Drug Interaction Report

Using erdafitinib together with ferric citrate may alter the levels of phosphate in the blood, which may affect the dose of erdafitinib. Your doctor will check your blood phosphate level between 14 and 21 days after starting treatment with erdafitinib and then monthly, and may change your dose if necessary. Talk to your doctor if you have any questions or concerns. Contact your doctor as soon as possible if you develop signs and symptoms of high phosphate levels in the blood (hyperphosphatemia) such as muscle cramps, convulsions, tingling or numbness around the mouth, and bone pain. 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.

Food may reduce the absorption and blood levels of ferric citrate. In addition, some oral medications can also interfere with ferric citrate absorption into the bloodstream, which may make the medication less effective in treating your condition. Likewise, ferric citrate may interfere with the absorption of other orally administered medications. You should take ferric citrate on an empty stomach at least one hour before or two hours after a meal. 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. Talk to your doctor or pharmacist if you have questions about how to take this or other medications you are prescribed. 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.