Pharmacokinetics of meloxicam administered orally to rabbits (Oryctolagus cuniculus) for 29 days.

OBJECTIVE To determine the pharmacokinetics and safety of meloxicam in rabbits when administered orally for 29 days. ANIMALS 6 healthy rabbits. PROCEDURES Meloxicam (1.0 mg/kg, PO, q 24 h) was administered to rabbits for 29 days. Blood was collected immediately before (time 0) and 2, 4, 6, 8, and 24 hours after drug administration on days 1, 8, 15, 22, and 29 to evaluate the pharmacokinetics of meloxicam. On day 30, an additional sample was collected 36 hours after treatment. Plasma meloxicam concentrations were quantified with liquid chromatography-mass spectrometry, and noncompartmental pharmacokinetic analysis was performed. Weekly plasma biochemical analyses were performed to evaluate any adverse physiologic effects. Rabbits were euthanatized for necropsy on day 31. RESULTS Mean ± SD peak plasma concentrations of meloxicam after administration of doses 1, 8, 15, 22, and 29 were 0.67 ± 0.19 μg/mL, 0.81 ± 0.21 μg/mL, 1.00 ± 0.31 μg/mL, 1.00 ± 0.29 μg/mL, and 1.07 ± 0.19 μg/mL, respectively; these concentrations did not differ significantly among doses 8 through 29. Results of plasma biochemical analyses were within reference ranges at all time points evaluated. Gross necropsy and histologic examination of tissues revealed no clinically relevant findings. CONCLUSIONS AND CLINICAL RELEVANCE Plasma concentrations of meloxicam for rabbits in the present study were similar to those previously reported in rabbits that received 1. 0 mg of meloxicam/kg, PO every 24 hours, for 5 days. Results suggested that a dosage of 1. 0 mg/kg, PO, every 24 hours for up to 29 days may be safe for use in healthy rabbits.