Finasteride

Products

Finasteride is commercially available as film-coated tablets (prostate: Proscar, generic, 5 mg; hair loss: Propecia, generic, 1 mg). It has been approved in many countries since 1993. Propecia was launched five years later, in 1998.

Structure and properties

Finasteride (C23H36N2O2, Mr = 372.5 g/mol) is a 4-azasteroid and structurally related to testosterone. It exists as a white crystalline powder that is practically insoluble in water.

Effects

Finasteride (ATC D11AX10, ATC G04CB01) is a selective and competitive inhibitor of 5alpha-reductase, which converts testosterone to 5α-dihydrotestosterone. 5α-Dihydrotestosterone represents an important growth stimulus for prostate enlargement and is involved in the development of inherited hair loss. Finasteride leads to a decrease in the volume of the enlarged prostate in the longer term, relieves symptoms, and stops inherited hair loss as long as the drug is taken.

Indications

Finasteride is used in varying doses to treat inherited hair loss in men (androgenetic alopecia) and to treat benign prostate enlargement in men. Another possible application is the prevention of prostate cancer. Finasteride is not approved for this purpose in many countries, however.

Dosage

According to the SmPC. The usual dose for treatment of prostate enlargement is 5 mg once daily regardless of meals; the dose for treatment of hair loss is lower and is 1 mg once daily.

Abuse

Finasteride is abused for bodybuilding to treat side effects of anabolic steroids.

Contraindications

  • Hypersensitivity
  • Women and children
  • Pregnancy
  • Women should not come into contact with crushed or broken tablets because finasteride has the potential to harm fertility.

For complete precautions, see the drug label.

Interactions

Finasteride is a substrate of CYP3A4. Corresponding drug-drug interactions with inhibitors and inducers of the isoenzyme are possible.

Adverse effects

The most common possible adverse effects include decreased libido, impotence, erectile dysfunction, ejaculatory dysfunction, breast tenderness to touch, breast enlargement, and skin rash.