Brief ReportsPriapism Associated With Antipsychotics Role of α1 Adrenoceptor AffinityAndersohn, Frank MD*; Schmedt, Niklas BPH†; Weinmann, Stefan MD*; Willich, Stefan N. MD, MPH*; Garbe, Edeltraut MD, PhD† Author Information From the *Institute for Social Medicine, Epidemiology and Health Economics, Charité-University Medical Center, Berlin; and †Bremen Institute for Prevention Research and Social Medicine, University of Bremen, Bremen, Germany. Received May 11, 2009; accepted after revision October 19, 2009. Reprints: Frank Andersohn, MD, Institute for Social Medicine, Epidemiology and Health Economics, Charité-University Medical Center, 10098 Berlin, Germany (e-mail: [email protected]). Journal of Clinical Psychopharmacology: February 2010 - Volume 30 - Issue 1 - p 68-71 doi: 10.1097/JCP.0b013e3181c8273d Buy Metrics Abstract Case reports indicate that antipsychotics can cause priapism, a persistent penile erection possibly leading to erectile dysfunction. The mechanism of antipsychotic-induced priapism is thought to be related to blockade of α1 adrenergic receptors, but clinical data supporting this hypothesis are lacking. The aim of this study was to investigate if the presence of safety signals for antipsychotics and priapism is associated with their α1 affinity. Spontaneous reports of adverse drug reactions contained in the US Adverse Event Reporting System database were used to calculate reporting odds ratios (RORs) of priapism for antipsychotics. In total, 426 cases of priapism with 144 of them attributed to antipsychotics were identified. For antipsychotics with high α1 affinity, the adjusted ROR was markedly elevated (ROR = 9.9; 95% CI, 7.9-12.4), whereas a weaker signal was observed for antipsychotics with low/medium α1 affinity (ROR = 3.6; 95% CI, 2.4-5.2). Signals were present for chlorpromazine, quetiapine, risperidone, ziprasidone, and aripiprazole. After restricting the analysis to cases with medical intervention or disability, the safety signal remained evident only for antipsychotics with high but not for those with low/medium affinity. The observed pattern of signals indicates a relationship between α1 affinities of antipsychotics and the occurrence of priapism. © 2010 Lippincott Williams & Wilkins, Inc.