No

Antiandrogen

Early data indicate that finasteride is useful in the treatment of symptomatic benign prostatic hyperplasia (BPH); male pattern baldness

X

History of hypersensitivity to drug, pregnancy, lactation, children

A minimum of 6 months of treatment may be necessary to determine whether an individual will respond to finasteride. Use with caution in those patients with liver function abnormalities. Carefully monitor patients with a large residual urinary volume or severely diminished urinary flow for obstructive uropathy. These patients may not be candidates for finasteride therapy.

1% to 10%:

Genitourinary: <4% incidence of impotence, decreased volume of ejaculate

CYP3A3/4 enzyme substrate

Finasteride is a 4-azo analog of testosterone and is a competitive inhibitor of both tissue and hepatic 5-alpha reductase. This results in inhibition of the conversion of testosterone to dihydrotestosterone and markedly suppresses serum dihydrotestosterone levels; depending on dose and duration, serum testosterone concentrations may or may not increase. Testosterone-dependent processes such as fertility, muscle strength, potency, and libido are not affected by finasteride.

Onset of clinical effect: Within 12 weeks to 6 months of ongoing therapy

Duration of action:

After a single oral dose as small as 0.5 mg: 65% depression of plasma dihydrotestosterone levels persists 5-7 days

After 6 months of treatment with 5 mg/day: Circulating dihydrotestosterone levels are reduced to castrate levels without significant effects on circulating testosterone; levels return to normal within 14 days of discontinuation of treatment

Absorption: Oral: Extent may be reduced if administered with food

Metabolism: Unchanged finasteride is major circulating component; two active metabolites have been identified

Protein binding: 90%

Bioavailability: Mean: 63%

Half-life, serum: Parent drug: ~5-17 hours (mean: 1.9 fasting, 4.2 with breakfast)

Half-life: Elderly: 8 hours; Adults: 6 hours (3-16)

Time to peak serum concentration: Oral: 2-6 hours

Elimination: As metabolites in urine (39%) and feces (57%); elimination rate is decreased in the elderly, but no dosage adjustment is needed

Adults: Male:

Male pattern baldness: Oral: 1 mg daily

Dosing adjustment in renal impairment: No dosage adjustment is necessary

Dosing adjustment in hepatic impairment: Use with caution in patients with liver function abnormalities because finasteride is metabolized extensively in the liver

Food: Administration with food may delay the rate and reduce the extent of oral absorption

Objective and subjective signs of relief of benign prostatic hyperplasia, including improvement in urinary flow, reduction in symptoms of urgency, and relief of difficulty in micturition

None reported

None reported

No information available to require special precautions

No effects or complications reported

Results of therapy may take several months. Take as directed, with fluids, 30 minutes before or 2 hours after meals. You may experience decreased libido or impotence during therapy. Report any increase in urinary volume or voiding patterns occurs. Pregnancy precautions: This drug will cause fetal abnormalities - use barrier contraceptives and do not allow childbearing age women to touch or handle drug.

Monitor objective and subjective signs of relief of benign prostatic hyperplasia, including improvement in urinary flow, reduction in symptoms of urgency, and relief of difficulty in micturition

Tablet, film coated: 1 mg, 5 mg

Jeffrey LP, Chairman, National Study Commission on Cytotoxic Exposure. Position Statement. "The Handling of Cytotoxic Agents by Women Who Are Pregnant, Attempting to Conceive, or Breast-Feeding," January 12, 1987.

Lepor H, Williford WO, Barry MJ, et al, "The Efficacy of Terazosin, Finasteride, or Both in Benign Prostatic Hyperplasia," N Engl J Med, 1996, 335(8):533-9.