Sodium zirconium cyclosilicate ( ZS-9 ), sold under the brand name Lokelma, is a medication used to treat high blood potassium . The onset of effect occurs in one to six hours.  It is taken by mouth.
Common side effects include bloating and low blood potassium .  Use in pregnancy and breast-feeding is likely to be safe. It works by binding to potassium ions in the gastrointestinal tract which are then lost in the stool.
Sodium zirconium cyclosilicate was approved for medical use in the European Union and the United States in 2018. It was developed by AstraZeneca .
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Sodium zirconium cyclosilicate is used to treat high blood potassium .  The onset of effect occurs in one to six hours. 
One review found a reduction in potassium by 0.17 mEq/L at one hour and 0.67 mEq/L at 48 hours. 
It appears to be effective in people with chronic kidney disease, diabetes, and heart failure.  Use has been studied for up to one year.
Arrangement of action
ZS-9 is a zirconium silicate. Zirconium silicates have been widely used in medical and dental applications due to their proven safety.  11 zirconium silicates were tested by an iterative optimization process. ZS-9 selectively captures potassium ions, possibly by mimicking the functions of physiological potassium channels.  ZS-9 is an inorganic cation exchanger crystalline with a high ability to trap monovalent cations, particularly potassium and ammonium ions, in the GI tract. ZS-9 is not absorbed systemically; Accordingly, the risk of systemic toxicity can be minimized.
Hyperkalemia is rare in people who are otherwise healthy.  Among those who are in hospital, the rate is between 1% and 2.5%.  Common causes include renal failure, hypoaldosteronism, and rhabdomyolysis.  Several drugs can also cause high blood potassium, including spironolactone, NSAIDs, and angiotensin converting enzyme inhibitors. 
There is no universally accepted definition of what level of hyperkalemia is mild, moderate, or severe.  However, if hyperkalemia causes any ECG changes, it is considered a medical emergency  because of the risk of potentially fatal abnormal heart rhythms and is treated promptly.  Potassium levels greater than 6.5 to 7.0 mmol/L are aggressively managed in the absence of ECG changes.  Several methods are used to treat hyperkalemia.  Other approved potassium binders in the United States include patiromer and sodium polystyrene sulfonate. 
Hyperkalemia, especially when severe, is a marker for increased risk of death.  However, there is disagreement about whether moderately high levels directly cause problems. One view is that mild to moderate hyperkalemia is a secondary effect reflecting underlying medical problems.  Accordingly, these problems are both the near and final cause of death, 
In the United States, regulatory approval of ZS-9 was denied in May 2016 by the Food and Drug Administration (FDA) due to manufacturing issues.  On May 18, 2018, the FDA approved sodium zirconium cyclosilicate for the treatment of adults with hyperkalemia. 
It was first practically synthesized by UOP in the late 1990s. (References—Zirconium Silicate and Zirconium Germinate Molecular Sieve and Process Using the Same, US Patent 5,891,472) Recognition of unique ion exchange properties and potential use to remove toxins from the body were quickly identified (“Toxicants Removal process” from bodily fluids using zirconium or titanium microporous compositions, US Patent 6,332,985).