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