Potassium-Lowering Drug Decreases Oral Prescription Effectiveness

On September 6, 2017, the FDA recommended that patients avoid taking the potassium-lowering drug sodium polystyrene sulfonate (Kayexalate) at the same time as other medicines taken by mouth. A study found that sodium polystyrene sulfonate binds to many commonly prescribed oral medicines, decreasing the absorption and, therefore, the effectiveness of those oral medicines.


To reduce this likelihood, the FDA recommended separating the dosing of sodium polystyrene sulfonate from other orally administered medicines by at least three hours. The FDA is updating the sodium polystyrene sulfonate drug labels to include information about this dosing separation.


Sodium polystyrene sulfonate is used to treat hyperkalemia, a serious condition in which the amount of potassium in the blood is too high. It works by binding with potassium in the intestines so it can be removed from the body. Potassium is a mineral that helps the body function properly. Too much potassium in the blood can cause problems with heart rhythm, which in rare cases can be fatal. Sodium polystyrene sulfonate is available as the brand name Kayexalate, as generic brands, and also as non-branded generics.


Patients should take orally administered prescription and over-the-counter (OTC) medicines at least three hours before or three hours after taking sodium polystyrene sulfonate. Patients should not stop taking their potassium-lowering medicines without talking to their health care professional first.


When prescribing sodium polystyrene sulfonate, health care professionals should advise patients to separate dosing from other orally administered medicines by at least three hours. That time should be increased to six hours for patients with gastroparesis, a condition that affects the stomach muscles and prevents proper stomach emptying, or other conditions resulting in delayed emptying of food from the stomach into the small intestine.


See the FDA Safety Alert


See also Medical Law Perspectives Report: Drugs, Dosage, and Damage: Physician Liability for Prescribing or Administering Medication