J. Pharm. Pharmacol. 2000, 52: 107±110 # 2000 J. Pharm. Pharmacol. Received May 18, 1999 Accepted August 18, 1999 Comparison of Analgesic Effects of Khat (Catha edulis Forsk) Extract, D-Amphetamine and Ibuprofen in Mice JOHN CONNOR, EYASU MAKONNEN* AND AMR ROSTOM* Department of Pharmacology, MC H-078, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA and *Department of Pharmacology, Faculty of Medicine, Addis Ababa University, Addis Ababa, Ethiopia Abstract We have compared the analgesic properties of khat (Catha edulis Forsk) extract, amphet- amine and ibuprofen in mice. After intragastric administration of the drugs analgesia was measured relative to water-injected controls using the hot-plate, the tail-¯ick, 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 ef®cacy varied with the test. Khat and ibuprofen were signi®cantly different from the control in the hot-plate assay at three or more time points post-injection. In the tail-¯ick test, khat and amphetamine were ef®cacious; ibuprofen means were somewhat lower but still sig- ni®cantly 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 re¯ect differences in modes and sites of action, as well as in the type of pain generated by the chemical and thermal stimuli for nociception. When chewed, the leaves of the khat tree (Catha edulis Forsk) release many substances into saliva, including a number of alkaloids. One of these alkaloids, cathinone, is thought to be responsible for at least some effects desired by leaf chewers e.g. euphoria, alertness and anorexia, as well as for undesirable effects, e.g. drug dependence, hyper- tension and tachycardia (Widler et al 1994). Nencini & Ahmed (1982) reported that cathinone has analgesic properties in mice which they as- cribed to monoaminergic and endogenous opioid mechanisms. Cathinone and its analogues have emerged as drugs of abuse in economically developed nations (Sparago et al 1996), but are generally unavail- able elsewhere. However, a huge number of East African and Arabian peoples have khat readily and legally available to them at low cost. Data on the analgesic properties of khat are sparse. Our aim in this study was to compare khat with amphetamine and ibuprofen in quantitative tests of analgesia. Amphetamine, which is often compared with cathinone because they share many pharmacologic effects (Kalix 1992), has antinociceptive activity (Go Èrlitz & Frey 1972). Ibuprofen was included because it has unambiguous, clinically signi®cant, analgesic and anti-in¯ammatory properties (Brooks & Day 1991). Materials and Methods Animals All experiments were performed on mice (albino males, in-house bred, 25±35 g). They were kept 12 to a cage on straw bedding in an animal holding room with a 12-h light±dark cycle. Balanced diet pellets and tap water were con- tinuously available. Changes in pain perception due to drug treatments were determined in a quiet laboratory with ambient illumination and tem- perature close to those of the holding room. Mice were allowed to acclimate to the testing area for 1h before the experiments began. Models of Correspondence: J. Connor, Department of Pharmacology, MC H-078, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA. Downloaded from https://academic.oup.com/jpp/article/52/1/107/6157485 by guest on 27 July 2022