The Food and Drug Administration (FDA) is asking Concordia Pharmaceuticals, the maker of Kayexalate (sodium polystyrene sulfonate) to conduct studies on the medication’s potential to interact with other drugs that could affect its effectiveness.
Keyexalate, which is also known generically as Kionex and SPS, is used to treat hyperkalemia, a potentially life threatening condition in which there are abnormally high levels of potassium in the blood.
The drug’s label describes its potential to decrease absorption of lithium and thyroxine, however there have been no extensive drug-drug interaction studies performed with Kayexalate, the FDA said in a Safety Communication.
The agency issued the notice a day after approving another potassium-lowering medication, Veltassa, Relypsa (patiromer). During the review of Veltassa, the FDA noted that the drug bound to about half of the medications tested, “some of which are commonly used in patients who require potassium-lowering drugs,” the agency said. “Such binding could decrease the effects of these medications.”
Veltassa was approved with a warning not to take other orally administered medications within six hours of taking Veltassa.
“To reduce this potential risk, prescribers and patients should consider separating Kayexalate dosing from other medications taken by mouth by at least 6 hours. This includes both prescription medications, such as antibiotics, blood pressure lowering agents and blood thinners, and those purchased over-the-counter without a prescription, such as antacids and laxatives. Health care professionals should monitor blood levels or clinical response to the other medications when appropriate,” the agency advised.
If the studies conducted by Concordia Pharmaceuticals reveal any significant interactions between Kayexalate and other medications, all manufacturers of sodium polystyrene sulfate drugs will be required to update their drugs’ safety labels to reflect these drug interactions.