Comparison of the Inhibitory Effects of Flunixin Meglumine and Meloxicam on the Smooth Muscles Motility of the Gastrointestinal Tract of Cattle

This study aimed to compare the inhibitory effect of flunixin meglumine and meloxicam on the smooth muscles of the gastrointestinal tract in male cattle. Tissue samples, including the abomasum, ileum, proximal loop and centripetal gyri of the ascending colon, were collected from routinely slaughtered male cattle. These samples were sectioned into strips and mounted in an isolated tissue bath system. Smooth muscle contractions were evoked using carbachol, and cumulative doses of atropine, flunixin meglumine and meloxicam were administered to assess smooth muscle activity. Atropine, used as a positive control, did not abolish contractions in the abomasum and centripetal gyri tissues, even at a high concentration of 10 µM. Based on area-under-curve values, flunixin meglumine demonstrated a greater inhibitory effect than meloxicam by factors of 8.57, 4.28, 12.44 and 3.93 in the abomasum, ileum, proximal loop and centripetal gyri tissues, respectively. For beats-per-minute values, flunixin meglumine exhibited a stronger inhibitory effect than meloxicam by factors of 7.22, 3.88, 7.03 and 3.35 in the abomasum, ileum, proximal loop and centripetal gyri tissues, respectively. Finally, based on peak maximum values, flunixin meglumine's inhibitory effect was 6.13, 4.43, 7.07 and 7.02 times greater than that of meloxicam in the abomasum, ileum, proximal loop and centripetal gyri tissues, respectively. In conclusion, flunixin meglumine was more potent than meloxicam in inhibiting smooth muscle activity. Conversely, meloxicam is associated with fewer adverse effects due to its selective action on the cyclooxygenase-2 enzyme. However, flunixin meglumine may be more advantageous than meloxicam for applications in beef and milk production due to its shorter residue elimination time.