Application of ultrasound-assisted compression in pharmaceutical technology. Design and optimization of oral sustained-release dosage forms


Ultrasound-assisted compression (USAC) is a technology combining a conventional compression process and US irradiation. These mechanical and thermal effects lead to heating, melting and sintering of materials. This article reviews the principles of ultrasound-assisted compression and its main applications in pharmaceutical technology. Physical properties of the materials and process parameters such as time, energy and inter-punch distances should be carefully controlled to guarantee reproducibility and a complete transition of the material. The application of ultrasounds during compression improves the mechanical strength of tablets, a clear advantage for formulations with high-doses of poor compressible drugs. Ultrasounds have also demonstrated its usefulness as a technique to prepare solid dispersions, enhancing the bioavailability of poorly soluble drugs. The formulation of sustained-release oral dosage forms has also benefit from the application of USAC, as a better control of drug release with a minor quantity of excipient could be obtained. The continuum percolation model provides a physical basis to explain the important decrease in the excipient percolation threshold using this technology. This model together with the quantification of the Excipient Efficiency parameter, are valuable tools to understand the drug release properties from sustained-release systems.