minoxidil

minoxidil, medication that is used to treat both high blood pressure (hypertension) and baldness. Minoxidil is one of a class of medications known as antihypertensive vasodilators. As a hair loss treatment, it is marketed under the brand name Rogaine.

History

In the 1950s the Upjohn Company developed minoxidil to treat stomach ulcers. However, testing conducted on laboratory animals found that the drug neither cured nor treated ulcers. Instead, the drug was found to relax blood vessels, which opened them and thus allowed for better blood flow (such medications are called vasodilators). This relaxation lowers a patient’s blood pressure. In the 1970s the U.S. Food and Drug Administration (FDA) approved the drug for use on patients suffering from high blood pressure. Initially it was marketed under the name Loniten as tablets that were to be taken orally.

Many patients taking minoxidil for high blood pressure reported having hair growth as a side effect. This side effect was investigated, and in 1988 the FDA approved the drug as a medication causing hair growth in males, reversing the processes that cause male pattern baldness, under the name Rogaine. In 1991 Rogaine for women was introduced. How minoxidil works to promote hair growth is not completely understood.

Rogaine is marketed as a hair loss treatment, but it is not a cure for hair loss. Many patients who stopped taking the medication reported a cessation of the hair growth that the drug had initially created, and in some cases this newly grown hair was reported to have fallen out after application of the medication stopped. Rogaine is applied to the scalp as a topical solution.

Side effects

While the side effects of minoxidil are rare, some users have reported an itching or rash near the application site. Some have also reported acne, reddened skin, a burning feeling, and inflammation or soreness. In extremely rare instances, blurred vision, dizziness, headaches, lightheadedness, and chest pain have also been reported.

Properties

Minoxidil has a molecular weight of 209.25 grams per mole. In its pure form, it is an odourless white crystalline powder. Minoxidil has a melting point of 248 °C (478 °F) and a solubility of 220 milligrams per litre. When heated, minoxidil decomposes and emits toxic nitrogen oxide fumes. Minoxidil has a molecular formula of C₉H₁₅N₅O.