Dr. Harris, why do you not like using finasteride? It’s a common question our clients ask when we discuss agents to block the effects of dihydrotestosterone (DHT), the primary driving force behind androgenic alopecia. Let’s dive into our decision not to use finasteride in Nimbus protocols.
Finasteride is one of the FDA-approved medications to treat androgenic alopecia. It blocks an enzyme called 5-alpha reductase which converts testosterone into DHT. The 5-alpha reductase enzyme has two versions, type I and type II. Finasteride blocks the type II version of the enzyme. The hair root sheath has a high concentration of type II 5 alpha-reductase. 1 Finasteride, both orally and topical, is effective in treating androgenic alopecia. 2 3, However, systemic side effects often limit its use.
DHT is the more potent version of testosterone, and finasteride effectively lowers blood DHT levels by up to 70%.3 Topical finasteride can reduce blood DHT levels by up to 30%. Reported side effects include sexual dysfunction, growth of breast tissue, allergic reactions, nipple discharge, and chest tenderness. Men often discontinue finasteride because of sexual dysfunction. The rate of those symptoms in clinical trials is about 1%, but in our practice, we saw erectile dysfunction frequently happening with finasteride that reversed upon its discontinuation. 4
What do we use for clients with genetic changes in the 5-alpha reductase enzymes? We use topical dutasteride. Dutasteride is similar to finasteride, but blocks type I and type II 5-alpha reductase. Dutasteride is three times more effective at blocking type II and 100 times more effective at blocking type I. Clinically, because of the more significant inhibition of 5-alpha reductase, dutasteride is more effective than finasteride for hair growth. 5
The reduction in DHT levels between oral and topical 5-alpha reductase inhibitors in the scalp was shown to be similar in one clinical trial.6 This means we are getting the same effect at the cellular level in the scalp with topical therapy, but are we affecting systemic DHT levels. We use topical dutasteride to minimize the risk of systemic side effects. Another study found no significant difference in systemic DHT levels with topical dutasteride therapy. Topical dutasteride is well tolerated. Reported adverse effects are mild skin reactions like itching at the application site.7
To put it all together, our protocol at Nimbus uses topical dutasteride instead of oral dutasteride or finasteride, given the improved safety profile and comparable efficacy. One of the core concepts of precision medicine is getting the proper medication or supplement to the right person via the right vehicle. Topical dutasteride is our precision medicine drug of choice for our clients whose genetics indicate that preventing the conversion of testosterone to DHT in the scalp would benefit regrowing hair.
1 Imperato-McGinley J, Zhu YS. Androgens and male physiology the syndrome of 5alpha-reductase-2 deficiency. Mol Cell Endocrinol. 2002 Dec 30;198(1-2):51-9. doi: 10.1016/s0303-7207(02)00368-4. PMID: 12573814.
2 Kaufman KD, Olsen EA, Whiting D, et al. Finasteride in the treatment of men with androgenetic alopecia. Finasteride Male Pattern Hair Loss Study Group. J Am Acad Dermatol. 1998;39(4 Pt 1):578-589. doi:10.1016/s0190-9622(98)70007-6doi:10.1046/j.1523-1747.2003.12167.x
3 Shapiro J, Kaufman KD. Use of finasteride in the treatment of men with androgenetic alopecia (male pattern hair loss). J Investig Dermatol Symp Proc. 2003;8(1):20-23. doi:10.1046/j.1523-1747.2003.12167.x
4 Hajheydari Z, Akbari J, Saeedi M, Shokoohi L. Comparing the therapeutic effects of finasteride gel and tablet in treatment of the androgenetic alopecia. Indian J Dermatol Venereol Leprol. 2009;75(1):47-51. doi:10.4103/0378-6323.45220
5 Zhou, Z., Song, S., Gao, Z., Wu, J., Ma, J., & Cui, Y. (2019). The efficacy and safety of dutasteride compared with finasteride in treating men with androgenetic alopecia: A systematic review and meta-analysis. Clinical Interventions in Aging, Volume 14, 399-406. doi:10.2147/cia.s192435
6 Caserini M, Radicioni M, Leuratti C, Terragni E, Iorizzo M, Palmieri R. Effects of a novel finasteride 0.25% topical solution on scalp and serum dihydrotestosterone in healthy men with androgenetic alopecia. Int J Clin Pharmacol Ther. 2016;54(1):19-27. doi:10.5414/CP202467
7 Nada, Essam & Sharkawy, Reham & Abd Elmaged, Wafaa & Elmagd, Marwa. (2018). Topical dutasteride with microneedling in treatment of male androgenetic alopecia. Sohag Medical Journal. 22. 387-400. 10.21608/smj.2018.42083
