Indications for Antiandrogen Use

Updated January 23, 2014​

Effective immediately bicalutamide 50 mg daily will replace flutamide 250 mg tid as the preferred antiandrogen for prostate cancer. Apart from more convenient once-daily administration it is also better tolerated, and is now available. Patients currently on flutamide may switch to bicalutamide at the physician's discretion.

Indications include:

  • Prevention of the flare phenomenon during the first month of LHRH agonist treatment (bicalutamide 50 mg daily; flutamide 250 mg t.i.d; nilutamide 50 mg daily [class II] if intolerant to bicalutamide or flutamide)
  • Biochemical (PSA) or clinical progression in patients medically or surgically castrated. A three month trial with continuation only if there is a decrease in the serum PSA. Second-line treatment should not be continued in the face of progressive disease although permanent castration (surgical or medical) is recommended to avoid stimulation by androgens
  • During neoadjuvant therapy prior to radical radiation therapy, an antiandrogen will be added if there is a PSA rise, or if an inadequate PSA response is observed (defined as failure to achieve a PSA of greater than 1 ng/mL after 4 months of adequate therapy as defined by castrate testosterone levels)
  • Total androgen blockade of advanced prostate cancer (approved indication only for bicalutamide or flutamide)

Monotherapy with bicalutamide 150 mg/day is not approved. The drug does not have a license for this use in Canada as a result of efficacy and safety concerns.

All three antiandrogens (bicalutamide, flutamide, and nilutamide) are equally efficacious. Side effects of bicalutamide include diarrhea, nipple tenderness and gynecomastia. Side effects of flutamide include diarrhea, abnormalities in liver function enzymes, and occasional jaundice. Liver function tests should be monitored periodically if used continuously for long (over 3 months) periods of time. Side effects of nilutamide include night blindness, alcohol intolerance and rarely, interstitial pneumonitis.

  • Patients who are intolerant to bicalutamide may be switched to other antiandrogens (flutamide, [class1] or nilutamide if flutamide intolerant [Class 2])
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