Chelating Agent ZS-9 Approved for Hyperkalemia | Medscape

The US FDA has approved the cation chelator sodium zirconium cyclosilicate (ZS-9, Lokelma®) for the treatment of hyperkalemia.

Sodium Zirconium Cyclosilicate

  • Oral potassium cation-exchange agent, not systemically absorbed
  • Onset of action 1 hour, median 2.2 hours until normokalemic
  • Not approved for life-threatening potassium elevations at this time
  • Daily dosing for 1 year twice as likely as placebo to maintain normokalemia
  • Most common adverse effects: GI distress, hypokalemia, UTI, edema
  • Adverse effects less frequent than patiromer (alternative chelating agent for hyperkalemia)


  • 2 Phase II, 4 Phase III clinical trials, 1393 patients
  • All randomized placebo-controlled, some industry-funded
  • 5-15 mg dose for moderate-severe hyperkalemia
  • Approved for hyperkalemia in March 2018 in EU


What is hyperkalemia?

Hyperkalemia is a potentially dangerous elevation of potassium in the blood.  It is commonly observed in chronic kidney disease and heart failure patients, as well as individuals taking RAAS-modulators (ACE inhibitors, ARBs, aldosterone antagonists).  Untreated hyperkalemia can cause fatal arrythmias.


What is a potassium chelator drug?

Potassium chelators like sodium zirconium cyclosilicate or patiromer are compounds that selectively bind to potassium ions, rendering them unavailable for use by the body.  These medications scavenge dietary potassium in the gastrointestinal tract, decreasing absorption and lowering serum potassium.


Source: FDA Approves Lokelma for Hyperkalemia