The Genetic Association Study in The Central Type Pruritus nduced by Epidural Morphine

Topic: he Genetic Association Study in The Central Type Pruritus induced by Epidural Morphine for Postcesarean analgesiaackground: ntrathecal or epidural morphine; which was wildly used for postoperative analgesia, frequently induced some annoying side effects, especially central type pruritus. There were seldom previous studies focusing on the influence of genetic variability on those side effects induced by neuroaxial morphine. The purpose of this study was to investigate the association between central type pruritus induced by epidural morphine for postcesarean analgesia and A118G polymorphism of human µ-opioid receptor gene (OPRM1).aterials and methods: fter obtaining the informed consent, 212 pregnant women were recruited to receive pure epidural morphine 2mg twice per day for postcesarean analgesia. Blood samples were collected and sequenced with high resolution melting analysis to detect three different genotypes of OPRM1 (AA, AG and GG) by using the LightCycler® 480 Gene Scanning Software. We interviewed all candidates postoperative 24 hours to record the clinical phenotype (focusing on the side effects) with subjective complaint and objective observations. esults: he genotyping after laboratory analysis showed that 99 women (46%) were AA, 91 (41%) were AG and 25 (11%) were GG. 62 of 212 women suffered from significant pruritus (29.25%), and 150 of 212 women had non-significant pruritus (70.75%). In genotype AA, 33 patients (53.2%) experienced significant pruritus, 26 (41.9%) in genotype AG and 3 (4.84%) in genotype GG, respectively. Allele G in A118G was a statistically independent protective factor for individual developing pruritus, the multivariate-adjusted odds ratio was 0.27 (95% CI 0.08-0.95, p=0.041). For the severity score of pruritus, there were a trend with progressively decreasing among three groups. The GG group experienced the lowest severity score (0.72) for pruritus (p>0.05).onclusion: he incidence of significant pruritus in recessive type (GG) was significantly lower compared with dominant type (AA + AG). The recessive G allele in A118G may have protective effect on significant pruritus after epidural morphine for postcesarean analgesia.