Antiandrogens: a summary review of pharmacodynamic properties and tolerability in prostate cancer therapy.
This article provides a summary of the pharmacodynamic properties of major antiandrogens as well as an extensive review of their tolerability. Presently there are two classes of androgen receptor antagonists: the so-called pure, non-steroidal antiandrogens which include flutamide, nilutamide and the more recent bicalutamide and the steroidal antiandrogens cyproterone acetate, megestrol acetate and WIN 49596. Although non steroidal and steroidal compounds have been found to be equally effective in the treatment of prostate cancer presently no studies comparing the use of steroidal or non steroidal antiandrogens with chemical or surgical castration have evaluated quality of life per se. The only advantage of cyproterone acetate on pure antiandrogens seems to be the low incidence of hot flushes; a commonly reported adverse effect of androgen ablative therapy. However, hepatotoxicity associated with long term daily doses of 300 mg daily and the unacceptably high incidence of cardiovascular side effects (10%) should restrict its use to patients who are intolerant of pure antiandrogen compound. In contrast to steroidal compound nonsteroidal compounds let sexual potency to be retained, which is an important consideration with respect to the quality of life of some patients and, at present, the main indication for monotherapy with the pure antiandrogens. As regard as pure antiandrogens clinically important adverse events including gastrointestinal events, particularly diarrhea and occasional disturbances of liver function related to flutamide treatment and antabuse effect, problems with light-dark adaptation and rare interstitial pneumonitis related to nilutamide indicates the bicalutamide, due to its better tolerability profile, together with its once-daily oral administration regimen, could be considered the antiandrogen of first choice in the treatment of prostatic cancer.