Prospective Pharmacogenetic Cohort Study of CYP2D6 Metabolizer Phenotype, Analgesic Failure, and Adverse Effects in Postoperative Patients Receiving Tramadol by Elastomeric Infusion Pump

Overview

This prospective pharmacogenetic cohort will enroll postoperative patients receiving a standardized tramadol-containing elastomeric analgesia pump. CYP2D6 genotype will be measured but will not determine treatment during the 72-hour study window. Participants with non-normal metabolizer phenotypes will be compared with normal metabolizers for analgesic treatment failure and adverse effects. Pain, rescue medication, pump discontinuation, sedation, respiratory status, nausea/vomiting, and other adverse events will be assessed at prespecified times.

All participants will receive the same institutional tramadol pump regimen as routine postoperative care. A preoperative or immediate postoperative sample will undergo CYP2D6 genotyping, including copy-number assessment under the validated laboratory method. Pain and adverse effects will be recorded repeatedly through 72 hours while clinical care remains unrestricted. The primary analysis compares any non-normal phenotype with normal metabolizers, as proposed by the investigator. Because reduced- and increased-function phenotypes may affect different outcomes, separate poor/intermediate and rapid/ultrarapid analyses are prespecified. Models will account for CYP2D6 inhibitors, organ function, surgical procedure, anesthesia, and concomitant analgesia.

Conditions