The pharmacological treatment of premature ejaculation.

Premature ejaculation (PE) is a common sexual dysfunction in men that is characterized by a short time to ejaculation, and a lack of control over ejaculation, and is associated with distress for men and their partners. Lack of knowledge about the aetiology of PE and lack of approved treatments might contribute to its under-diagnosis and under-treatment. The organic factors involved in PE are not well understood but serotonin (5-hydroxytryptamine, 5-HT) is important at the level of the central nervous system in the complex regulatory mechanisms involved in ejaculation. Selective serotonin reuptake inhibitor (SSRI) antidepressants (paroxetine, fluoxetine and sertraline) and the tricyclic antidepressant clomipramine increase ejaculatory control and delay ejaculation in men with PE, suggesting that pharmacological intervention might be useful for PE. These agents are intended for chronic dosing for treating psychiatric disorders because of their pharmacokinetic profile and pharmacodynamic activity, which might result in limitations when used for treating PE. Indeed, these properties might limit the utility of these drugs, whether administered on-demand or chronically, for the episodic treatment requirements of PE. Elevated synaptic 5-HT levels achieved with acute SSRI treatment might be self-limiting because of activation of presynaptic 5-HT(1A) autoreceptors, and chronic 5-HT(1A) autoreceptor desensitization might contribute to an increase in side-effects and withdrawal symptoms. Short-acting SSRIs such as dapoxetine, currently under development for the on-demand treatment of PE, might circumvent these limitations and offer better ejaculatory control and sexual satisfaction for men with PE. Phosphodiesterase-5 inhibitors have also been evaluated for treating PE, as have topical anaesthetics and the narcotic analgesic tramadol.