Finasteride, marketed by Merck under the brand names Proscar and Propecia, is a type II 5a-reductase inhibitor. As 5a-reductase is the enzyme which converts testosterone into the more potent form dihydrotestosterone (DHT), the drug is sometimes used to treat some of the symptoms of PCOS which relate to hyperandrogenism or high testosterone levels, such as acne, hirsutism and hair loss.
The drug is used predominantly for the treatment of men with benign prostatic hyperplasia and male pattern baldness (androgenic alopecia).
For the treatment of PCOS symptoms, finasteride (Propecia) may be prescribed in a dosage ranging between 1 mg and 5 mg.Finasteride (Propecia) is a category X drug during pregnancy, meaning that it is known to cause birth defects in male foetuses. Women who are intending to become pregnant or who are pregnant must not take this drug.