Abstract: Objective To evaluate the muscular irritation of Parecoxib Sodium injection in rabbits, and to provide a guideline for clinical safety. Methods The sample was injected intramuscularly in quadriceps of the rabbits, and reactions in the intra-individual left and right self-comparison method were compared in the same rabbit. The high and low concentrations of sample were 20 and 5 mg·mL^-1 (in a volume of 0.5 mL) respectively. The general status, local visual observation of drug administration, anatomical observation and histopathological examination were used to synthesize the muscular irritation of the subject (or Parecoxib Sodium) in rabbits. Results The results showed a significant concentration-dependent irritation relationship after i.m. injection in rabbit quadriceps, namely 20 mg·mL^-1 induced a moderate and irreversible irritation while 5 mg·mL^-1 induced a minor and reversible irritation. Conclusion The common clinical concentration of Parecoxib Sodium for injection (20 mg·mL^-1) has a high risk of muscle irritation, and under this test condition, 5 mg·mL^-1 is the safe concentration for intramuscular injection.

Key words: parecoxib sodium, injection, rabbit, muscular irritation