Therapeutic frequency sonophoresis

Numerous attempts of sonophoresis have been performed over the last 40 years. As described earlier, these attempts can be classified into three categories therapeutic frequency, high-frequency and low-frequency ultrasound. 

Sonophoresis has employed three distinct categories of US high-frequency or diagnostic US (2-10 MHz), mid-frequency or therapeutic US (0.7-3 MHz), and low-frequency US (5-100 kHz). It appears, from a general overview of the literature, that the efficiency of US-mediated drug delivery depends on several factors, including US frequency, intensity (i.e., power per unit area), continuous versus pulsed mode, duty cycle, duration, coupling medium, and so on. The fact that very few studies have used common values for some or any of these parameters almost certainly accounts for the different and sometimes contradictory results in the public domain. 

Ultrasound at various frequencies in the range of 20 kHz to 16 MHz has been used for sonophoresis. These studies of sonophoresis can be classified into three categories based on the ultrasound frequency used, i.e., therapeutic, high-frequency, and low-frequency ultrasound. 

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