Has decreased testosterone been reported as a side-effect of lamotrigine treatment?/nA 26-year-old

Fråga: Has decreased testosterone been reported as a side-effect of lamotrigine treatment?

A 26-year-old man with epilepsy has been treated with lamotrigine for two years. He experiences decreased libido and has a low level of unbound testosterone (4.5 nmol/L, reference value 6.3 16 nmol/L), and also a low level of sex hormone-binding globulin. He has no other known diseases or medications.

Sammanfattning: We have found no support in the literature that lamotrigine should cause a decrease in testosterone levels or of the sexual function.

Svar: It has been suggested that sexual dysfunction is common in patients with epilepsy, and that the etiology is probably multifactorial, involving neurological, endocrine, psychosocial and pharmacological causes (1). Enzyme inducing antiepileptic drugs, such as carbamazepine and fenytoin, are known to increase the metabolism of sex hormones, leading to an increased risk of sexual dysfunction (2, 3). Lamotrigine has in several studies been shown not to affect the levels of sex hormones or sexual function (2-5). On the contrary, there are a few case reports in the literature describing hypersexuality or improved sexual function after starting lamotrigine therapy (6, 7). Finally, in the Swedish register of adverse drug reactions, there is one report (among a total of 338) concerning impotence in a 57-year-old man after a dose increase from 200 mg to 400 mg daily of lamotrigine. No dechallenge was performed and the report was evaluated as unclassifiable (8). Lambert MV. Seizures, hormones and sexuality. Seizure 2001;10(5):319-340 Mikkonen K, Tapanainen P, Pakarinen AJ, Paivansalo M, Isojarvi JI, Vainionpaa LK. Serum androgen levels and testicular structure during pubertal maturation in male subjects with epilepsy. Epilepsia 2004;45(7):769-776 Herzog AG, Drislane FW, Schomer DL, Pennell PB, Bromfield EB, Dworetzky BA et al. Differential effects of antiepileptic drugs on neuroactive steroids in men with epilepsy. Epilepsia 2006;47(11):1945-1948 Morrell MJ, Isojarvi J, Taylor AE, Dam M, Ayala R, Gomez G et al. Higher androgens and weight gain with valproate compared with lamotrigine for epilepsy. Epilepsy Res 2003;54(2-3):189-199 Stephen LJ, Sills GJ, Leach JP, Butler E, Parker P, Hitiris N et al. Sodium valproate versus lamotrigine: a randomised comparison of efficacy, tolerability and effects on circulating androgenic hormones in newly diagnosed epilepsy. Epilepsy Res 2007;75(2-3):122-129 Grabowska-Grzyb A, Naganska E, Wolanczyk T. Hypersexuality in two patients with epilepsy treated with lamotrigine. Epilepsy Behav 2006;8(3):663-665 Husain AM, Carwile ST, Miller PP, Radtke RA. Improved sexual function in three men taking lamotrigine for epilepsy. South Med J 2000;93(3):335-336