What is Finasteride?

Karyn Maier

Finasteride is a synthetic drug engineered to act as an androgen antagonist. This means that its mechanism of action is to suppress the activity of androgens, or steroid hormones, at receptor sites. Specifically, finasteride inhibits 5-alpha-reductase (5 ar) Type II, the enzyme responsible for the conversion of testosterone to dihydrotestosterone (DHT). This is significant since certain conditions affecting men, such as male pattern balding (hair loss), benign prostatic hyperplasia (BPH), and prostate cancer, may otherwise be triggered by this conversion. In fact, 5 ar increases in circulation in response to the age-related decline in testosterone production in men.

The drug finasteride may decrease the synthesis of DHT.
The drug finasteride may decrease the synthesis of DHT.

Merck & Co., the manufcaturer of finasteride, has been granted several patents for the drug in various formulations. However, the concentration of finasteride varies in the final product according to its application. Propecia, for example, is the formula produced for the treatment of baldness in men and contains only 3.52-5 ounces (1.0 milligram) of finasteride. Proscar, on the other hand, is intended to treat BPH with a finasteride concentration five times greater. In addition, finasteride is marketed under several different trade names, including Finara, Gefina, Appecia, and Finasterid Alternova.

Finasteride has shown promise as a hair loss treatment.
Finasteride has shown promise as a hair loss treatment.

There are also several non-U.S. companies that manufacture generic versions of finasteride medications, which are available at less cost. For instance, Ranbaxy Laboratories Limited of India produces a generic form of Finara. Another Indian-based pharmaceutical company, Ajanta Pharma Limited, manufactures a generic version of Appecia. However, while some of these generic forms may be purchased on the Internet, the U.S. brand names of Propecia and Proscar are only available by prescription.

Numerous studies have been conducted on the efficacy of finasteride as a treatment for hair loss, in both men and women. One five-year study revealed that 48% of men who used Propecia experienced the growth of new hair. This study also demonstrated that this particular finasteride preparation most successfully restores hair growth to the crown of the head, exactly where hair loss typically occurs in male pattern balding. However, if treatment is discontinued, any new hair growth will be lost within 12 months.

Studies involving finasteride treatment for hair loss in women have not been as positive however. In addition, although many physicians are willing to prescribe finasteride for hair loss in women, they only do so if there is zero chance that she may become pregnant. This is because there is adequate evidence that pregnant women, or women that may become pregnant, should not use finasteride due to a higher risk of birth defects. In fact, such women are advised to avoid handling the tablets or even coming into contact with its packaging at all. While there has been little research done on the negative impact of finasteride in breastfeeding women, it is assumed that the drug should be avoided while nursing as well.

Pregnant women or those who could become pregnant should not use finasteride due to a risk for birth defects.
Pregnant women or those who could become pregnant should not use finasteride due to a risk for birth defects.

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Discussion Comments


Just a warning, common side effects of Finasteride are decreased libido and erectile dysfunction.

These problems are usually reversed pretty quickly in men who stop taking the drug. However, like the article says, the hair growth will also stop after patients stop taking Finasteride.

Talk to a doctor to weigh the benefits of taking the drug against the side effects and to find out if there are other options available to promote hair growth.

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