Q 2-24.
Absorption and Metabolism of Oral Minoxidil and Topical Minoxidil:
What about pharmacokinetics of minoxidil tablet and topical minoxidil?
A 2-24.
After oral intake of minoxidil tablet, about 90% of minoxidil is absorbed from the intestine.
Then, approximately 15% of oral minoxidil enters systemic circulation and it is distributed to the body.
About 85% of oral minoxidil is metabolized in the liver. It changes to less effective compounds by metabolic pathways of glucuronidation, hydroxylation, sulphation, and conversion to uncharacterized polar products.
Finally, all the metabolites are excreted in the urine as the glucuronide conjugate.
Concentration of oral minoxidil in plasma rises to the maximum level in one hour, and it drops gradually.
The average half-life of oral minoxidil in human plasma is reported to be 4.2 hours.
On the other hand, 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. Blood concentration of topical minoxidil decreases in a short time.
Topical minoxidil has been reported to prevent and reverse the balding process.
