Association of priapism in phenothiazine therapy

We present 4 patients seen in the last 5 years who had taken thioridazine (Mellaril) prior to development of priapism. One of the 4 patients suffered penile trauma while taking the phenothiazine drug and this is another possible etiologic factor in that case. No underlying urologic or hematologic disorders were present. All patients were treated by corporeal aspiration and corpus cavernosum-corpus spongiosum shunts. The mechanism of phenothiazine=induced priapism is hypothesized as being related to its peripheral adrenergic blockade, perhaps directly blocking the sympathetic impulse for detumescence, although a central nervous system effect must be considered as well. Lastly there exists the possibility of coincidence since phenothiazine treatment is becoming more common and was unrelated to the condition in an additional 6 patients with priapism seen during the same period.