Abstract
Individualization of acute postoperative pain treatment on an evidence-based decision process is a major health concern. The aim of this study is to investigate the influence of genetic and non-genetic factors on the variability of response to morphine in acute postoperative pain. A group of nighty-five patients undergoing major surgery were included prospectively. At 24 h, a logistic regression model was carried out to determine the factors associated with morphine doses given by a Patient Controlled Analgesia device. The dose of morphine was associated with age (p = 0.011), patient weight (p = 0.025) and the duration of operation (p = 0.030). This dose decreased with patient's age and duration of operation and increased with patient's weight. OPRM1 and ABCB1 polymorphisms were significantly associated with administered dose of morphine (p = 0.038 and 0.012 respectively). Patients with at least one G allele for c.118A>G OPRM1 polymorphism (AG/GG) needed 4 times the dose of morphine of AA patients. Additionally, patients with ABCB1 CT and CC genotypes for c.3435C>T polymorphism were 5.6 to 7.1 times more prone to receive higher dose of morphine than TT patients. Our preliminary results support the evidence that OPRM1/ABCB1 genotypes along with age, weight and duration of operation have an impact on morphine consumption for acute postoperative pain treatment.