Oral Minoxidil Has Dose-Dependent Effect in Androgenetic Alopecia

Low-dose oral minoxidil (LDOM) has a positive dose-dependent effect on hair diameter, hypertrichosis, cardiovascular adverse events, and hair density in patients with androgenetic alopecia (AGA), researchers reported in study findings published in Skin Appendage Disorders.

The systematic review and meta-analysis was conducted to determine if the efficacy and safety of oral minoxidil were correlated with the drug’s dosage.

Researchers searched the PubMed and Scopus databases on December 3, 2021. Eligible studies were published in English and assessed the efficacy of monotherapy with oral minoxidil in patients diagnosed with AGA.

The 3 primary endpoints were the 6-month change in hair density (total and terminal) and hair diameter. The 2 safety-related secondary endpoints were risk forhypertrichosis at 6 months and risk for cardiovascular adverse events at 6 months.

A total of 6 studies were included in the quantitative analyses, with drug dosages ranging from 0.25 to 5 mg daily.

An increase in the dosage of oral minoxidil by 1 mg daily was significantly associated with an expected increase of 47.1 and 9.1 hairs/ cm² in total hair density (P =.0071) and terminal hair density (P =.0014), respectively, after 6 months in patients with AGA after adjustment for sex differences. Also, increasing the dosage of oral minoxidil by 1 mg daily was, on average, significantly associated with a sex-adjusted increase of 1.4 μm in hair diameter (P =.013) after 6 months.

After adjustment for sex, an increase in the dosage of oral minoxidil by 1 mg daily was, on average, significantly associated with a higher risk of hypertrichosis and cardiovascular adverse events by 17.6% (P =.0057) and 4.8% (P =.00382), respectively, among patients with AGA after 6 months. The cardiovascular adverse events that occurred were hypotension, edema, increased heart rate, palpitation, and abnormal electrocardiogram.

“Our work is the first to show that, for individuals with AGA, the use of LDOM is associated with an increase in hair diameter, hair density, risk of hypertrichosis, and risk of cardiovascular adverse events in a dose-dependent manner,”  stated the study authors. “Our findings support the conduct of large head-to-head trials [that] aimed to search for the perfect dose of oral minoxidil to treat AGA, and coming full circle could affect a paradigm shift.”