Pathophysiology of prolonged penile erection associated with trazodone use.

Treatment with the antidepressant trazodone has been associated with the occurrence of prolonged penile erection and priapism. To evaluate the effect of trazodone on erection we monitored the periodic physiological sleep-related erections in 6 healthy volunteers in a double-blind crossover study comparing the effect of trazodone, trimipramine (a tricyclic antidepressant) and placebo. In addition, to determine the effects of trazodone on the neurovascular control of penile smooth muscle we performed in vitro studies on corpus cavernosum tissue obtained from patients undergoing penile prosthesis implantation. Trazodone significantly increased the total interval of nocturnal erectile activity, while trimipramine had no effect. During the high dose treatment (nights 4 and 5) the average duration of erectile activity per night with placebo was 158 +/- 41 minutes (mean +/- standard deviation) for night 4 and 177 +/- 21 minutes for night 5. During trazodone treatment the erectile activity per night was significantly prolonged to 285 +/- 115 minutes during night 4 and 232 +/- 86 during night 5 (p less than 0.01). Analysis of the erectile activity in relation to the rapid eye movement sleep period during which erectile activity usually occurs revealed that the detumescence phase of erection, under sympathetic control, was significantly prolonged an average of 2.4 times by trazodone compared to placebo (p less than 0.05). In vitro, trazodone at concentrations comparable to those reached in plasma significantly impaired corporeal smooth muscle contractions elicited by electrical stimulation of adrenergic nerves and antagonized contractions induced by exogenous norepinephrine. We conclude that trazodone can enhance penile erection in man and propose a mechanism related to the alpha-adrenoceptor blocking properties of trazodone by interference with the sympathetic control of penile detumescence.

Increased deep sleep after trazodone use: a double-blind placebo-controlled study in healthy young adults.

The effects of trazodone on sleep were compared with those of placebo and the sedating tricyclic antidepressant trimipramine in a double-blind crossover study in six healthy young men. Only trazodone significantly increased deep sleep without otherwise altering the normal architecture of sleep. The alpha-adrenergic receptor-blocking property of trazodone and a relative lack of noradrenergic reuptake blocking and the lack of anticholinergic effects are hypothesized to be responsible for the effects on sleep.

Effects on sleep: a double-blind study comparing trimipramine to imipramine in depressed insomniac patients.

Trimipramine, a sedating tricyclic antidepressant, and imipramine were compared on polysomnographic parameters during a 4-week double-blind trial in depressed patients with insomnia and anxiety. Trimipramine eliminated objective evidence of sleep disturbance. This was not the case with imipramine, although depression improved similarly in both groups. Subjects' sleep appeared unchanged or more disturbed at the end of the treatment with imipramine. For trimipramine, the major changes in sleep parameters occurred during the first week of drug administration and did not parallel the gradual changes seen in the measures of depression. Additionally, trimipramine did not suppress REM sleep even in a subgroup of six trimipramine patients who had short rapid-eye-movement (REM) sleep latencies during the placebo baseline period, even though their depression was alleviated. The data demonstrate that (a) antidepressants may vary in their effects on sleep, even though they have similar effects on depression; (b) REM sleep suppression does not necessarily accompany improvement in depression; and (c) reports of improved sleep by patients undergoing antidepressant therapy may not reflect improvement on objective measures of sleep. The different sleep effects suggest the possibility of different antidepressant pathways.

Peripheral vasoconstriction in patients with sleep related periodic leg movements.

Two patients complaining of insomnia had sleep-related periodic leg movements (nocturnal myoclonus) on polysomnographic evaluation. Both also complained of cold feet and had abnormal peripheral pulse examinations. Treatment with phenoxybenzamine, alpha-adrenergic blocker, normalized the peripheral pulse responses, reduced the complaint of insomnia, and reduced the sleep related leg movements but resulted in only mild sleep improvements. Peripheral pulse examinations of ten other patients with sleep-related periodic leg movements revealed abnormal responses in four. From these and other results, it is hypothesized that the sympathetic nervous system may mediate the periodicity of sleep related periodic leg movements.