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Clinical Q & A; on male pattern baldnessMarch 16, 1998Q. What pharmacological agents are available for male pattern baldness? A. Male pattern baldness (MPB) is an extremely common condition. Hair loss in males may begin in the late teens or early 20s, and, by the age of 35 to 40, approximately 66% of male Caucasians will display some degree of hair loss. It is a familial condition and has genetic and hormonal etiologies. Typical presentation includes hair loss beginning in the lateral frontal areas or over the vertex. It may be extensive, depending on the person's age at the time of onset. It is now believed that hair loss can be attributed to the action of dihydrotestosterone (DHT), a metabolite of testosterone. This metabolic conversion, catalyzed by the enzyme 5-alpha reductase, takes place in the scalp. The activity level of 5-alpha reductase has been shown to adversely affect hair follicles and correlate with increased hair loss. In the United States, there are two drugs approved by the Food & Drug Administration for the treatment of male pattern baldness: topical minoxidil (Rogaine, Pharmacia & Upjohn), and oral finasteride (Propecia, Merck & Co.). Minoxidil 2% solution has been available for almost 10 years, initially by Rx only and currently as an OTC item; in November 1997, minoxidil 5% (Rogaine Extra Strength for Men) solution was approved by the FDA for sale as an OTC item as well. Finasteride, under the trade name Proscar, has been used in the United States for the treatment of benign prostatic hypertrophy (BPH) since 1992. Patients taking finasteride for BPH reported increased growth of scalp hair, which led to investigation of the drug and its approval for the treatment of MPB. The recommended dose of finasteride for MPB is 1 mg daily. The mechanism of action of minoxidil on hair growth is not known, but it is believed that the drug opens potassium channels, which could increase blood flow to the scalp or even stimulate hair follicles directly; it does not appear to have any antiandronergic effects. The 5% solution appears superior to the 2% solution, as measured by hair regrowth and overall hair density. Regrowth may occur as early as two months after initiation of therapy with the 5% solution and after four months with the 2% solution. After 48 weeks of treatment, users of the 5% solution displayed 46% greater overall hair regrowth than did users of the 2% solution. There is no significant difference between the two concentrations in terms of systemic side effects; however, cardiovascular--but minor and localized--side effects such as erythema, itchiness, and dryness are PAGE 10 Drug Topics March 16, 1998 more frequent with the 5% solution. In contrast to minoxidil, the mechanism of action of finasteride is well documented. The drug acts by blocking the enzyme 5-Alpha reductase. The reduced activity of 5-alpha reductase results in a 66% decrease in DHT concentration in the scalp. Clinical trials reported 83% of male patients with mild to moderate hair loss kept their hair or had grown more hair after one year of finasteride treatment. Compared with placebo, the frequency of side effects associated with finasteride appear minimal, although statistically significant. Reported side effects, caused by the drug's antiandronergic properties, include difficulty achieving erection, a diminished desire for sex, and/or a decreased amount of semen. The 5-mg dosage of finasteride carries a warning against exposure of women to semen from men who are taking the drug; the 1-mg dosage carries no such warning. A literature search did not reveal any controlled clinical trials directly; comparing minoxidil and finasteride. However, based on clinical trials comparing either agent to placebo, it appears a similar number of subjects (50%) reported an increase in hair growth for both drugs. Demographic data and degree of hair loss may have varied at the start of the trials, so a hue comparison of efficacy cannot be made. One apparent advantage of minoxidil over finasteride is the approval of the 2% solution for the treatment of some types of hair loss in women. Finasteride is currently not marketed for women; safety and efficacy have not been established. A drawback to minoxidil therapy, however, is its twice-daily topical application regimen. The monthly cost of therapy of MPB ranges from $ 12.00 to $ 47.00. (See table.) Encouraging results were seen in a patient treated with topical minoxidil in a tretinoin base in combination with oral finasteride. Tretinoin is believed to enhance minoxidil absorption, follicle differentiation, and dermal vessel formation, which may enhance the response to minoxidil. More studies are needed to compare the available treatment options in order to decide which agent--or, possibly, combination of agents--should be used. Recently, researchers have identified the gene for alopecia universalis (total loss of scalp and body hair). This discovery helps scientists understand the molecular basis for inherited forms of baldness. This finding may be useful in developing future treatment options. RELATED ARTICLE: Cost comparison of agents used in treating male pattern baldness Recommended Monthly dose cost(*) minoxidil 2% solution 1 ml topically twice daily $ 12.00 Rogaine 2% solution 1 ml topically twice daily 19.40 Rogaine 5% solution 1 ml topically twice daily 21.64 PAGE 11 Drug Topics March 16, 1998 Propecia 1 mg orally once daily 46.88 (*) Based on Average Wholesale Price (AWP), Red Book, January 1998 This column was prepared by the staff of the International Drug Information Center, Arnold & Marie Schwartz College of Pharmacy & Health Sciences, Long Island University, Brooklyn, N.Y. Copyright 1998 Information Access Company, a Thomson Corporation Company; ASAP Copyright 1998 Medical Economics Publishing Drug Topics SECTION: No. 6, Vol. 142; Pg. 2; ISSN: 0012-6616 IAC-ACC-NO: 20443876 LENGTH: 989 words |
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