Minoxidil, 5-a Reductase Inhibitors Relatively Efficacious for Androgenetic Alopecia

Aditya K. Gupta, MD, PhD

A recent meta-analysis into 3 different drugs for the management of androgenetic alopecia (AGA) including minoxidil and the 2 different 5-a reductase inhibitors (Ais) dutasteride and finasteride suggested that there could be a better sense of relative efficacy of different doses.

Investigators added that the meta-analysis contributed to the comparative effectiveness literature for AGA therapies regarding the compared interventions.

Though numerous studies have investigated the efficacy of minoxidil and the 5-ARIs for the treatment of male AGA, the evidence on their relative efficacy has been limited.

As such, investigators led by Aditya K. Gupta, MD, PhD, Mediprobe Research Incorporated, London, Ontario, examined the relative efficacy of monotherapy with the 5-ARIs and minoxidil for the treatment of male AGA in various doses and administration routes.

The Methods

Gupta and colleagues had 4 outcomes of interest for the present study including a change in total and terminal hair count after 24 and 48 weeks of therapy.

The studies were eligible for inclusion in the quantitative analyses if it investigated the therapeutic outcomes associated with monotherapy with minoxidil, dutasteride, and finasteride for male AGA. The team noted that the 3 agents could be of any dose and administration route.

From there, they systematically searched PubMed on March 5, 2021 without date restrictions. Keywords included in the search were topical finasteride AND hair loss; oral finasteride AND hair loss; topical minoxidil AND hair loss; oral minoxidil AND hair loss; and dutasteride AND hair loss.

Titles and abstracts were screened and full-texts were reviewed before data were extracted from all eligible studies.

The network of interventions was depicted through a network plot, a diagram with nodes and edges, for each possible outcome. Additionally, data on the mean (SD) difference and sample size were used for the Bayesian network meta-analyses, and league tables and surface under the cumulative ranking curve values were used to examine the relative efficacy of the interventions.

Study end points were a change in total and terminal hair count after 24 and 48 weeks of therapy, and the 4 end points would then be quantified in hairs per square centimeters.

The Findings

The PubMed search yielded 848 records, and 23 studies were eligible for quantitative analyses following 2 stages of screening.

Investigators observed the greatest increase in total hair count at 24 weeks was with 0.5 mg/d of dutasteride, which was significantly more efficacious than 1 mg/d of finasteride (mean difference, 7.1 hairs/cm2; 95% CI, 5.1-9.3 hairs/cm2) and minoxidil (0.25 mg/d [mean difference, 23.7 hairs/cm2; 95% CI, 9.5-38.0 hairs/cm2], 5 mg/d [mean difference, 15.0 hairs/cm2; 95% CI, 3.9-26.1 hairs/cm2], and 2% solution [mean difference, 8.5 hairs/cm2; 95% CI, 4.8-12.3 hairs/cm2]).

The greatest increase in terminal hair count at 24 weeks was with 5 mg/d of minoxidil, which was significantly more efficacious than the 0.25-mg/d dose (mean difference, 43.6 hairs/cm2; 95% CI, 29.7-57.7 hairs/cm2) and its topical forms.

Finally, the greatest increase in total hair count at 48 weeks was with 5 mg/d of finasteride (mean difference, 10.4 hairs/cm2; 95% CI, 2.2-18.6 hairs/cm2), which was significantly more efficacious than 2% topical minoxidil (mean difference, 20.7 hairs/cm2; 95% CI, 9.5-31.9 hairs/cm2), while the greatest increase in terminal hair count at 48 weeks was with 1 mg/d of finasteride, which was significantly more effective than topical minoxidil in 2% and 5%.

The investigators concluded that the findings of their meta-analysis “contribute to the comparative effectiveness literature for AGA therapies vis-à-vis the compared interventions.”

The study, "Relative Efficacy of Minoxidil and the 5-α Reductase Inhibitors in Androgenetic Alopecia Treatment of Male PatientsA Network Meta-analysis," was published online in JAMA Dermatology.