Receptors and channels: Analyses of Inter-Individual differences in Nociception and Morphine Analgesia in relationship to A118g Mu-Receptor polymorphism

Abstract

Effective morphine requirements during neonatal intensive care treatment are difficult to predict as neonatal infants show large inter-individual variability in nociception and pain response after morphine administration. The objective was to determine the effects of the A118G single nucleotide polymorphism (SNP) of the ı̀-receptor gene on the inter-individual variability of nociception and morphine requirements among neonatal patients. The DNA of 118 neonates, who participated in a randomized placebo controlled trial investigating the effects of continuous morphine in ventilated neonates, was analyzed for the A118G SNP. (Simons SH et al, JAMA 2003) Relationships between the different genotypes and pain scores and morphine requirements were investigated. Eighty-four patients were wild type, 30 patients were heterozygous and 4 patients were homozygous for the mutation. No significant differences in pain scores and morphine requirements were found between the wild type and heterozygous patients. No homozygous patient needed additional morphine. No relationship between the ı̀-receptor A118G genotype and inter-individual variability in pain scores or morphine requirements was detected in our study population. In other words genotype analysis does not preclude morphine need.