A method for monitoring drug effects on male sexual response: the effect of single dose labetalol.

Abstract
1 A method for monitoring the effect of drugs on the genital response to stimulation provided by vibration is described. 2 Using this method, the effect on male sexual response of two oral doses (100 mg and 300 mg) labetalol were studied and compared with placebo in six subjects. 3 Labetalol did not affect the attainment or maintenance of erection. 4 Labetalol delayed ejaculation in a dose‐related manner. 5 Labetalol treatment resulted in a significant dose‐related delay in detumescence.