subject: Male Hair Loss - Medical Treatment [print this page] Today, only two medical drugs, minoxidil and finasteride, are approved by FDA, to benefit in male hair loss and balding. Both drugs will stimulate regrowth of hair in some men but are perhaps better regarded as preventative treatments. Both drugs have a good safety record, a consideration of paramount importance when treating hair growth disorders.
Minoxidil - Minoxidil was licensed as an oral drug to treat hypertension in the early 1970s. It soon became apparent that a high proportion of those taking minoxidil tablets developed significant hypertrichosis, a side-effect that has almost eliminated its use as an anti-hypertensive agent. Following a report of increased hair growth on the scalp of a balding man taking minoxidil tablets, extemporaneous formulations of minoxidil lotion were developed for topical application in the treatment of hair loss (initial reports concentrated mainly on alopecia areata). A 2% formulation of minoxidil lotion was subsequently licensed by the American Food and Drug Administration for the treatment of male balding and marketed by the Upjohn Company in 1986. A 5% formulation was marketed in 1993. The recommended dose is 1 ml twice daily (for both 2% and 5% formulations).
The mechanism of action of minoxidil on hair growth is uncertain. There is convincing evidence that its vasorelaxant activity is due to opening of ATP-sensitive potassium channels (KATP channels). There is circumstantial evidence that its effect on hair growth is also due to opening of KATP channels but direct proof is lacking and it is unclear how this action modulates hair growth. The rapid response of hair growth to minoxidil suggests that the drug acts mainly to promote entry into anagen of follicles in a latent stage of the hair cycle. There is no convincing evidence that minoxidil reverses follicular miniaturization although it may prevent or delay it.
Clinical trials using various endpoints, including hair counts, hair weight and global photography, have confirmed improvement in male balding with the use of minoxidil lotion. The mean increase in target area hair counts is about 8% with 2% minoxidil lotion and 10%-12% with the 5% formulation. When assessed by global photography nearly 60% of men show improvement with 5% minoxidil lotion and 40% with 2%, compared to 23% with placebo. The response to minoxidil in terms of increased hair counts and hair weight is rapid and peaks by 16 weeks although the cosmetic response may take longer to become apparent. Trials continued for up to 2 years suggest the improvement is sustained providing treatment is maintained. Any positive effect on hair growth is lost within 4-6 months of stopping treatment.
Adverse effects of minoxidil are mainly dermatological. Constituents of the vehicle occasionally cause scalp irritation, more commonly with the 5% formulation. Allergic reactions to minoxidil or propylene glycol (a component of the vehicle) are rare but necessitate stopping treatment. Some patients notice an increase in hair shedding 2-8 weeks after starting treatment. This is self limiting but patients should be forewarned not to stop treatment if this happens.
A new topical foam preparation containing 5% minoxidil has recently been approved for use in men by the USA Food and Drug Administration. It is less messy than the current lotion formulation and is potentially less irritant as it does not contain propylene glycol. The results of clinical trials are awaited.
