Major
Methadone × Rifampicin
Synthetic opioid, full mu-receptor agonist×Antituberculous antibiotic
Mechanism
Rifampicin induces CYP3A4 and CYP2B6. Methadone falls 70% – opioid withdrawal within 5-7 days.
Symptoms
Agitation, sweating, muscle pain, diarrhoea, mydriasis after 5-7 days.
Management
For TB in OST patient – increase methadone by 50-100% with clinical monitoring. After rifampicin withdrawal – downward titration.
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.