Human anagen hair follicles were cultured in collagen gel in either the presence or absence of minoxidil sulfate. In the absence (control) and presense of the chemicals at 0.1, 1, and 10
μg/ml, the hair follicles and shafts continually grew for 7 days with a similar rate of increase in hair shaft length of 0.12mm/day. However, 100
μg/ml of minoxidil sulfate inhibited the hair growth compared with the control, and the elongation rate was about the half that of the control, 0.06 mm/day. We also examined the effect of minoxidil sulfate on cultured human outer root sheath cells. The drug at 0.1
μg/ml and 1
μg/ml appeared to slightly stimulate colony growth and colony formation compared with the controls. However, there was no statistic significance among three groups. On the other hand, 10
μg/ml of minoxidil sulfate significantly inhibited colony growth but did not influence colony formation. Only a few colonies were formed in 100
μg/ml. Minoxidil sulfate, a metabolite of minoxidil, has been suggested to be more potent than minoxidil in pharmacological activity. All results obtained here, however, indicated that minoxidil sulfate in the concentration range of 0.1 to 10
μg/ml had no influence on the hair growth of human anagen follicles or the colony growth of cultured human outer root sheath cells
in vitro.
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