Pharmacokinetics and bioavailability of solid dispersion formulation of tilmicosin in pigs

Tilmicosin (TMS) is a semisynthetic macrolide antibiotic restricted to veterinary use but is only partially soluble in aqueous solutions, which limits its administration in treatments. We developed a strategy to enhance the supersaturated solubility of TMS using amorphous solid dispersion (SD). The dissolution profile shown that the dissolution rate of TMS-SD was obviously faster than TMS. The pharmacokinetics of tilmicosin (TMS) and tilmicosin solid dispersion (TMS-SD) in pigs after oral administration at a single dose of 50 mg/kg b.w were investigated. The t_max of TMS-SD (2.50 hr) was 1.80 times faster than TMS (4.50 hr) (p < .05). There were no significant differences in the other PK parameters (C_max , t_1/2β , V/F, CL/F, MRT, and AUC_0-inf ) (p > .05). The mean relative bioavailability of TMS-SD compared with TMS was 140.39%, according to the AUC_0-inf values. These results demonstrated that the solid dispersion technique enhanced the bioavailability of TMS and the new formulation administered to animals via drinking water may be used as a therapeutic alternative for clinical treatments.