Pharmacokinetic/pharmacodynamic integration of tilmicosin against Pasteurella multocida in a piglet tissue cage model

Tilmicosin, a macrolide antibiotic, has the potential to treat bacterial infections in donkeys. However, the pharmacokinetics of tilmicosin in donkeys have not been reported. The aim of this study was to investigate the pharmacokinetics of tilmicosin in donkey plasma, urine, and feces after a single intragastric administration to determine the suitability of tilmicosin for donkeys. A total of 5 healthy male donkeys with similar body weights were selected. The donkeys were administered a single dose of 10 mg · kg−1 body weight (BW) tilmicosin by gavage. The concentrations of tilmicosin in plasma, urine, and feces were determined. The results showed that after a single intragastric administration of 10 mg · kg−1 body weight, tilmicosin in donkey plasma reached a maximum concentration of 11.23 ± 5.37 mg · L−1 at 0.80 ± 0.10 h, with a half‐life of 14.49 ± 7.13 h, a mean residence time of 28.05 ± 3.05 h, a Cl/F of 0.48 ± 0.18 L · kg−1 · h−1, and a Vd/F of 9.28 ± 2.63 Lkg−1. The percentage of tilmicosin excreted through the urine of donkeys is 2.47%, and the percentage excreted through the feces is 66.43%. Our study provides data to inform the use of tilmicosin in donkeys.

Section: Determination Of Tilmicosinmentioning

confidence: 99%

Pharmacokinetics of tilmicosin in plasma, urine and feces after a single intragastric administration in donkey (Equus asinus)

Yang,

Liu,

Guo

et al. 2024

Disposition kinetics and tissue residues of tilmicosin following intravenous, subcutaneous, single and multiple oral dosing in geese (Anser anser domesticus)

Bourdo,

Fadel,

Giorgi

et al. 2024

Tilmicosin (TMC), a semi‐synthetic macrolide antibiotic, is widely used in veterinary medicine due to its broad‐spectrum, bacteriostatic properties. Frequently administered in various birds species, it is likely used off‐label in geese as well. The study sought to investigate TMC's pharmacokinetics, tissue residues, in geese through in vivo experiments. The study involved longitudinal open studies on 15 healthy adult males, with three phases separated by one‐month washout periods. Geese were administered TMC through intravenous (IV, 5 mg/kg), subcutaneous (SC, 10 mg/kg), and oral (PO, 25 mg/kg for five consecutive days) routes, with blood samples drawn at specific intervals. Tissue samples were also collected for subsequent analysis at pre‐assigned times. TMC in goose plasma was quantified by a fully validated HPLC method. Plasma concentrations were quantified up to 4 hr for the PO and IV routes, and up to 10 hr in the SC route. Significant variations in bioavailability were observed between SC (87%) and PO (4%) routes. The body extraction ratio was low at 0.03, suggesting minimal ability of the liver and kidneys to eliminate TMC. Multiple oral doses showed no plasma accumulation, but tissue data revealed extensive distribution and prolonged residence, up to 120 h, suggesting a sustained therapeutic effect despite the brief plasma half‐life. Regarding the multiple PO doses, provisional withdrawal times of 6, 7.5, and 8 days were suggested for the liver, muscles, and kidneys, respectively, according to the MRL set for these matrices in chickens by EMA. In conclusion, while the practical oral administration is discouraged at the population level, SC administration of TMC may be appropriate for geese, albeit impractical for flock therapy.

The pharmacokinetics/pharmacodynamics integration of tilmicosin against Mycoplasma synoviae in vitro and in vivo

Yan,

Liu,

et al. 2024

Mycoplasma synoviae (MS) infection is a serious threat to poultry industry in China. Tilmicosin is a semisynthetic macrolide antibiotic used only in animals and has shown potential efficacy against MS, but there were no reported articles concerning the pharmacokinetics/pharmacodynamics (PK/PD) interactions of tilmicosin against MS in vitro and vivo. This study aimed to assess the antibacterial activity of tilmicosin against MS in vitro and in vivo using PK/PD model to provide maximal efficacy. The minimum inhibitory concentration (MIC) and killing rates of different drug concentrations were measured using the microdilution method in vitro. Then, tilmicosin was administered orally to the MS‐infected chickens at doses of 7.5 and 60 mg/kg, and the PK parameters of tilmicosin in joint dialysates were determined using high‐pressure liquid chromatography/tandem mass spectrometry (HPLC‐MS/MS) combined with the microdialysis technique. The antibacterial effect (△E) was calculated when the infected chickens were administered a single oral dose of tilmicosin at 4, 7.5, 15, 30, and 60 mg/kg b.w. The PK and PD data were fitted using the Sigmoid Emax model to evaluate the PK/PD interactions of tilmicosin against MS. The bactericidal activity of tilmicosin against MS was concentration dependent. Furthermore, the PK/PD index of AUC0–72h/MIC exhibited the most optimal fitting results (R2 = .98). The MS load decreased by 1, 2, and 3 Log10 CFU/mL, then AUC/MIC was determined as 13.99, 20.53, and 28.23 h, respectively, and the bactericidal effect can be achieved when the dose of MS‐infected chickens is at 31.64 mg/kg b.w. The findings of this study hold significant implications for optimizing the treatment regimen for MS infection.