From the Guidelines
Kayexalate (sodium polystyrene sulfonate) is expected to lower serum potassium by approximately 0.5-1.0 mEq/L per dose, with each 15-gram dose removing about 0.5-1.0 mEq/L of potassium, as supported by its mechanism of action and clinical use 1. The medication works through a cation exchange mechanism in the intestines, where it releases sodium ions and binds potassium, which is then eliminated in the stool.
- The potassium-lowering effect begins within several hours after administration, which is why Kayexalate is not suitable for emergency management of severe hyperkalemia.
- Multiple factors affect its efficacy, including gastrointestinal transit time, the patient's overall potassium load, and renal function.
- Side effects can include constipation, so it's often administered with sorbitol to prevent this complication, although the use of sorbitol is also associated with its own risks, as seen in the provided evidence 1. For patients requiring more rapid potassium reduction, other interventions such as insulin with glucose, beta-agonists, or dialysis should be considered instead of or alongside Kayexalate, given the potential for serious adverse events associated with Kayexalate, including intestinal ischemia and colonic necrosis 1.
From the FDA Drug Label
The practical exchange ratio is 1 mEq K per 1 gram of resin. In pediatric patients, as in adults, sodium polystyrene sulfonate is expected to bind potassium at the practical exchange ratio of 1 mEq potassium per 1 gram of resin. The amount of potassium that sodium polystyrene sulfonate (also known as kayexalate) can drop is approximately 1 mEq of potassium per 1 gram of resin 2, 2, 2.
- Key points:
- The practical exchange ratio is the amount of potassium that is bound by the resin.
- This ratio is 1 mEq of potassium per 1 gram of resin.
- This means that for every gram of sodium polystyrene sulfonate administered, approximately 1 mEq of potassium is bound and removed from the body.
From the Research
Kayexalate (Sodium Polystyrene Sulfonate) and Potassium Reduction
- Kayexalate, also known as sodium polystyrene sulfonate (SPS), is a cation exchange resin used to treat hyperkalemia by exchanging sodium for potassium in the colon.
- The amount of potassium reduction achieved by kayexalate can vary depending on the dose and individual patient characteristics.
Dose-Response Relationship
- A study published in 2016 found that serum potassium levels were reduced by 0.39,0.69,0.91, and 0.22 mEq/L following 15-, 30-, and 60-g oral doses and a 30-g rectal dose of SPS, respectively 3.
- Another study from 2011 reported a mean decrease in potassium concentration of 0.82 ± 0.48 mmol/L in the 15 gm group, 0.95 ± 0.47 in the 30 gm group, 1.11 ± 0.58 in the 45 gm group, and 1.40 ± 0.42 in the 60 gm group 4.
- A 2016 study found that the mean change in serum potassium from baseline to first repeat level following administration of SPS was -1.1 mEq/L 5.
Average Potassium Reduction
- A retrospective study published in 2016 reported an average decrease in serum potassium of 0.93 mEq/L after SPS administration 6.
- Another study from 2011 found that after a single dose of SPS, the mean potassium concentration was within normal range in 94% of patients 4.