ANALGESIC EFFECTS OF AMLODIPINE AND ITS INTERACTION WITH MORPHINE ANDKETOROLAC-INDUCED ANALGESIA

1. The antinociceptive effects of amlodipine, administered subcutaneou sly (s.c.), intracerebroventricularly (i.c.v.) and intrathecally (i.t. ) were examined with the acetic acid writhing and tail-flick tests in mice. Amlodipine was also tested in combination with morphine and keto rolac. Isobolographic analyses were used to define the nature of funct ional interactions between amlodipine and morphine or ketorolac. 2. Th e s.c. (0.1, 1.25, 2.5, 5 and 10 mg/kg), i.c.v. (2.5, 5, 10 and 20 mu g/mice) and i.t. (2.5, 5, 10 and 20 mu g/mice) administration of amlod ipine exhibited a dose-dependent antinociceptive effect in the writhin g test but had no effect on the tail-flick latency. Isobolographic ana lyses revealed an additive interaction between amlodipine and morphine or ketorolac in the writhing test.3. These results suggest that amlod ipine induces antinociception and increases antinociceptive action of morphine and ketorolac, possibly through a decrease in cellular calciu m availability. (C) 1997 Elsevier Science Inc.