EFFECT OF ULTRASOUND ON RATE OF DRUG ABSORPTION THROUGH SKIN

Ultrasound frequency of 1.0 MHz was applied with an ultrasound probe t o a piece of excised hairless mouse skin for enhancing the rate of pre dnisolone (PN) transfer across the skin in vitro. The results showed t hat the rate of PN transfer through the intact skin was greatly enhanc ed according to the application time of ultrasound. Although ultrasoun d increases the temperature adjacent to the probe, its effect on enhan cing the rate of PN transfer through the intact skin was found to be i nsignificant. Pretreatment experiments in which ultrasound was applied before performing normal permeation experiments were also performed. Although ultrasound was not applied in the normal permeation experimen ts following the pretreatment, the results showed that pretreatment al so enhanced the rate of PN transfer through the intact skin in proport ion to the period of pretreatment time. This implied that the ultrasou nd might have changed some structures of the skin. Pretreatment of 180 0 s or more made the rate of PN transfer through the intact skin close to that through tape-stripped skin. This was caused either by a morph ology change of the skin or by enlargement of the diameters of some fo llicles, or by both.