site of analgesic action of zomepirac sodium a potent nonnarcotic analgesic in experimental animals zomepirac sodium inhibited the reflex hypertension caused by an injection of bradykinin into the splenic artery of anaesthetized dogs but not that by injection of bradykinin plus pge1 in the rat acetic acid writhing test the potency ratio of intraperitoneal ed50 041 microgramkg to intravenous ed50 335 microgramskg antiwrithing activity of zomepirac sodium was 792 371173 though the ratio of codeine phosphate 373 microgramskg ip 352 microgramskg iv was 0934 when equipotent doses of zomepirac sodium were administered to rats receiving intraperitoneally acetic acid the plasma zomepirac level after iv administration was more than 200 times that after ip administration while the peritoneal exudate zomepirac contents were nearly equal after administration by both routes zomepirac sodium 5 microgramskg did not produce significant antiwrithing activity after intracerebroventricular administration from these results it was suggested that zomepirac sodium produced analgesic action through a strong blockade of the hyperalgesia in the peripheral system