Priapism trazodone-induced

Trazodone-induced priapism may be mediated by alpha-adrenoceptor antagonism. While the mechanism for cocaine-induced priapism is unclear, it may result from vasospasm, venous pooling, and sludging of blood in the penis. The authors proposed that the two drugs may act in an additive or synergistic manner, posing a greater hazard than either alone. 

Trazodone, 25 to 100 mg, is often used for insomnia induced by selective serotonin reuptake inhibitors or bupropion. Side effects include serotonin syndrome (when used with other serotonergic drugs), oversedation, a-adrenergic blockade, dizziness, and rarely priapism. 

SERT. However, trazodone has rarely been associated with inducing priapism. The effects of both nefazodone and trazodone since tx-blocking agents result in a dose-related orthostatic hypotension in some patients. Nefazodone has been associated with hepatotoxicity, including rare fatalities and cases of fulminant hepatic failure requiring transplantation. The rate of serious hepatoxicity with nefazodone has been estimated at 1 in 250,000 to 1 in 300,000 patient-years of nefazodone treatment. 

A rare but potentially serious adverse effect of trazodone is priapism, which is reported to occur in approximately 1 in 6000 male patients. Some cases have required surgical intervention (1 in 23,000), and permanent impotence may result. There have been no reports of priapism associated with nefazodone use in men, but there is a published case report of nefazodone-induced clitoral priapism. ... 

The MAO inhibitor tranylcypromine is amphetamine-like in structure but interacts only weakly at DA transporters. The phenylpiperazine nefazodone, and to a lesser extent, the structurally related trazodone have weak inhibitory actions on 5-HT transport nefazodone also may have a minor effect on NE transport. This agent also has a prominent direct antagonistic effect at S-HT receptors that may contribute to antidepressant and anxiolytic activity. Both drugs also may inhibit presynaptic 5-HTj subtype autoreceptors to enhance neuronal release of 5-HT, though they probably also exert at least partial-agonist effects on postsynaptic 5-HTj receptors. Trazodone also blocks cerebral and Hj receptors, possibly contributing to its tendency to induce priapism and sedation, respectively. 

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