Drug General Information (ID: DDII7MPRCZ)
  Drug Name Phenytoin Drug Info Eslicarbazepine Drug Info
  Drug Type Small molecule Small molecule
  Therapeutic Class Anticonvulsants Anticonvulsants
  Structure

 Mechanism of Phenytoin-Eslicarbazepine Interaction (Severity Level: Moderate)
     CYP450 enzyme inhibition Click to Show/Hide Mechanism Graph
Could Not Find 2D Structure
      Drug Name Phenytoin Eslicarbazepine
      Mechanism 1 CYP450 2C19 substrate CYP450 2C19 inhibitor
      Key Mechanism Factor 1
Factor Name Cytochrome P450 2C19
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Structure Sequence
MDPFVVLVLCLSCLLLLSIWRQSSGRGKLPPGPTPLPVIGNILQIDIKDVSKSLTNLSKIYGPVFTLYFGLERMVVLHGYEVVKEALIDLGEEFSGRGHFPLAERANRGFGIVFSNGKRWKEIRRFSLMTLRNFGMGKRSIEDRVQEEARCLVEELRKTKASPCDPTFILGCAPCNVICSIIFQKRFDYKDQQFLNLMEKLNENIRIVSTPWIQICNNFPTIIDYFPGTHNKLLKNLAFMESDILEKVKEHQESMDINNPRDFIDCFLIKMEKEKQNQQSEFTIENLVITAADLLGAGTETTSTTLRYALLLLLKHPEVTAKVQEEIERVIGRNRSPCMQDRGHMPYTDAVVHEVQRYIDLIPTSLPHAVTCDVKFRNYLIPKGTTILTSLTSVLHDNKEFPNPEMFDPRHFLDEGGNFKKSNYFMPFSAGKRICVGEGLARMELFLFLTFILQNFNLKSLIDPKDLDTTPVVNGFASVPPFYQLCFIPV
Gene Name CYP2C19
Uniprot ID CP2CJ_HUMAN
KEGG Pathway hsa:1557
Protein Family Cytochrome P450 family
Protein Function
A cytochrome P450 monooxygenase involved in the metabolism of polyunsaturated fatty acids (PUFA) (PubMed:18577768, PubMed:19965576, PubMed:20972997). Mechanistically, uses molecular oxygen inserting one oxygen atom into a substrate, and reducing the second into a water molecule, with two electrons provided by NADPH via cytochrome P450 reductase (NADPH--hemoprotein reductase) (PubMed:18577768, PubMed:19965576, PubMed:20972997). Catalyzes the hydroxylation of carbon-hydrogen bonds. Hydroxylates PUFA specifically at the omega-1 position (PubMed:18577768). Catalyzes the epoxidation of double bonds of PUFA (PubMed:20972997, PubMed:19965576). Also metabolizes plant monoterpenes such as limonene. Oxygenates (R)- and (S)-limonene to produce carveol and perillyl alcohol (PubMed:11950794). Responsible for the metabolism of a number of therapeutic agents such as the anticonvulsant drug S-mephenytoin, omeprazole, proguanil, certain barbiturates, diazepam, propranolol, citalopram and imipramine. Hydroxylates fenbendazole at the 4' position (PubMed:23959307).
    Click to Show/Hide
      Mechanism Description
  • Decreased metabolism of Phenytoin caused by Eslicarbazepine mediated inhibition of CYP450 enzyme
     UGT induction Click to Show/Hide Mechanism Graph
Could Not Find 2D Structure
      Drug Name Phenytoin Eslicarbazepine
      Mechanism 2 UGT inducer UGT substrate
      Key Mechanism Factor 2
Factor Name UDP-glucuronosyltransferase Structure Sequence
Protein Family UDP-glycosyltransferase family
Protein Function
[Isoform 1]: UDP-glucuronosyltransferase (UGT) that catalyzes phase II biotransformation reactions in which lipophilic substrates are conjugated with glucuronic acid to increase the metabolite's water solubility, thereby facilitating excretion into either the urine or bile (PubMed:12181437, PubMed:15472229, PubMed:18004206, PubMed:18004212, PubMed:18719240, PubMed:19830808, PubMed:23288867). Essential for the elimination and detoxification of drugs, xenobiotics and endogenous compounds (PubMed:12181437, PubMed:18004206, PubMed:18004212). Catalyzes the glucuronidation of endogenous estrogen hormones such as estradiol, estrone and estriol (PubMed:15472229, PubMed:18719240, PubMed:23288867). Involved in the glucuronidation of bilirubin, a degradation product occurring in the normal catabolic pathway that breaks down heme in vertebrates (PubMed:17187418, PubMed:18004206, PubMed:19830808). Also catalyzes the glucuronidation the isoflavones genistein, daidzein, glycitein, formononetin, biochanin A and prunetin, which are phytoestrogens with anticancer and cardiovascular properties (PubMed:18052087, PubMed:19545173). Involved in the glucuronidation of the AGTR1 angiotensin receptor antagonist losartan, a drug which can inhibit the effect of angiotensin II (PubMed:18674515). Involved in the biotransformation of 7-ethyl-10-hydroxycamptothecin (SN-38), the pharmacologically active metabolite of the anticancer drug irinotecan (PubMed:12181437, PubMed:18004212, PubMed:20610558).
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      Mechanism Description
  • Increased metabolism of Eslicarbazepine caused by Phenytoin mediated induction of UGT

Recommended Action
      Management Close observation for clinical and laboratory evidence of altered effects is recommended during concomitant use of eslicarbazepine acetate and phenytoin, particularly when one drug is started or discontinued. Patients should be advised to contact their physician if they experience loss of seizure control or signs and symptoms of phenytoin toxicity such as nausea, vomiting, tremors, ataxia, lethargy, slurred speech, visual disturbances, or changes in mental status. A dosage increase for eslicarbazepine acetate and/or dosage reduction for phenytoin may be required based on efficacy and tolerability.

References
1 Bialer M, Soares-da-Silva P "Pharmacokinetics and drug interactions of eslicarbazepine acetate." Epilepsia 53 (2012): 935-46. [PMID: 22612290]
2 Cerner Multum, Inc. "UK Summary of Product Characteristics.".
3 Product Information. Aptiom (eslicarbazepine). Sunovion Pharmaceuticals Inc, Marlborough, MA.