Finasteride

1 - INTRODUCTION

Finasteride is a 4-azasteroid that inhibits a human enzyme, 5 alpha-reductase which allows the conversion of testosterone (T) into dihydrotestosterone (DHT). In humans, there are two different types of 5 alpha-reductases, i.e. 5 alpha-reductase type I (5AR1) and 5 alpha-reductase type II (5AR2). The inhibitory effect of finasteride on 5AR2 is 100 times greater than its inhibitory effect on 5AR1.

Finasteride was first developed for the indication “benign prostatic hyperplasia” for which a marketing authorization was granted in June 1992 in the United States and then in France at the oral dose of 5 mg/day.

Finasteride was then developed for the indication “male androgenetic alopecia”. It was granted a marketing authorization for “mild to moderate androgenetic alopecia in males between 18 and 41 years of age” in December 1997 in the United States, and then in December 1998 in France. It was marketed at the dose of 1 mg under the name Propecia^® in February 1998 in the United States, and then in February 1999 in France.

Finasteride is not indicated for use in women and is contraindicated during pregnancy because of a risk of poor differentiation of the genitals of a male foetus. It is also contraindicated in children before the age of 18.

Currently, more than 25 000 boxes of finasteride 1 mg are sold in France every month. Its effectiveness has been demonstrated in 18 controlled studies including 12 double-blind placebo controlled studies in almost all the countries of the world. The recent marketing of generics and new brands has reduced the cost of treatment to under 20 Euros for 1 month and under 40 Euros for 3 months, making it easier to help all the patients requesting treatment.