The aim of this study was to investigate the pharmacokinetic properties of gamithromycin in pigs after an intravenous (i.v.) or subcutaneous (s.c.) bolus injection of 6 mg/kg body weight. The plasma concentrations of gamithromycin were determined using a validated high-performance liquid chromatography-tandem mass spectrometry method, and the pharmacokinetics were noncompartmentally analysed. Following i.v. administration, the mean area under the plasma concentration-time curve extrapolated to infinity (AUCinf) and the mean elimination half-life (t1/2λz) were 3.67 ± 0.75 μg.h/mL and 16.03 h, respectively. The volume of distribution at steady state (Vss) and the plasma clearance were 31.03 ± 6.68 L/kg and 1.69 ± 0.33 L/h.kg, respectively. The mean residence time (MRTinf) was 18.84 ± 4.94 h. Gamithromycin administered subcutaneously to pigs demonstrated a rapid and complete absorption, with a mean maximal plasma concentration (Cmax) of 0.41 ± 0.090 μg/ml at 0.63 ± 0.21 h and a high absolute bioavailability of 118%. None of the reported pharmacokinetic variables significantly differed between both administration routes.
Keywords: Absolute bioavailability; Gamithromycin; Pharmacokinetics; Pig; Subcutaneous.
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