Update on Male Pattern Hair Loss

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

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

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.

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-