatograms were recorded in electron impact-single ion recording-mode using internal standardization with stable isotope labeled vitamin K as described. The limit of dedection was found to be 1.0 pg (actually injected) at a signal/noise ratio of at least 1:4. Interassay variations (mean⫾SD) were esti-

m f

m f f

m

m f m m

f

m

6 7

8 9 10

11

12 13 14 15

16 17

18

1.53

1.07 1.52

1.47 2.3 2.78 2.06

2.01

2.55 0.93 2.84

1.86 2.93

3.89 3.16 2.57 1.35 0.84

30

31 34

30 31 39 36

36

35 37 39

34 37

40 39 37 29 27

BF, breast-feeding; FF, supplementary formula feeding.

f f m f m

1 2 3 4 5

Sex

Weight (kg)

Gestational age (weeks) meconium aspiration amnionitis, septiceamia IRDS, septiceamia IRDS, septiceamia intraventricular hemorrhage, IRDS, septiceamia septiceamia, plexus hemorrhage septiceamia, IRDS septiceamia IRDS, meconium aspiration amniotic fluid aspiration septiceamia asphyxia asphyxia amniotic fluid aspiration, IRDS, septiceamia IRDS, septiceamia small for date, IRDS IRDS

Diagnosis

FF FF FF FF

BF

BF BF

BF, BF, BF, BF,

BF, FF

BF BF, FF BF

BF, FF BF, FF

BF, FF BF, FF BF, FF BF, FF BF

Nutrition

0.3

0.4 0.4

0.3 0.3 0.4 0.2

0.3

0.2 0.5 0.4

0.2 0.3

0.3 0.3 0.4 0.7 0.4

Vit K1 mg/kg

37.0

19.5 26.0

11.0 12.5 14.5 18.5

3.3

45.0 52.4 71.4

25.1 25.2

1.3 2.5 10.6 17.6 19.5

1stbloodsample (h)

94.0 123.1 94.5

191.5 49.2

174.0 117.5 145.5 88.6 40.3

2nd bloodsample (h)

199.9 10.9 5.9 307.9 23.6 23.8

428.1 286.1 143.9 362.6 65.4 68.9

79.2

100.7 146.0 180.0

15.8 982.9 105.0 182.5

9.5 26.6 13.0 130.5

Vitamin K1 (ng/mL) 2ndbloodsample

357.7 330.4 237.5 105.0

Vitamin K1 (ng/mL) 1st bloodsample

Table 1. Sex, weight, diagnosis, nutrition, the exact amount of vitamin K1, the time of blood sampling, and the measured plasma concentration of vitamin K after intravenous administration

W. Raith et al./Thrombosis Research 99 (2000) 467–472

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W. Raith et al./Thrombosis Research 99 (2000) 467–472

mated to be 10.96⫾0.77 ng/mL and 237.3⫾6.9 pg/ mL plasma, respectively. Intraassay variations (mean⫾SD) were estimated to be 10.98⫾0.47 ng/mL and 233.6⫾3.1 pg/ mL plasma, respectively. The calibration graph established was linear within the range of 4.0–4000 pg per sample (r2⫽0.998). The assay has been established by the use of plasma samples of healthy adult and vitamin K1 concentrations between the lower limit of quantitation (2.0 pg/mL) and 650 pg/mL have been measured, which are in close agreement with the literature [11]. To achieve standardized sample preparation, we decided to add 200 ␮L of plasma directly after centrifugation to a prepared and chilled vitamin K1- standard solution. Because only small amounts of plasma were available, we decided to use 200 ␮L plasma instead of 1mL. The basic points of the evaluation were tested. Furthermore, double estimation of vitamin K1 was possible in only 2 cases. The results are within the limits of variation. Terminal half lives were estimated as described by Stoeckel et al. [14].

2. Results The exact amount of vitamin K1 administered to each specific child, diagnosis, gestational age, nutrition, the time of blood sampling, and the measured plasma concentrations of vitamin K1 are summarized in Table 1. Figure 1 shows the measured plasma vitamin K1 concentrations. Blood was collected 22.9⫾18.4 hours after the first intravenous administration of vitamin K1; the measured plasma concentrations were 191.3⫾102.6 ng vitamin K1/mL. In 10 neonates a second sample was obtained 111.8⫾49.1 hours after the first vitamin K1 administration. The measured vitamin K1 plasma concentrations were 98.7⫾75.2 ng/mL for the second samples. A terminal half life of 5.4– 226.3 hours (median 65.5 hours) was estimated.

3. Discussion There are only a few reports about direct measurements of plasma concentrations of vitamin K after

oral and intramuscular vitamin K administration. And there are no reports about plasma concentrations after intravenous administration of vitamin K in neonates. Blood sampling in small neonates presents several problems: in our neonatology unit it is general practice to reduce irritation of the neonates to a minimum. Due to the small blood volume, sample volumes have to be very small. The same reasons probably are why there is so little information in the literature about vitamin K levels especially in neonates and sick neonates. Gas chromatography-mass spectrometry (GCMS) was used as the method for analysis of vitamin K [10,11]. Since the development of modern gas chromatographs and the introduction of relatively low-priced, small, simple, and stable GC-MS combinations, this method offers an alternative to other chromatographic methods. Another advantage of this method is that losses of plasma vitamin K1-amounts in the course of storage and sample preparations do not affect the results, due to the presence of an internal standard with identical chemical properties. Schubiger et al. [12] investigated plasma vitamin K concentrations in breast-fed neonates after oral and intramuscular administration, and has shown that a single dose of traditional emulsion-based preparations of phylloquinone or menaquinone given at birth does not give complete protection against VKDB. More detailed pharmakokinetic studies in adults have shown that there are marked interindividual variations in the availability of phylloquinone [13] and even greater variations may be expected in neonates with an immature digestive tract. Stoeckel et al. [14] investigated plasma levels after oral and intramuscular vitamin K administration in infants and postulated that the terminal half-life of vitamin K in newborns is considerably longer than has previously been reported. On the other hand, a very short half-life has been described in adults after intravenous administration of vitamin K [15,16,17]. A possible explanation for this might be that there are higher peaks of vitamin K after intravenous administration, but that the plasma levels decline faster as compared to plasma levels after intramuscular administration of vitamin K, delaying release from the injection site, and, thereby, leading to smaller uptake from blood into

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471

Fig. 1. Individual vitamin K1 plasma concentrations after intravenous administration of 0, 3⫾0, 1 mg vitamin K1.

the vitamin K deposits after intravenous administration. In line with this hypothesis is a case report about two neonates who had received intravenous vitamin K and both developed VKDB [18]. The authors of this report suggested that intravenous vitamin K may be less effective than intramuscular, and should not be relied upon for the long-term prophylaxis against late-onset HDN. One child had an undiagnosed chronic liver disease, which is known to impair vitamin K absorption. Both children received 0.1 mg/kg vitamin K intravenously 2 to 30 hours and 3 to 5 days after birth. A third dose of oral vitamin K (1.0 mg) was given on days 28 and 30. Bleeding occurred in the tenth and twelfth week, respectively. This was diagnosed as vitamin K deficiency bleeding and was stopped by giving 1.0 mg vitamin K intravenously and intramuscularly. Our results do not support the notion that plasma levels after administration of vitamin K intravenously decline faster than after intramuscular administration during the first week of life. A dose of 0.3⫾0.1 mg/kg/weekly of vitamin K was given to our patients. After one week none of the investigated patients had plasma vitamin K

levels below 0.4 ng/mL, the plasma level below that clinical manifestation of vitamin K deficiency can be expected [14,19]. Because of the problems we had collecting blood samples for our investigation, as discussed above, we cannot present complete half-life studies. However, our measured plasma concentrations and estimated half lives using the same calculation method are very similar to that described by Stoeckel et al. [14] in their investigation of plasma levels in newborns after oral administration of 3 mg vitamin K and after intramuscular administration of 1.5 mg vitamin K. In conclusion, our study shows that in neonates after intravenous administration of 0.2–0.7 mg vitamin K1 plasma levels comparable to that after intramuscular prophylaxis are obtained. Whether such plasma levels are the best way to provide vitamin K prophylaxis has to be established in large epidemiological studies that cannot be done in preterm or severely sick neonates. But until the question about the best way of vitamin K prophylaxis is answered, it probably is prudent to compare plasma levels to that obtained after intramuscular administration with which the most experience exists. Therefore, based on our results, the recom-

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mendation of the producer to give 0.4 mg/kg of vitamin K1 intravenously to neonates, in whom oral or intramuscular administration is not feasible, seems to be rational. But since it has been shown that for the prevention of VKDB repeated administration of vitamin K after birth is mandatory [20], we suggest that all neonates, even when they had intravenous vitamin K during their intensive care, should receive an oral dose prior to release from the hospital or several weeks after the last intravenous application.

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