Influence of uridine diphosphate-glucuronyltransferase 2B7 (UGT2B7) variants on postoperative buprenorphine analgesia.

Background: Genetic factors are known to influence individual differences in pain and sensitivity to analgesics. Different genetic polymorphisms in opioid-metabolizing enzymes that can affect the analgesic response to opioids have been proposed. This study investigates a possible difference in the response to postoperative buprenorphine analgesia related to the presence of different isoforms (cytosine or thymine substitution at nucleotide 802) of UGT2B7 gene.

Methods: Transdermal buprenorphine was administered to 91 patients who underwent muscle-sparing thoracotomy. UGT2B7 polymorphism at locus C802T (His268Tyr) was detected using a PCR Taqman-based procedure. The severity of postoperative pain at rest and during coughing or deep inspiration was assessed by visual analog scale score after surgery. Hospital stay and perioperative opioid consumption were collected.

Results: Genotype frequencies were 18.4% for UGT2B7*1/*1, 52.9% for UGT2B7*1/*2, and 28.7% for UGT2B7*2/*2. VAS pain scores at rest were statistically similar among the groups except at 24, 60, and 120 hours (UGT2B7*2/*2 genotype showing higher pain scores). Patients with the UGT2B7*2/*2 genotype showed higher VAS scores triggered by coughing after the 48 hours (P < 0.05). In addition, patients with this genotype reported a higher prevalence of severe pain after 48 postoperative hours (P < 0.05). Thirty-eight percent of patients carrying genotype UGT2B7*2/*2 experienced severe pain in a final survey vs. 17% in the group with UGT2B7*1/*1 (P = 0.36).

Conclusions: The presence of the SNP 802C>T UGT2B7 (UGT2B7*2/*2) is associated with a worse analgesic response to transdermal buprenorphine in the postoperative period of thoracic surgery.