Objective: To evaluate the overall treatment benefit of dapoxetine for premature ejaculation (PE), with specific emphasis on improvements in personal distress and interpersonal difficulty related to ejaculation. Although these factors are key elements of numerous sets of diagnostic criteria for PE, they have rarely been evaluated as outcome measures in clinical trials.
Patients and methods: In this randomized, double-blind, placebo-controlled, phase III trial we enrolled men aged > or =18 years, from the USA and Canada, who had a Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revision, diagnosis of PE (1238 men). Men were randomized to receive placebo or dapoxetine 60 mg as needed or once daily for 9 weeks. The once-daily treatment arm was included for analysis of withdrawal symptoms (primary endpoint; presented elsewhere). Patients completed the Premature Ejaculation Profile (PEP) on day 1 (before dosing), and on days 28 and 63 (or study endpoint), which comprised the outcome measures for perceived control over ejaculation, satisfaction with sexual intercourse, and personal distress and interpersonal difficulty related to ejaculation. The patient-reported global impression of change in PE was reported on day 63 (or study endpoint). Treatment benefit measures included the composite criteria of at least a two-category increase in perceived control over ejaculation and at least a one-category decrease in personal distress related to ejaculation from baseline at study endpoint.
Results: At baseline, approximately 5% of patients in any treatment group reported 'not at all' or 'a little bit' of personal distress related to ejaculation, which increased to 54.3% of those receiving dapoxetine (vs 35.3% with placebo; P < 0.001). Similarly, 43.0% and 40.9% of men in the placebo and dapoxetine groups, respectively, reported 'not at all' or 'a little bit' of interpersonal difficulty related to ejaculation at baseline, which increased to 76.8% and 64.2% of those with dapoxetine and placebo, respectively (P < 0.001). The percentage of men who achieved the composite criteria with dapoxetine 'as needed' was 47.6%, vs 21.7% with placebo (difference from placebo, 25.9%; P < 0.001). The distribution of responses for the PEP among men who achieved the composite criteria was similar to that reported for men without PE in a previous observational study in the USA. The most common adverse events were nausea, dizziness, headache, diarrhoea and insomnia, which were more common with dapoxetine than with placebo.
Conclusion: Dapoxetine reduced the personal distress and interpersonal difficulty associated with PE, and was associated with patient-reported improvements in their condition. The percentage of patients who achieved a composite of a two-category or greater increase in perceived control over ejaculation and a one-category or greater decrease in personal distress related to ejaculation was substantially greater than with placebo, as were all outcome measures.