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. Enzalutamide is a therapeutic alternative on the World Health Organization's List of Essential Medicines.

Enzalutamide is indicated for the treatment of people with castration-resistant prostate cancer; metastatic castration-sensitive prostate cancer; and non‑metastatic castration‑sensitive prostate cancer with biochemical recurrence at high risk for metastasis.

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.

Enzalutamide can be used as an antiandrogen in feminizing hormone therapy for transgender women.

Enzalutamide is provided as a capsule or tablet.

Enzalutamide is contraindicated in women during pregnancy. It may cause fetal harm.