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SLOW HYDROXYLATION OF NORTRIPTYLINE AND CONCOMITANT POOR DEBRISOQUINE HYDROXYLATION: CLINICAL IMPLICATIONS
560 ACETYLSALICYLIC ACID IN DIABETES
SiR,-A beneficial effect of sodium salicylate in human diabetesI mellitus has been reported in the older pharmacopoeias. Ebstein,l Bartels,2and Williamson3noted that this drug progressively diminished glycosuria, polyuria, and polydipsia and increased weight and strength when given to diabetics in doses of 5-16 g daily. Later studies have also reported reduction of fasting blood glucose in non-diabetics 5,6 and improvement of blood-glucose in noninsulin-dependent diabetics.6 These effects were associated with markedly enhanced insulin levels. Since the prostaglandins of the E series seem to have the opposite effects of salicylates,°9 it has been suggested that the mechanism of salicylate action upon both insulin secretion and carbohydrate tolerance may be through inhibition of endogenous prostaglandin E synthesis. We have studied the effect of lysine acetylsalicylate, a watersoluble salt of acetylsalicylic acid (ASA), upon insulin responses to glucose in eight patients with non-insulin-dependent diabetes mellitus (NIDDM) and seven with insulin-dependent diabetes (IDDM). The patients with NIDD were aged 42-60 and had fasting plasma glucose values of 175±20 mg/dl (18 mg/dl =mmol/1) (insulin 12±3 U/ml), they were receiving diet alone and at the time of the study were taking no drugs. Patients with IDD ranged in age from 21 to 55 and were known to have had diabetes for 2-35 years; fasting plasma glucose concentrations were 160±19 mg/dl (C-peptide = 0’92±0-12 ng/ml); and they were on insulin therapy, one or two injections daily. All diabetics received two consecutive glucose pulses (20 g) 90 min apart. therapie des diabetes mellitus insbesondere uber die anwendeng der salicylsauren natron bei demselben. Berliner Klin Wschr 1876; 13: 337-40. Bartels (Kiel). Uber die therapeutische verwerthung der salicylsaure und ihres
In
patients with NIDDM (fig. 1), the acute insulin response to glucose was significantly increased by ASA. The response before ASA was 5±2%; during ASA it was 70±12%, response being expressed as the mean change in 3-10 min insulin (% basal) Second phase insulin secretion was also altered (p<0’01). (800±90% before ASA; 3460±570% during ASA) response here being judged as the mean change at 10-60 min in U ml-1 expressed as % basal (p<0 - 01). These effects were associated with a significant increase in glucose disappearance rates (first KG 0 -. 48±004, second KG 0 -98:t0 .09 %/min, p<0’ 01).). In patients with IDDM, ASA did not alter the acute C-peptide response to the same glucose pulse (fig. 2) or the glucose disappear=
=
1. Ebstein W. Zur
2.
natronsalzesin der inneren medicin. Dtsch Med Wschr 1878; 4: 423-25. glycosuria and diabetes mellitus with sodium salicylate. Br Med J 1901; i: 760-62. 4. Giugliano D, Torella R, Siniscalchi N, Improta L, D’Onofrio F. The effect of acetylsalicylic acid on insulin response to glucose and arginine in man. Diabetologia 1978; 14: 359-62. 5. Torella R, Giugliano D, Siniscalchi N, Sgambato S, D’Onofrio F. Effect of acetylsalicylic acid on plasma glucose, insulin, glucagon and growth hormone levels following tolbutamide stimulation in man. Metabolism 1979; 28: 887-89. 6. Giugliano D, Cacciapuoti F, Varricchio M. Acetylsalicylic acid augments insulin and C-peptide response to arginine in diabetes mellitus Prostaglandins Med 1979, 2: 109-10. 7. Giugliano D, Torella R. Prostaglandin E1 inhibits glucose-induced insulin secretion in man. Prostaglandins Med 1978; 1: 166-67. 8. Giugliano D, Torella R, Improta L, D’Onofrio F. Effects of prostaglandin E1 and prostaglandin F2a on insulin and glucagon plasma levels during the intravenous glucose tolerance test in man. Diabète Metab 1978; 4: 187-91. 9. Robertson RP, Chen M. A role for prostaglandin E in defective insulin secretion and carbohydrate intolerance in diabetes mellitus. J Clin Invest 1977; 60: 747-53.
Fig. 2-IDDM: C-peptide response during ASA administration.
to
glucose pulses before and
3. Williamson RT. On the treatment of
(first I = 032:t0’03, second Ke =0’29i:0’03 %/min). These results suggest that endogenous PGEs may be one of the factors that impair insulin secretion in NIDDM, and they add further evidence to the concept of a different pathogenesis between NIDDM and IDDM.
ance rates
Institute of Medical Pathology, I Faculty of Medicine,
80138 Naples, Italy
D. GIUGLIANO
SLOW HYDROXYLATION OF NORTRIPTYLINE AND CONCOMITANT POOR DEBRISOQUINE HYDROXYLATION: CLINICAL IMPLICATIONS
SIR,-Genetically determined slow hydroxylation of tricyclic antidepressants explains why occasional patients experience concentration dependent side effects on low doses.I-3The ability of a patient to accumulate these drugs to toxic levels can be predicted from the the kinetics of a single oral dose2and prevented by monitoring concentration continuous during steady-state plasma therapy. Polymorphisms in drug oxidation involving aliphatic hydroxylation of debrisoquineand N-oxidation of sparteine5 have been described. 5-8% of White British and German populations are poor hydroxylators of these drugs. It has been suggested that poor debrisoquine hydroxylators may be at risk of side effects from other drugs whose hydroxylation is subjected to the same
polymorphism. We have found evidence for a covariation between Sjöqvist F. Steady-state plasma levels of nortriptyline in Influence of genetic factors and drug therapy. Br Med J1969; iv: 764-68. 2. Alexanderson B. Prediction of steady-state plasma levels of nortriptyline from single oral dose kinetics: a study in twins. Eur J Clin Pharmacol 1973; 6: 44-53 3. Sjöqvist F. Assessment of antidepressants: Pharmacokinetic aspects. In: Breckenridge AM ed. Advanced medicine: Topics in therapeutics. London: Pitman Medical Publishing, 1975: 198-217. 4. Mahgoub A, Idle JR, Dring LG. et al. Polymorphic hydroxylation of debrisoquine in man. Lancet 1979; ii: 584-86. 5. Eichelbaum M, Spannbrucker N, Steinecke B. et al. Defective N-oxidation of spartein in man a new pharmacogenetic defect. Eur J Clin Pharmacol 1979; 16: 183-87 6. Sloan TP, Mahgoub A, Lancaster R. et al. Polymorphism of carbon oxidation of drugs and clinical implications. Br Med J 1978; ii: 655-57. 1. Alexanderson B, Evans DAP, twins:
Fig. I-NIDDM: insulin response to glucose pulses before and during ASA administration.
561
nortriptyline (NT) and debrisoquine hydroxylation,7and report here a patient who had unusually high plasma concentrations of NT and adverse reactions on a low dose and who also had an inability to hydroxylate debrisoquine. A 69-year-old woman (weighing 51 kg) was admitted to hospital foramoderately severe depression of the endogenous type and given nortriptyline in a low dosage (25 mg three times daily). 2 days after the start of treatment she complained of dizziness (blood pressure 110170 mm Hg). After a further 6 days of treatment (total dose 525 mg) she complained of increasing tiredness and vertigo and since she also appeared slightly confused, slow clearance of nortriptylinewas suspected. A blood sample was taken for NT analysis, and the dosage was immediately reduced to 25 mg once daily. The plasma concentration of nortriptyline after 8 days’ treatment was 1300 nmol/l (usual range on this dosage 200-600). The concentration on 25 mg daily for 12 days was 742 nmol/l. The plasma clearance of NT was 100 ml/h/kg body weight (usual range 200-1300), calculated from the ratio between the dosage and the area under the plasma-concentration/time curve during one dosage interval. Urinary analysis revealed that 49% of the dose was excreted as 10-hydroxynortriptyline. When the dosage was further reduced to 20 mg nortriptyline at night the patient had no side effects and made an excellent recovery. Her previous history had been uneventful, but she had noticed that she tended to react with exaggerated tiredness to sedatives of the benzodiazepine type. 1 mg of diazepam and 255 mg of nitrazepam were the highest dosages of these compounds that she would tolerate. 30 days after she had stopped taking nortriptyline the patient was
subjected to a debrisoquine (10 mg) phenotyping test.4Urinary recovery within the first 6 h was 24% as unchanged debrisoquine but only 0’6% as 4-hydroxydebrisoquine, both being determined by mass fragmentography. The ratio between parent compound and metabolite (426) is the highest found so far in a Swedish population (n= 150) and classifies the patient as a poor debrisoquine hydroxylator. 7 Together with findings in healthy volunteers our observation suggests that slow hydroxylation of nortriptyline and poor debrisoquine hydroxylation may be determined by similar genetic factors. The much higher frequency of poor debrisoquine hydroxylators in Britons than in Swedes (81’ 5%) is of interest in relation to the report by Montgomery et al.8 describing plasma concentrations of nortriptyline in British patients. They found a higher proportion of patients with excessive plasma concentrations of NT relative to dosage than we have even seen. Since the metabolism of various tricyclic antidepressants shows intraindividual covariation9the
possibility of slow hydroxylation should be considered by any physician prescribing this group of drugs. Department of Clinical Pharmacology, (at Huddinge Hospital), Karolinska Institute, S-141 86 Huddinge, Sweden
Department of Psychiatry, (at Karolinska Hospital), Karolinska Institute, Stockholm
LEIF BERTILSSON BRITT MELLSTRÖM FOLKE SJÖQVIST
BJÖRN MÅRTENSSON MARIE ÅSBERG
ORGANIC SOLVENTS AND T LYMPHOCYTES
SIR,-As Dr Moszczynski (Feb. 21. p. 438) says, there is a need for far more measurement of the biological effects of exposure to industrial chemicals. To prevent occupational disease, effective action needs to be taken at the point where there is evidence of excessive absorption but none of frank illness; but to determine where that point is for a particular toxic substance requires many more studies of the kind he has undertaken. There are a few
industrial poisons, notably lead, on whose effects sufficient work has been done to enable us to define with reasonable confidence the level of absorption calling for removal from exposure, but for the vast majority we lack any such criteria. Hence his work is to be welcomed, and his findings are interesting. However, it is in general desirable that the exposure of the population studied should be specified with the same degree of precision as is applied to the measurement of the effects. All too often this is not done. Moszczynski does not provide the timeweighted average air concentration of the solvents, and we are left wondering whether the alarming maximum figure for benzene (370 mg/m3, which is more than 12 times the threshold limit value of 30 recommended by the American Conference of Governmental Industrial Hygienists) was a sporadic freak reading or whether working levels were habitually at or near this figure. Benzene is known, as he says, to be associated with neoplasms of the lymphoreticular system but toluene and xylene are not, and it is unfortunate that his population was exposed to all three solvents in unknown proportions. Presumably he did not have access to a group exposed to only one of them; but his results would have been much more useful if he had. It is, incidentally, disquieting to read that benzene is still in use as a solvent in the paint and varnish industry, when so many safer substitutes are available. The Homestead, Bettws Newydd,
F. H. TYRER
Usk, Gwent NP5 1JN
TRILOSTANE INTERFERENCE WITH FLUORIMETRIC STEROID ASSAYS
SIR,-Trilostane (’Modrenal’; Sterling Research Laboratories) is a new
synthetic steroid which is now freely available as an adrenal
blocking agent. It lacks any innate hormonal activity and is a competitive inhibitor of the 3(3-hydroxysteroid dehydrogenase: A5-isomerase enzyme system in both laboratory animals and in man.
It is recommended for
overactivity such
use
in conditions of adrenocortical and primary
Cushing’s syndrome
aldosteronism. We have used trilostane in the preoperative treatment of a woman with Cushing’s syndrome due to an adrenal adenoma, monitoring the adrenal response by measuring plasma and urinary 11-hydroxycorticosteroids by fluorimetry. 1,2,3 The plasma 11-hydroxycorticosteroid levels were unexpectedly high, and preliminary experiments showed that trilostane fluoresces strongly in ethanolic sulphuric acid. Thus it seemed probable that trilostane or one of its metabolites was causing a spurious fluorescence which interferes with this assay. If the methylene dichloride extract of a standard solution of trilostane is subjected to an alkali wash, all fluorescence disappears. We have modified the original plasma method by shaking the methylene dichloride extracts with 2 ml of 01 mol/1 sodium hydroxide for 30 s. The aqueous layer is then removed by suction before the extracts are added to the fluorescence reagent. This procedure appears to remove the spurious fluorescence completely without affecting the plasma corticosteroid levels. This modification is unnecessary when estimating urinary corticosteroids by fluorescence since an alkali wash is an integral part of that method. Now that trilostane is freely available it is likely that it will be given to an increasing number of patients, and other workers may also have difficulty in interpreting results obtained by fluorimetric assay. For this reason, we felt that it was worthwhile to make this preliminary report. Postgraduate Medical School, University of Exeter, Exeter EX2 5DW
7. Bertilsson L, Eichelbaum M, Mellström B. et al. Nortriptyline and antipyrine clearance in relation to debrisoquine hydroxylation m man. Life Sci 1980; 27: 1673-77. 8. Montgomery S, Braithwaite RA, Crammer JL. Routine nortriptyline levels in the treatment of depression. Br Med J 1977; iii: 166-67. 9. Sjöqvist F, Bertilsson L, Asberg M. Monitoring tricyclic antidepressants. Ther Drug Monitoring 1980; 2: 85-93.
as
1.
Mattingly
D.
A
D. MATTINGLY CHRISTINE TYLER
simple fluorimetric method for the
estimation
of free
11-hydroxycorticoids in human plasma J Clin Pathol 1962; 15: 374. 2. Mattingly D, Dennis PM, PearsonJ, Cope CL. Rapid screening test for adrenal cortical 3.
function. Lancet 1964; ii: 1046. James VHT, Mattingly D, Daly JR. Recommended method for the determination of plasma cortico-steroids. Br Med J 1971; ii: 310.
SiR,-A beneficial effect of sodium salicylate in human diabetesI mellitus has been reported in the older pharmacopoeias. Ebstein,l Bartels,2and Williamson3noted that this drug progressively diminished glycosuria, polyuria, and polydipsia and increased weight and strength when given to diabetics in doses of 5-16 g daily. Later studies have also reported reduction of fasting blood glucose in non-diabetics 5,6 and improvement of blood-glucose in noninsulin-dependent diabetics.6 These effects were associated with markedly enhanced insulin levels. Since the prostaglandins of the E series seem to have the opposite effects of salicylates,°9 it has been suggested that the mechanism of salicylate action upon both insulin secretion and carbohydrate tolerance may be through inhibition of endogenous prostaglandin E synthesis. We have studied the effect of lysine acetylsalicylate, a watersoluble salt of acetylsalicylic acid (ASA), upon insulin responses to glucose in eight patients with non-insulin-dependent diabetes mellitus (NIDDM) and seven with insulin-dependent diabetes (IDDM). The patients with NIDD were aged 42-60 and had fasting plasma glucose values of 175±20 mg/dl (18 mg/dl =mmol/1) (insulin 12±3 U/ml), they were receiving diet alone and at the time of the study were taking no drugs. Patients with IDD ranged in age from 21 to 55 and were known to have had diabetes for 2-35 years; fasting plasma glucose concentrations were 160±19 mg/dl (C-peptide = 0’92±0-12 ng/ml); and they were on insulin therapy, one or two injections daily. All diabetics received two consecutive glucose pulses (20 g) 90 min apart. therapie des diabetes mellitus insbesondere uber die anwendeng der salicylsauren natron bei demselben. Berliner Klin Wschr 1876; 13: 337-40. Bartels (Kiel). Uber die therapeutische verwerthung der salicylsaure und ihres
In
patients with NIDDM (fig. 1), the acute insulin response to glucose was significantly increased by ASA. The response before ASA was 5±2%; during ASA it was 70±12%, response being expressed as the mean change in 3-10 min insulin (% basal) Second phase insulin secretion was also altered (p<0’01). (800±90% before ASA; 3460±570% during ASA) response here being judged as the mean change at 10-60 min in U ml-1 expressed as % basal (p<0 - 01). These effects were associated with a significant increase in glucose disappearance rates (first KG 0 -. 48±004, second KG 0 -98:t0 .09 %/min, p<0’ 01).). In patients with IDDM, ASA did not alter the acute C-peptide response to the same glucose pulse (fig. 2) or the glucose disappear=
=
1. Ebstein W. Zur
2.
natronsalzesin der inneren medicin. Dtsch Med Wschr 1878; 4: 423-25. glycosuria and diabetes mellitus with sodium salicylate. Br Med J 1901; i: 760-62. 4. Giugliano D, Torella R, Siniscalchi N, Improta L, D’Onofrio F. The effect of acetylsalicylic acid on insulin response to glucose and arginine in man. Diabetologia 1978; 14: 359-62. 5. Torella R, Giugliano D, Siniscalchi N, Sgambato S, D’Onofrio F. Effect of acetylsalicylic acid on plasma glucose, insulin, glucagon and growth hormone levels following tolbutamide stimulation in man. Metabolism 1979; 28: 887-89. 6. Giugliano D, Cacciapuoti F, Varricchio M. Acetylsalicylic acid augments insulin and C-peptide response to arginine in diabetes mellitus Prostaglandins Med 1979, 2: 109-10. 7. Giugliano D, Torella R. Prostaglandin E1 inhibits glucose-induced insulin secretion in man. Prostaglandins Med 1978; 1: 166-67. 8. Giugliano D, Torella R, Improta L, D’Onofrio F. Effects of prostaglandin E1 and prostaglandin F2a on insulin and glucagon plasma levels during the intravenous glucose tolerance test in man. Diabète Metab 1978; 4: 187-91. 9. Robertson RP, Chen M. A role for prostaglandin E in defective insulin secretion and carbohydrate intolerance in diabetes mellitus. J Clin Invest 1977; 60: 747-53.
Fig. 2-IDDM: C-peptide response during ASA administration.
to
glucose pulses before and
3. Williamson RT. On the treatment of
(first I = 032:t0’03, second Ke =0’29i:0’03 %/min). These results suggest that endogenous PGEs may be one of the factors that impair insulin secretion in NIDDM, and they add further evidence to the concept of a different pathogenesis between NIDDM and IDDM.
ance rates
Institute of Medical Pathology, I Faculty of Medicine,
80138 Naples, Italy
D. GIUGLIANO
SLOW HYDROXYLATION OF NORTRIPTYLINE AND CONCOMITANT POOR DEBRISOQUINE HYDROXYLATION: CLINICAL IMPLICATIONS
SIR,-Genetically determined slow hydroxylation of tricyclic antidepressants explains why occasional patients experience concentration dependent side effects on low doses.I-3The ability of a patient to accumulate these drugs to toxic levels can be predicted from the the kinetics of a single oral dose2and prevented by monitoring concentration continuous during steady-state plasma therapy. Polymorphisms in drug oxidation involving aliphatic hydroxylation of debrisoquineand N-oxidation of sparteine5 have been described. 5-8% of White British and German populations are poor hydroxylators of these drugs. It has been suggested that poor debrisoquine hydroxylators may be at risk of side effects from other drugs whose hydroxylation is subjected to the same
polymorphism. We have found evidence for a covariation between Sjöqvist F. Steady-state plasma levels of nortriptyline in Influence of genetic factors and drug therapy. Br Med J1969; iv: 764-68. 2. Alexanderson B. Prediction of steady-state plasma levels of nortriptyline from single oral dose kinetics: a study in twins. Eur J Clin Pharmacol 1973; 6: 44-53 3. Sjöqvist F. Assessment of antidepressants: Pharmacokinetic aspects. In: Breckenridge AM ed. Advanced medicine: Topics in therapeutics. London: Pitman Medical Publishing, 1975: 198-217. 4. Mahgoub A, Idle JR, Dring LG. et al. Polymorphic hydroxylation of debrisoquine in man. Lancet 1979; ii: 584-86. 5. Eichelbaum M, Spannbrucker N, Steinecke B. et al. Defective N-oxidation of spartein in man a new pharmacogenetic defect. Eur J Clin Pharmacol 1979; 16: 183-87 6. Sloan TP, Mahgoub A, Lancaster R. et al. Polymorphism of carbon oxidation of drugs and clinical implications. Br Med J 1978; ii: 655-57. 1. Alexanderson B, Evans DAP, twins:
Fig. I-NIDDM: insulin response to glucose pulses before and during ASA administration.
561
nortriptyline (NT) and debrisoquine hydroxylation,7and report here a patient who had unusually high plasma concentrations of NT and adverse reactions on a low dose and who also had an inability to hydroxylate debrisoquine. A 69-year-old woman (weighing 51 kg) was admitted to hospital foramoderately severe depression of the endogenous type and given nortriptyline in a low dosage (25 mg three times daily). 2 days after the start of treatment she complained of dizziness (blood pressure 110170 mm Hg). After a further 6 days of treatment (total dose 525 mg) she complained of increasing tiredness and vertigo and since she also appeared slightly confused, slow clearance of nortriptylinewas suspected. A blood sample was taken for NT analysis, and the dosage was immediately reduced to 25 mg once daily. The plasma concentration of nortriptyline after 8 days’ treatment was 1300 nmol/l (usual range on this dosage 200-600). The concentration on 25 mg daily for 12 days was 742 nmol/l. The plasma clearance of NT was 100 ml/h/kg body weight (usual range 200-1300), calculated from the ratio between the dosage and the area under the plasma-concentration/time curve during one dosage interval. Urinary analysis revealed that 49% of the dose was excreted as 10-hydroxynortriptyline. When the dosage was further reduced to 20 mg nortriptyline at night the patient had no side effects and made an excellent recovery. Her previous history had been uneventful, but she had noticed that she tended to react with exaggerated tiredness to sedatives of the benzodiazepine type. 1 mg of diazepam and 255 mg of nitrazepam were the highest dosages of these compounds that she would tolerate. 30 days after she had stopped taking nortriptyline the patient was
subjected to a debrisoquine (10 mg) phenotyping test.4Urinary recovery within the first 6 h was 24% as unchanged debrisoquine but only 0’6% as 4-hydroxydebrisoquine, both being determined by mass fragmentography. The ratio between parent compound and metabolite (426) is the highest found so far in a Swedish population (n= 150) and classifies the patient as a poor debrisoquine hydroxylator. 7 Together with findings in healthy volunteers our observation suggests that slow hydroxylation of nortriptyline and poor debrisoquine hydroxylation may be determined by similar genetic factors. The much higher frequency of poor debrisoquine hydroxylators in Britons than in Swedes (81’ 5%) is of interest in relation to the report by Montgomery et al.8 describing plasma concentrations of nortriptyline in British patients. They found a higher proportion of patients with excessive plasma concentrations of NT relative to dosage than we have even seen. Since the metabolism of various tricyclic antidepressants shows intraindividual covariation9the
possibility of slow hydroxylation should be considered by any physician prescribing this group of drugs. Department of Clinical Pharmacology, (at Huddinge Hospital), Karolinska Institute, S-141 86 Huddinge, Sweden
Department of Psychiatry, (at Karolinska Hospital), Karolinska Institute, Stockholm
LEIF BERTILSSON BRITT MELLSTRÖM FOLKE SJÖQVIST
BJÖRN MÅRTENSSON MARIE ÅSBERG
ORGANIC SOLVENTS AND T LYMPHOCYTES
SIR,-As Dr Moszczynski (Feb. 21. p. 438) says, there is a need for far more measurement of the biological effects of exposure to industrial chemicals. To prevent occupational disease, effective action needs to be taken at the point where there is evidence of excessive absorption but none of frank illness; but to determine where that point is for a particular toxic substance requires many more studies of the kind he has undertaken. There are a few
industrial poisons, notably lead, on whose effects sufficient work has been done to enable us to define with reasonable confidence the level of absorption calling for removal from exposure, but for the vast majority we lack any such criteria. Hence his work is to be welcomed, and his findings are interesting. However, it is in general desirable that the exposure of the population studied should be specified with the same degree of precision as is applied to the measurement of the effects. All too often this is not done. Moszczynski does not provide the timeweighted average air concentration of the solvents, and we are left wondering whether the alarming maximum figure for benzene (370 mg/m3, which is more than 12 times the threshold limit value of 30 recommended by the American Conference of Governmental Industrial Hygienists) was a sporadic freak reading or whether working levels were habitually at or near this figure. Benzene is known, as he says, to be associated with neoplasms of the lymphoreticular system but toluene and xylene are not, and it is unfortunate that his population was exposed to all three solvents in unknown proportions. Presumably he did not have access to a group exposed to only one of them; but his results would have been much more useful if he had. It is, incidentally, disquieting to read that benzene is still in use as a solvent in the paint and varnish industry, when so many safer substitutes are available. The Homestead, Bettws Newydd,
F. H. TYRER
Usk, Gwent NP5 1JN
TRILOSTANE INTERFERENCE WITH FLUORIMETRIC STEROID ASSAYS
SIR,-Trilostane (’Modrenal’; Sterling Research Laboratories) is a new
synthetic steroid which is now freely available as an adrenal
blocking agent. It lacks any innate hormonal activity and is a competitive inhibitor of the 3(3-hydroxysteroid dehydrogenase: A5-isomerase enzyme system in both laboratory animals and in man.
It is recommended for
overactivity such
use
in conditions of adrenocortical and primary
Cushing’s syndrome
aldosteronism. We have used trilostane in the preoperative treatment of a woman with Cushing’s syndrome due to an adrenal adenoma, monitoring the adrenal response by measuring plasma and urinary 11-hydroxycorticosteroids by fluorimetry. 1,2,3 The plasma 11-hydroxycorticosteroid levels were unexpectedly high, and preliminary experiments showed that trilostane fluoresces strongly in ethanolic sulphuric acid. Thus it seemed probable that trilostane or one of its metabolites was causing a spurious fluorescence which interferes with this assay. If the methylene dichloride extract of a standard solution of trilostane is subjected to an alkali wash, all fluorescence disappears. We have modified the original plasma method by shaking the methylene dichloride extracts with 2 ml of 01 mol/1 sodium hydroxide for 30 s. The aqueous layer is then removed by suction before the extracts are added to the fluorescence reagent. This procedure appears to remove the spurious fluorescence completely without affecting the plasma corticosteroid levels. This modification is unnecessary when estimating urinary corticosteroids by fluorescence since an alkali wash is an integral part of that method. Now that trilostane is freely available it is likely that it will be given to an increasing number of patients, and other workers may also have difficulty in interpreting results obtained by fluorimetric assay. For this reason, we felt that it was worthwhile to make this preliminary report. Postgraduate Medical School, University of Exeter, Exeter EX2 5DW
7. Bertilsson L, Eichelbaum M, Mellström B. et al. Nortriptyline and antipyrine clearance in relation to debrisoquine hydroxylation m man. Life Sci 1980; 27: 1673-77. 8. Montgomery S, Braithwaite RA, Crammer JL. Routine nortriptyline levels in the treatment of depression. Br Med J 1977; iii: 166-67. 9. Sjöqvist F, Bertilsson L, Asberg M. Monitoring tricyclic antidepressants. Ther Drug Monitoring 1980; 2: 85-93.
as
1.
Mattingly
D.
A
D. MATTINGLY CHRISTINE TYLER
simple fluorimetric method for the
estimation
of free
11-hydroxycorticoids in human plasma J Clin Pathol 1962; 15: 374. 2. Mattingly D, Dennis PM, PearsonJ, Cope CL. Rapid screening test for adrenal cortical 3.
function. Lancet 1964; ii: 1046. James VHT, Mattingly D, Daly JR. Recommended method for the determination of plasma cortico-steroids. Br Med J 1971; ii: 310.