Class: 5 α-Reductase Inhibitor
Dosage Forms. Tablet: 1 mg, 5 mg
Common FDA Label Indication, Dosing, and Titration.
1. Benign prostatic hyperplasia: 5 mg po daily
2. Male pattern alopecia: 1 mg po daily
1. Prostate cancer prevention: 5 mg po daily
MOA. Finasteride inhibits the conversion of testosterone to 5α-dihydrotestosterone (DHT) by 5α-reductase, isoform 2.
Drug Characteristics: Finasteride
Medication Safety Issues: Finasteride
Drug Interactions: Finasteride
Adverse Reactions: Finasteride
Efficacy Monitoring Parameters. American Urologic Association (AUA) Symptom Score, decrease in residual urine volume, increased urine flow if using for BPH; increased hair growth if using for male pattern alopecia.
Toxicity Monitoring Parameters. Shortness of breath, swelling, breast pain or mass.
Key Patient Counseling Points. For hair loss, you may need to take this medicine for 3 mo or longer before you see an effect. For an enlarged prostate, you may need to take this medicine for up to 6 mo to see the full effect. Women who are pregnant or may become pregnant should avoid touching or handling this medicine. This medicine can get into the body through the skin and may prevent development of genitalia in an unborn male baby. They should also avoid semen of a man taking finasteride.
Clinical Pearls. Not effective for the treatment of prostate cancer. Is effective in reducing the overall incidence of prostate cancer, although an increase in the incidence of high-grade prostate cancers has been observed. Draw baseline PSA before initiating therapy. Note that PSA will decrease by 50% with treatment, double PSA values when assessing for prostate cancer. Hazardous agent: Use appropriate precautions for handling and disposal.