Pharmacokinetics and ex vivo pharmacodynamics of Minocycline against Salmonella abortus equi in donkey plasma and tissue cage fluid

Abstract Tissue Cage (TC) model was used to evaluate the pharmacokinetics and ex vivo pharmacodynamics of Minocycline (MINO) after intramuscular (IM) administration to donkeys at 4 mg/kg body-weight. The Cmax of MINO with 1.79 and 2.63 μg mL−1 was obtained at 2.96 and 1.41 h in TCF (tissue cage fluid) and plasma respectively. The absorption half-lives (t1/2ka) of MINO were calculated to be 0.71 h in TCF and 0.32 h in plasma, whereas the elimination half-lives (t1/2ke) were 10.46 h in TCF and 5.95 h in plasma. The distribution volume (Vd/F) of MINO was estimated to be 1.84 L kg−1 in TCF and 1.28 L kg−1 in plasma. The total clearance (CLb/F) of MINO was computed as 0.12 and 0.15 L/ (h·kg) in TCF and plasma respectively. The area under the concentration-time curve (AUC) of MINO was 32.77 μg mL−1h in TCF and 25.27 μg mL−1h in plasma, respectively.The ex vivo time-kill curves were established for plasma and TCF samples using Salmonella abortus equi. The MIC and MBC of MINO against salmonella were 0.08 and 0.16 μg mL−1 for plasma, 0.04 and 0.08 μg mL−1 for TCF. The plasma Cmax/MIC and AUC/MIC values after IM administration were 32.88 ± 9.87 and 315.88 ± 42.65 h, respectively. The TCF Cmax/MIC and AUC/MIC values after IM administration were 44.75 ± 9.32 and 819.25 ± 65.23 h, respectively. The values of T > MIC were approximately >36 h in plasma and > 65 h in TCF. These findings from this study suggest that MINO may be therapeutically effective in diseases of donkeys caused by salmonella when used at a dose of 4 mg/kg IM administration.