Non-Steroidal Antiandrogens (NSAAs)

Nonsteroidal Antiandrogens (NSAAs) work by directly blocking the action of testosterone through antagonizing the androgen receptor, without changing androgen levels in the body. They are utilized in the management of conditions such as prostate cancer, male to female transgender therapy, polycystic ovarian syndrome (PCOS), priapism, and congenital adrenal hyperplasia. As a group, NSAAs share side effects like impotence, gynecomastia, hot flashes, osteoporosis, and gastrointestinal disturbances. There are two generations of NSAAs. The first generation includes flutamide and nilutamide, which don't completely obstruct the receptors. However, both of these are infrequently used due to the risk of serious side effects like hepatotoxicity with flutamide, and interstitial pneumonitis with nilutamide. Bicalutamide, another first-generation NSAA, is more popular and better tolerated, with a lower incidence of serious side effects. Moving on to second-generation NSAAs, they have a higher affinity for the androgen receptors and therefore, manifest more effective androgen receptor blockade. Apalutamide may cause hypothyroidism and hypertension, but has less central nervous system (CNS) effects than enzalutamide, another second generation NSAA, which could lead to common back pain, insomnia, anxiety and in rare cases, seizures.