Pharmacokinetics and bioavailability of valnemulin in broiler chickens

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(z)) of 4.27 ± 0.99 L /kg. Mean valnemulin t(1/2β)(h), Cl(β)(L /h /kg), V(ss)(L /kg) and AUC((0-∞))(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(max) of 2.2 μg/mL achieved at 0.43 h (t(max)), 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.