Minoxidil causes a redistribution of cellular iron through its apparent capacity to bind this metal ion. Ī number of in vitro effects of minoxidil have been described in monocultures of various skin and hair follicle cell types including stimulation of cell proliferation, inhibition of collagen synthesis, and stimulation of vascular endothelial growth factor, prostaglandin synthesis and leukotriene B4 expression. Minoxidil induces cell growth factors such as VEGF, HGF, IGF-1 and potentiates HGF and IGF-1 actions by the activation of uncoupled sulfonylurea receptor on the plasma membrane of dermal papilla cells. The expression of SUR2B in dermal papilla cells might play a role in the production of adenosine. Minoxidil acts as an activator of the Kir6/ SUR2 channel upon selective binding to SUR2. The effect of minoxidil is mediated by adenosine, which triggers intracellular signal transduction via both adenosine A1 receptors and two sub-types of adenosine A2 receptors ( A 2A and A 2B receptors). Minoxidil is a prodrug that is converted by sulfation via the sulfotransferase enzyme SULT1A1 to its active form, minoxidil sulfate. This may cause follicles in the telogen phase to shed, which are then replaced by thicker hairs in a new anagen phase. Moreover, minoxidil contains a nitric oxide moiety and may act as a nitric oxide agonist. Theoretically, by widening blood vessels and opening potassium channels, it allows more oxygen, blood, and nutrients to the follicles. Minoxidil is an adenosine 5'-triphosphate-sensitive potassium channel opener, causing hyperpolarization of cell membranes. The mechanism by which minoxidil promotes hair growth is not fully understood. Its effect in people with alopecia areata is unclear.

Minoxidil must be used indefinitely for continued support of existing hair follicles and the maintenance of any experienced hair regrowth. It is effective in helping promote hair growth in people with androgenic alopecia regardless of sex. Minoxidil, applied topically, is widely used for the treatment of hair loss.

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