Letters to the Editor
Gabapentin Treatment for Premature Ejaculation
Dear Editor:
Premature or rapid ejaculation (PE) is the commonest sexual dysfunction in men, with a reported prevalence of up to 39% in the general male population and an even greater prevalence in the first-degree male relatives of men with PE (1). The essential feature of PE is persistent or recurrent ejaculation with minimal sexual stimulation before, on, or shortly after penetration and before the person wishes it (2). However, no standardized method of assessing PE has been defined, and research criteria have included the following measures: reduced latency to ejaculation after intromission or reduced intravaginal latency time (IELT), limited control over the occurrence of ejaculation, concern about ejaculating too soon, dissatisfaction with the inability to select the moment of ejaculation, and the occurrence of antiportal ejaculation.
PE is postulated to be a neurobiological phenomenon involving primarily a disturbance of serotonin 5-HT2C and 5-HT1A receptor function. However, ejaculation in male humans is a complex physiological process: other central inputs and neurotransmitters, such as dopamine, and autonomic and somatic reflexes dependent on alpha 1-adrenergic and cholinergic neurons, respectively, all play a role (1). Consequently, numerous medications known to influence different receptors are reported to delay ejaculation. These include serotonergic drugs such as selective serotonin reuptake inhibitors (SSRIs) and clomi- pramine, alpha-adrenergic antagonists such as prazosin, and benzodiazepines such as clonazepam (3). I report the successful use of gabapentin, an anticonvulsant, in the treatment of PE.
Case Report
Mr X, aged 40 years, has a DSM-IV diagnosis of PE, lifelong situational type attributable to combined factors. Stop-pause, stop-squeeze coital alignment techniques and the use of a condom with topical anesthetic (5% lidocaine) were associated with limited response. Conventional pharmacotherapies were also minimally effective and had dose-limiting side effects. Treatment with paroxetine, sertraline, and to a lesser extent, venlafaxine was associated with restless legs, gastrointestinal disturbance, headache, decreased libido, and erectile dysfunction. Trazodone and lorazepam caused sedation and cognitive slowing, while bupropion accelerated ejaculation. Mr X had previously found that alcohol produced satisfactory ejaculatory delay with no loss of erectile capacity, but clearly this was not a feasible regular option. A trial of gabapentin 300 mg taken 1 to 2 hours prior to intercourse resulted in a similar effect with no side effects. Higher doses of 600 mg resulted in further retardation of ejaculation but also in somnolence.
The mechanism of action of gabapentin is not clear, but it is believed to increase GABA through increased GABA release and synthesis and to decrease the release of monoamine neurotransmitters (4). Since benzodiazepines and alcohol can also delay ejaculation and are also GABAergic through a direct action on GABA-A receptors, it is postulated that gabapentins effect on ejaculation may be mediated via its action on GABA. Further, anorgasmia has been described in a male patient with bipolar disorder receiving gabapentin (5).
Currently, there are no specific treatments for PE, although dapoxetine, an SSRI-type drug with a short half-life, is undergoing clinical trials. Thus, gabapentin merits further consideration, particularly in those men for whom other therapies are ineffective or poorly tolerated.
References
1. Waldinger MD. The neurobiological approach to premature ejaculation. Urol 2002;168:235967.
2. Grenier G, Byers SE. Operationalizing premature or rapid ejaculation. Sex Res 2001;38:36978.
3. Rowland DL, Burnett Al. Pharmacotherapy in the treatment of male sexual dysfunction. J Sex Res 2000;37:22643.
4. Taylor CP. Mechanisms of action of gabapentin. Rev Neurol 1997;153:S39S45.
5. Brannon GE, Rolland PD. Anorgasmia in a patient with bipolar disorder type 1 treated with gabapentin. J Clin Psychopharmacol 2000;20:37981.
Pierre Chue, FRCPC
Edmonton, Alberta
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