Update on Male Pattern Hair Loss openaccess articles

November 2014 | Volume 13 | Issue 11 | Feature | 1308 | Copyright © 2014

Leopoldo Duailibe Nogueira Santos MD and Jerry Shapiro MD FRCPC

Department of Dermatology and Skin Science
University of British Columbia, Vancouver, Canada
The Ronald O. Perelman Department of Dermatology
New York University Langone Medical Center, New York, NY

Abstract

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Leopoldo Duailibe Nogueira Santos MD

Department of Dermatology and Skin Science
University of British Columbia, Vancouver, Canada
table 3

Jerry Shapiro MD FRCPC

Department of Dermatology and Skin Science
University of British Columbia,Vancouver, Canada
The Ronald O. Perelman Department of Dermatology
New York University Langone Medical Center, New York, NY

Male pattern hair loss (MPHL) is the most common cause of alopecia in men. It affects approximately 30% of Caucasian men by the age of 30 and its prevalence increases with age. The influence of male hormones has been well studied and is the main target of the some of the most effective treatments. The main alteration in MPHL occurs in the hair growth cycle where the anagen phase becomes shorter resulting in shorter and thinner hairs. This process is called miniaturization. Generally, hair loss starts with a receding hairline and rarefaction at the vertex and progresses until the top of the scalp is completely bald. The sides of the scalp and the lower occipital areas are preserved even in longstanding MPHL. Other diseases such as diffuse alopecia areata and telogen effluvium must be excluded. To date, the first-line treatment still is topical minoxidil combined with oral finasteride. Surgery and other treatments will also be discussed.

Minoxidil

The literature shows that minoxidil acts by shortening telogen phase and increasing hair diameter especially in miniaturized hairs. The mechanism of action is not established yet but the hypothesis involves increasing level/activity of vascular endothelial growth factor (VEGF). New insights into its mechanism are the stimulation of production of PGE2 and minoxidil influences on androgen receptor.1

Topical minoxidil 5% solution has been proved to work better than minoxidil 2% in men.2 Minoxidil 5% foam once daily is as effective as minoxidil 2% solution twice daily in women.3 Approximately 40% of male patients experience hair regrowth with 5% minoxidil and therapeutic response should be seen within 3-6 months. A new method to detect patient responsiveness to the treatment has been suggested using sulfotransferase activity in plucked hair.4

Minoxidil is a topical treatment that should be applied on dry scalp twice daily. It is a lifelong treatment and hair shedding can occur in the first 1-3 months. The most common side effects are irritant dermatitis, contact dermatitis, and hypertrichosis on the face. The latter side effect is not of much consequence is adult males. Topical minoxidil is available in solution as the 2% and 5% and as a 5% foam.

5-alpha-reductase Inhibitors (5ARI)

This group of medications inhibit the 5-alpha-reductase enzyme type I, II, and/or III resulting in decreased conversion of testosterone to dihydrotestosterone (DHT).

Finasteride mainly inhibits type II/III enzyme. The approved dose to MPHL is 1mg daily. Two thirds of the patients are expected to improve their condition and one third to stabilized hair loss. Patients are asked to be on finasteride for one year until deciding to discontinue if there is no improvement. Improvement is not only due to hair regrowth but also to changes in hair growth rate (length) and thickness.5

Dutasteride inhibits types I/II of 5-alfa-reductase enzyme. It is three times more potent than finasteride. Dustasteride 0.5mg is prescribed off-label for MPHL. Olsen et al found that 2.5mg of dutasteride was superior to 0.5mg in promoting hair growth. Also 2.5mg was more efficient in suppressing scalp DHT compared to 0.5mg dutasteride and 5mg finasteride (79% x 51% x 41%). As a result, 2.5mg dutasteride was associated with higher prevalence of sexual complaints (decreased libido).6 Jeung et al treated non-responders to 1mg finasteride with 0.5mg dutasteride. Following 6 months of dutasteride, 75% of the patients showed improvement on global photographic assessment and phototrichogram. How-

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