Frågedatum: 1993-09-14
RELIS database 1993; id.nr. 9688, DRUGLINE
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A 73-year-old female patient has been treated with amitriptyline (Tryptizol) 125 mg/day since 15/1.



Fråga: A 73-year-old female patient has been treated with amitriptyline (Tryptizol) 125 mg/day since 15/1. The plasma concentrations of amitriptyline (150 nmol/l) and its metabolite nortriptyline (<100 nmol/l) together were less than 250 nmol/l on 25/1 (the recommended therapeutic range is 400-800 nmol/l). The patient has been treated for a long time with medroxyprogesterone (Gestapuran) 5 mg x1 and conjugated oestrogen (Premarina) 1.25 mg x1. The patient also takes oxazepam (Sobril) when necessary.

Could the low concentration of amitriptyline possibly be caused by an interaction with the hormonal treatment? Could these hormonal drugs cause depression?

Sammanfattning: No documentation has been found concerning an interaction between amitriptyline and hormonal drugs. It is unlikely that the low concentration of amitriptyline in this patient was caused by the use of hormonal drugs. Depression caused by female hormones has been reported.

Svar: Chronic oral contraceptive steroid use has been reported to reduce the clearance of some oxidatively metabolised drugs. It has been proposed that oestrogens may affect the metabolism of tricyclic antidepressants (1). In a study of imipramine disposition, users of oral contraceptive steroids had an increased bioavailability and decreased apparent oral clearance compared with controls (2). However, there is no report of any inductive effect of female hormones on the enzymes responsible for the metabolism of antidepressants, although such an effect has been reported for drugs biotransformed by hepatic conjugation (cf 2).

Concerning the side-effects of gestagen drugs, depression has been reported. The risk for this adverse effect is dose dependent (3). 1 Hansten, Drug interactions and updates, page 372 2 Abernethy DR, Greenblatt DJ, Shader RI: Imipramine disposition in users of oral contraceptive steroids. Clin Pharmacol Ther 1984; 35: 792-797 3 Drugline nr 06388 (year 1988) (enclosed)

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