Effects of medroxyprogesterone acetate on subjective arousal, arousal to erotic stimulation, and nocturnal penile tumescence in male sex offenders.

Three chronic pedophiliac sex offenders were treated individually with medroxyprogesterone acetate (MPA) over a minimum of 3 months. Genital and subjective response to erotic stimulation, nocturnal penile tumescence, self-reporting of sexual urges, and testosterone levels were recorded repeatedly throughout the study. A single-subject reversal design was used and medication was administered through a double-blind procedure. The results showed that self-report of arousal outside of a laboratory setting was unreliable as a measure of the drug effect. In a laboratory setting, however, there appeared to be a significant reduction in the report of arousal to erotic stimuli while genital arousal decreased only slightly. Reversal of these responses occurred in only one subject during a final placebo phase. Nocturnal penile tumescence was significantly decreased during MPA administration and appeared to be related to decreases in total testosterone.