The Oxytocin Antagonist Cligosiban Fails to Prolong Intravaginal Ejaculatory Latency in Men with Lifelong Premature Ejaculation: Results of a Randomized, Double-Blind, Placebo-Controlled Phase IIb trial (PEDRIX)

Abstract

Introduction: Cligosiban is an orally administered, centrally penetrant oxytocin receptor antagonist being developed to treat premature ejaculation (PE).

Aim: To determine the efficacy of 3 dose levels of cligosiban caplets to prolong intravaginal ejaculation latency time (IELT) and improve patient-reported outcomes in men with lifelong PE.

Methods: Patients recorded details of at least 4 sexual intercourse events during a 4-week run-in period, after which they underwent baseline assessments. Patients were eligible for the study if their stopwatch-assessed IELT was ≤1 minute in ≥75% of intercourse attempts and if they met other diagnostic criteria for lifelong PE. Eligible patients (target 220 evaluable) were randomized to double-blind cligosiban 400, 800, or 1200 mg or matching placebo caplets (to be taken 1 to 6 hours prior to sexual activity). Assessments were conducted at 2, 4, and 8 weeks.

Main outcome measure: Efficacy measures were comprised of IELT, self-rating of ejaculation control and ejaculation-related distress (recorded in an electronic diary after each intercourse attempt), premature ejaculation profile, Patient's Global Impression of Severity, and the Clinical Global Impression of Change.

Results: There were no clinically or statistically significant differences between cligosiban (at any dose level) and placebo for the primary endpoint (change in geometric IELT) or any of the secondary endpoints. Cligosiban was well tolerated with a side-effect profile similar to placebo.

Clinical implications: This Phase IIb study failed to demonstrate the potential for cligosiban, an oxytocin antagonist, to successfully treat symptoms of severe lifelong PE at doses up to 1200 mg.

Strengths and limitations: This was a Phase IIb, randomized, double-blind, placebo-controlled study that was adequately powered but failed to detect a clinically meaningful or statistical difference in change in IELT between cligosiban at 3 dose levels and placebo. This is in contrast to a similarly designed proof-of-concept study where cligosiban was flexibly dosed at doses up to 800 mg and did demonstrate clinically meaningful and statistically significant changes in efficacy parameters. The reasons for this disparity are not known.

Conclusions: Cligosiban was well tolerated but failed to demonstrate efficacy for the treatment of men with lifelong PE at doses up to 1200 mg. Althof S, Osterloh IH, Muirhead GJ, et al. The Oxytocin Antagonist Cligosiban Fails to Prolong Intravaginal Ejaculatory Latency in Men with Lifelong Premature Ejaculation: Results of a Randomized, Double-Blind, Placebo-Controlled Phase IIb trial (PEDRIX). J Sex Med 2019; 16:1188-1198.

Trial registration: ClinicalTrials.gov NCT03055806.

Keywords: Cligosiban; Efficacy; IX-01; Oxytocin receptor antagonist; Premature ejaculation.