Topical minoxidil solution is the only approved drug available for promoting hair growth in women with AGA (Price, 1999). Efficacy has been shown in double blind, placebo-controlled studies using hair counts and hair weight as the primary end points (Price, 1999). Minoxidil-treated women had significantly higher hair counts and an increase in hair weight compared to women who received placebo. A double-blind study of women ages 22-41 years using 2% topical minoxidil solution showed a significant increase over placebo in mean change in hair weight at 16 weeks (Price and Menefee, 1990). It should be noted that clinical perception of improved scalp coverage may take longer, up to 6-12 months, until hair length and mass are increased sufficiently. Minoxidil solution must be applied twice daily to a dry scalp.
Finasteride is a competitive inhibitor of type II 5x-reductase, and is contraindicated in women who are or may become pregnant, because 5x-reductase inhibitors may cause abnormalities of the external genitalia of a male fetus. Finasteride was not effective in postmenopausal women in a placebo-controlled study (Price et al, 2000).
Some drugs are not approved by the FDA but are potentially helpful medications.19 In women with androgenetic alopecia, especially those with a component of hyperandrogenism, drugs that act as androgen suppressants or antagonists (eg, spironolactone, oral contraceptives) may be beneficial. Evidence exists of an association between androgenetic alopecia, hypertension, and hyperaldosteronism. Spironolactone could play a dual role in treatment.
Phase III US Food and Drug Administration (FDA) trials of dutasteride to treat androgenetic alopecia are currently on hold. This drug inhibits both type I and type II 5-a reductase isoenzymes and is felt to be 3 times as potent as finasteride in inhibiting the type II enzyme and 100 times as potent in inhibiting the type I enzyme.
Low-level laser light therapy, in particular a red light hairbrush–like device has been marketed as an over-the-counter technique for hair growth. In a double blind, sham-device controlled, multicenter, 26-week trial, 110 patients in the active treatment group who completed the study showed a significantly greater improvement in overall hair regrowth than did the sham group.20 Marketed as the HairMax LaserComb, it has obtained 510K FDA approval for use as a medical device. Note that this approval refers to safety rather than actual efficacy and that the data required for medical devices are quite different from those required to demonstrate the safety and efficacy of drugs.
Androgenetic alopecia is very common; therefore, not surprisingly, it may accompany other forms of hair loss. Cases of telogen effluvium often occur in patients with underlying androgenetic alopecia. Therefore, a search for treatable causes of telogen effluvium (eg, anemia, hypothyroidism), especially in patients with an abrupt onset or a rapid progression of their disease, is indicated.
