Finasteride

5-Alpha Reductase Inhibitor·Urology

BPH to reduce acute urinary retention and need for surgery

Authority requiredPBS5-ARIProscar (5 mg), Propecia (1 mg)1 mg tablet+2

Max Dose

5 mg/day

Half-life

6 h

Teratogenic

CATEGORY X

Onset

3-6 MONTHS

Rapid Summary

Overview

5-Alpha Reductase Inhibitor. Blocks the conversion of testosterone to DHT. Physically shrinks the prostate gland over time and halts male pattern baldness.

Maximum Dose

Max 5 mg/day (for BPH) or 1 mg/day (for alopecia).

Clinical Focus

Highly teratogenic. Pregnant women must not handle crushed or broken tablets.

Bottom Line

Finasteride is a 5-alpha reductase inhibitor for BPH and male pattern baldness, but takes 3-6 months for effect and causes sexual dysfunction that may persist after discontinuation.

Formulation & Access

Brand Names

Proscar (5 mg), Propecia (1 mg)

Oral Routes

Tablets (1 mg, 5 mg).

Prescribing & PBS

Authority Required (PBS) for BPH.

Indications & Use

Primary

PBSTGA

BPH to reduce acute urinary retention and need for surgery. Male pattern baldness.

Clinical Place

Disease-modifying agent for BPH. Used when the prostate is significantly enlarged (>40g).

Quick reference

Class & Role

5-Alpha Reductase Inhibitor — 5-Alpha Reductase Inhibitor.

Route / Formulation

Tablets (1 mg, 5 mg). (Proscar (5 mg), Propecia (1 mg))

Usual Dose & Max

PO 5 mg OD. Max 5 mg/day (for BPH) or 1 mg/day (for alopecia).

Key Indication Doses

Benign Prostatic Hyperplasia: PO 5 mg OD. Androgenetic Alopecia: PO 1 mg OD.

Best Uses

Finasteride is a 5-alpha reductase inhibitor for BPH and male pattern baldness, but takes 3-6 months for effect and causes sexual dysfunction that may persist after discontinuation.

Avoid / Cautions

Women, children. Pregnancy Category X. Extreme risk of feminizing male fetuses. Pregnant nurses/pharmacists must not handle crushed pills.

Key Risks

Endocrine/GU: Decreased libido, erectile dysfunction, decreased ejaculate volume (can persist even after stopping the drug). Endocrine: Gynecomastia, breast tenderness. Psychiatric: Depression, anxiety (Post-finasteride syndrome).

Key Interactions

No major clinically significant drug interactions.

Monitoring

Finasteride artificially halves serum PSA levels. You MUST double the reported PSA value to accurately screen for prostate cancer while a patient is on this drug.

Clinical Pearl

If a patient on Finasteride 5mg has a PSA of 3.0, their true PSA is 6.0. Failing to double the number leads to missed prostate cancers.

Access

Authority requiredProscar (5 mg), Propecia (1 mg)1 mg tablet

Brand: Proscar (5 mg), Propecia (1 mg)
PBS status: Authority required
Formulation: Tablets (1 mg, 5 mg)

Finasteride

5-Alpha Reductase Inhibitor·Urology

BPH to reduce acute urinary retention and need for surgery

Authority requiredPBS5-ARIProscar (5 mg), Propecia (1 mg)1 mg tablet+2

Max Dose

5 mg/day

Half-life

6 h

Teratogenic

CATEGORY X

Onset

3-6 MONTHS

Rapid Summary

Overview

5-Alpha Reductase Inhibitor. Blocks the conversion of testosterone to DHT. Physically shrinks the prostate gland over time and halts male pattern baldness.

Maximum Dose

Max 5 mg/day (for BPH) or 1 mg/day (for alopecia).

Clinical Focus

Highly teratogenic. Pregnant women must not handle crushed or broken tablets.

Bottom Line

Finasteride is a 5-alpha reductase inhibitor for BPH and male pattern baldness, but takes 3-6 months for effect and causes sexual dysfunction that may persist after discontinuation.

Formulation & Access

Brand Names

Proscar (5 mg), Propecia (1 mg)

Oral Routes

Tablets (1 mg, 5 mg).

Prescribing & PBS

Authority Required (PBS) for BPH.

Indications & Use

Primary

PBSTGA

BPH to reduce acute urinary retention and need for surgery. Male pattern baldness.

Clinical Place

Disease-modifying agent for BPH. Used when the prostate is significantly enlarged (>40g).

Quick reference

Class & Role

5-Alpha Reductase Inhibitor — 5-Alpha Reductase Inhibitor.

Route / Formulation

Tablets (1 mg, 5 mg). (Proscar (5 mg), Propecia (1 mg))

Usual Dose & Max

PO 5 mg OD. Max 5 mg/day (for BPH) or 1 mg/day (for alopecia).

Key Indication Doses

Benign Prostatic Hyperplasia: PO 5 mg OD. Androgenetic Alopecia: PO 1 mg OD.

Best Uses

Finasteride is a 5-alpha reductase inhibitor for BPH and male pattern baldness, but takes 3-6 months for effect and causes sexual dysfunction that may persist after discontinuation.

Avoid / Cautions

Women, children. Pregnancy Category X. Extreme risk of feminizing male fetuses. Pregnant nurses/pharmacists must not handle crushed pills.

Key Risks

Key Interactions

No major clinically significant drug interactions.

Monitoring

Finasteride artificially halves serum PSA levels. You MUST double the reported PSA value to accurately screen for prostate cancer while a patient is on this drug.

Clinical Pearl

If a patient on Finasteride 5mg has a PSA of 3.0, their true PSA is 6.0. Failing to double the number leads to missed prostate cancers.

Access

Authority requiredProscar (5 mg), Propecia (1 mg)1 mg tablet

Brand: Proscar (5 mg), Propecia (1 mg)
PBS status: Authority required
Formulation: Tablets (1 mg, 5 mg)