Pryor JL, Althof SE, Steidle C, Rosen RC, Hellstrom WJ, Shabsigh R, Miloslavsky M, Kell S. Efficacy and tolerability of dapoxetine in treatment of premature ejaculation: an integrated analysis of two double-blind, randomised controlled trials. Lancet 2006;368:929-937.

Premature ejaculation is thought to be the commonest male sexual dysfunction with a prevalence of 20-33%. It causes significant distress and breakdown of relationships and is under treated and often dismissed by doctors as trivial. Patients on chronic treatment with selective serotonin reuptake inhibitors (SSRI) reported delayed ejaculation and it was this that lead to the development of dapoxetine, a SSRI with short time to maximum serum concentration (about 1 hour) and rapid elimination. Two characteristics that make it suitable for on demand dosing for the potential treatment of PE.
This paper details the analysis of two randomized, double blind, placebo controlled phase 3 trials from the United States. Heterosexual men in stable relationships with moderate to severe PE were randomized to placebo, 30mg or 60mg of dapoxetine with over 850 men in each arm. Intravaginal ejaculatory latency time was measured by the partner using a stopwatch from the moment of penetration to ejaculation. For this study all patients had a IELT of <2 minutes. Tablets were to be taken 1- 3 hours preintercourse and only one tablet could be taken per 24 hours. The primary endpoint was IELT at 12 weeks. A 3-4 fold increase in IELT was seen with dapoxetine on demand compared to placebo with 60mg more effective than 30mg. Interestingly, the effect was seen after only one dose. The drug was well tolerated.
The pharmacokinetic profile of this SSRI make it ideal for on demand dosing. With so many men suffering from PE in the community, and as it is preferable to dose them on demand as opposed to chronically, clearly dapoxetine will do well when it eventually comes to market. I look forward to it being available for our patients.