Finasteride (Propecia) for Men
Finasteride 1mg was FDA-approved in 1997 for the treatment of male pattern hair loss. Since then, it has been used extensively and successfully in men of all ages for the treatment of hair loss. It is only approved for persons over age 18 but has been used off-label in younger men. It is not recommended for use prior to puberty. Finasteride works by blocking the type II enzyme 5-alpha-reductase, which converts testosterone to dihydrotestosterone (DHT). Evidence that this enzyme contributes to male pattern hair loss comes from the fact that eunichs, who lack the enzyme, never develop hair loss.
Side effects can include breast tenderness or enlargement, breast cancer (seen in a very small number of men in the post-marketing reports) and sexual side effects (reported in less than 2% of patients in the clinical trials). New 10-year data demonstrated no connection between breast cancer and 5-alpha reductase inhibitors (finasteride and dutasteride). Merck recently added long-term sexual side effects to their package labeling, based on a recent study. This study was a retrospective set of interviews with several limitations including selection bias, recall bias, and lack of control for confounding factors. Any patient who has side effects should stop the drug as soon as possible, and it should be out of their system in a matter of 3-4 days.
Men over the age of 50 should be sure to inform their internist or urologist they are taking finasteride. This medication artificially lowers the value of the PSA (prostate specific antigen). This is because the finasteride also works to help shrink the prostate preventing benign prostatic hypertrophy (BPH). To interpret the PSA in a man taking finasteride, your doctor should double the PSA in order to get the true value.D’Amico AV, Roehrborn CG. Effect of 1mg/day finasteride on concentrations of serum prostate-specific antigen in men with androgenic alopecia: a randomised controlled trial. Lancet Oncol. 2007;8:21-5.^]. Men who are taking it should not donate blood for 6 months after their last dose to avoid inadvertent administration to a pregnant female.