Quetiapine

Quetiapine substantially potentiates oxycodone-induced CNS and respiratory depression, and both drugs prolong the QT interval.

Co-administration of alprazolam and quetiapine produces additive CNS depression with risk of profound sedation and respiratory compromise.

Diazepam and quetiapine together significantly increase CNS depression and carry risk of severe sedation and cardiorespiratory compromise.

Fluconazole substantially increases quetiapine plasma concentrations via CYP3A4 inhibition, raising the risk of quetiapine-mediated QT prolongation and torsades de pointes.

Azithromycin and quetiapine both prolong the QT interval via hERG blockade; concurrent use significantly increases the risk of life-threatening arrhythmias.

Escitalopram and quetiapine both prolong the QT interval; concurrent use carries a substantial risk of torsades de pointes and sudden cardiac death.

Ciprofloxacin and quetiapine both prolong the QT interval and ciprofloxacin also increases quetiapine exposure via CYP3A4 inhibition.

Carbamazepine dramatically reduces quetiapine plasma concentrations, potentially rendering antipsychotic treatment ineffective.

Phenytoin drastically reduces quetiapine plasma levels through potent CYP3A4 induction, risking complete loss of antipsychotic effect.

Diltiazem is a potent CYP3A4 inhibitor that significantly increases quetiapine plasma concentrations, raising risk of quetiapine toxicity and QT prolongation.

Quetiapine, a D2 receptor antagonist, pharmacodynamically opposes levodopa's dopaminergic effect, worsening Parkinson's disease motor symptoms.

Quetiapine combined with morphine significantly increases CNS and respiratory depression, creating a high-risk combination for overdose.