FDA Calls For Separate Dosing For Kayexalate Due To Interactions With Other Drugs

Federal drug regulators warn that individuals should not take the potassium-lowering drug Kayexalate at the same time as other oral medications, as the interactions may decrease the effectiveness of the medications, potentially causing serious side effects. 

In a safety alert issued on September 6, the FDA recommends that patients not to take Kayexalate, known by the generic name sodium polystyrene sulfonate, within three hours of taking other oral medications.

The FDA alert indicates Kayexalate may decrease the absorption of other oral medications, as well as reduce the effectiveness of those medications.

In 2015, the FDA ordered the drug manufacturer Concordia Pharmaceuticals to conduct clinical Kayexalate studies to determine whether the medication impacts the effectiveness of other medications.

Other research released at the time indicated similar potassium-lowering drugs, such as Veltassa, affected medication efficacy in about half of prescription drugs it was tested. Drugs affected included prescription blood pressure medications and blood thinners, as well as over-the-counter (OTC) drugs.

One of the new studies conducted did, in fact, indicate Kayexalate binds to many commonly prescribed oral medications, thus decreasing the absorption and effectiveness of those medicines.

To minimize the chance of reducing the effectiveness of other oral medications, the FDA recommends separating the dose of Kayexalate from the dose of any other oral medications by at least three hours. If a person has gastroparesis or other conditions causing delayed emptying of food from the stomach or small intestine, that delay should be increased to a minimum of six hours.

Sodium polystyrene sulfonate, sold under brand names such as Kayexalate and various generic formulas, is used to treat hyperkalemia, a serious condition that occurs when potassium levels in the blood are too high.

Kayexalate counteracts this by binding with the potassium in the intestines and allowing it to be removed from the body. Kayexalate is often taken from one to four times per day, to allow the potassium to bind and drain from the large intestine.

Potassium is a mineral which aids in the transmission of nerve signals, muscle contractions, fluid balance and other chemical reactions within the body. Too much, as in the case with hyperkalemia, can cause problems with heart rhythm, or in rare cases may cause death.

The FDA indicates that drug labels will be updated to include information about separating the doses of oral medications from Kayexalate.