-
Quote:Dr. Rassman wrote: The minoxidil will have been absorbed by the skin within an hour or so, so that should be the time in between applying and showering.
Troligtvis är FOAM snabbare än så.
THE JOURNAL OF INVESTIGATIVE DERMATOLOGY
ABSTRACTS A1
124:4 APRIL 2005
Uptake of minoxidil from a new foam formulation devoid of propylene glycol to hamster ear
hair follicles
R Stehle,1 G Ewing,1 J Rundegren2 and B Kohut2 1 Pharmaceutical Sciences, Pfizer, Inc,
Kalamazoo, MI and 2 Consumer Healthcare, Pfizer, Inc, Morris Plains, NJ
Post-marketing studies show that the present topical minoxidil formulations are considered oily and
in some cases there are reports of skin irritation. A major cause of the apparent inferior cosmetic
properties and adverse effects of the current formulations on the skin is the rather high content of
propylene glycol. Thus a more cosmetically acceptable minoxidil foam formulation, devoid of propylene glycol was developed.
In order to test the availability of minoxidil to hair follicles hamster ears were treated with minoxidil 5% foam in comparison to the current minoxidil 5% solution (Rogaine?® Extra Strength), which served as a positive control. The foam was liquefied by gentle heating to 40C and then 20 ??l was withdrawn with a positive displacement syringe and spread on the ventral earsurfaces of a hamster, continuously and lightly anesthetized by controlled inhalation of isoflurane.
After 1 to 2 hours, the animal was sacrificed and the ears removed and carefully dissected to isolate
the sebaceous gland minoxidil content as an aqueous solution. Each sample was analyzed by HPLC
with electrochemical detection against minoxidil as an external standard. After one hour of minoxidil
treatment of the hamster ears the foam showed a sebaceous gland uptake of 5.9% of the total
minoxidil, while the positive control showed an uptake of 2.0% of the total minoxidil. After 2 hours
of treatment the uptake from the foam was 6.5% in one series of experiments and 4.1% in another
series of experiments, while the uptake from the positive control was 1.2% only. Thus the delivered
dose of minoxidil from the foam to the hamster ear sebaceous glands after one hour treatment was
about three times higher than for the minoxidil 5% solution. After two hours of treatment the minoxidil
delivery from the foam formulation increased to 3.4 to 5.4 higher than for the minoxidil 5% solution.
It is concluded that the new minoxidil 5% foam formulation is delivering minoxidil more
effectively to the sebaceous gland of the hamster ear than does the current minoxidil 5% solution.