Is thioridazine-induced ejaculation failure peripheral in origin?

Area of Science:

• Pharmacology
• Neuroscience
• Urology

Background:

• Thioridazine and chlorpromazine are antipsychotic medications with known side effects.
• Ejaculation dysfunction is a reported side effect of these drugs, particularly thioridazine.
• The peripheral adrenergic mechanisms in the vas deferens play a crucial role in ejaculation.

Purpose of the Study:

• To investigate the effects of thioridazine and chlorpromazine on the contractile response of the rabbit vas deferens.
• To compare the sympatholytic potencies of thioridazine and chlorpromazine.
• To explore the potential role of peripheral adrenergic mechanisms in thioridazine-induced ejaculation failure.

Main Methods:

• Rabbit vas deferens preparations were subjected to field stimulation.
• The contractile responses were measured in the presence of varying concentrations of thioridazine, chlorpromazine, and phenoxybenzamine.
• The effects of these drugs on responses to exogenously administered noradrenaline were also assessed.

Main Results:

• Both thioridazine and chlorpromazine significantly depressed the contractile response to field stimulation.
• Phenoxybenzamine showed a dose-dependent effect, augmenting at lower doses and depressing at higher doses.
• Thioridazine and chlorpromazine markedly reduced the response to noradrenaline, while phenoxybenzamine abolished it.

Conclusions:

• Thioridazine and chlorpromazine exhibit similar sympatholytic effects on the rabbit vas deferens.
• The higher incidence of ejaculation failure with thioridazine compared to chlorpromazine is unlikely to be solely due to peripheral adrenergic inhibition.
• Further research is needed to elucidate the central mechanisms underlying thioridazine-induced ejaculation dysfunction.