Selecting excipient combinations for microencapsulating veterinary bitter drugs via spray drying

Abstract

For veterinary medicinal products for pets, precise excipient selection is essential for masking the bitter taste of active ingredients. Microencapsulation of veterinary drugs via spray drying is an attractive methodology due to its industrial applicability. This study aims to streamline the selection process by using methylene blue to identify suitable coating material combinations for albendazole (ABZ) and praziquantel (PZQ). Dye release from films was evaluated in media with pH 8.5 and 2.1 (saliva and gastric pH, respectively), using 12 binary combinations of poly(butyl methacrylate-co-(2-dimethylaminoethyl) methacrylate-co-methyl methacrylate) 1:2:1 (EEPO) and other excipients. The results revealed a promising combination, EEPO and beeswax (1:1), which effectively prevented dye release at pH 8.5. This finding was confirmed by evaluating films containing the antiparasitic drugs. Additionally, the selected excipients were used to microencapsulate ABZ and PZQ via spray drying, achieving yields above 55 %. The in vitro release test at pH 8.5 showed that the product reduced the release of both APIs, with PZQ and ABZ concentrations being 1.9 and 1.2 times lower, respectively, than in the physical mixture, while further optimization is possible through adjustments in the operating conditions. The coating does not interfere with drug release from powders at pH 2.1. An HPLC analytical method was also developed for simultaneous quantification of ABZ and PZQ in pH 8.5 and 2.1 samples. In summary, successful microencapsulation of ABZ and PZQ was achieved using a coating composition selected based on dye testing.