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 (prostate volume >30 mL, prostate-specific antigen >1.5 ng/dL, or palpable prostate enlargement on digital rectal exam) or those with hematuria associated with benign prostatic hyperplasia (AUA [Lerner 2021a]; AUA [Lerner 2021b]; McVary 2022).
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 [Lerner 2021a]; 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 2021; Endocrine Society [Martin 2018]).
The renal dosing recommendations are based upon the best available evidence and clinical expertise. Senior Editorial Team: Bruce Mueller, PharmD, FCCP, FASN, FNKF; Jason Roberts, PhD, BPharm (Hons), B App Sc, FSHP, FISAC; Michael Heung, MD, MS.
Altered kidney function: Mild to severe impairment: No dosage adjustment necessary (Steiner 1996; manufacturer's labeling).
Hemodialysis, intermittent (thrice weekly): Unlikely to be dialyzed (highly protein bound, moderate Vd): No supplemental dose or dosage adjustment necessary (expert opinion).
Peritoneal dialysis: Unlikely to be dialyzed (highly protein bound, moderate Vd): No dosage adjustment necessary (expert opinion).
CRRT: No dosage adjustment necessary (expert opinion).
PIRRT (eg, sustained, low-efficiency diafiltration): No dosage adjustment necessary (expert opinion).
There are no dosage adjustments provided in the manufacturer’s labeling. Use with caution (finasteride is metabolized extensively in the liver)
Refer to adult dosing.
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
Yes
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Tablet, Oral:
Propecia: 1 mg
Proscar: 5 mg [contains corn starch, fd&c blue #2 aluminum lake]
Generic: 1 mg, 5 mg
Oral: May be administered with or without meals. Pregnant patients and patients who could become pregnant should not touch or handle crushed or broken tablets.
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).
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-1 adrenergic antagonist to reduce the risk of symptomatic progression.
Limitations of use: Not approved for the prevention of prostate cancer.
Hirsutism
Finasteride may be confused with dutasteride, furosemide
Proscar may be confused with Prograf, ProSom, Provera, PROzac
The Institute for Safe Medication Practices (ISMP) includes this medication among its list of drugs that have a heightened risk of causing significant patient harm when used in error.
Finasteride may cause sexual dysfunction, including impotence, decreased libido, ejaculatory disorder, and sexual disorder (Ref), which may persist after discontinuation (Ref). Of note, it has been hypothesized that persistent sexual dysfunction may contribute to psychological adverse reactions (eg, anxiety and depression) and suicidal ideation and suicidal tendencies in younger patients treated for alopecia (Ref).
Mechanism: Dose and time-related; may be related to antiandrogenic effects and subsequent decreased nitric oxide in the corpus cavernosum (Ref).
Onset: Delayed; may begin after ~6 months of therapy and peak during the first year (Ref).
Risk factors:
• Independent risk factors include older patients and benign prostatic hyperplasia (Ref)
• Higher dosage of finasteride (5 mg/day) (Ref)
• Length of therapy ≥1 year (Ref)
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.
>10%: Genitourinary: Impotence (5% to 19%) (table 1)
Drug (Finasteride) |
Placebo |
Dose |
Indication |
Number of Patients (Finasteride) |
Number of Patients (Placebo) |
Comments |
---|---|---|---|---|---|---|
19% |
12% |
5 mg per day |
BPH |
768 |
737 |
N/A |
8% |
4% |
N/A |
BPH |
1524 |
1516 |
Year 1 |
5% |
5% |
N/A |
BPH |
1524 |
1516 |
Years 2 to 4 |
1% to 10%:
Cardiovascular: Hypotension (1%), orthostatic hypotension (9%) (table 2) , peripheral edema (1%)
Drug (Finasteride) |
Placebo |
Dose |
Indication |
Number of Patients (Finasteride) |
Number of Patients (Placebo) |
---|---|---|---|---|---|
9% |
8% |
5 mg/day |
BPH |
768 |
737 |
Endocrine & metabolic: Decreased libido (2% to 10%) (table 3) , gynecomastia (1% to 2%)
Drug (Finasteride) |
Placebo |
Dose |
Indication |
Number of Patients (Finasteride) |
Number of Patients (Placebo) |
Comments |
---|---|---|---|---|---|---|
10% |
6% |
5 mg/day |
BPH |
768 |
737 |
N/A |
6% |
3% |
N/A |
BPH |
1524 |
1516 |
Year 1 |
3% |
3% |
N/A |
BPH |
1524 |
1516 |
Years 2 to 4 |
2% |
1% |
1 mg/day |
Male pattern hair loss |
945 |
934 |
N/A |
Genitourinary: Breast tenderness (≤1%), decreased ejaculate volume (2% to 4%), ejaculatory disorder (≤7%) (table 4) , sexual disorder (3%) (table 5)
Drug (Finasteride) |
Placebo |
Dose |
Indication |
Number of Patients (Finasteride) |
Number of Patients (Placebo) |
Comments |
---|---|---|---|---|---|---|
7% |
2% |
5 mg/day |
BPH |
768 |
737 |
N/A |
0.8% |
0.1% |
N/A |
BPH |
1524 |
1516 |
Year 1 |
0.2% |
0.1% |
N/A |
BPH |
1524 |
1516 |
Years 2 to 4 |
1% |
0.7% |
1 mg/day |
Male pattern hair loss |
945 |
934 |
N/A |
Drug (Finasteride) |
Placebo |
Dose |
Indication |
Number of Patients (Finasteride) |
Number of Patients (Placebo) |
---|---|---|---|---|---|
3% |
0.9% |
5 mg/day |
BPH |
768 |
737 |
Hematologic & oncologic: Prostate cancer - high grade (2%) (Thompson 2003, Thompson 2013)
Respiratory: Rhinitis (1%)
<1%: Hematologic & oncologic: Malignant neoplasm of the breast (men)
Postmarketing:
Cardiovascular: Hypersensitivity angiitis (Lear 1996)
Dermatologic: Acute generalized exanthematous pustulosis (T-cell mediated localized exanthematous pustulosis) (Tresch 2011), erythematous rash (erythema annulare centrifugum) (Al Hammadi 2007), urticaria (Moreno-Fernandez 2010)
Genitourinary: Hemospermia (Fouda 2017), male infertility (temporary) (Chiba 2010; Ricci 2012), testicular pain (Pereira 2020)
Hypersensitivity: Fixed drug eruption (Oyama 2009)
Nervous system: Anxiety (Nguyen 2021), depression (may persist after discontinuation) (Nguyen 2021, Welk 2017), suicidal ideation (may persist after discontinuation) (Ali 2015; Nguyen 2021, Welk 2017), suicidal tendencies (may persist after discontinuation) (Nguyen 2021, Welk 2017)
Hypersensitivity to finasteride or any component of the formulation; pregnancy or patients who may potentially be pregnant.
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. Patients who could become pregnant 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. Reestablish new PSA baseline after initiation. 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.
Substrate of CYP3A4 (minor); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential
There are no known significant interactions.
Although use is contraindicated in patients who may potentially be pregnant, finasteride has been evaluated for various indications in premenopausal patients, including the treatment of hirsutism and female pattern hair loss. Adequate contraception is recommended (ACOG 2018; Carmina 2019; ES [Martin 2018]; Hu 2019; Iamsumang 2020). Contraception should be used during treatment and for at least 30 days after the last finasteride dose (Carmina 2019).
Patients who could become pregnant 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).
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. Pregnancy outcome information following inadvertent finasteride exposure during pregnancy is limited (AlSaad 2018). Use is contraindicated during pregnancy.
Pregnant patients are advised to avoid contact with crushed or broken tablets and immediately wash the contact area with soap and water if exposure occurs.
It is not known if finasteride is present in breast milk.
Patients who could become pregnant should not touch or handle crushed or broken tablets.
To interpret serial prostate-specific antigens (PSAs), establish a new PSA baseline ≥6 months after treatment initiation and monitor PSA periodically thereafter; International Prostate Symptom Score (baseline and 3 to 12 months after treatment initiation); urinalysis (baseline); objective and subjective signs of relief of benign prostatic hyperplasia and lower urinary tract symptoms (AUA [Lerner 2021a; McVary 2022; manufacturer's labeling).
Finasteride competitively inhibits type II 5-alpha reductase, resulting in inhibition of the conversion of testosterone to dihydrotestosterone and markedly suppresses serum dihydrotestosterone levels
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)
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%.
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
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