Advances in Understanding the Actions of Nitrous Oxide

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Advances in Understanding the Actions of Nitrous Oxide
Anesthesia Progress
Volume 54, Issue 1 (Spring 2007)

Dimitris E. Emmanouil, DDS, MS, PhD*, Raymond M. Quock, PhD‹
* Department of Pediatric Dentistry, School of Dentistry, Athens University, Athens, Greece
‹ Department of Pharmaceutical Sciences, College of Pharmacy, Washington State University, Pullman, Washington

Nitrous oxide (N2O) has been used for well over 150 years in clinical dentistry for its analgesic and anxiolytic properties. This small and simple inorganic chemical molecule has indisputable effects of analgesia, anxiolysis, and anesthesia that are of great clinical interest. Recent studies have helped to clarify the analgesic mechanisms of N2O, but the mechanisms involved in its anxiolytic and anesthetic actions remain less clear. Findings to date indicate that the analgesic effect of N2O is opioid in nature, and, like morphine, may involve a myriad of neuromodulators in the spinal cord. The anxiolytic effect of N2O, on the other hand, resembles that of benzodiazepines and may be initiated at selected subunits of the Ñ-aminobutyric acid type A (GABAA) receptor. Similarly, the anesthetic effect of N2O may involve actions at GABAA receptors and possibly at N-methyl-D-aspartate receptors as well. This article reviews the latest information on the proposed modes of action for these clinicaleffects of N2O.

Keywords: Nitrous oxide, Pharmacology, Anesthesia, Analgesia, Anxiolysis

Received: May 11, 2006; Accepted: September 9, 2006

DOI: 10.2344/0003-3006(2007)54[9:AIUTAO]2.0.CO;2

Address correspondence to Dr Dimitris Emmanouil, Department of Pediatric Dentistry, Dental School, University of Athens, 2 Thivon str., Athens 115 27, Greece; emmand@dent.uoa.gr.
© 2007 The American Dental Society of Anesthesiology