Merck, the American drug manufacturer, is offering a money back guarantee with finasteride (Proscar), its new drug treatment for benign prostatic hyperplasia. The company is offering to refund the cost of the drug if it fails to improve symptoms within six months or if the patient needs prostatic surgery within two years.

Finasteride is an antiandrogen, prescribed by general practitioners and urologists, which inhibits the metabolism of testosterone, reducing the volume of prostatic tissue and improving urinary flow rates in men with benign prostatic hyperplasia. It is the only drug of its class and, according to …