Pharmacokinetic evaluation of aqueous solution of enrofloxacin after single intramuscular injection in layers

Abstract

The effective use of enrofloxacin (ENX) in control of bacterial diseases of commercial egg layers is dependent on knowledge of pharmacokinetics (PK) and use of appropriate drug dosage formulation that guarantee sustainable and adequate drug delivery. This study aside from determining PK indices of aqueous ENX preparation administered to hens intramuscularly will also investigate the capacity of this dosage formulation in delivering therapeutic and sustainable serum drug levels against common pathogenic bacteria of chickens in our environment. A total of 108 hens assigned to 3 groups of 36 birds each were administered with 10mg/kg aqueous ENX intramuscularly. A parallel sampling technique involving one blood draw from each bird at each of the 12 time points was used. Therefore 3 birds were sampled at each time point. This was repeated in each of the experimental groups. The serum ENX concentration was determined using enzyme linked immuno-sorbent assay (ELISA). The peak serum concentration (Cmax), time to achieve peak serum concentration (Tmax), area under curve _0-24hrs (AUC), area under the first moment curve (AUMC), clearance (CL), volume of distribution (V_D), mean residence time (MRT) and elimination half-life (t_1/2) were obtained from Non-compartmental analysis of concentration-time data. The Mean ± SEM of AUC, AUMC, CL, V_D, t_1/2, MRT, Cmax and T max were; 5.32 ± 0.10, 64.99 ± 2.15, 0.12 ± 0.03, 1.52 ± 0.25, 8.46 ± 0.92, 12.20 ± 0.34, 0.23±0.01, 6.12 ± 0.22 respectively. In conclusion, bolus intramuscular administration of aqueous ENX to hens is capable of achieving therapeutic and sustainable drug concentrations against highly sensitive pathogenic bacteria. This formulation may prove useful in chemoprophylaxis but not in treating acute bacterial infections.