Surfactant-modified phillipsite and chabazite as novel excipients for pharmaceutical applications?

This work aimed to investigate the possible use of phillipsite (PHI) and chabazite (CHA), superficially modified with the cationic surfactant cetylpyridinium chloride (CP), for the controlled release of diclofenac sodium (DS) and compare them with the commercial clinoptilolite (CLI). Zeolites were characterized by confocal scanning laser microscopy (CLSM), powder X-ray diffraction and laser light scattering (LS). Furthermore, drug loading, powder flowability and in vitro drug release kinetics in simulated intestinal fluid (SIF), were investigated to assess the relationship between rock mineralogy and their pharmaceutical properties. Results showed that surfactant-modified natural zeolites (SMNZ)-CLI powder presents the best flow properties, followed by SMNZ-PHI and SMNZ-CHA. DS loading was very rapid (<5 min); SMNZ_CLI and SMNZ_PHI could load comparable amounts of DS, while SMNZ_CHA showed the lowest drug loading capacity. DS release was controlled by particle drug diffusion in the case of SMNZ_CLI and SMNZ_PHI while, as for SMNZ_CHA, a combined (film + particle diffusion control) mechanism was envisaged. This different behavior can be reasonably ascribed to a different distribution of the patchy bilayer on the zeolite surface.