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The androgenic hormones are internal endocrine secretions circulating in the bloodstream and manufactured mainly by the testes under stimulation from the pituitary gland. To a lesser extent, androgens are produced by the adrenal glands in both sexes, as well as by the ovaries in women. Thus women normally have a small percentage of male hormones, in the same way that men's bodies contain some female sex hormones, the estrogens. Male secondary sex characters include growth of the beard and deepening of the voice at puberty. Androgens also stimulate the growth of muscle and bones throughout the body and thus account in part for the greater strength and size of men as compared to women.
Pharmacologic class: Antiandrogen
Therapeutic class: Antineoplastic
Pregnancy risk category C
FDA Box Warning
Drug may cause interstitial pneumonitis. Though rare, interstitial changes have led to hospitalization and death postmarketing. Most cases occurred within first 3 months of therapy and reversed after drug was stopped. Obtain routine chest X-ray before starting treatment, and be prepared to obtain baseline pulmonary function tests if ordered. Instruct patient to report new or worsening shortness of breath; this symptom warrants immediate drug withdrawal pending evaluation.
Inhibits testosterone uptake in target tissue, preventing normal androgenic response and arresting tumor growth in androgen-sensitive tissue
Tablets: 50 mg, 150 mg
Indications and dosages
➣ Metastatic prostate cancer (used with surgical castration)
Adults: 300 mg/day P.O. for 30 days, starting on day of or day after surgery; then 150 mg/day P.O.
• Hypersensitivity to drug or its components
• Severe hepatic or respiratory insufficiency
Use cautiously in:
• renal impairment.
• Give with or without food.
• Start therapy on same day as or day after surgical castration.
CNS: dizziness, depression, hyperes-thesia, insomnia
CV: hypertension, peripheral edema, heart failure
EENT: abnormal vision, impaired dark and light adaptation, chromatopsia
GI: nausea, vomiting, constipation, dyspepsia, anorexia
GU: hematuria, nocturia, urinary tract infection, gynecomastia, testicular atrophy, decreased libido, erectile dysfunction
Hematologic: anemia, aplastic anemia
Respiratory: dyspnea, upper respiratory infection, interstitial pneumonia
Other: flulike symptoms, pain, fever, hot flushes, alcohol intolerance
Drug-drug. Phenytoin, theophylline, vitamin K: increased risk of toxicity from these drugs
Drug-diagnostic tests. Alanine aminotransferase, aspartate aminotransferase: increased levels
Drug-behaviors. Alcohol use: disulfiram-like reaction
• Check for signs and symptoms of hepatitis. Monitor liver function tests.
• Monitor CBC.
• Assess fluid intake and output and weight. Watch for signs and symptoms of heart failure.
• Monitor respiratory status, including chest X-rays.
• Advise patient he may take with or without food.
• Tell patient therapy will start on day of or day after surgical castration.
• Caution patient not to stop taking drug without consulting prescriber.
• Instruct patient to weigh himself daily and report sudden increases.
Advise patient to report new onset or worsening of dyspnea as well as signs and symptoms of hepatotoxicity, such as nausea, vomiting, abdominal pain, unusual tiredness, or yellowing of skin or eyes.
• Advise patient to avoid alcohol during therapy, because serious adverse reactions may occur.
• Tell patient drug may impair his adaptation to darkness and light, which may cause difficulty driving at night or through tunnels.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, test, and behaviors mentioned above.