Enzalutamide, sold under the brand name Xtandi, is a nonsteroidal antiandrogen (NSAA) medication which is used in the treatment of prostate cancer. It is indicated for use in conjunction with castration in the treatment of metastatic castration-resistant prostate cancer (mCRPC), nonmetastatic castration-resistant prostate cancer, and metastatic castration-sensitive prostate cancer (mCSPC). It is taken by mouth. Side effects of enzalutamide when added to castration include asthenia, back pain, diarrhea, arthralgia, and hot flashes. Rarely, it can cause seizures. It has a high potential for drug interactions. Enzalutamide is an antiandrogen, and acts as an antagonist of the androgen receptor, the biological target of androgens like testosterone and dihydrotestosterone. In doing so, it prevents the effects of these hormones in the prostate gland and elsewhere in the body. Enzalutamide was first described in 2006, and was introduced for the treatment of prostate cancer in 2012. It was the first second-generation NSAA to be introduced. It is on the World Health Organization's List of Essential Medicines. Medical uses Prostate cancer There is good evidence that enzalutamide is an effective treatment for increasing overall survival among people with high-risk non-metastatic castration-resistant prostate cancer, particularly those with a PSA doubling time ≤ 6 months. Other uses Enzalutamide can be used as an antiandrogen in feminizing hormone therapy for transgender women. Available forms Enzalutamide is provided in the form of a 40 mg Capsule. It is taken orally at a dosage of 160 mg once per day (four capsules). Contraindications Enzalutamide is contraindicated in women during pregnancy. It may cause fetal harm. Side effects Notable side effects of enzalutamide seen in clinical trials have included gynecomastia, breast pain/tenderness, fatigue, diarrhea, hot flashes, headache, sexual dysfunction, and, less commonly, seizures. Other "common" side effects reported in clinical trials have included neutropenia, visual hallucinations, anxiety, cognitive disorder, memory impairment, hypertension, dry skin, and pruritus (itching). Enzalutamide monotherapy is regarded as having a moderate negative effect on sexual function and activity, significantly less than that of GnRH analogues but similar to that of other NSAAs such as bicalutamide. Central adverse effects Seizures have occurred in approximately 1% of patients treated with enzalutamide in clinical trials. This is thought to be due to enzalutamide crossing the blood–brain barrier and exerting off-target binding to and inhibition of the GABAA receptor in the central nervous system (it has been found to inhibit the GABAA receptor in vitro ( = 3.6 μM) and