TUGAIN Solution 5
Minoxidil ............................... 5% w/v
Also contains:
Absolute alcohol ................ 30% v/v
 
Pharmacology
Pharmacodynamics
Minoxidil stimulates hair growth in persons with early and moderate stages of androgenic alopecia. It is not intended for frontal baldness or a receding hairline.
The mechanism by which minoxidil stimulates hair growth is not established, but possible mechanisms of action of minoxidil may include the following:
K+ATP-mediated stimulation of hair follicular cells by one of its sulphated active metabolites.
Stimulation and prolongation of the anagen phase of hair and increase in the follicular size, thereby preventing premature entry into the telogen phase.
Improvement in local microcirculation through its vasodilatory effect. Minoxidil stimulates VEGF (vascular endothelial growth factor) which is responsible for increased capillary fenestration, indicative of high metabolic activity, observed in anagen phase.
Increasing  diameter of the hair shaft
Stimulating anagen recovery from the telogen phase.
All people may not be responsive to topical minoxidil treatment. The amount of hair regrowth differs from person to person. Although data suggest that those users who have been balding for a shorter period or who have a smaller area of baldness on the vertex are more likely to respond to topical minoxidil, individual responses cannot be predicted. It is unlikely anyone will be able to grow back all of his or her hair.
Pharmacokinetics
Following topical application of minoxidil 2% Solution, an average of about 1.4% (range: from 0.3% to 4.5%) of the total applied dose is absorbed from the normal intact scalp, but this reflects poor absorption of topical minoxidil. Topical minoxidil absorption is increased by increasing the dose applied, increasing the frequency of dosing and decreasing the barrier function of the stratum corneum.
Results of the extensive pharmacokinetic studies indicate that the three major factors by which topical minoxidil absorption are increased by are: increasing the dose applied, increasing the frequency of dosing and decreasing the barrier function of the stratum corneum.
In a study in males, the minoxidil serum concentration time curve (AUC) for the 2% solution averaged 7.54 ng·h/ml compared to a mean AUC of 35.1 ng·h/ml for the 2.5 mg oral formulation. The mean peak plasma concentration (Cmax) for the topical solution was 1.25 ng/ml, compared to 18.5 ng/ml following the 2.5 mg oral dose.