Randomized controlled trial of sildenafil for preventing recurrent ischemic priapism in sickle cell disease

Abstract

Background: Successful preventive therapy for ischemic priapism, a disorder of penile erection with major physical and psychologic consequences, is limited. We conducted a randomized, double-blind, placebo-controlled clinical trial to assess the efficacy and safety of sildenafil by a systematic dosing protocol to prevent recurrent ischemic priapism associated with sickle cell disease.

Methods: Thirteen patients with sickle cell disease reporting priapism recurrences at least twice weekly were randomized to receive sildenafil 50 mg or placebo daily, unassociated with sleep or sexual activity, for 8 weeks, followed by open-label use of this sildenafil regimen for an additional 8 weeks.

Results: Priapism frequency reduction by 50% did not differ between sildenafil and placebo groups by intention-to-treat or per protocol analyses (P = 1.0). However, during open-label assessment, 5 of 8 patients (62.5%) by intention-to-treat analysis and 2 of 3 patients (66.7%) by per protocol analysis met this primary efficacy outcome. No significant differences were found between study groups in rates of adverse effects, although major priapism episodes were decreased 4-fold in patients monitored "on-treatment."

Conclusions: Sildenafil use by systematic dosing may offer a strategy to prevent recurrent ischemic priapism in patients with sickle cell disease.

Keywords: Erectile dysfunction; Erection; Nitric oxide; Phosphodiesterase type 5.

Figure 1

(A) Difference in patient episode scores at the end of phase 1 from the initial baseline. (B) Difference in patient episode scores at the end of phase 2 from the reset baseline. Decreasing scores indicate improvement in reported episode score. *Patients meeting protocol adherence. Pt = patient.