Pharmacokinetics and urinary excretion of subcutaneously administered meloxicam in cross bred calves on coadministration with levofloxacin

Pharmacokinetics and urinary excretion of meloxicam were investigated in cross-bred calves after its single subcutaneous administration of 0.5 mg.kg⁻¹ followed by intravenous injection of levofloxacin (4 mg.kg⁻¹). The concentration of meloxicam in plasma and urine was estimated spectrophotometrically and the kinetic parameters were calculated by applying mono-compartment open model. The peak plasma drug concentration was attained at 4 h and minimum therapeutic plasma concentration was maintained from 0.5 to 16 h of administration. Slow absorption and limited tissue distribution was evident by the small values of absorption half-life (1.65±0.11 h) and Vd_area(0.07±0.003 L.kg⁻¹). The elimination half-life and total body clearance were 10.3±0.27 h and 4.74±0.32 ml.kg⁻¹.h⁻¹, respectively. About 6% of the total administered drug was excreted in urine within 24 h. A suitable subcutaneous dosage regimen of meloxicam was calculated to be 0.6 mg.kg⁻¹ followed by 0.5 mg.kg⁻¹ at 24 h intervals when prescribed with levofloxacin in calves. The pharmacokinetics of meloxicam was significantly altered by concurrent administration of levofloxacin in calves.