Comparison of analgesic effects of khat (Catha edulis Forsk) extract, D-amphetamine and ibuprofen in mice

We have compared the analgesic properties of khat (Catha edulis Forsk) extract, amphetamine and ibuprofen in mice. After intragastric administration of the drugs analgesia was measured relative to water-injected controls using the hot-plate, the tail-flick, and abdominal-constriction tests. At the highest doses examined (amphetamine 1.8 mg kg(-1), ibuprofen 90 mg kg(-1), khat extract 1800 mg kg(-1)), all three substances produced analgesia, but the order of efficacy varied with the test. Khat and ibuprofen were significantly different from the control in the hot-plate assay at three or more time points post-injection. In the tail-flick test, khat and amphetamine were efficacious; ibuprofen means were somewhat lower but still significantly different from control. Higher doses of the drugs decreased the number of responses in the acetic acid-induced abdominal-constriction assay. We conclude that khat, like amphetamine and ibuprofen, can relieve pain. Differences in assay results may reflect differences in modes and sites of action, as well as in the type of pain generated by the chemical and thermal stimuli for nociception.