Note: Combinations containing any of the following medications, depending on the amount present, may also interact with this medication: Alcohol or;
Central nervous system (CNS) depression-producing medications, other (Quetiapine has been shown to potentiate the cognitive and motor effects of alcohol);
Antihypertensive agents (hypotensive effects of these medications may be enhanced);
Cimetidine (oral clearance of Quetiapine was decreased by 20% when coadministered with Cimetidine 400 mg three times a day).
Cytochrome P450 3A (CYP3A) isoenzyme inhibitors, such as: Diltiazem, Erythromycin, Fluconazole, Itraconazole, Ketoconazole, Nafazodone, Verapamil (although there is no experience with the combination of Quetiapine and a potent CYP3A enzyme inhibitor, caution is advised since Quetiapine's major route of metabolism involves CYP3A4), Dopamine agonists or Levodopa (effects of these medications may be antagonized by Quetiapine).
Enzyme inducers, hepatic, cytochrome P450 (mean oral clearance of Quetiapine was increased five-fold in patients receiving Phenytoin; Higher doses of Quetiapine may be required during concomitant therapy with an enzyme-inducing medication; A decrease in Quetiapine dosage may be required when enzyme-inducer therapy is discontinued);
Lorazepam (mean oral clearance of Lorazepam was decreased by 20% when coadministered with Quetiapine 250 mg three times a day);
Thioridazine (oral clearance of Quetiapine was increased by 65% when coadministered with Thioridazine 200 mg two times a day).
(>>= major clinical significance)