Critical
Clarithromycin × Methadone
Macrolide antibiotic×Synthetic opioid, full mu-receptor agonist
Mechanism
Clarithromycin inhibits CYP3A4 (raises methadone) and itself prolongs QT. Dual torsades risk in OST patient.
Symptoms
QT above 500 ms, syncope.
Management
Combination contraindicated. Alternative – azithromycin.
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.