Minoxidil promotes hair growth through increasing the duration of anagen(1-3). It causes hair follicles at rest to grow, and enlarges suboptimal follicles. While minoxidil was developed for treatment of hypertension, and this feature of the drug’s action is best understood, its mechanism of action on hair growth is poorly understood.
Minoxidil is a potassium-channel opener and vasodilatator, and has been reported to stimulate the production of VEGF in cultured dermal papilla cells (Lachgar et al., 1998). There is evidence that this effect is mediated by adenosine and sulfonylurea receptors, which are well-known target receptors for adenosine-triphosphate-sensitive potassium channel openers (Li et al., 2001).
It also acts by increasing the proliferation of cultured human dermal papilla cells in a dose-dependent manner. It has been shown that promotes the survival of human DPCs by activating both ERK as well as Akt and by preventing cell death by increasing the ratio of Bcl-2/Bax.
It has also been suggested that minoxidil stimulates the growth of human hairs by prolonging anagen through these proliferative and anti-apoptotic effects on DPCs.(11-14)
Topical solutions of 2 and 5 percent minoxidil are available for treatment of AGA in men and women.(4-10) Unfortunately, the efficacy of minoxidil is variable and temporary, making it difficult to predict the success of treatment on an individual basis. Minoxidil Plant extracts are another possible method to treat hair loss. Rho et al. have explored 45 oriental plant extracts for hair loss treatment and suggested that Asiasari radix had a stimulatory effect on hair growth in C57BL/6 and C3H mice. This extract promoted the expression of vascular endothelial growth factor in the cultured human DPCs that strongly played a role in control of hair growth, particularly during the anagen phase (6)
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- Rho SS, Park SJ, Hwang SL, Lee MH, Kim CD, LeeI H, Chang SY and Rang MJ. (2005). The hair growth promoting effect of asiasari radix extract and its molecular regulation. J Dermatol Sci 38:89–97. [CrossRef][Medline]
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- Buhl AE, Baker CA, Dietz AJ. Minoxidil sulfotransferase activity influences the efficacy of Rogaine topical solution (TS): enzyme studies using scalp and platelets. J Invest Dermatol. 1994;102:534.
- Olsen EA, Dunlap FE, Funicella T, Koperski JA, Swinehart JM, Tschen EH, et al. A randomized clinical trial of 5 % topical minoxidil versus 2 % topical minoxidil and placebo in the treatment of androgenetic alopecia in men. J Am Acad Dermatol. 2002;47(3):377–85.PubMedCrossRef
- Olsen E, Whiting D, Bergfeld W, Miller J, Hordinsky M, Wanser R, et al. A multicenter, randomized, placebo-controlled, double-blind clinical trial of a novel formulation of 5 % minoxidil topical foam versus placebo in the treatment of androgenetic alopecia in men. J Am Acad Dermatol. 2007;57:767–74.PubMedCrossRef
- Blume-Peytavi U, Hillmann K, Dietz E, Canfield D, Bartels NG. A randomized, single-blind trial of 5 % minoxidil foam once daily versus 2 % minoxidil solution twice daily in the treatment of androgenetic alopecia in women. J Am Acad Dermatol. 2011;65(1126–34):e2.PubMed
- Lucky A, Picquadio D, Ditre C, et al. A randomized, placebo-controlled trial of 5 % and 2 % topical minoxidil solutions in the treatment of female pattern hair loss. J Am Acad Dermatol. 2004;50:541–53.PubMedCrossRef
- Dawber RP, Rundegren J. Hypertrichosis in females applying minoxidil topical solution and in normal controls. J Eur Acad Dermatol Venereol. 2003;17(3):271–5.PubMedCrossRef