Minoxidil is a medication primarily used for the treatment of androgenetic alopecia (male-pattern baldness) and female pattern hair loss. It was initially developed as an oral antihypertensive drug but later found to have hair growth-promoting effects when applied topically. The exact mechanism of action of minoxidil in promoting hair growth is not entirely understood, but several proposed methods have been identified.
Vasodilation: Minoxidil is a potassium channel opener, which causes hyperpolarization of cell membranes. This leads to the relaxation of vascular smooth muscle cells and results in vasodilation. By increasing blood flow to the hair follicles, minoxidil may promote the delivery of nutrients and oxygen, stimulating hair growth.
Increase in hair follicle size: Minoxidil is believed to prolong the anagen (growth) phase of the hair follicle cycle, thereby increasing the size of the hair follicles. This promotes the growth of thicker and stronger hair strands.
Antiandrogenic effects: Although minoxidil is not a direct antiandrogen, it may have some indirect antiandrogenic effects. It is thought to counteract the effects of dihydrotestosterone (DHT), a hormone that contributes to hair follicle miniaturization and hair loss in individuals with androgenetic alopecia.
Growth factor modulation: Minoxidil may stimulate the production of various growth factors, such as vascular endothelial growth factor (VEGF) and insulin-like growth factor-1 (IGF-1), which play a role in promoting hair growth.
Activation of prostaglandin E2 (PGE2) synthesis: Some studies suggest that minoxidil may increase PGE2 levels in the scalp, which has been associated with hair growth promotion.
Inhibition of collagen synthesis: Minoxidil may inhibit the synthesis of collagen around the hair follicle, thereby reducing fibrosis and promoting hair growth.