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Pronunciation:

(fi NAS teer ide)

U.S. Brand Names:

Propecia®; Proscar®

Generic Available:

Canadian Brand Names:

Propecia®; Proscar®

Use:

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

Use - Unlabeled/Investigational:

Adjuvant monotherapy after radical prostatectomy in the treatment of prostatic cancer; female hirsutism

Pregnancy Risk Factor:

Pregnancy Implications:

Abnormalities of external male genitalia were reported in animal studies. Pregnant women are advised to avoid contact with crushed or broken tablets.

Lactation:

Excretion in breast milk unknown/contraindicated

Contraindications:

Hypersensitivity to finasteride or any component of the formulation; pregnancy; not for use in children

Warnings/Precautions:

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 hepatic dysfunction. 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.

Adverse Reactions:

Note: "Combination therapy" refers to finasteride and 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

Drug Interactions:

Substrate of CYP3A4 (minor)

Ethanol/Nutrition/Herb Interactions:

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

Stability:

Store below 30°C (86°F); protect from light

Mechanism of Action:

Finasteride 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

Pharmacodynamics/Kinetics:

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

Dosage:

Oral: Adults:

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

Administration:

Administration with food may delay the rate and reduce the extent of oral absorption. Women of childbearing age should not touch or handle broken tablets.

Monitoring Parameters:

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

Patient Education:

Inform prescriber of all prescriptions, OTC medications, or herbal products you are taking, and any allergies you have. Do not take any new medication during therapy unless approved by prescriber. Results of therapy may take several months. Take with or without meals. May cause decreased libido or impotence during therapy. Report any increase in urinary volume or voiding patterns occurs. Report changes in breast condition (pain, lumps, or nipple discharge) in male and female patients. Pregnancy precautions: This drug will cause fetal abnormalities - use barrier contraceptives and do not allow women of childbearing age to touch or handle broken or crushed tablets.

Nursing Implications:

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.

Anesthesia and Critical Care Concerns/Other Considerations:

Finasteride may be useful in men with moderately symptomatic BPH who either refuse prostatectomy or are poor surgical candidates. Currently, there is no way to predict which men will respond to finasteride. Treatment with finasteride does not alter the ratio of free to total PSA, which is used to detect prostatic cancer.

Dental Health: Effects on Dental Treatment:

No significant effects or complications reported

Dental Health: Vasoconstrictor/Local Anesthetic Precautions:

No information available to require special precautions

Mental Health: Effects on Mental Status:

None reported

Mental Health: Effects on Psychiatric Treatment:

None reported

Oncology: Emetic Potential:

Very low (<10%)

Dosage Forms:

Tablet [film coated]:

Propecia®: 1 mg

Proscar®: 5 mg

International Brand Names:

Alfasin® (BR); Anatine® (AR); Andropel® (AR); Avertex® (AR); Chibro-Proscar® (FR); Conef® (AR); Dilaprost® (TR); Eucoprost® (ES); Eutiz® (AR); Finarid® (TR); Finasterin® (AR); Finastid® (IT); Finastil® (BR); Finast® (RU); Fincar® (IN); Finex® (CZ); Finired® (ID); Finpro® (ID); Finprostat® (AR); Fistrin® (CO); Flaxin® (BR); Flutiamik® (AR); Gefina® (FI); Genaprost® (IT); Gropecia® (AR); HPB Panalab® (AR); Nasterid-A® (BR); Nasterid® (BR); Nasteril® (AR); Nasterol® (BR, CO); Pelicrep® (AR); Penester® (CZ, PL); Pro-Cure® (IL); Prohair® (CL); Pronor® (BD); Propecia® (AR, AT, AU, BR, CA, CH, CO, CR, CZ, DE, DK, EC, ES, FI, FR, GB, GT, HN, HR, IL, IT, NZ, PA, PL, PT, RO, SE, SG, SI, SV, TH, TR); Propeshia® (MX); Proscar® (AR, AT, AU, BE, BR, CA, CH, CL, CR, CZ, DE, DK, EC, ES, FI, GB, GT, HN, HR, HU, ID, IE, IT, LU, MX, NL, NO, NZ, PA, PL, PT, RO, RU, SE, SG, SV, TH, TR, YU); Prosfin® (BD); Prosh® (ID); Prosmin® (AR); Prostacom® (ID); Prostanovag® (AR); Prostasax® (DO); Prostene® (AR); Prosterid® (HU); Prosterit® (TR); Prostide® (BR, IT, SI); Reprostom® (ID); Rowesteride® (EC); Sutrico® (AR); Tealep® (AR); Tricofarma® (AR)

References

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.

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