Major
Carbamazepine × tacrolimus
Antiepileptics. Carboxamide derivatives×Calcineurin inhibitor (immunosuppressant)
Mechanism
Carbamazepine strongly induces CYP3A4 and P-glycoprotein. Tacrolimus plasma levels fall 2- to 3-fold; immunosuppression is lost, raising rejection risk.
Symptoms
Rejection symptoms depend on the organ: fever, graft tenderness, rising creatinine (kidney); jaundice and rising liver enzymes (liver). Symptoms appear 1–3 weeks after starting carbamazepine.
Management
Avoid the combination. Alternative anticonvulsants without induction: levetiracetam, lamotrigine, gabapentin. If carbamazepine is unavoidable, raise tacrolimus 2- to 3-fold with trough (C0) twice weekly.
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.