Dilantin ER (phenytoin extended-release) interacts with numerous medications. Always inform your doctor about all medications, supplements, and herbal remedies you take. This includes over-the-counter drugs.
Significant interactions include: Disulfiram (Antabuse) can increase phenytoin levels, leading to toxicity. Concurrent use with anticoagulants like warfarin increases bleeding risk. Theophylline levels decrease when taken with Dilantin ER. Some antibiotics (such as isoniazid) and antifungals (such as ketoconazole) can significantly raise phenytoin levels, potentially causing adverse effects. Oral contraceptives may lose effectiveness with Dilantin ER use.
Other notable interactions: Dilantin ER can alter the metabolism of many drugs, affecting their efficacy. This includes certain antidepressants, antipsychotics, and calcium channel blockers. Grapefruit juice inhibits the metabolism of Dilantin ER, raising blood levels and increasing the risk of side effects.
Recommendations: Regular blood tests monitor phenytoin levels are necessary, especially when starting or changing medications. Your doctor might adjust Dilantin ER dosage based on these results. Do not start or stop any medication without consulting your doctor or pharmacist first. Always report any new symptoms while on Dilantin ER.
