Finasteride

Pharmacologic Category

5 Alpha-Reductase Inhibitor

Dosing: Adult

Androgenetic alopecia (male pattern hair loss): Males: Oral: 1 mg once daily. Continue for at least 12 months to assess full effect; continued daily use is required to sustain benefit (Donovan 2019; Leyden 1999; Whiting 1999).

Benign prostatic hyperplasia (alternative agent): Note: Reserve use for patients with significantly enlarged prostates, those intolerant of or refractory to alpha-1 adrenergic antagonists, or those with hematuria associated with benign prostatic hyperplasia (AUA [McVary 2010]; Cunningham 2019).

Males: Oral: 5 mg once daily (either as a single agent or in combination with an alpha-1 adrenergic antagonist); 6 to 12 months of treatment is usually needed to improve symptoms (AUA [McVary 2010]; Cunningham 2019; McConnell 2003).

Hirsutism (alternative agent) (off-label use): Note: Typically given in addition to oral contraceptives (OCs) if inadequate response to OCs is observed after 6 months. May be considered as initial therapy for females who cannot conceive or who are using reliable contraception.

Females: Oral: 2.5 to 5 mg once daily. Assess response at 6-month intervals before adjusting dose, adding additional agents, or switching to alternative therapy (Barbieri 2019; Endocrine Society [Martin 2018]).

* See Dosage and Administration in AHFS Essentials for additional information.

Dosing: Geriatric

Refer to adult dosing.

Dosing: Renal Impairment: Adult

No dosage adjustment is necessary.

Dosing: Hepatic Impairment: Adult

There are no dosage adjustments provided in the manufacturer’s labeling. Use with caution (finasteride is metabolized extensively in the liver)

Use: Labeled Indications

Androgenetic alopecia (male pattern hair loss): Treatment of male pattern hair loss in men.

Limitations of use: Efficacy in bitemporal recession has not been established.

Benign prostatic hyperplasia: Treatment (monotherapy) of symptomatic benign prostatic hyperplasia (BPH) to improve symptoms, reduce the risk of acute urinary retention, and reduce the risk of need for BPH-related surgery; used in combination with an alpha-blocker (doxazosin) to reduce the risk of symptomatic progression.

Limitations of use: Not approved for the prevention of prostate cancer.

* See Uses in AHFS Essentials for additional information.

Use: Off-Label: Adult

​HirsutismLevel of Evidence [B, G]

Data from a systematic review and network meta-analysis of published randomized trials of women with hirsutism (idiopathic, related to polycystic ovary syndrome or nonclassic congenital adrenal hyperplasia) support the use of finasteride for treatment of hirsutism Ref.

Based on the Endocrine Society clinical practice guideline on the evaluation and treatment of hirsutism in premenopausal women, finasteride is effective and may be considered among other antiandrogens in the management of this condition. Finasteride may be considered for initial therapy, either as monotherapy in women who are not at risk for becoming pregnant, or in combination with an oral contraceptive in select women with severe hirsutism causing distress and/or a prior history of inadequate response to oral contraceptive therapy. Finasteride may also be considered for add-on therapy in women who fail to achieve a satisfactory response to initial oral contraceptive monotherapy Ref. Access Full Off-Label Monograph

Level of Evidence Definitions

​Level of Evidence Scale

Use: Unsupported: Adult

Prostate cancer prevention

A large, randomized, placebo-controlled study evaluating the effects of finasteride on prevention of prostate cancer in men considered at increased risk for prostate cancer found a statistically significant increase in the incidence of higher-grade prostate cancer (Gleason score ≥7) in men who received finasteride (Thompson 2003; Thompson 2013).

Class and Related Monographs

5-Alpha Reductase Inhibitors

Clinical Practice Guidelines

Benign Prostatic Hyperplasia:

AUA, “Management of Benign Prostatic Hyperplasia,” 2010

CUA, “Guideline on Male Lower Urinary Tract Symptoms/Benign Prostatic Hyperplasia (MLUTS/BPH),” 2018

Hirsutism:

Endocrine Society, “The Evaluation and Treatment of Hirsutism in Premenopausal Women: An Endocrine Society Clinical Practice Guideline,” 2018

Administration: Oral

May be administered with or without meals. Pregnant women and females of childbearing potential should not touch or handle crushed or broken tablets.

Hazardous Drugs Handling Considerations

Hazardous agent (NIOSH 2016 [group 3]).

Use appropriate precautions for receiving, handling, administration, and disposal. Gloves (single) should be worn during receiving, unpacking, and placing in storage. NIOSH recommends single gloving for administration of intact tablets or capsules (NIOSH 2016). Assess risk to determine appropriate containment strategy (USP-NF 2017).

Storage/Stability

Propecia: Store at 15°C to 30°C (59°F to 86°F). Keep container tightly closed and protect from moisture.

Proscar: Store below 30°C (86°F). Protect from light. Keep container tightly closed.

Medication Patient Education with HCAHPS Considerations

What is this drug used for?

• It is used to help hair growth in male pattern baldness. It may take 3 months to see the full effect.

• It is used to treat the signs of an enlarged prostate. It may take a few months to see the full effect.

• It may be given to you for other reasons. Talk with the doctor.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Sexual dysfunction

• Fatigue

• Loss of strength and energy

• Decreased sex drive

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Enlarged breasts

• Severe dizziness

• Passing out

• Depression

• Testicle pain

• Lump in breast

• Breast soreness or pain

• Nipple discharge

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Medication Safety Issues

​Sound-alike/look-alike issues:

Contraindications

Hypersensitivity to finasteride or any component of the formulation; pregnancy or women of childbearing potential

Warnings/Precautions

Disease-related concerns:

• Diminished urinary flow: 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.

• Hepatic impairment: Use with caution in patients with hepatic impairment; finasteride is extensively metabolized in the liver.

• Prostate cancer: When compared to placebo, 5-alpha-reductase inhibitors (5-ARIs) have been associated with an increase in the incidence of high-grade prostate cancers; 5-ARIs are not approved in the United States or Canada for the prevention of prostate cancer.

Special handling:

• Females: Active ingredient of crushed or broken tablets can be absorbed through the skin; unbroken tablets are coated, which prevents contact with the active ingredient during normal handling. Females of childbearing potential should not touch or handle crushed or broken tablets.

Other warnings/precautions:

• Appropriate use: Other urological diseases (including prostate cancer) should be ruled out before initiating (in benign prostatic hyperplasia [BPH] management). Not indicated for use in pediatric patients.

• Duration of therapy: For BPH, a minimum of 6 months of treatment may be necessary to determine whether an individual will respond to finasteride; for male pattern hair loss, daily use for ≥3 months may be required before benefit is observed (withdrawal of treatment leads to reversal of hair growth effect within 12 months).

• Prostate specific antigen monitoring: Reduces prostate specific antigen (PSA) concentration by ~50% within 6 months of treatment. To interpret serial PSAs, a new PSA baseline should be established ≥6 months after treatment initiation and PSA monitored periodically thereafter. A confirmed PSA increase while on this medication, even if within normal limits, may be associated with an increased risk for prostate cancer and should be evaluated. Finasteride does not interfere with free PSA levels.

* See Cautions in AHFS Essentials for additional information.

Geriatric Considerations

Clearance of finasteride is decreased in the elderly, but no dosage reductions are necessary.

Reproductive Considerations

Use is contraindicated in females of childbearing potential. Adequate contraception is recommended if used off label in the management hirsutism in females associated with polycystic ovary syndrome (ACOG 194 2018). Females of childbearing potential should not touch or handle crushed or broken tablets.

Finasteride is present in semen. Male infertility and poor seminal quality have been reported and may be reversible upon discontinuation of finasteride. Adverse events may be dose related and, less likely, associated with doses used for male pattern hair loss (Zakhem 2019).

Pregnancy Risk Factor

X

Pregnancy Considerations

Based on the mechanism of action and data from animal reproduction studies, in utero exposure to finasteride may lead to abnormal development of the male genital tract. Use is contraindicated during pregnancy. Pregnant females are advised to avoid contact with crushed or broken tablets.

Breast-Feeding Considerations

It is not known if finasteride is present in breast milk.

Use is contraindicated in females of childbearing potential. Females of childbearing potential should not touch or handle crushed or broken tablets.

Adverse Reactions

>10%: Genitourinary: Impotence (monotherapy: 5% to 19%)

1% to 10%:

Cardiovascular: Orthostatic hypotension (monotherapy: 9%), peripheral edema (monotherapy: 1%), hypotension (monotherapy: 1%)

Endocrine & metabolic: Decreased libido (monotherapy: 2% to 10%), gynecomastia (monotherapy: 1% to 2%)

Genitourinary: Ejaculatory disorder (monotherapy: <1% to 7%), decreased ejaculate volume (monotherapy: 2% to 4%), sexual disorder (3%), breast tenderness (monotherapy: ≤1%)

Hematologic & oncologic: Prostate cancer (high grade: 2%)

Respiratory: Rhinitis (monotherapy: 1%)

<1%, postmarketing, and/or case reports: Altered mental status, breast hypertrophy, change in libido, depression, hypersensitivity reaction, male infertility (temporary), malignant neoplasm of the breast (men), suicidal ideation (Welk 2017), suicidal tendencies (Welk 2017), testicular pain

* See Cautions in AHFS Essentials for additional information.

Allergy and Idiosyncratic Reactions

• 5-Alpha Reductase Inhibitor Allergy

Metabolism/Transport Effects

Substrate of CYP3A4 (minor); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential

Drug Interactions Open Interactions

There are no known significant interactions.

Test Interactions

PSA levels decrease in treated patients. After 6 months of therapy, PSA levels stabilize to a new baseline that is ~50% of pretreatment values. If following serial PSAs in a patient, re-establish a new baseline after ≥6 months of use.

Monitoring Parameters

To interpret serial PSAs, establish a new PSA baseline ≥6 months after treatment initiation and monitor PSA periodically thereafter. 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.

Advanced Practitioners Physical Assessment/Monitoring

For interpretation of serial PSAs, a new baseline should be established after 6 months of therapy. Any increase from the lowest PSA value should be evaluated as a possible signal of prostate cancer even if it is considered within normal limits. Assess for 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.

Nursing Physical Assessment/Monitoring

Check ordered labs and report any abnormalities. Instruct pregnant women to avoid contact with crushed or broken tablets.

Dosage Forms: US

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Propecia: 1 mg

Proscar: 5 mg [contains fd&c blue #2 aluminum lake]

Generic: 1 mg, 5 mg

Dosage Forms: Canada

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Propecia: 1 mg

Proscar: 5 mg [contains fd&c blue #2 aluminum lake]

Generic: 1 mg, 5 mg

Anatomic Therapeutic Chemical (ATC) Classification

• D11AX10
• G04CB01

Generic Available (US)

Yes

Pricing: US

Tablets (Finasteride Oral)

1 mg (per each): $2.71 - $2.72

5 mg (per each): $0.11 - $3.19

Tablets (Propecia Oral)

1 mg (per each): $4.14

Tablets (Proscar Oral)

5 mg (per each): $5.65

Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.

Mechanism of Action

Finasteride competitively inhibits type II 5-alpha reductase, resulting in inhibition of the conversion of testosterone to dihydrotestosterone and markedly suppresses serum dihydrotestosterone levels

Pharmacodynamics/Kinetics

Duration: Dihydrotestosterone levels return to normal within 14 days of discontinuation of treatment; BPH: Prostate volume returns to baseline within ~3 months after discontinuation; Male pattern baldness: Reversal of increased hair count within 12 months

Distribution: Vdss: 76 L

Protein binding: ~90%

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

Bioavailability: Mean: 5 mg: ~63%; 1 mg: 65% (not affected by food)

Half-life elimination, serum: 5 to 6 hours (range: 3 to 16 hours); Elderly (≥70 years): 8 hours (range: 6 to 15 hours)

Time to peak, serum: 1 to 2 hours

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

Pharmacodynamics/Kinetics: Additional Considerations

Renal function impairment: Urinary excretion of metabolites was decreased in patients with renal impairment. This decrease was associated with an increase in fecal excretion of metabolites. Plasma concentrations of metabolites were significantly higher in patients with renal impairment (based on a 60% increase in total radioactivity AUC).

Geriatric: Mean AUC0-24 increases 15%.

Local Anesthetic/Vasoconstrictor Precautions

No information available to require special precautions

Effects on Dental Treatment

No significant effects or complications reported

Effects on Bleeding

No information available to require special precautions

Related Information

• Oral Medications That Should Not Be Crushed or Altered
• Safe Handling of Hazardous Drugs

FDA Approval Date

June 19, 1992

References

<800> Hazardous Drugs—Handling in Healthcare Settings. United States Pharmacopeia and National Formulary (USP 40-NF 35). Rockville, MD: United States Pharmacopeia Convention; 2017:83-102.

American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 194: Polycystic Ovary Syndrome. Obstet Gynecol. 2018;131(6):e157-e171. doi: 10.1097/AOG.0000000000002656.[PubMed 29794677]

Barbieri RL, Chang J. Treatment of hirsutism. Post TW, ed. UpToDate. Waltham, MA: UpToDate Inc. http://www.uptodate.com. Accessed September 26, 2019.

Barrionuevo P, Nabhan M, Altayar O, et al. Treatment options for hirsutism: a systematic review and network meta-analysis. J Clin Endocrinol Metab. 2018;103(4):1258-1264. doi: 10.1210/jc.2017-02052.[PubMed 29522176]

Cunningham GR, Kadmon D. Medical treatment of benign prostatic hyperplasia. Post TW, ed. UpToDate. Waltham, MA: UpToDate Inc. http://www.uptodate.com. Accessed September 26, 2019.

Donovan J, Goldstein BG, Goldstein AO. Treatment of androgenetic alopecia in men. Post TW, ed. UpToDate. Waltham, MA: UpToDate Inc. http://www.uptodate.com. Accessed September 26, 2019.

Leyden J, Dunlap F, Miller B, et al. Finasteride in the treatment of men with frontal male pattern hair loss. J Am Acad Dermatol. 1999;40(6, pt 1):930-937. doi: 10.1016/s0190-9622(99)70081-2.[PubMed 10365924]

Martin KA, Anderson RR, Chang RJ, et al. Evaluation and treatment of hirsutism in premenopausal women: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2018;103(4):1233-1257. doi: 10.1210/jc.2018-00241.[PubMed 29522147]

McConnell JD, Roehrborn CG, Bautista OM, et al; Medical Therapy of Prostatic Symptoms (MTOPS) Research Group. The long-term effect of doxazosin, finasteride, and combination therapy on the clinical progression of benign prostatic hyperplasia. N Engl J Med. 2003;349(25):2387-2398. doi: 10.1056/NEJMoa030656.[PubMed 14681504]

McVary KT, Roehrborn CG, Avins AL, et al. American Urological Association guideline: management of benign prostatic hyperplasia. https://www.auanet.org/guidelines/benign-prostatic-hyperplasia-(bph)-guideline/benign-prostatic-hyperplasia-(2010-reviewed-and-validity-confirmed-2014). Published 2010. Accessed September 26, 2019.

Propecia (finasteride) [prescribing information]. Whitehouse Station, NJ: Merck & Co; January 2014.

Proscar (finasteride) [prescribing information]. Whitehouse Station, NJ: Merck & Co; September 2013.

Thompson IM, Goodman PJ, Tangen CM, et al. The influence of finasteride on the development of prostate cancer. N Engl J Med. 2003;349(3):215-224. doi: 10.1056/NEJMoa030660.[PubMed 12824459]

Thompson IM Jr, Goodman PJ, Tangen CM, et al. Long-term survival of participants in the prostate cancer prevention trial. N Engl J Med. 2013;369(7):603-610. doi: 10.1056/NEJMoa1215932.[PubMed 23944298]

US Department of Health and Human Services; Centers for Disease Control and Prevention; National Institute for Occupational Safety and Health. NIOSH list of antineoplastic and other hazardous drugs in healthcare settings 2016. http://www.cdc.gov/niosh/topics/antineoplastic/pdf/hazardous-drugs-list_2016-161.pdf. Updated September 2016. Accessed October 5, 2016.

Welk B, McArthur E, Ordon M, Anderson KK, Hayward J, Dixon S. Association of suicidality and depression with 5α-reductase inhibitors. JAMA Intern Med. 2017;177(5):683-691. doi: 10.1001/jamainternmed.2017.0089.[PubMed 28319231]

Whiting DA, Waldstreicher J, Sanchez M, Kaufman KD. Measuring reversal of hair miniaturization in androgenetic alopecia by follicular counts in horizontal sections of serial scalp biopsies: results of finasteride 1 mg treatment of men and postmenopausal women. J Investig Dermatol Symp Proc. 1999;4(3):282-284.[PubMed 10674382]

Zakhem GA, Motosko CC, Mu EW, Ho RS. Infertility and teratogenicity after paternal exposure to systemic dermatologic medications: A systematic review. J Am Acad Dermatol. 2019;80(4):957-969. doi:10.1016/j.jaad.2018.09.031[PubMed 30287313]

Brand Names: International

Alofecid (KR); Alopec (BD); Androfin (LV); Aprodil (EC); Atepros (PH); Bearfina (KR); Benstat (TH); Binfin (SG); Binfin 5 (ZW); Borealis (CR, DO, GT, HN, NI, PA, SV); Caosol (CR, DO, GT, HN, NI, PA, SV); Chibro-Proscar (FR); Damocare (HK); Damopecia (KR); Daric (PY); Finapecia (EG); Finapros (PH); Finarid (PH); Finas (BD, SG); Finascar (JO); Finaspro (TW); Finaspros (CO); Finast (LK, VN); Finasta (AU); Finastar (KR); Finastid (HR); Finated (KR); Finatra (CN); Fincar (EG, HK, IN, KR, LK, MY); Finide (PH); Finiscar (QA); Finnacar (AU); Finpro (ID, ZA); Finstal-5 (PH); Finster (LV); Fintrid (IE); Firide (TH); Fistrin (CO); For-BPH (PH); Fynasid (TW); GPO-Finax (TH); Harifin (TH); Jun Neng (CN); Maxteride (HK); Monastar (KR); Nopecia (EG); Oilpp (NI); Olipp (CR, DO, GT, HN, PA, SV); Penester (LV, UA); Pro-Cure (IL); Profal (IE); Prohair (QA); Pronax (PH); Pronor (LK); Propecia (AE, AR, AT, AU, BR, BS, BZ, CN, CO, CY, EC, ES, HK, HR, IL, IS, JM, JP, KW, LB, LU, MT, MY, NL, NZ, PE, PH, RO, SA, SE, SG, TH, TT, TW); Propeshia (MX); Proscar (AE, AR, AT, AU, BB, BD, BE, BG, BH, BM, BO, BR, CH, CL, CN, CR, CY, CZ, DE, DK, DO, EC, EE, EG, ES, FI, GB, GR, GT, GY, HK, HN, HR, HU, ID, IE, IT, JO, KR, KW, LB, LU, MT, MX, MY, NI, NO, NZ, PA, PE, PH, PK, PL, PR, PT, RO, RU, SA, SE, SG, SK, SR, SV, TH, TR, TW, VE, VN); Proseride (TH); Prosfin (BD); Prostacare (LB, QA); Prostan (UA); Prostanus (PH); Prostarinol (LV); Prosterid (HU); Prosteride (HK, PH, TH); Prostide (ID); Prostop (UY); Proteside (JO); Reprostom (ID); Skarex (KR); Stercia (SG); Stercia-5 (TH); Sterzar (TH); Tealep (CR, DO, GT, HN, NI, PA, SV); Tensen (TW); Uromedin (PY)

Last Updated 9/19/20