Priapism due to a single dose of quetiapine: a case report.

Priapism is characterized by a prolonged and painful erection in the absence of sexual desire and arousal. Priapism is a rare and serious side effect of psychotropic drugs, and is thought to be attributable to blockage of alpha-1 adrenergic receptors in the corpus cavernosum. Although priapism is commonly associated with typical antipsychotics, there are some (but not many) case reports of priapism due to atypical antipsychotics. This side effect has been reported in patients taking ziprasidone, risperidone, clozapine, quetiapine, aripiprazole, and olanzapine. Not all antipsychotics bind to alpha-1 adrenergic receptors with the same intensity; as compared to other antipsychotics, quetiapine has an intermediate affinity. Priapism could be considered an idiosyncratic reaction, because it is correlated neither with the dose nor duration of psychotropic drug use. Herein we present a case of priapism caused by a single 300-mg dose of quetiapine, and a brief review priapism in the light of this case.