ABSTRACT
BACKGROUND: The mechanism of enhancing effect of ultrasound on the percutaneous absorption of a drug is unclear. But thermal, chemical and mechanical effects are assumed to play a role in enhancing transdermal drug delivery. OBJECTIVE: The aim of this study was to determine if ultrasound enhances percutaneous absorption of methyl nicotinate(MN) without raising the skins surface temperature. METHODS: Treatment consisted of the application of ultrasound massage(1.0 MHz, 1.0 watt/cm2, continuous output) or placebo massage(0 MHz) for 3 min to the forearms of the volunteers, followed by a standardized application of MN at intervals of 15 sec and 10 min postmassage. Percutaneous absorption of MN was monitored using laser doppler flowmetry. RESULTS: 1. Data from the ultrasound treated sites after 15 sec showed significant decrease(p<0.05, paired t-test) in the T(0)(time between MN application and its initial response), T(MAX)(time between MN application and maximuvi response) and increase in the LDF(MAX) .(maximum cutaneous blood flow) compared to those of the control sites. 2. Data from the ultrasound treated sites after 10 min showed no difference in the T(0) and T(MAX) but significant increase in the LDF(MAX) compared to those of the control sites. 3. Data from ultrasound trvated sites both after 15 sec and 10 min showed significant increase in basal cutaneous blood flow(LDF(DH2O)) compared to those of the control sites. 4. There was no difference between the ultrasound treated sites and the control sites in the skins surface temper ature. CONCLUSION: The results of this study suggest that ultrasound may affect the skin structure to provide skin penetration enharcement even without raising the skins surface temperature.