Effects of Clomipramine on Sleep EEG and Nocturnal Penile Tumescence

The effects of the tricyclic antidepressant clomipramine on sleep EEG and nocturnal penile tumescence (NPT) were investigated during a long-term study in a normal male control subject. During 21 consecutive days the subject received first placebo for 3 days, then stepwise increasing dosages of clomipramine for 10 days, and finally placebo after withdrawal for 8 days. Under clomipramine, rapid eye movement (REM) sleep was suppressed markedly; an REM rebound occurred after withdrawal. Awake and stages 1 and 2 increased while slow wave sleep was diminished under clomipramine. Those non-REM parameters returned to baseline values after drug cessation. NPT was reduced simultaneously with REM sleep under clomipramine 30 to 75 mg. Under this dosage range, full erections occurred during the later hours of sleep in association with the delayed REM periods. Clomipramine 100 mg prompted a further decrease of NPT, which exceeded the REM suppression. Most of the changes and NPT parameters depended significantly on the dosage and the plasma concentration of clomipramine. After withdrawal, NPT needed 6 days to normalize. Although NPT was disturbed distinctly, no erectile dysfunction, but a decrease of sexual interest and, once, a lack of ejaculation, were reported.