First-generation antipsychotic, diphenylbutylpiperidine derivative×Class Ia antiarrhythmic (sodium channel blocker with intermediate kinetics)
Mechanism
Quinidine is a strong CYP2D6 inhibitor (secondary pimozide pathway) and itself a QT prolonger. Double torsades risk. FDA Orap Section 4.
Symptoms
QT prolongation by day 3, syncope, torsades de pointes.
Management
Combination contraindicated. If antiarrhythmic is needed in a pimozide patient, discuss catheter ablation or rate control with a beta-blocker without QT effect.
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.