The lack of effect of sodium valproate on the pharmacokinetics of oral contraceptive steroids

• Published in: Contraception (Stoneham) Vol. 33; no. 1; pp. 23 - 29
• Main Authors: Crawford, P., Chadwick, D., Cleland, P., Tjia, J., Cowie, Anne, Back, D.J., L'E Orme, M.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 1986; Elsevier Science
• Subjects: Adolescent; Adult; Biological and medical sciences; Birth control; Contraceptives, Oral - metabolism; Drug Interactions; Ethinyl Estradiol - blood; Female; Gynecology. Andrology. Obstetrics; Hormonal contraception; Humans; Kinetics; Levonorgestrel; Medical sciences; Norgestrel - blood; Valproic Acid - pharmacology; Human; Estroprogestagen; Gynecology; Oral administration; Anticonvulsant; Contraceptive; Drug interaction; Sex steroid hormone; Pharmacokinetics; Contraceptive Agents; Ethinyl Estradiol > administraction and dosage; Contraceptive Agents, Progestin > administraction and dosage; Contraceptive Agents > administraction and dosage; Reproductive Control Agents; Levonorgestrel; Contraceptive Agents, Estrogen > administraction and dosage; Biology; Contraception; Hormones; Family Planning; Endocrine System; Treatment; Drugs > pharmacodynamics; Contraceptive Methods > pharmacodynamics; Physiology; Oral Contraceptives > pharmacodynamics; Contraceptive Agents, Female
• ISSN: 0010-7824; 1879-0518
• DOI: 10.1016/0010-7824(86)90028-4

Patients taking anticonvulsants such as phenobarbitone, phenytoin and carbamazepine together with their oral contraceptive steroid may suffer contraceptive failure because of the enzyme-inducing properties of these anticonvulsants. We have examined, in six women, the effect of sodium valproate, an effective broad spectrum anticonvulsant, on the area under the plasma concentration versus time profile (AUC) of ethinyloestradiol (EE 2) and levonorgestrel (Ng). Prior to sodium valproate therapy the mean AUC for EE 2 was 880 ± 109 pg/ml × h (± S.E.) and for levonorgestrel it was 29.1 + 2.9 ng/ml × h (n = 4). Between two and four months after sodium valproate therapy the mean AUC figures had not changed significantly, the figure for EE 2 being 977 ± 130 pg/ml × h and for levonorgestrel 29.2 ± 1.9 ng/ml × h (p ⩾ 0.1 in each case). We conclude that sodium valproate in the dose used (200mg b.d.) does not interact with oral contraceptive steroids.