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Emetic and antiemetic effects of opioids in the dog

1986; Elsevier BV; Volume: 128; Issue: 3 Linguagem: Inglês

10.1016/0014-2999(86)90760-0

1879-0712

Jean-Pierre Blancquaert, Romain A. Lefebvre, Jan Willems,

Veterinary Pharmacology and Anesthesia

The emetic and antiemetic effects of opioid agonists were studied in awake dogs. The μ-agonists morphine, fentanyl and methadone, in sedative doses, prevented the emetic response to apomorphine and copper sulphate; only morphine induced emesis, at doses lower than those required to prevent emesis. The δ-agonist [D-Ala2,Met5]enkephalinamide (DALA) and [Leu5]enkephalin induced emesis in some of the dogs studied but had no antiemetic activity. The κ-agonists bremazocine and ethylketocyclazocine (EKC) did not induce emesis but, at sedative doses, prevented the emetic response to apomorphine. The emetic effect of DALA was antagonized by naloxone in some dogs; the antiemetic effect of morphine, bremazocine and EKC was blocked by both naloxone and MR 2266. The non-opioid sedatives diazepam, phenobarbital and xylazine, administered in sedative doses, did not prevent apomorphine-induced emesis. Our results suggest that a δ-receptor is involved in the emetic effect and a μ- and/or or κ-receptor in the antiemetic effect of opioids.