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.

The effect of nonrecurring alcohol administration on pain perception in humans: a systematic review

“…When comparing the different methods of pain induction, pain-dampening effects were most pronounced in the studies using pressure pain stimulation, with four of five studies reporting effects on pain threshold 1 , 28 , 32 and one reporting effects on pain tolerance. 23 Of three investigations using electrical stimulation, two detected an effect using pain ratings, 26 , 27 whereas one found an increase in half-maximal pain intensity but not in pain threshold.…”

“…Two of the reviewed studies tested the effect of alcohol on pain after the administration of the opioid antagonist naloxone. Saddler et al 32 found that naloxone blocked the antinociceptive action of morphine but not that of alcohol, despite comparable effects of both substances on the pain threshold. Unfortunately, neither the effect of alcohol nor the effect of naloxone was controlled by a placebo condition.…”

A review of the effects of opioids on psychomotor and cognitive functioning in humans.

“…Six other studies used visual RTs to assess the effect of morphine. Three of these studied healthy volunteers and found no increase in visual RT with morphine (Berman, Taylor, & Marged, 1993; Ivy et al, 1944; Saddler, James, & Harington, 1985). However, two of these studies did not include a placebo control condition (Ivy et al, 1944; Saddler et al, 1985).…”

Effect of Ethanol on Morphine State-Dependent Learning in the Mouse: Involvement of Gabaergic, Opioidergic and Cholinergic Systems

“…According to Prunell et al (1987) both the CNS stimulant and depressant effects of ethanol in rats have been antagonized by naloxone. However, other investigators suggested that the effects of naloxone are probably due to a non-specific analeptic action rather than blockade of opioid receptors (Saddler et al, 1985).…”