Praziquantel systems with improved dissolution rate obtained by high pressure homogenization

Praziquantel (PZQ), an antihelmintic agent commonly administered to humans and cattle, has low aqueous solubility, which compromises its bioavailability and efficacy. The purpose of this study was to develop a new formulation, in order to improve PZQ dissolution rate. PZQ dispersions have been developed by high-pressure homogenization (HPH) using different stabilizers, selected upon PZQ saturation solubility. After the screening, two promising formulations were developed, combining poloxamer 188 with polyvinylpyrrolidone or maltodextrin. Characterization studies including particle size distribution, crystallinity, morphology, drug content, and in vitro dissolution profiles, were performed over selected formulations. The scanning electronic micrographs revealed that the morphology of suspended particles corresponded to elongated shapes, with an average particle size close to the micron range. X-ray powder diffractometry and differential scanning calorimetry results confirmed the drug crystallinity, before and after the HPH process. Besides, differential scanning calorimetry revealed the absence of interactions between PZQ and excipients. The dissolution rate of PZQ dispersions was significantly enhanced compared with raw PZQ, either in phosphate buffer or hydrochloric acid, mainly due to particle size reduction, thus improved saturation solubility.