Is impotence a side effect of lithium?/nA patient treated with lithium for one year (5 tabl/day, S-

Fråga: Is impotence a side effect of lithium? A patient treated with lithium for one year (5 tabl/day, S-Li is about 0.8 mmol/L). After one year he reported impaired erection without loss of libido. Is treated also with imipramine (Tofranil) 100 mg/day. Received perphenazine until June 1987.

Sammanfattning: Erectile impotence has been reported as an adverse effect associated with lithium and imipramine therapy.

Svar: To our knowledge there have been only two reports on the effect of lithium on sexual function. Blay et al (1) reported in 1982 two cases of male patients with loss of libido and impairment of erection ability associated with lithium therapy. One case remitted after placebo substitution and the other disappeared spontaneously despite continued lithium treatment. Vinarova et al (2) reported difficulty in achieving and maintaining erection in 5 out of 33 patients on lithium. Potency promptly returned after these patients were taken off the drug and/or substituted with placebo. Lithium carbonate has been proposed to impair erectile potency by a number of different mechanisms such as depression of dopaminergic activity by decreasing receptor sensitivity, increasing intraneuronal transmitter turnover, or impairing release (3). However, as the mechanism of action of lithium in the treatment of mania and manic-depressive illness remains unknown it is impossible to suggest pharmacological mechanism of action for this adverse effect.

Impotence due to loss of erectile function has been reported in at least 30 patients taking most of the commonly used tricyclic compounds in the low normal dose range (4). Theoretically any drug with anticholinergic properties may produce erectile impotence by affecting the dilation of the blood vessels in the penis and imipramine (Tofranil) has been associated with this effect in some investigations (5,6,7). Furthermore imipramine is also a prolactin releasing agent and may cause decrease of libido and erectile impotence by hormonal mechanisms (3,5,8,9).