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.
Description
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.
Eligibility
Inclusion Criteria:
- Elective surgery followed by the institution's standardized tramadol-containing elastomeric analgesia pump.
- Ability to report pain on a 0-to-10 numeric rating scale.
- Provision of a blood or buccal sample for CYP2D6 genotyping before or immediately after surgery.
- Written informed consent for genetic testing, storage of genotype data, and clinical follow-up.
Exclusion Criteria:
- Known tramadol allergy or contraindication.
- Chronic opioid therapy, opioid use disorder, or opioid tolerance requiring an individualized regimen.
- Severe renal or hepatic dysfunction outside the standardized pump eligibility criteria.
- Concomitant medication or condition that requires deviation from the standard pump before the first outcome assessment.
- Pregnancy or breastfeeding.
- Inability to provide reliable pain scores or complete 72-hour monitoring.
