Absorption & Utility of Topical Minoxidil
A part of topical minoxidil is absorbed through the scalp in a short time. Not all of topical minoxidil is absorbed through the skin. Then, minoxidil enters into systemic circulation, and it is distributed to the body.
Minoxidil has direct effect on hair follicular cells. It normalizes morphology and proliferation of inner root sheath.
It also increases DNA synthesis and proliferation of follicular and perifollicular cells. Topical minoxidil helps differentiation above the dermal papilla and proliferation at the base of hair bulb.
Topical minoxidil has been reported to prevent and reverse the balding process in animal studies. Details of the mechanism of action of topical minoxidil has not been known yet.
Blood concentration of topical minoxidil decreases in a short time. The vasodilator effect lasts longer than 1 hour after application of topical minoxidil because some of minoxidil stays longer in the vascular smooth muscle.
On the other hand, most of oral minoxidil is absorbed through intestine. About 15% of oral minoxidil enters systemic circulation.
Utilization of oral minoxidil is about 15% and the other 85% is metabolized in the liver and excreted in the urine as the glucuronide conjugate.
The half-life of oral minoxidil in the serum is about 4 hours.