MajorSynthetic opioid, full mu-receptor agonist×Fourth-generation fluoroquinolone
Updated · Methodology
Mechanism
Methadone prolongs QT (especially above 80 mg/day). Moxifloxacin adds 10-20 ms. Torsades de pointes risk.
Symptoms
QTc above 500 ms, syncope, torsades de pointes risk.
Management
Alternative – levofloxacin or other class.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- FDA: Methadone hydrochloride tablets (SpecGx) – Prescribing Information (2014)
- AEMPS: Ficha técnica: Metadona (nº registro 62423), sección 4.5 (2026)– AEMPS, CIMA, nº registro 62423, sección 4.5