Efficacy and Safety of Low-Dose (0.2 mg) Dutasteride for Male Androgenic Alopecia: A Multicenter, Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Phase III Clinical Trial

Abstract

Background: Dutasteride, a 5-alpha reductase inhibitor, is prescribed for male androgenetic alopecia (AGA) in Korea and Japan. Despite its efficacy, its use is limited by its long half-life, potent dihydrotestosterone suppression, and adverse effects.

Objective: To investigate the efficacy and safety of 0.2 mg dutasteride for male AGA.

Methods: Patients with male AGA were randomized to receive 0.2 mg dutasteride, placebo, or 0.5 mg dutasteride (2:2:1) once daily for 24 weeks. Safety and efficacy endpoints were assessed.

Results: Overall, 139 men were analyzed. At week 24, the change in hair count within the target area at the vertex from baseline was significantly higher in the 0.2 mg dutasteride group than in the placebo group (21.53 vs. 5.96, p=0.0072). Dutasteride (0.2 mg) treatment led to greater hair growth improvement, as assessed by investigators at week 24 (p=0.0096) and an independent panel at weeks 12 and 24 (p=0.0306, p=0.0001). For all efficacy endpoints, 0.2 mg dutasteride was as effective as 0.5 mg dutasteride. The incidence of adverse events was low and not statistically different between the 0.2 mg dutasteride and placebo groups. The limitation of this study is the limited number of participants.

Conclusion: Low-dose (0.2 mg) dutasteride for male AGA showed significant efficacy and favorable safety profile.

Trial registration: ClinicalTrials.gov Identifier: NCT04825561.

Keywords: 5-Alpha reductase inhibitor; Androgenic alopecia; Dutasteride.

Fig. 1. Patient disposition.

Fig. 2. Change in the hair count. Change in the LS mean hair count within the target area (1 cm²) at the vertex from baseline.

LS: least squares, ANCOVA: analysis of covariance. ^*The presented LS mean (standard error) values are based on the full analysis set. ^†ANCOVA test using baseline values as covariate for difference between dutasteride 0.2 mg and placebo groups. ^‡ANCOVA test using baseline values as covariate for difference between dutasteride 0.2 mg and dutasteride 0.5 mg groups. ^§ANCOVA test using baseline values as covariate for difference between dutasteride 0.5 mg and placebo groups.

Fig. 3. Change in the hair count and thickness. Placebo-adjusted LS mean (A) hair count change and (B) hair thickness (μm) change from baseline.

FAS: full analysis set, PPS: per-protocol set, LS: least squares, CI: confidence interval.

Fig. 4. Serum androgen levels. Mean serum (A) total testosterone and (B) DHT levels. The error bars denote the standard deviations.

DHT: dihydrotestosterone.