A double-blind placebo controlled trial of medroxyprogesterone acetate and cyproterone acetate with seven pedophiles

Abstract

Seven of ten pedophiles in hospital completed a double-blind, placebo-controlled two-dose comparison of medroxyprogesterone acetate and cyproterone acetate. Sequential measures during the 28 week study were: patient self-reports, nurses' observations, phallometry, hormone levels and side-effects. The drugs, which performed equivalently, reduced sexual thoughts and fantasies, the frequency of early morning erections on awakening, the frequency and pleasure of masturbation, and level of sexual frustration. Penile responses were also reduced but to a lesser degree and were more variable. Serum testosterone FSH and LH all declined during drug administration, but by the end of the final placebo phase had essentially returned to (or exceeded) pre-drug values. Our experience suggests that only a minority of pedophiles are likely to accept libido-reducing drugs.

PIP: Psychiatric clinicians intended to recruit 25 pedophiles into a 28-week, double-blind, placebo-controlled trial at a psychiatric hospital in St. Thomas, Ontario, to examine the ability of medroxyprogesterone acetate (MPA) and cyproterone acetate (CPA) to suppress psychologic and physiologic sexual arousal. They screened 28 pedophiles, but only 10 agreed to take part in the study and just 7 completed the study. The researchers used the following sequential measures: patient self-reports, nurses' observations, phallometry, hormone levels, and side effects. The small numbers prevented the researchers from conducting statistical analysis. Both drugs performed similarly. Their effects appeared to depend on dose (e.g., 200 mg had a greater effect than 100 mg). The drugs inhibited sexual thoughts, fantasies, and sexual frustration. They also reduced the frequency of early morning erections on awakening and the frequency and pleasure of masturbation. The drugs also reduced the percentage of erection, but the reductions were not as great as those of the aforementioned effects, and the responses were more variable. The drugs led to a decline in serum levels of testosterone, follicle stimulating hormone, and luteinizing hormone, but by the end of the third placebo phase, almost all serum levels either returned to or exceeded predrug levels. These findings indicate that CPA or MPA use may provide modest short-term improvement in the behavior of pedophiles, but this improvement is largely limited to psychologic responses. In addition, this study shows that few pedophiles voluntarily agreed to take an antiandrogen, suggesting the need for more research identifying more acceptable treatments.