Pharmacokinetics and bioavailability of a long-acting formulation of cephalexin after intramuscular administration to cats

The pharmacokinetic profile and bioavailability of a long-acting formulation of cephalexin after intramuscular administration to cats was investigated. Single intravenous (cephalexin lysine salt) and intramuscular (20% cephalexin monohydrate suspension) were administered to five cats at a dose rate of 10 mg/kg. Serum disposition curves were analyzed by noncompartmental approaches. After intravenous administration, volume of distribution (V_z), total body clearance (Cl_t), elimination constant (λ_z), elimination half-life (t_½λ) and mean residence time (MRT) were: 0.33 ± 0.03 L/kg; 0.14 ± 0.02 L/h kg, 0.42 ± 0.05 h⁻¹, 1.68 ± 0.20 h and 2.11 ± 0.25 h, respectively. Peak serum concentration (C_max), time to peak serum concentration (T_max) and bioavailability after intramuscular administration were 15.67 ± 1.95 μg/mL, 2.00 ± 0.61 h and 83.33 ± 8.74%, respectively.