Priapism has been associated with many antipsychotic agents, including clozapine, risperidone, and olanzapine. This prolonged, usually painful, penile erection rarely results from the alpha-adrenergic blocking action of antipsychotics. A 22-year-old African-American man developed priapism during treatment with risperidone and, on a later occasion, during treatment with ziprasidone. The problem resolved only with substitution of other drugs for these antipsychotics. Certain patients may be more vulnerable than others to this adverse effect. Clinicians must be aware of such complications and use caution when prescribing these drugs.

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A 43-year-old man with chronic back and shoulder pain was treated with hydrocodone. He began taking excessive amounts of the drug, so his physicians stopped prescribing it. The patient then obtained the muscle relaxant carisoprodol on his own from several sources. He was consuming up to 30 or more tablets/day (> or =10,500 mg/day) for several weeks, then abruptly stopped taking the drug. Within 48 hours he developed anxiety, tremors, muscle twitching, insomnia, auditory and visual hallucinations, and bizarre behavior. The symptoms intensified and peaked on the fourth day after carisoprodol cessation. The patient required brief treatment with olanzapine and tapering dosages of lorazepam while the symptoms gradually resolved. To our knowledge, this is the first documented case of a withdrawal syndrome with carisoprodol. The symptoms most likely resulted because of accumulation of meprobamate, the active metabolite of carisoprodol in humans. Clinicians prescribing carisoprodol should be aware of the possibility for abuse or addiction. Further, we recommend that carisoprodol be designated a controlled substance at the federal level.

Electric shock-like sensations may occur after cessation of treatment with serotonin selective reuptake inhibitors but are reported in the literature only rarely with discontinuation of venlafaxine. Two patients experienced severe shock-like sensations during venlafaxine withdrawal. For both patients symptoms occurred with lowering of the dosage and persisted for 5 days after complete discontinuation of the drug. These sensations may represent significant alteration of neuronal activity in the central nervous system.

Clinicians should be aware of potentially serious adverse reactions that may occur during concomitant treatment with antipsychotics and selective serotonin-reuptake inhibitors.

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Clinicians should closely monitor patients receiving both haloperidol and risperidone or combinations of similar medications.

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