Androgenic alopecia, or male-pattern baldness, is mediated by the action of the hormone dihydrotestosterone (DHT) on the hair follicles. Hair follicles express androgen receptors in the cells of the dermal papilla. Individuals who inherit a predisposition to androgenic alopecia seem to express higher levels of androgen receptors in the dermal papilla (1). The hormone DHT binds to the androgen receptors and stimulates the hair follicle to spend more time resting and less time growing hair. Over time, repeated exposure to DHT causes the hair follicle to undergo a process called miniaturization, after which the follicle only produces tiny, barely noticeable hairs called vellum.
Since the process of balding is mediated by DHT, researchers speculated that blocking the production of or the action of DHT may prevent, stop, and possibly even reverse the balding process. DHT is manufactured in the tissues from testosterone through the action of an enzyme called 5-alpha-reductase. A number of drugs that block the production of DHT have been developed to treat benign prostatic hyperplasia. One such 5-alpha-reductase blocker, called finasteride, has been approved by the FDA to treat androgenic alopecia.
Finasteride (trade name : Propecia)
Finasteride is an oral medication. It has been proven in clinical trials to be somewhat effective in treating baldness in men; however, it does not appear to work in women affected by androgenic alopecia (2). Around 70% of men who take finasteride stop losing hair. A tiny minority experience some hair regrowth. The drug has to be taken continuously because the effect rapidly goes away as soon as the drug is discontinued. As a systemic treatment, finasteride decreases the amount of DHT throughout the entire body, not just in the scalp. As such, it can cause sexual side effects such as decreased libido and erectile dysfunction, and these side effects may be permanent even after the drug is discontinued. It may also increase the risk of certain types of aggressive prostate cancer and male breast cancer (3). It can cause fetal defects if pregnant women are accidentally exposed to it. Also, some men report feeling depressed and “foggy” while taking the drug.
Dutasteride is similar to finasteride in that it blocks the creation of DHT. Dutasteride is a more potent drug than finasteride because it blocks all three forms of the 5-alpha-reductase enzyme whereas finasteride only blocks two of the forms, and finasteride has a much shorter half-life in the body. Dutasteride is primarily used to treat benign prostatic hyperplasia. Although not approved by the FDA for balding, it has been used off-label to treat androgenic alopecia. It has been shown to be slightly more effective than finasteride for stopping balding and stimulating the re-growth of hair (4). However, it has the same systemic side effects as finasteride, except they seem to occur even more frequently because dutasteride significantly lowers serum levels of DHT relative to finasteride.
Unlike finasteride, RU58841 does not affect production of DHT. Instead, it binds to the androgen receptors and blocks them from interacting with DHT. Blocking DHT prevents the hormone from causing the balding process. Preliminary studies suggest that RU58841 is at least as effective as finasteride in stopping balding, and it seems to be much more effective than finasteride in promoting hair re-growth, particularly if used in combination with minoxidil. However, the real advantage of RU58841 is the lack of systemic side effects. It is only applied to the scalp. It does not enter the systemic circulation, and it does not affect hormonal levels in the body. As such, it does not appear to have any side effects at all (5).
RU58841 versus Finasteride/ Dutasteride
All three of these agents are quite effective in stopping the balding process. RU58841 may be more effective than finasteride or dutasteride for re-growing hair. However, finasteride and dutasteride have systemic side effects that may be unacceptable to most men, particularly men in their 20s and 30s who are beginning to experience balding and want to stop the process as soon as possible. RU58841 does not appear to have any systemic side effects.
(1) J Endocrinol. 1998 Jan;156(1):59-65. Balding hair follicle dermal papilla cells contain higher levels of androgen receptors than those from non-balding scalp.
(2) Am J Clin Dermatol. 2014 Jul;15(3):217-30. doi: 10.1007/s40257-014-0077-5. Androgenetic alopecia: an evidence-based treatment update.
(4) J Am Acad Dermatol. 2014 Mar;70(3):489-498.e3. doi: 10.1016/j.jaad.2013.10.049. Epub 2014 Jan 9. A randomized, active- and placebo-controlled study of the efficacy and safety of different doses of dutasteride versus placebo and finasteride in the treatment of male subjects with androgenetic alopecia.
(5) Endocrine. 1998 Aug;9(1):39-43. Evaluation of RU58841 as an anti-androgen in prostate PC3 cells and a topical anti-alopecia agent in the bald scalp of stumptailed macaques.