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Trileptal (Oxcarbazepine) - Drug Interactions, Contraindications, Overdosage, etc



Oxcarbazepine can inhibit CYP2C19 and induce CYP3A4/5 with potentially important effects on plasma concentrations of other drugs. The inhibition of CYP2C19 by oxcarbazepine and MHD can cause increased plasma concentrations of drugs that are substrates of CYP2C19. Oxcarbazepine and MHD induce a subgroup of the cytochrome P450 3A family (CYP3A4 and CYP3A5) responsible for the metabolism of dihydropyridine calcium antagonists, oral contraceptives and cyclosporine resulting in a lower plasma concentration of these drugs. [see Clinical Pharmacology]

In addition, several AEDs that are cytochrome P450 inducers can decrease plasma concentrations of oxcarbazepine and MHD. No autoinduction has been observed with Trileptal. 

Antiepileptic Drugs

Potential interactions between Trileptal and other AEDs were assessed in clinical studies. The effect of these interactions on mean AUCs and Cmin are summarized in Table 7.

Table 7  Summary of AED Interactions with Trileptal
Dose of AED
Trileptal Dose
Influence of
Trileptal on AED

(Mean Change,

90% Confidence

Influence of


(Mean Change,

90% Confidence

Carbamazepine 400-2000 900 nc1 40% decrease
[CI: 17% decrease,
57% decrease]
Phenobarbital 100-150 600-1800 14% increase
[CI: 2% increase,
24% increase]
25% decrease
[CI: 12% decrease,
51% decrease]
Phenytoin 250-500 600-1800
up to 40%
[CI: 12% increase,
60% increase]
30% decrease
[CI: 3% decrease,
48% decrease]
Valproic acid 400-2800 600-1800 nc1 18% decrease
[CI: 13% decrease,
40% decrease]

1 nc denotes a mean change of less than 10%

2 Pediatrics

3 Mean increase in adults at high Trileptal doses

In vivo, the plasma levels of phenytoin increased by up to 40% when Trileptal was given at doses above 1200 mg/day. Therefore, when using doses of Trileptal greater than 1200 mg/day during adjunctive therapy, a decrease in the dose of phenytoin may be required. The increase of phenobarbital level, however, is small (15%) when given with Trileptal.

Strong inducers of cytochrome P450 enzymes (i.e., carbamazepine, phenytoin and phenobarbital) have been shown to decrease the plasma levels of MHD (29%-40%).

No autoinduction has been observed with Trileptal.

Hormonal Contraceptives

Coadministration of Trileptal with an oral contraceptive has been shown to influence the plasma concentrations of the two hormonal components, ethinylestradiol (EE) and levonorgestrel (LNG). The mean AUC values of EE were decreased by 48% [90% CI: 22-65] in one study and 52% [90% CI: 38-52] in another study. The mean AUC values of LNG were decreased by 32% [90% CI: 20-45] in one study and 52% [90% CI: 42-52] in another study. Therefore, concurrent use of Trileptal with hormonal contraceptives may render these contraceptives less effective. Studies with other oral or implant contraceptives have not been conducted.

Calcium Antagonists

After repeated coadministration of Trileptal, the AUC of felodipine was lowered by 28% [90% CI: 20-33]. Verapamil produced a decrease of 20% [90% CI: 18-27] of the plasma levels of MHD.

Other Drug Interactions

Cimetidine, erythromycin and dextropropoxyphene had no effect on the pharmacokinetics of MHD. Results with warfarin show no evidence of interaction with either single or repeated doses of Trileptal.

Drug/Laboratory Test Interactions

There are no known interactions of Trileptal with commonly used laboratory tests.


Human Overdose Experience

Isolated cases of overdose with Trileptal have been reported. The maximum dose taken was approximately 24,000 mg. All patients recovered with symptomatic treatment.

Treatment and Management

There is no specific antidote. Symptomatic and supportive treatment should be administered as appropriate. Removal of the drug by gastric lavage and/or inactivation by administering activated charcoal should be considered.


Trileptal should not be used in patients with a known hypersensitivity to oxcarbazepine or to any of its components.



The abuse potential of Trileptal has not been evaluated in human studies.


Intragastric injections of oxcarbazepine to four cynomolgus monkeys demonstrated no signs of physical dependence as measured by the desire to self-administer oxcarbazepine by lever pressing activity.

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