Primidone, phenytoin, barbiturates, carbamazepine, oxcarbazepine, topiramate, felbamate; rifampicin; PIs, NNRTIs; griseofulvin, azole antifungals eg, itraconazole, voriconazole, fluconazole, ketoconazole; macrolide antibiotics eg, clarithromycin, erythromycin; Ca channel blockers eg, verapamil, diltiazem; etoricoxib; St. John's wort; grapefruit juice. Influenced effects of cyclosporine, lamotrigine, melatonin, midazolam, theophylline, tizanidine. Drugs known to increase K levels.