Ketipinor Drug Interactions

Given the primary central nervous system effects of quetiapine, Ketipinor should be used with caution in combination with other centrally acting drugs and alcohol.
Cytochrome P450 (CYP) 3A4 is the enzyme that is primarily responsible for the cytochrome P450 mediated metabolism of quetiapine. Concomitant administration of quetiapine (dosage of 25 mg) with ketoconazole, a CYP3A4 inhibitor, has been reported to cause a 5- to 8-fold increase in the AUC of quetiapine. On the basis of this, concomitant use of quetiapine with CYP3A4 inhibitors is contraindicated. It is also not recommended to take quetiapine together with grapefruit juice. As a consequence of this interaction, lower plasma concentrations can occur, which could affect the efficacy of quetiapine therapy.
Co-administration of quetiapine with phenytoin (another microsomal enzyme inducer) can cause a greatly increased clearance of quetiapine by approx. 450%.
In patients receiving a hepatic enzyme inducer, initiation of Ketipinor treatment should only occur if the physician considers that the benefits of quetiapine outweigh the risks of removing the hepatic enzyme inducer. It is important that any change in the inducer is gradual, and if required, replaced with a non-inducer (e.g. sodium valproate) (see also Precautions).
The pharmacokinetics of quetiapine were not significantly altered by co-administration of the antidepressants imipramine (a known CYP2D6 inhibitor) or fluoxetine (a known CYP3A4 and CYP2D6 inhibitor).
The pharmacokinetics of quetiapine were not significantly altered by co-administration of the antipsychotics risperidone or haloperidol. Concomitant use of quetiapine and thioridazine caused an increased clearance of quetiapine with approx. 70%.
The pharmacokinetics of quetiapine were not altered when co-administered with cimetidine.
The pharmacokinetics of lithium were not altered when co-administered with quetiapine.
The pharmacokinetics of sodium valproate and quetiapine were not altered to a clinically relevant extent during concomitant administration.
Formal interaction studies with commonly used cardiovascular drugs have not been performed.
As with other antipsychotics, caution should be exercised when quetiapine is prescribed with medicines known to increase the QTc interval (see also Precautions).
Caution should be exercised when quetiapine is prescribed with drugs causing electrolyte imbalance.