Proscar

Proscar is a medicine Finasteride in 5mg dose, registered trademark of Merck&Co. While other brand name of this manufacturer Propecia (contains 1mg of Finasteride) is prescripebed for male pattern hair loss, Proscar (in larger dose - Finasteride 5mg) is prescribed to help shrink an enlarged prostate.
More information about differences between Propecia and Proscar

Proscar (Finasteride 5mg)

Proscar is used to treat benign prostatic hyperplasia (enlarged prostate). Proscar may also be used to reduce hair loss due to male pattern baldness, becouse its active ingrendient is Finasteride, U.S. FDA (United States Food and Drug Administration) approved for the treatment of male pattern hair loss (the dosage necessary to produce significant hair restoration benefits is a 1-milligram tablet, taken daily). Proscar (finasteride) tablets for oral administration are film-coated tablets that contain 5mg of Finasteride.

Proscar is indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate to improve symptoms; reduce the risk of acute urinary retention (AUR); and reduce the risk of the need for surgery, including transurethral resection of the prostate (TURP) and prostatectomy.

Safety information, possible side effects, drug interactions... are the same for all trademarks of Finasteride.

External links:
Proscar Manufacturer's website
Proscar Patient Information