Association of μ-opioid receptor gene polymorphism (A118G) with variations in fentanyl analgesia consumption after total abdominal hysterectomy in female Egyptian patients

Abstract

Opioid analgesics are widely used for the treatment of moderate to severe pain. However, the analgesic efficacy of opioids is well known to vary widely among individuals, making it difficult to predict optimal pain management for each patient. The current clinical study was designed to investigate the association of the A118G single nucleotide polymorphism of the μ-opioid receptor gene with the individual variation in pain sensitivity and fentanyl consumption with patient-controlled analgesia (PCA) in 60 adult female Egyptian patients after total abdominal hysterectomy. All patients received general anesthesia according to the same protocol. During the first 24 h after surgery, pain was assessed using a visual analogue scale. In addition, total amount of fentanyl consumption, sedation score, and any other side effects of opioids were recorded; the A118G single nucleotide polymorphism of the μ-opioid receptor gene was detected by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Our main finding was that in Egyptian gynecological patients, subjects homozygous for the 118G allele needed more fentanyl (488.5 ± 23.91 μg) for 24-h postoperative analgesia than 118A homozygotes (359.82 ± 19.63 μg) and heterozygotes (400± 8.99 μg) (P = 0.001). There was no association of G or A allele and opioid side effects. This study may provide support for the potential use of genetic data in predicting patient’s individual fentanyl doses for adequate postoperative pain control.