Occurrence of stuttering priapism on low dose of quetiapine.

Abstract

Stuttering priapism, a distinct category of ischaemic priapism, is characterised by intermittent prolonged penile erections that persist beyond or are unrelated to sexual stimulation (Morrison and Burnett, 2012). Ischaemic priapism can be a rare and idiosyncratic adverse effect of antipsychotics (Sood et al., 2008). It has been suggested that antipsychotics with lower affinity for α1 receptors have reduced potential to cause priapism, and less than a dozen cases of priapism have been reported with quetiapine (Maakaron et al., 2013). Furthermore, the majority of these patients were on higher dosage of quetiapine. We report a case of stuttering priapism which occurred abruptly with 25 mg of quetiapine. A 27-year-old Caucasian single man with no history of coagulopathy, perineal injury or other significant medical conditions or substance abuse presented at a suburban mental health clinic with repeated episodes of painful penile erections after taking 25 mg of quetiapine for anxiety. He was also on duloxetine 60 mg which was initiated 2 weeks previously for obsessive ruminations. Priapism occurred an hour after taking the first dose of quetiapine, and over the next 4 weeks, he had five similar episodes lasting from 2 to 6 hours. No interventions were required to achieve detumescence, and he did not discuss the symptoms with others until his next psychiatric follow-up. Results of blood investigations were unremarkable. Quetiapine was ceased, but duloxetine was continued at the same dosage. There were no further episodes of priapism during next 3 months of follow-up. Quetiapine is widely used in clinical practice and often at relatively lower dosages for anxiety, insomnia and other symptoms. Priapism is not uniquely associated with quetiapine and has been reported as an idiosyncratic adverse effect with typical and atypical antipsychotics and with other psychotropics (Sood et al., 2008). While blockade of α1 receptors with antipsychotics has been proposed by some authors to explain its aetiology, the genesis of ischaemic priapism is likely to be much more complex, with various neural, endothelial, vascular and molecular factors playing a significant role (Morrison and Burnett, 2012). Although in this patient priapism did not recur after quetiapine was ceased, a synergistic role for duloxetine cannot be completely discounted. Psychiatric patients often under-report significant sexual and other adverse effects for a variety of reasons, and our report illustrates the need to be vigilant about monitoring for rare but devastating side effects such as priapism.