Journal of veterinary pharmacology and therapeutics

Intravenous infusion of electrolyte solution changes pharmacokinetics of drugs: pharmacokinetics of ampicillin.

PMID 24666465


The pharmacokinetics of ampicillin in dogs was determined after intravenous (i.v.) bolus and constant rate infusion. Ampicillin was administered to six beagle dogs as an i.v. bolus at 20xa0mg/kg and as a constant rate i.v. infusion (CRI) at 20xa0mg/kg during 8xa0h (0.042xa0mL/min/kg) in Ringer's lactate (Hartmann's) solution. The concentrations were determined by an LC/MS/MS method. After i.v. bolus, ampicillin total body clearance, apparent volume of distribution at steady-state, mean residence time (MRT), and half-life were 4.53xa0±xa00.70xa0mL/min/kg, 0.275xa0±xa00.044xa0L/kg, 61xa0±xa013xa0min, and 111 (85-169) min, respectively. The corresponding parameters calculated after CRI were 13.5xa0±xa01.06xa0mL/min/kg, 0.993xa0±xa00.415xa0L/kg, 73xa0±xa027xa0min, and 49 (31-69) min. Ampicillin concentration decreased by 30% in the Ringer's lactate infusion solution mostly during the first hour after preparation of the solution. Constant rate infusion of Ringer's lactate solution during 8xa0h caused significant changes in ampicillin pharmacokinetics. The results suggested that special attention should be given to drug pharmacokinetics when co-administered intravenously with electrolyte solutions.