African Journal of
Pharmacy and Pharmacology

  • Abbreviation: Afr. J. Pharm. Pharmacol.
  • Language: English
  • ISSN: 1996-0816
  • DOI: 10.5897/AJPP
  • Start Year: 2007
  • Published Articles: 2272

Full Length Research Paper

Nitrous oxide versus pethidine with promethasine for reducing labor pain

Batool Teimoori1, Nahid Sakhavar1, Masoome Mirteimoori1 and Behzad Narouie2*
1Department of Obstetrics and Gynecology, Health Promotion Research Center, Zahedan University of Medical Sciences, Zahedan, Iran. 2Clinical Research Development Center, Ali-ebne-Abitaleb hospital, Zahedan University of Medical Sciences, Zahedan, Iran.
Email: [email protected]

  •  Accepted: 17 October 2011
  •  Published: 08 November 2011


Systemic opioids are widely used for the relief of labor pain. Self-administered nitrous oxide with concentration of 50% is a new form of analgesia. The aim of this study was to compare the analgesic efficacy and side effects of the patient controlled inhaled nitrous oxide (50% ‘‘Entonox’’) with systemic intramuscular pethidine, in reducing pain during normal vaginal labor in Iranian population. In a randomized controlled study, the analgesic efficacy of inhaled 50% nitrous oxide (Entonox) was evaluated as compared to intra muscular pethidine for reducing labor pain among 100 women undergoing normal vaginal delivery. Mean maternal age was 26.2 and 27.2 years in entonox and pethidine groups, respectively. Duration of first and second stages was significantly shorter in patients receiving nitrous oxide as analgesia as compared to pethidine group (P < 0.05). Pain severity according to visual analog scale (VAS) score was significantly lower in patient that received nitrous oxide (P = 0.0001). We also showed significantly higher satisfaction of pain reduction in nitrous oxide group during labor (P = 0.01). No significant difference was observed among the groups regarding neonatal complications. Although, nitrous oxide is certainly not a potent analgesic, we found that it has more beneficial effects than pethidine in parturient women which is yet to be cleared.


Key words: Entonox, labor pain, pethidine, nitrous oxide.