Table 2.
Drugs which have been found to increase the serum concentration of antiepileptic drugs, presumably by inhibiting their metabolism
| Affected drug | Interfering drug | |
|---|---|---|
| Carbamazepine | Antiepileptic drugs: | Felbamate1, valproic acid1, valpromide1 |
| Antidepressants: | Fluoxetine, fluvoxamine, nefazodone, trazodone, viloxazine | |
| Antimicrobials: | Clarithromycin, erythromycin, fluconazole, isoniazid, ketoconazole, metronidazole, ritonavir, troleandomycin | |
| Miscellaneous: | Cimetidine, danazol, dextropropoxyphene, diltiazem, risperidone, quetiapine1, ticlopidine, verapamil | |
| Ethosuximide | Antimicrobials: | Isoniazid |
| Lamotrigine | Antiepileptic drugs: | Valproic acid |
| Antidepressants: | Sertraline | |
| Phenobarbital | Antiepileptic drugs: | Felbamate, phenytoin, sulthiame, valproic acid |
| Antimicrobials: | Chloramphenicol | |
| Miscellaneous: | Dextropropoxyphene | |
| Phenytoin | Antiepileptic drugs: | Felbamate, oxcarbazepine, sulthiame, valproic acid2 |
| Antidepressants: | Fluoxetine, fluvoxamine, imipramine, sertraline, trazodone, viloxazine | |
| Antimicrobials: | Chloramphenicol, fluconazole, isoniazid, miconazole, sulfaphenazole | |
| Antineoplastic drugs: | Doxifluridine, fluorouracil, tamoxifen, tegafur, UFT | |
| Miscellaneous: | Allopurinol, amiodarone, azapropazone, cimetidine, chlorpheniramine, dextropropoxyphene, diltiazem, disulfiram omeprazole, phenylbutazone, sulfinpyrazone tacrolimus, ticlopidine, tolbutamide | |
| Valproic acid | Antiepileptic drugs: | Felbamate |
| Antidepressants: | Sertraline | |
| Antimicrobials: | Isoniazid | |
| Miscellaneous: | Cimetidine |
The list should not be regarded as exhaustive. For further information and a list of references, see Patsalos and Perucca [1, 2].
1
These drugs increase the concentration of the active metabolite carbamazepine-10,11-epoxide, the effect being most clinically relevant with valpromide. The concentration of carbamazepine is not affected by valproic acid and valpromide, ands it is decreased by felbamate.
2
Interaction inconsistent and limited to an increase in unbound phenytoin concentration. Total serum phenytoin concentration usually decreases due to displacement from plasma protein binding sites.