Antinociceptive effects of H1- and H2-antihistaminics in mice

1. Two methods were used to study the analgesic effects of subcutaneous injections of antihistaminics in mice: the p-benzoquinone(PBQ)-writhing test and caudal compression test. 2. Mepyramine, lupitidine (SKF 93479), and famotidine produced significant antinociceptive effects dose-dependently, during both the PBQ-writhing and caudal compression tests. 3. However, ranitidine did not reveal any antinociceptive effect. 4. Icotidine (SKF 93319) produced significant antinociception and also augmented the analgesic effect of morphine, on the caudal compression test. 5. However, mepyramine, famotidine, and lupitidine did not affect morphine-induced analgesia on the caudal compression test and displayed a nonsignificant potentiation on morphine-induced analgesia in the PBQ-writhing test.