ABSTRACT
Sonochemistry is the branch of science which deals with passage of ultrasonic waves to enhance or alter chemical reactions. The use of ultrasound in chemical reactions in solution provides specific activation based on a physical phenomenon: acoustic cavitation. The range from 20 kHz to around 1 MHz is used in sonochemistry whereas frequencies far above 1 MHz are used as medical and diagnostic ultrasound. Ultrasonic waves induce chemical effects on the reaction system, such as generation of free radicals which augment the rate of reaction. Besides this, ultrasound may have other mechanical effects on the reaction system, such as increasing the surface area between the reactants, accelerating dissolution rate. This review elucidates several applications of sonochemistry in the pharmaceutical industry including sonophoresis, sonocrystallization, lowering extraction time, solution atomization and crystallization by sonication, melt sonocrystallization and particle rounding technology. This review also gives an idea about the applications of sonocrystallization in formation of aerosols, enhancing inhalation drug delivery and sonochemical preparation of biomaterials. Its significance in transdermal drug delivery, chemotherapy and cell therapy is also discussed herewith. It has been proved that ultrasound can be effectively used for treatment of sewage sludge and degradation of dangerous chemicals including chlorinated hydrocarbons, aromatic compounds, agrochemicals and pesticides from the agricultural industry, explosives, dyes from the textile industry and surfactants etc. The purpose of this review paper is to put forth the information available in the literature so as to promote further research in the field of sonochemistry.