Pharmacokinetics of meloxicam after oral administration of a granule formulation to healthy horses.

backgroundNonsteroidal anti-inflammatory drugs are administered in horses for several systemic diseases. Selective cyclooxygenase-2 inhibitors are preferred because of lower risk of adverse effects. Several meloxicam formulations have been tested in horses, but a recently marketed granule oral formulation has not been studied.

objectiveTo characterize the pharmacokinetics of a novel granule meloxicam formulation in fasted and fed horses, and to compare pharmacokinetic features with oral suspension and tablets. ANIMALS: Seven healthy adult horses.

methodsMeloxicam was administered at 0.6 mg/kg in fasted or fed horses. Blood samples were collected for pharmacokinetic analysis, and vital signs, hematology, and biochemistry variables were monitored for 72 hours.

resultsNo adverse effects were detected. Volume of distribution and clearance after intravenous administration of meloxicam were 0.36 L/kg and 29.12 mL/h/kg, respectively, with a 12.39 hours of terminal half-life. Protein binding was of 97%. Bioavailability was high for every oral formulation, ranging 70%-110%, without feed effect. Because of a slower absorption, meloxicam after administration of granules had a longer half-life (24 and 34 hours, fasted and fed, respectively) and mean residence time (31 and 47 hours), than suspension and tablets (ranging 10-13 and 13-15 hours, respectively). In addition, the time above therapeutic concentration was higher for the granule formulation than other formulations. CONCLUSIONS AND CLINICAL IMPORTANCE: Granule formulation has different PK parameters compared to other oral formulations, which could enable this formulation to be used for different dosage regimens in order to reach a desired clinical effect or decrease the risk of adverse effects.