title: Effect of cocaine on xylazine analgesic activity.
abstract: The effect of cocaine on the antinociceptive action of xylazine (XLZ) was studied by the method of abdominal contortions in mice. While XLZ alone (0.5 mg/kg, sc) inhibited the contortions by 43%, cocaine (5 mg/kg, sc) produced 39% inhibition and combination of the two drugs reduced the contortions by 77%. Cocaine acted synergistically with XLZ, decreasing the ED50 from 0.42 to 0.13 mg/kg. The mechanism involved does not seem to be directly mediated by activation of alpha-2 receptors since pretreatment of the animals with yohimbine did not significantly influence the XLZ effect.
authors.affiliation: Departamento de Farmacologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil.
authors.forename: J H
authors.initials: JH
authors.lastname: Leonhardt
authors.forename: A C
authors.initials: AC
authors.lastname: Freire
mesh_terms: D000698:Analgesia; D000818:Animals; D003042:Cocaine / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D008297:Male; D051379:Mice; D013843:Thiazines / Q000037:antagonists & inhibitors*; D014991:Xylazine / Q000008:administration & dosage / Q000037:antagonists & inhibitors*
chemical_list: D013843:Thiazines; D014991:Xylazine; D003042:Cocaine