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To estimate the valnemulin pharmacokinetic profile in a swine population and to assess a dosage regimen for increasing the likelihood of optimization. This study was, respectively, performed in 22 sows culled by p.o. administration and in 80 growing-finishing pigs by i.v. administration at a single dose of 10 mg/kg to develop a population pharmacokinetic model and Monte Carlo simulation. The relationships among the plasma concentration, dose, and time of valnemulin in pigs were illustrated as C i, v = X0(8.4191 × 10-4 × e−0.2371 t + 1.2788 × 10−5 × e−0.0069 t) after i.v. and C p. o = X0(−8.4964 × 10−4 × e−0.5840 t + 8.4195 × e−0.2371 t + 7.6869 × 10−6 × e−0.0069 t) after p.o. Monte Carlo simulation showed that T> MIC was more than 24 h when a single daily dosage at 13.5 mg/kg BW in pigs was administrated by p.o., and MIC was 0.031 mg/L. It was concluded that the current dosage regimen at 10-12 mg/kg BW led to valnemulin underexposure if the MIC was more than 0.031 mg/L and could increase the risk of treatment failure and/or drug resistance. [ABSTRACT FROM AUTHOR]

Yuan, L. G., Luo, X. Y., Zhu, L. X., Wang, R., Liu, Y. H. A physiologically based pharmacokinetic model for valnemulin in rats and extrapolation to pigs. J. vet. Pharmacol. Therap., 224-231. A flow-limited, physiologically based pharmacokinetic (PBPK) model for predicting the plasma and tissue concentrations of valnemulin after a single oral administration to rats was developed, and then the data were extrapolated to pigs so as to predict withdrawal interval in edible tissues. Blood/tissue pharmacokinetic data and blood/tissue partition coefficients for valnemulin in rats and pigs were collected experimentally. Absorption, distribution and elimination of the drug were characterized by a set of mass-balance equations. Model simulations were achieved using a commercially available software program. The rat PBPK model better predicted plasma and tissue concentrations. The correlation coefficients of the predicted and experimentally determined values for plasma, liver, kidney, lung and muscle were 0.96, 0.94, 0.96, 0.91 and 0.91, respectively. The rat model parameters were extrapolated to pigs to estimate valnemulin residue withdrawal interval in edible tissues. Correlation ( R) between predicted and observed liver, kidney and muscle were 0.95, 0.97 and 0.99, respectively. Based on liver tissue residue profiles, the pig model estimated a withdrawal interval of 10 h under a multiple oral dosing schedule (5.0 mg/kg, twice daily for 7.5 days). PBPK models, such as this one, provide evidence of the usefulness in interspecies PK data extrapolation over a range of dosing scenarios and can be used to predict withdrawal interval in pigs. [ABSTRACT FROM AUTHOR]

Wang, R., Yuan, L.G., He, L.M., Zhu, L.X., Luo, X.Y., Zhang, C.Y., Yu, J.J., Fang, B.H., Liu, Y.H. Pharmacokinetics and bioavailability of valnemulin in broiler chickens. J. vet. Pharmacol. Therap., 247-251. The objective of this study was to investigate the pharmacokinetics and bioavailability of valnemulin in broiler chickens after intravenous (i.v.), intramuscular (i.m.) and oral administrations of 10 mg/kg body weight (bw). Plasma samples were analyzed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Pharmacokinetic characterization was performed by non-compartmental analysis using WinNonlin program. After intravenous administration, distribution was wide with the volume of distribution based on terminal phase(V) of 4.27 ± 0.99 L /kg. Mean valnemulin t(h), Cl(L /h /kg), V (L /kg) and AUC(μg·h /mL) values were 2.85, 0.99, 2.72 and 10.34, respectively. After intramuscular administration, valnemulin was rapidly absorbed with a C of 2.2 μg/mL achieved at 0.43 h (t), and the absolute bioavailability (F) was 88.81%; and for the oral route the same parameters were 0.66 ± 0.15 μg/mL, 1.54 ± 0.27 h and 74.42%. A multiple-peak phenomenon was present after oral administration. The plasma profile of valnemulin exhibited a secondary peak during 2-6 h and a tertiary peak at 32 h. The favorable PK behavior, such as the wide distribution, slow elimination and acceptable bioavailability indicated that it is likely to be effective in chickens. [ABSTRACT FROM AUTHOR]

The article presents a study on the pharmacokinetic characteristics of the fluoroquinolone Marbofloxacin administered via various drug routes to Muscovy ducks. The study assessed 30 healthy Muscovy ducks divided into three groups of 10 in a controlled environment, which were then examined using a parallel study design. Results showed that an oral dosage of 2.5 milligrams (mg) per kilogram (kg) is the treatment recommended for infections caused by Gram-negative bacteria in ducks.