Application of topical minoxidil in acne vulgaris treatment

Background: Acne vulgaris (AV) results from increased sebum production and Cutibacterium acnes (C. acnes) overgrowth, leading to pilosebaceous unit inflammation. The androgen-androgen receptor (AR) pathway significantly contributes to acne development, with minoxidil showing promise in suppressing AR-related activities. Objectives: This study aims to examine the mechanism and effectiveness of minoxidil in treating AV. Methods: The effects of minoxidil on lipid metabolism and bacterial infection/inflammation were tested. A clinical trial was performed to evaluate the effect of topical minoxidil on AV. Results: Minoxidil suppressed fatty acid synthase activity and lipid formation in an androgen-sensitive prostate cancer cell line in vitro and sebum formation in hamster flank organs in vivo. For C. acnes, minoxidil had a half-maximum inhibitory concentration of 5 mM. Both 2% and 5% minoxidil suppressed C. acnes-induced infection/inflammation in an animal model. A phase I/II clinical trial of topical minoxidil in treating AV using a split-face model demonstrated a good response and well-tolerated side effects. Compared to the untreated side, the numbers of all types of lesions decreased significantly on the treated side on day 3 (mean: -2.238, 95% confidence interval [CI]: -3.821 to -0.655, P = 0.008), day 8, and reached the maximum effect on day 15 (mean: -1.286, 95% CI: -2.151 to -0.420, P = 0.006). Responders to topical minoxidil may experience rapid regression of acne as early as 3 days of treatment. Conclusion: Our collective data indicate that minoxidil could inhibit AR-related functions and C. acnes growth in treating AV.