Drug Interaction Report

Using palbociclib together with phenytoin is not recommended. Combining these medications may significantly reduce the blood levels of palbociclib, which may make the medication less effective in treating your cancer. Talk to your doctor if you have any questions or concerns. Your doctor may be able to prescribe alternatives that do not interact. 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.

Palbociclib oral capsules (Ibrance) should be taken with food to help with its absorption. Palbociclib oral tablets (Ibrance) may be taken with or without food. Do not consume grapefruit or grapefruit juice during treatment with palbociclib. Grapefruit and grapefruit juice can interact with palbociclib and increase the levels of palbociclib in your body. You may be more likely to experience side effects such as nausea; vomiting; diarrhea; loss of appetite; mouth sores; hair loss; weakness; pain, numbness, or tingling in the hands and feet; and impaired bone marrow function resulting in low numbers of different types of blood cells, which can increase the risk of anemia, bleeding problems, and infections. 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.