Effects of naloxone on nitrous oxide actions in healthy volunteers.
James P Zacny, Aisling Conran, Helene Pardo, Dennis W Coalson, Matthew Black, Allan P Klock, Jerome M Klafta
Pain December 1, 1999 DOI: 10.1016/s0304-3959(99)00127-x via PubMed
Summary
AI-generated from the abstractA high dose of naloxone (30 mg/70 kg) did not reverse the pain-relieving effects of 30% nitrous oxide in a crossover trial with 14 subjects. Participants inhaled either 30% nitrous oxide or pure oxygen, then received intravenous naloxone or saline. Naloxone increased pain ratings overall and impaired mood and psychomotor performance, but it did not counteract nitrous oxide's analgesic or subjective effects. The findings question whether the opioid system mediates nitrous oxide's effects in humans.
Study at a glance
| Characteristics | Randomized crossover trial Peer reviewed |
|---|---|
| Sample size | 14 |
| Population | Human subjects |
| Interventions | Naloxone Nitrous oxide |
| Dose | 30 mg/70 kg naloxone; 30% nitrous oxide in oxygen |
| Duration | 35-minute inhalation period; testing 10 minutes after naloxone administration |
| Key finding | Naloxone did not reverse nitrous oxide-induced analgesia, mood effects, or psychomotor impairment, questioning the role of the opioidergic system in mediating nitrous oxide's effects in humans. |
Abstract
A number of studies have examined the effects of naloxone on nitrous oxide-induced analgesia with conflicting results. In the present study the effects of a relatively high dose of naloxone was examined to determine its effects on nitrous oxide-induced analgesia, as well as on the subjective and psychomotor effects of nitrous oxide. Fourteen subjects participated in a four-session crossover trial in which they received intravenous injections of either saline or 30mg/70kg naloxone 10min into a 35min period in which they were inhaling either 100% oxygen or 30% nitrous oxide in oxygen. Ten minutes after the naloxone administration, subjects were tested on the cold pressor test. Mood and psychomotor performance were also assessed before, during and after the inhalation period. Subjects reported higher pain ratings after the naloxone injection than the saline injection, but there was no evidence of naloxone reversing the analgesic effects of nitrous oxide. Similarly while naloxone also affected mood and impaired psychomotor performance, there was no evidence of naloxone reversing the effect of nitrous oxide on these measures. The results of this study call into question the role of the opioidergic system in mediating various effects of nitrous oxide in humans.