FDA approves Sodium Zirconium Cyclosilicate for Hyperkalemia

In May, 2018, FDA approved Sodium Zirconium Cyclosilicate (ZS-9) for treatment of hyperkalemia. This is available as Lokelma in USA, manufactured by AstraZeneca.
This is the third drug in the category of Gastrointestinal cation exchangers for treatment of hyperkalemia. Earlier two drugs are sodium polystyrene sulfonate(Kayexalate, approved in 1958) and patiromer(Approved in 2015).

Its efficacy in patients with markedly elevated potassium (>6.5) or in patients undergoing dialysis has not been studied, but they can be used as adjuvant after rapidly correcting with other agents.


Mechanism of Action

ZS-9 is a highly selective cation exchanger that entraps potassium in the intestinal tract in exchange for sodium and hydrogen.  In vitro, it traps about 10 times as much potassium as Kayexalate does. It is insoluble and remains in the intestine during transit.

Serum potassium levels within an hour and restoring normal levels after about 2 hours in most patients.



The four efficacy studies reviewed (ZS-002, ZS-003, ZS-004 and ZS-005) and showed  effectiveness in lowering serum potassium in patients with hyperkalemia.



Patients with serum potassium levels greater than 6.5 mmol per liter or electrocardiographic changes, hospitalized patients, and patients undergoing dialysis.



Most common side effect was edema and hypokalemia.



10 gm three times a day up to 48 hrs and then 5 gm daily but can increase up to 15 gm daily.



Kayexalate, which was developed in the mid-20th century, requires administration with water, most often with sorbitol added. The preparation, which is taken by mouth, has a noxious taste and may cause diarrhea. When administered as an enema, it is also unpleasant. On rare occasions, necrosis of the colon may occur with its administration(Black box warning by FDA).



Patiromer, was approved in 2015, is a dry powder, primarily a spherical bead that is not absorbed and that binds potassium when mixed in small amounts of water. However, it does so mainly in the colon; it does not appear to bind potassium in the small intestine. It exchanges potassium for calcium. The most common adverse events reported are constipation (in 11% of the patients), and hypokalemia ( in 3% of the patients).

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