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WASHINGTON -- Patiromer for oral suspension (Veltassa) is now approved for treatment of hyperkalemia, the FDA announced.
The drug, a powder to be mixed with water, is a nonabsorbed polymer that binds potassium in exchange for calcium, predominantly in the distal colon where the concentration of free potassium is the highest.
In a study published in The New England Journal of Medicine, 76% patients treated with patiromer achieved the target potassium level of 3.8 to 5.0 mmol/L within 4 weeks. The most frequently reported adverse event was constipation.
"Too much potassium in the blood can lead to dangerous, even fatal, changes in heart rhythm," said Norman Stockbridge, MD, PhD, director of the Division of Cardiovascular and Renal Products in the FDA's Center for Drug Evaluation and Research, in a statement. "It is important to have treatment options for hyperkalemia available to patients."
The FDA noted that the drug will carry a boxed warning on its label because "it binds many other orally administered drugs, which could decrease their absorption and reduce their effects."
That warning recommends an interval of at least 6 hours between patiromer dosing and any other orally administered drug. Additionally, the "drug must be dispensed with a patient Medication Guide that describes important information about its uses and risks," the FDA said.
Because the studies suggested patiromer bound to about half of drugs tested, including many commonly used by patients who require potassium-lowering drugs, the FDA announced it would require drug-drug interaction studies for fellow potassium-lowering agent sodium polystyrene sulfonate (Kayexalate).
That drug currently carries a warning of interactions with lithium and thyroxine, but the FDA noted that extensive interaction studies were never done.
"If the studies conducted by the Kayexalate manufacturer, Concordia Pharmaceuticals, confirm significant interactions with other medications, FDA will require all manufacturers of sodium polystyrene sulfonate products to update the drug labels to include information about these drug interactions," the agency warned.
Veltassa is manufactured by Relypsa of Redwood City, Calif.