Subcutaneous meloxicam suspension pharmacokinetics in mice and dose considerations for postoperative analgesia

Meloxicam is a cyclooxygenase (COX) inhibitor with a higher selectivity for cyclooxygenase-2 (COX-2) than for cyclooxygenase-1 (COX-1). In the laboratory setting, this nonsteroidal anti-inflammatory drug (NSAID) is commonly selected for analgesia in mice and administered every 24 h. This study characterizes the plasma concentration achieved from a dose of 1.6 mg/kg of meloxicam administered once every 24 h subcutaneously for 72 h in male and female C57BL/6 mice. These values were compared, over time, to reference COX-2 inhibition constants for meloxicam. No significant differences in trough plasma concentrations were noted between genders. The plasma concentrations were below the COX-2 IC50 after 12 h. To maintain a plasma concentration at or above the COX-2 whole blood IC50, the study results suggest an administration frequency of every 12 h when using a dose of 1.6 mg/kg in C57BL/6 mice.