Premature ejaculation (PE) is defined as “persistent or recurrent onset of orgasm and ejaculation with minimal sexual stimulation before, on, or shortly after penetration and before the person wishes it.”
The psychological elements of distress and dissatisfaction may account for the traditional view of PE as a psychological condition. It has recently been suggested that PE might be associated with perturbations in serotonergic 5-hydroxytrptamine (5-HT) neurotransmission. This had led to the development of targeted therapies for PE that might alter the 5-HT system.
In a recent study by Francisco Giuliano from Garches Frances studies the efficacy of a novel therapeutic agent, dapoxetine, for the treatment of premature ejaculation. The study is published in the July 2007 European Urology Supplements.
Dapoxetine hydrochloride is a selective serotonin reuptake inhibitor (SSRI) with a short half-life developed specifically for the treatment of men with PE. SSRI’s increase 5-HT neurotransmission however, most available SSRI’s such as fluoxetine, sertraline, and paroxetine, which have been shown to increase ejaculatory latency time, do not reach peak plasma concentrations for several hours.
This does not allow for the available drugs to be used as on-demand preparations. Dapoxetine has inhibitory effects on serotonin reuptake and the time to maximal plasma concentration is only 1 hour. The initial elimination half-life is 1.2 hours and the plasma concentration at 24 hours is < 5% of the maximal concentration. These properties allow for dapoxetine to be delivered as an on-demand preparation.
In two-placebo controlled trials involving > 2600 men with PE dapoxetine 30 or 60 mg was given as needed 1-3 hours prior to sexual intercourse on an as needed basis was evaluated for the treatment of the condition. The mean age of the participant was 40 years. Lifelong PE was reported by 65% of the participants and 35% had PE that developed after a period of normal sexual function. The primary endpoint of the study was intravaginal ejaculatory latency time (IELT) as measured by stopwatch during intercourse.
Analysis of the results showed a statistically significant dose-dependent increase in mean IELT and was observed during dapoxetine treatment at the study end point; 0.9 – 1.75 min, 0.92 – 2.78 min, and 0.91 – 3.32 minutes for placebo, dapoxetine 30 mg, and dapoxetine 60 mg. It was equally effective on the first dose and with subsequent doses and the improvement was sustained over the 12-week study period.
Dapoxetine was generally well tolerated with mild nausea and headache being the most common side effects. Nausea was reported in 8.7% of the 30 mg group and 20.1% of the 60 mg group. Headache was seen in 5.9% of the 30 mg group and 6.8% of the 60 mg group. Discontinuation rates due to adverse events for placebo, dapoxetine 30 mg and dapoxetine 60 mg were 0.9%, 4%, and 10%, respectively.
Reference: Giuliano F, Eur Urol Supp. 6(13):780-6, July 2007, doi:10.1016/j.eursup.2007.04.005
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