Pharmacogenetic features of tramadol metabolism affecting the quality of postoperative analgesia in vascular surgery

BACKGROUND: The issue of the efficacy and safety of medications employed for postoperative analgesia has not been resolved to date. Insufficient analgesia constitutes one of the primary risk factors for developing cardiovascular complications postoperatively. Tramadol is a medication that is frequently used for postoperative pain relief following minor and moderately traumatic operations. The biotransformation of this drug is considerably slowed by the presence of CYP2D6 gene polymorphisms G1846A and C100T, which play a significant role in its metabolism. In such patients, a decrease in the quality of postoperative analgesia can be anticipated, which will consequently lead to an increase in cardiac complications.

AIM: To assess the efficacy of a postoperative analgesia regimen based on tramadol and the incidence of cardiac complications during vascular operations depending on the presence/absence of polymorphisms of the CYP2D6 gene polymorphisms, an isoenzyme of cytochrome P-450.

MATERIALS AND METHODS: An examination of 109 patients undergoing planned vascular surgery was conducted. The frequency of occurrence of polymorphisms G1846A and C100T of the CYP2D6 gene was determined. All patients were assessed for the severity of postoperative pain syndrome during activity and at rest using a visual analog scale on the first day following surgery. Cardiovascular complications that arose while the patients were in the hospital were documented. To assess the autonomic nervous system, patients underwent cardiointervalography.

RESULTS: Polymorphism G1846A was detected in 28 (25.7%), while C100T was detected in four (3.7%) patients. Patients without polymorphisms were included in group 1 (n=77). Patients with polymorphisms were assigned to group 2 (n=32). Pain syndrome at rest and during activity was higher in group 2 patients (p <0.05). The tension index before surgery did not differ between the groups; however, it was greater in group 2 patients after surgery (p <0.001). Cardiac complications were identified in 9.1% of group 1 and 18.8% of group 2 patients (p=0.20).

CONCLUSION: The frequency of polymorphisms G1846A and C100T of the CYP2D6 gene in patients who underwent vascular surgery was 29.4%. Such patients experienced pain syndrome of greater severity. The patient groups did not exhibit any significant differences in the frequency of cardiac complications.