Influence of ultrasound on the percutaneous absorption of ketorolac tromethamine in vitro across rat skin.

The influence of ultrasound on percutaneous absorption of ketorolac tromethamine was studied in vitro across rat skin. Sonication was carried out with a continuous mode, at an intensity of 1-3 W/cm2 and a frequency of 1 MHz for 30 min. A significant increase in permeation of ketorolac through rat skin was observed with the applied sonication at 3 W/cm2 when compared with permeation at 1 and 2 W/cm2. Enhanced ketorolac penetration at 3 W/cm2 can be explained by the mechanical and/or thermal action of ultrasound waves. The distance of the ultrasound probe from the skin surface did not influence the flux of the drug. Pretreatment of skin by 5% d-limonene in ethanol for 2 hr followed by sonication at 3 W/cm2 (30 min) significantly enhanced the permeation of ketorolac when compared with passive flux with or without enhancer pretreatment.