Thermoplastic polyurethane as matrix forming excipient using direct and ultrasound-assisted compression

Thermoplastic polyurethanes (TPU) are block copolymers utilized in a wide variety of applications due to their superior characteristics as resistance, flexibility and biocompatibility. However, the use of TPU as a matrix tablet forming excipient is more limited. For the first time, matrix tablets based on TPU have been developed by direct compression and ultrasound-assisted compression (USAC) allowing a comparison between these two methods. TPU powder has been rheologically characterized according to SeDeM method, demonstrating the suitability of the polymer (Pearlbond™ 523) to be compressed. TPU matrices have shown an inert behavior and a sustained drug release with a very low quantity of excipient. The better drug release control of matrices obtained by USAC has been explained based on the sintering of the TPU particles, resulting in lower porous structures and a quasi-continuum medium instead of particulate systems. The Excipient Efficiency values show the high ability of this TPU to control drug release by both methods. Finally, the estimation of the percolation threshold of TPU by both methods has contributed to the deep knowledge of the systems and allows defining the Design Space of a formulation.