title: Naloxone does not reverse ethanol analgesia in man.
abstract: The effects of intravenously administered ethanol and morphine on pain threshold, reaction time, motor skills and short-term memory were investigated, and the ability of naloxone to reverse any changes was studied. Morphine (loading dose 0.2 mg/kg with an infusion of 0.004 mg/kg per min) and ethanol (loading dose 0.75 ml/kg with an infusion of 0.0025 ml/kg per min) produced a similar increase in pain threshold of 6.3 (s.e.m. = 1.5, n = 8) pain units and 7.7 (s.e.m. = 1.9, n = 8) pain units, respectively. Naloxone 0.015 mg/kg produced a significant reduction in pain threshold in the morphine group, but not in the ethanol group, and there was a significant difference between the groups following naloxone (P less than 0.05, t-test, 7 d.f.). Ethanol produced a significantly greater deterioration in motor skills than did morphine (P less than 0.05, t-test, 7 d.f.) and performance in both groups was improved following naloxone (P less than 0.05, t-test, 7 d.f.). There was no significant change in the other modalities studied. It is concluded that the reversal of ethanol effects by naloxone is probably due to a non-specific analeptic action rather than blockade of opioid receptors.
mesh_terms: D000700:Analgesics; D004347:Drug Interactions; D000431:Ethanol / Q000097:blood / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology*; D010146:Pain / Q000503:physiopathology; D011597:Psychomotor Performance / Q000187:drug effects; D011930:Reaction Time / Q000187:drug effects; D012684:Sensory Thresholds / Q000187:drug effects
chemical_list: D000700:Analgesics; D009270:Naloxone; D000431:Ethanol