Dilantin Infatabs and Quetiapine

In the database of official manuals used in the service creation an interaction registered by statistical results of studies was found, which can either lead to negative consequences for the patient health or strengthen a mutual positive effect. A doctor should be consulted to address the issue of joint drug administration.

Phenytoin may significantly reduce the blood levels of QUEtiapine, which may make the medication less effective in treating your condition. Talk to your doctor if you have any questions or concerns. Your doctor may already be aware of the interaction, but has determined that this is the best course of treatment for you and has taken appropriate precautions or made dose adjustments and is monitoring you closely for any potential complications. Your doctor may also be able to prescribe alternatives that do not interact. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

ADJUST DOSE: Coadministration with potent inducers of CYP450 3A4 may significantly decrease the plasma concentrations of quetiapine, which is primarily metabolized by the isoenzyme. In 18 psychiatric patients receiving quetiapine 300 mg twice daily, addition of the potent CYP450 3A4 inducer carbamazepine (200 mg three times daily) decreased mean quetiapine peak plasma concentration (Cmax) and systemic exposure (AUC) by 80% and 87%, respectively, and increased oral clearance (Cl/F) by 7.5-fold compared to quetiapine administered alone. The interaction has also been reported with phenytoin, another potent CYP450 3A4 inducer. In ten subjects with various affective disorders, coadministration of quetiapine (250 mg orally three times a day) with phenytoin (100 mg orally three times a day) decreased the mean steady-state Cmax, trough plasma concentration (Cmin) and AUC of quetiapine by 66%, 89% and 80%, respectively. The mean oral clearance increased by 5.5-fold.

MANAGEMENT: Increased dosages of quetiapine may be required during chronic treatment (greater than 7 to 14 days) with potent CYP450 3A4 inducers. The manufacturer recommends an increase of up to 5-fold the original dosage of quetiapine. Further adjustments should be made based on clinical response and tolerance. The safety of dosages above 800 mg/day has not been established in clinical trials. Continued treatment at higher dosages should only be considered following careful consideration of risks and benefits. When the CYP450 3A4 inducer is discontinued, the dosage of quetiapine should be reduced to the original level within 7 to 14 days.

Dilantin Infatabs

Generic Name: phenytoin

Brand name: Dilantin, Phenytek, Dilantin Infatabs, Phenytoin Sodium, Prompt

Synonyms: Dilantin

What is Dilantin Infatabs?

Quetiapine

Generic Name: quetiapine

Brand name: Seroquel, Seroquel XR

Synonyms: QUEtiapine

What is Quetiapine?