How does flutamide work in prostate cancer?

Flutamide is an anti-androgen and works by binding to androgen receptors found in prostate cancer cells. When flutamide binds to the androgen receptors and blocks the action of the male hormone such as testosterone, it can help keep the prostate cancer from growing and spreading.

Prostate cancer depends on male hormones (such as testosterone and (dihydrotestosterone) for growth. Anti-androgens block the action of the male hormones.

Flutamide does not kill the cancer directly, but has an effect on the testicles to block testosterone uptake or binding in the tissues. If the amount of testosterone in the body is reduced it is possible to slow down or shrink the cancer.

Flutamide has primarily been replaced by newer anti-androgen treatments such as bicalutamide (Casodex) and enzalutamide (Xtandi).

Some clinical practice guidelines no longer recommend the use of older anti-androgens like flutamide due to availability of newer options with better clinical data. However, they do state it may be used in patients with low disease burden or limited treatment options, if needed.

Flutamide is a capsule given by mouth three times per day and is only available as a generic drug. It is most often used in combination with a luteinizing hormone-releasing hormone (LHRH) analog. ​​LHRH agonists help prevent the testicles from producing testosterone.

When LHRH agonists are used as primary therapy, they actually boost androgen production for a short period before they reduce production. An increase in androgens can lead to a tumor flare and symptoms (like bone pain or trouble urinating). The use of anti-androgens for a few weeks can help to block the androgen production and symptoms that can occur at the beginning of treatment with LHRH agonists.

What are the anti-androgens?

Beside flutamide, other medicines in the anti-androgen class include:

• apalutamide (Erleada)
• bicalutamide (Casodex)
• darolutamide (Nubeqa)
• enzalutamide (Xtandi)

This is not all the information you need to know about flutamide for safe and effective use and does not take the place of talking to your doctor about your treatment. Review the full flutamide information and discuss this medicine and any questions you have with your doctor or other health care provider.