Preparation of tilmicosin-resin complex microsphere and its Pharmacokinetics study in rat

The objective of this study is to mask the extremely bitter taste of tilmicosin, and the tilmicosin-resin complex (DRC) microsphere were prepared by entrapping tilmicosin into resins (Tulsion® 339 and Eudragit® RS/ RL 100) for further pharmacokinetics study in rat. The DRC was characterized by FTIR and X-ray diffraction, and the microsphere containing DRC and Eudragit® RS/RL 100 were characterized by scanning electron microscopy (SEM). The rats were orally administrated with tilmicosin phosphate (10 mg/kg) and the microsphere containing the same dose of tilmicosin, respectively. These microspheres do not taste bitter and the kinetics study suggests that the drug released from microsphere meet the first order kinetics (r = 0.9911). The experimental results showed that T_½ and T_max of microsphere were much longer than tilmicosin phosphate, which indicates that the oral microsphere can be a promising long-active formulation for taste masking of tilmicosin.