Drug Interaction Report

Phenytoin may significantly reduce the blood levels of ivabradine, which may make the medication less effective in treating your heart condition. Using phenytoin with ivabradine may also increase the risk of an irregular heart rhythm that may be serious and potentially life-threatening, although it is a relatively rare side effect. You should seek immediate medical attention if you experience sudden dizziness, lightheadedness, fainting, shortness of breath, or heart palpitations during treatment with these medications, whether together or alone. Talk to your doctor if you have any questions or concerns. Your doctor may be able to prescribe alternatives that do not interact, or you may need a dose adjustment or more frequent monitoring to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Do not consume grapefruit or grapefruit juice during treatment with ivabradine. Grapefruit juice can significantly increase the blood levels and effects of ivabradine, which may result in excessive slowing of heart rate or other conduction disturbances. Talk to your doctor if you have any questions or concerns. Let your doctor know if you experience significant decreases in heart rate or symptoms such as dizziness, fatigue, or low blood pressure. Also seek medical attention if you develop heart palpitations, chest pressure, or worsened shortness of breath, as these may be symptoms of atrial fibrillation caused by ivabradine. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Phenytoin levels may decrease when the suspension is given with enteral feedings. This could lead to a loss of seizure control. You could interrupt the feeding for 2 hours before and after the phenytoin dose. Alternatively, you may give the phenytoin suspension diluted in water and flush the tube with water after administration. These would make it easier for your body to absorb the medication. However, this still may not entirely avoid the interaction and may not always be feasible. You should have your phenytoin levels checked upon starting and stopping of enteral feedings. In addition, using phenytoin together with food may alter the effects of phenytoin. Contact your doctor if you experience worsening of seizure control or symptoms of toxicity, including twitching eye movements, slurred speech, loss of balance, tremor, muscle stiffness or weakness, nausea, vomiting, feeling light-headed, fainting, and slow or shallow breathing. If your doctor does prescribe these medications together, you may need a dose adjustment or special test to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Ask your doctor before making any changes to your therapy.