Propecia®: Treatment of male pattern hair loss in men only. Safety and efficacy were demonstrated in men between 18-41 years of age.

Proscar®: Treatment of symptomatic benign prostatic hyperplasia (BPH); can be used in combination with an alpha blocker, doxazosin

>10%:

Endocrine & metabolic: Impotence (19%; combination therapy 23%), libido decreased (10%; combination therapy 12%)

Genitourinary: Neuromuscular & skeletal: Weakness (5%; combination therapy 17%)

1% to 10%:

Cardiovascular: Postural hypotension (9%; combination therapy 18%), edema (1%, combination therapy 3%)

Central nervous system: Dizziness (7%; combination therapy 23%), somnolence (2%; combination therapy 3%)

Genitourinary: Ejaculation disturbances (7%; combination therapy 14%), decreased volume of ejaculate

Endocrine & metabolic: Gynecomastia (2%)

Respiratory: Dyspnea (1%; combination therapy 2%), rhinitis (1%; combination therapy 2%)

<1%, postmarketing and/or case reports: Hypersensitivity (pruritus, rash, urticaria, swelling of face/lips); breast tenderness, breast enlargement, breast cancer (males), prostate cancer (high grade), testicular pain

Herb/Nutraceutical: St John's wort may decrease finasteride levels. Avoid saw palmetto (concurrent use has not been adequately studied).

Onset of action: 3-6 months of ongoing therapy

Duration:

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

Distribution: Vdss: 76 L

Protein binding: 90%

Metabolism: Hepatic via CYP3A4; two active metabolites (<20% activity of finasteride)

Bioavailability: Mean: 63%

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

Time to peak, serum: 2-6 hours

Excretion: Feces (57%) and urine (39%) as metabolites

Male:

Benign prostatic hyperplasia (Proscar®): 5 mg/day as a single dose; clinical responses occur within 12 weeks to 6 months of initiation of therapy; long-term administration is recommended for maximal response

Male pattern baldness (Propecia®): 1 mg daily

Female hirsutism (unlabeled use): 5 mg/day

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

Tablet [film coated]:

Propecia®: 1 mg

Proscar®: 5 mg

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.

McConnell JD, Roehrborn CG, Bautista OM, et al, "The Long-Term Effect of Doxazosin, Finasteride, and Combination Therapy on the Clinical Progression of Benign Prostatic Hyperplasia. Medical Therapy of Prostatic Symptoms (MTOPS) Research Group,"N Engl J Med, 2003, 349(25):2387-98.

Pole M and Koren G, "Finasteride. Does It Affect Spermatogenesis and Pregnancy,"Can Fam Physician, 2001, 47:2469-70.

Thompson IM, Goodman PJ, Tangen CM, et al, "The Influence of Finasteride on the Development of Prostate Cancer,"N Engl J Med, 2003, Jul 349(3):215-24.