Effect of MDR1 gene polymorphisms on neuromuscular block of rocuronium

Objective To evaluate the effect of MDR1 gene polymorphisms on the neuromuscular block of rocuronium. Methods One hundred thirty-five patients, aged 18-50 yr, with body mass index of 18-25 kg/m2, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, undergoing gynecologic laparoscopic operation under general anesthesia, were enrolled in the study.Anesthesia was induced with midazolam 0.06 mg/kg, sufentanil 0.7 μg/kg, propofol(target plasma concentration 6 μg/ml)and remifentanil(target plasma concentration 6 ng/ml). After the patients lost consciousness, neuromuscular block was assessed with TOF-Watch SX accelerometer, and rocuronium 0.6 mg/kg was intravenously injected.Anesthesia was maintained by target-controlled infusion of propofol(target plasma concentration 3-5 μg/ml)and remifentanil(target plasma concentration 3-6 ng/ml). Rocuronium 0.15 mg/kg was added when T1 reached 25% of control.The onset time of rocuronium, maintenance time of induction dose, maintenance time of additional dose and recovery index were recorded.Peripheral venous blood samples were collected for MDR1 genotype(MDR1 1236 C>T and 3435 C>T)analysis using polymerase chain reaction-restriction fragment length polymorphism. Results For MDR1 1236 C>T genotype, there were 19 cases of MDR1 1236 CC genotype, 72 cases of MDR1 1236 TT genotype, 44 cases of MDR1 1236 CT genotype.Compared with patients of MDR1 1236 CC, the maintenance time of induction dose, maintenance time of additional dose and recovery index were significantly prolonged in patients of MDR1 1236 TT and CT genotypes(P T genotype, there were 58 cases of MDR1 3435 CC genotype, 55 cases of MDR1 3435 TT genotype, 22 cases of MDR1 3435 TC genotype.There was no significant difference in maintenance time of induction dose, maintenance time of additional dose and recovery index among patients of different MDR1 3435 C>T genotypes(P>0.05). Conclusion MDR1 1236 C>T gene polymorphisms affects the neuromuscular block of rocuronium, and the genetic factor may be one of the reasons contributing to the individual variation in the efficacy. Key words: Polymorphism, single nucleotide; Andristanols; Neuromusclar blockade; Dose-response relationship, drug