Therapeutic and adverse effects of flunixin-meglumine in adult and young cats.

In this study, we elucidated the difference in nonsteroidal anti-inflammatory drug sensitivities between young and adult cats on therapeutic and adverse effects. In the prevention of lipopolysaccharide (LPS)-induced hyperthermia using flunixin-meglumine, young (<3 months old) and adult (>12 months old) cats of both sexes were given LPS (0.3 µg/kg, i.v.), and body temperature was measured 24 hr later. Flunixin (1 mg/kg, s.c.) was administered 30 min before the LPS injection. LPS-induced hyperthermia was almost completely inhibited by pre-treatment with flunixin in both adult and young cats. In addition, flunixin showed almost the same antipyretic effects in both young and adult cats. The animals were administered flunixin (1 mg/kg, s.c.) once a day for 3 days, and sacrificed 24 hr later to examine the gastrointestinal mucosal lesions. In adult cats, flunixin caused many severe lesions in the small intestine. In contrast, very few gastrointestinal lesions were produced by flunixin in young cats. In the pharmacokinetics of flunixin, plasma concentrations of flunixin were analysed using a high performance liquid chromatography. There were no significant differences in plasma concentration of flunixin between young and adult cats from 0.5 to 4 hr after the injection. These results demonstrated that NSAIDs could be used more safely in young than in adult cats from the points of gastrointestinal adverse effects. Furthermore, this difference in gastrointestinal lesions between adult and young cats was not related with the plasma concentration of flunixin.