FDA requires Concordia Pharmaceuticals to conduct postmarketing studies

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 - clinical trial

The FDA announced on Oct. 22 that it would require Concordia Pharmaceuticals, the manufacturer of sodium polystyrene sulfonate (Kayexalate), to conduct studies to investigate the drug’s potential to bind to other oral medications.

Sodium polystyrene sulfonate is used to treat patients with hyperkalemia, which occurs when there is too much potassium in the blood. Patients with hyperkalemia may have heart rhythm issues that could be fatal in rare cases. Although the labeling for sodium polystyrene sulfonate mentions it can decrease absorption of lithium and thyroxine, there have been no extensive drug-drug interaction studies performed.

The FDA noted that another potassium-lowering medication, patiromer (Veltassa), binded to approximately half of the medications tested. The labeling for patiromer, which was FDA-approved on Oct. 21, includes a warning that patients should not take other oral drugs within six hours of taking patiromer.

Prescribers and patients should also consider separating the dose of sodium polystyrene sulfonate from other oral prescription and over-the-counter medications by at least six hours, according to the FDA.

If the studies confirm significant interactions between sodium polystyrene sulfonate and other medications, the FDA said it would require manufacturers of sodium polystyrene sulfonate to update their drug labels.