Minoxidil is a vasodilator API primarily used to treat androgenetic alopecia (pattern hair loss) and hypertension. Originally developed as an oral antihypertensive, its hypertrichosis side effect led to topical formulation for hair growth stimulation. It is believed to act by opening potassium channels, enhancing cutaneous blood flow, and prolonging the anagen (growth) phase of the hair follicle. Available in solutions and foams (typically 2% and 5% strengths), it requires consistent, long-term application for sustained effect. Its exact mechanism for promoting hair growth is not fully understood but involves direct stimulation of follicular cells. As a Biopharmaceutics Classification System (BCS) Class III drug, it has high solubility and low permeability.