External control of drug release and penetration: enhancement of the transdermal absorption of indomethacin by ultrasound irradiation.

The effect of ultrasound (1 MHz) on transdermal absorption of indomethacin from an ointment has been studied in rats. Ultrasound energy was supplied for 10 min at a range of intensities (0.25, 0.5 and 0.75 W cm-2), energy levels commonly used for therapeutic purposes. The pronounced effect of ultrasound on transdermal absorption of indomethacin was observed for all three intensities studied. The mean AUC value (33.22 micrograms h mL-1) after irradiation at 0.75 W cm-2 was 3.4 times the control value (9.70 micrograms h mL-1).