O-Desmethyltramadol

Pre-existing respiratory depression or severe respiratory insufficiency (e.g., severe COPD, acute asthma, cor pulmonale) is an absolute contraindication. ODT's µOR agonism further suppresses respiratory drive. Respiratory depression is the established mechanism of death in ODT overdose (postmortem blood concentrations 0.4–4.3 µg/g in Krypton fatalities).

Traumatic brain injury, Raised intracranial pressure, Impaired consciousness of uncertain etiology

Standard µ-opioid agonist contraindication. Opioid-induced respiratory depression causes CO2 retention which can further elevate intracranial pressure. Sedation and pupil constriction may mask neurological deterioration.

Epilepsy, History of seizures, Conditions lowering seizure threshold

Epilepsy or pre-existing conditions that lower seizure threshold represent a relative contraindication. ODT shows a biphasic seizure profile in kindled rats: anticonvulsant at analgesic doses, proconvulsant at supratherapeutic doses. Tramadol-associated seizures are a significant clinical problem, particularly in regions of high misuse.

SSRIs, SNRIs, tricyclic antidepressants, triptans, linezolid

Concurrent use of SSRIs, SNRIs, tricyclic antidepressants, triptans, or linezolid elevates serotonin syndrome risk. The (-)-enantiomer of ODT inhibits SERT, and adding exogenous serotonergic activity can produce serotonin syndrome. Risk is dose-dependent and highest at elevated ODT doses.

Kidney disease or significant renal impairment prolongs elimination of ODT, increasing exposure and risk of adverse effects including respiratory depression. Dose adjustment is necessary in renally impaired populations.

CYP2D6 ultrarapid metabolizers (gene duplications, prevalence 1–10% depending on ethnicity) produce supraphysiological ODT levels from standard tramadol doses, increasing risk of respiratory depression and toxicity. This contraindication applies specifically to tramadol-derived ODT; standalone desmetramadol bypasses CYP2D6 entirely. CPIC guidelines recommend alternative analgesics for this population when using tramadol.

Chronic maternal use of ODT during pregnancy carries risk of neonatal opioid withdrawal syndrome. No ODT-specific pregnancy data exist; risk is inferred from the tramadol/opioid class. This contraindication lacks ODT-specific citation and is flagged for safety review.

Children demonstrate dose-related CNS and respiratory depression and seizures with tramadol/ODT exposure. CYP2D6 ultrarapid metabolizers are at disproportionate risk. Use in children is contraindicated in many jurisdictions.

Elderly patients demonstrate approximately 50% longer ODT elimination half-life compared to younger subjects, with corresponding increases in steady-state exposure. Dose reduction is required. Renal impairment, common in elderly populations, further prolongs elimination.

Monoamine oxidase inhibitors combined with O-desmethyltramadol's serotonin reuptake inhibitory component create risk of fatal serotonin syndrome. A fatal case involving moclobemide, clomipramine, and tramadol has been documented. This contraindication applies to all MAOIs including moclobemide, phenelzine, tranylcypromine, selegiline, and the antibiotic linezolid.

Administration during acute intoxication with alcohol, benzodiazepines, other opioids, GHB/GBL, or sedative-hypnotics is absolutely contraindicated. The Swedish Krypton fatalities demonstrate lethality of combining ODT with even moderate co-intoxicants (mitragynine). Alcohol is the most commonly co-detected substance in tramadol/opioid overdose fatalities.

Standard µ-opioid agonist contraindication. ODT suppresses gastrointestinal transit via µOR activation in gut (demonstrated in mice). Pre-existing paralytic ileus or mechanical bowel obstruction is an absolute contraindication.