A Systematic Review of Topical Finasteride in the Treatment of Androgenetic Alopecia in Men and Women
April 2018 | Volume 17 | Issue 4 | Original Article | 457 | Copyright © April 2018
Sung Won Lee MD, Margit Juhasz MD, Pezhman Mobasher MD, Chloe Ekelem MD, and Natasha Atanaskova Mesinkovska MD PhD
University of California, Irvine, CA
Introduction: Currently, only topical minoxidil (MNX) and oral finasteride (FNS) are approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for the treatment of androgenetic alopecia. Although FNS is efficacious for hair regrowth, its systemic use is associated with side effects limiting long-term utilization. Exploring topical FNS as an alternative treatment regimen may prove promising. Methods: A search was conducted to identify studies regarding human in vivo topical FNS treatment efficacy including clinically relevant case reports, randomized controlled trials (RCTs), and prospective studies. Results: Seven articles were included in this systematic review. In all studies, there was significant decrease in the rate of hair loss, increase in total and terminal hair counts, and positive hair growth assessment with topical FNS. Both scalp and plasma DHT significantly decreased with application of topical FNS; no changes in serum testosterone were noted. Conclusion: Preliminary results on the use of topical FNS are limited, but safe and promising. Continued research into drug-delivery, ideal topical concentration and application frequency, side effects, and use for other alopecias will help to elucidate the full extent of topical FNS’ use.
J Drugs Dermatol. 2018;17(4):457-463.
Androgenetic alopecia (AGA) is a common chronic, cutaneous condition encountered by dermatologists globally. AGA is androgen-dependent and characterized by a hereditary inheritance pattern, beginning with the advent of puberty. In predisposed males and females, scalp hair progressively thins in a defined pattern, most often at the vertex, with non-scarring, progressive miniaturization of the hair follicle and shaft.1 Unfortunately, AGA is often accompanied by low self-esteem and negatively impacts quality of life. Despite its prevalence and patient morbidity, the Food and Drug Administration (FDA) and the European Medicines Agency (EMA)-approved therapeutic options for AGA are limited to oral finasteride (FNS; Propecia®, Merck Pharmaceuticals, for men only) and topical minoxidil (MNX; Rogaine®, Johnson and Johnson Healthcare Products, for men and women).2,3 In the absence of other therapeutic modalities, practitioners may use surgical hair transplant; however, patients often encounter high cost because most insurance plans do not cover the procedure. In addition, transplants are associated with risks such as bleeding and infection.4Pathogenesis of AGA is related to the purported binding of dihydrotestosterone (DHT) to androgen receptors (AR) located at the hair follicle. DHT is produced by conversion of testosterone using 5-?-reductase type 2, an enzyme located in the follicle dermal papilla. DHT levels are affected by factors including the abundance of weak androgens, testosterone conversion,activity of androgen inactivating enzymes, and abundance of AR.5,6 AGA predisposed dermis exhibits high levels of DHT and increased expression of AR.7Systemic FNS, a 5-?-reductase inhibitor 4-aza-3-oxosteroid compound, has been extensively studied and is clinically used for the treatment of benign prostate hyperplasia (BPH) and AGA.8 FNS works by competitively inhibiting 5-?-reductase type 2, preventing the conversion of testosterone to DHT, markedly suppressing serum DHT levels. The mean terminal half-life of FNS is approximately five to six hours in men 18-60 years, and eight hours in men greater than 70 years of age. DHT levels return to normal within 14 days of treatment discontinuation. It is expected that after systemic FNS use for the treatment of AGA is stopped, reversal of hair regrowth occurs within 12 months.3 In its systemic form, various side effects such as gynecomastia, breast tenderness, malignant neoplasms of the male breast, decreased ejaculate volume, decrease in testicular size, testicular pain, reduction in penile curvature, reduction in penile size, sexual disorder, male infertility, high grade prostate cancer, and prostatitis have been reported.3 These side effects are often prohibitive as male patients are sensitive to sexual side effects.Animal studies have shown that topical FNS may have protective effects against AGA. Comparing topical FNS 2% solution to a fern