Design And Experimental Study Of Low-frequency Ultrasound Apparatus For Transdermal Drug Delivery

Diclofenac sodium is common used on clinical as a powerful nonsteroid anti inflammatory and antalgic drug(NSAIDs). And GI degradation and first-pass effect could be avoided after transdermal delivery. Because of the barrier of skin, transdermal drug delivery is limited. The application of ultrasound can promote the drug percutaneous absorption by increasing the permeability of the skin. Moreover, ultrasound have a special role of physiotherapy to increase blood flow, reduce inflammation, enhance fracture healing , etc. High frequencies(1～3 MHz)were first investigated as physical enhancers for transdermal delivery of drugs. These high frequencies are still used in current treatments. But the use of low frequency ultrasound was recently shown to be more effective in enhancing transdermal transport.The article makes an approach to analysis of the effect on percutaneous absorption of diclofenac sodium by each parameter of ultrasound through orthogonal experiment. First, thirty SD rats were randomly collected and their backside skins were selected for transdermal test in vitro. Thirty male rats were randomly collected and their backside skins were selected for transdermal test in vitro. Ultrasonic intensity, frequency, especially duration has very important influence on the increase in the penetration amount. And the optimized combination obtained by orthogonal design was composed of ultrasonic frequency(20kHz), intensity(0.75W/cm2) and duration (15min) .According to the experimental results of the diclofenac sodium, This paper determined the circuits of low frequency ultrasonic system parameters, and designed a high performance low frequency ultrasound equipment for transdermal drug delivery, and pulse amplitude width and rate, treating time each task on this device is adjustable, the ATmega16 is chosen as the control chip for the demand of the system control, analysis methods about the property parameters were obtained, and the related systems were designed ,such as the PWM signal generator, driven circuit, protection circuitand so on. For instance, the phase frequency model is used by the PWM control technique, and the half-bridge topology is used by circuit driving for its simplicity. Lastly, based on the theoretical design, the circuits of the ultrasonic power are practically manufactured. The results show that the system is reliable and eligible.