Lack of activity of ketorolac in hot-plate test and serotonin binding capacity of brain membranes in rats.

An increasing number of observations indicate that prostaglandin synthesis inhibition is not a satisfactory explanation for the antinociceptive activity of the non-steroidal anti-inflammatory drugs. In the hot-plate test performed 1 or 2 h after ketorolac at 40, 70 and 100 mg/kg i.p., the drug does not display any significant antinociceptive activity. Nor, at the two higher doses used, does it affect the cortical and pontine serotonin binding capacity of rat brain membranes 2 h after treatment. The data suggest that this lack of anti-nociceptive activity in the hot-plate test is associated with the drug's inability to affect the central serotoninergic system.