Major
Established
Descrição
Diltiazem is a potent CYP3A4 inhibitor that significantly increases quetiapine plasma concentrations, raising risk of quetiapine toxicity and QT prolongation.
Mecanismo
Diltiazem inhibits CYP3A4, the primary enzyme responsible for quetiapine metabolism, substantially increasing quetiapine AUC; both drugs also have modest QT-prolonging effects.
Significância Clínica
Quetiapine levels may increase 2- to 5-fold; sedation, metabolic adverse effects, and QTc prolongation are clinical risks.
Conduta
Reduce quetiapine dose substantially when adding diltiazem; monitor for excessive sedation, metabolic effects, and ECG changes.