Pharmacokinetics of Extended-Release Meloxicam in Tufted Titmice (Baeolophus bicolor) Following Subcutaneous...

Analgesic regimens for laboratory-housed avian species remain poorly defined, with limited pharmacokinetic data available, particularly in passerine birds. This study characterized the pharmacokinetics of extended-release (ER) meloxicam in tufted titmice (Baeolophus bicolor) following single subcutaneous dosages of 3 and 6 mg/kg. We hypothesized ER meloxicam would sustain therapeutic plasma concentrations (>3,500 ng/mL), previously established in zebra finches and larger avian species, for 72 hours. Pharmacokinetic analysis revealed significantly higher Cmax and faster clearance at 6 mg/kg compared with 3 mg/kg. Although therapeutic plasma levels (>3,500 ng/mL) were observed at 1 hour postadministration, concentrations decreased below previously established therapeutic thresholds by 4 hours postinjection at both dosages. Histopathologic examination revealed no significant drug-related adverse effects. These findings suggest subcutaneous administration of ER meloxicam at 3 and 6 mg/kg does not sufficiently prolong therapeutic analgesia in tufted titmice, with a shorter therapeutic duration of action than previous findings with intramuscular meloxicam in small passerines.