Pharmacokinetics of sodium meclofenamate in pre-ruminant cattle

The pharmacokinetic profile of sodium meclofenamate, a non-steroidal antiinflammatory drug, was determined in six pre-ruminant calves after intravenous and intramuscular administration at a dose of 2.2mg/kg of body weight. Meclofenamate concentrations were measured using a high performance liquid chromatography assay. The pharmacokinetics of sodium meclofenamate after intravenous and intramuscular administration to calves were characterised by a rapid distribution phase (t1⁄2α), 15.45±4.85min and 23.14±7.24min for the intravenous and intramuscular administration, respectively, followed by a longer elimination phase (t1⁄2β) after intramuscular treatment (17.55±6.52h.). The apparent volume of distribution (Vd) of the drug after intravenous administration was moderate (0.72±0.12l/kg), and high (3.51±1.05l/kg) after intramuscular administration. This can be explained by the flip-flop effect or by enterohepatic shunting. The bioavailability achieved after intramuscular administration was 61%.