Let's make sure we know the differences
Going bananas over potassium
Potassium binders have given patients another treatment modality for maintenance of chronic hyperkalemia. Indicated to be given for patients with chronic kidney disease, the role of potassium binder has seen increased use in the emergency department.
Keep in mind that roughly 90% of potassium is renally eliminated; diuresis and hemodialysis are key for resolution of hyperkalemia. Even though 10% of potassium is eliminated through the feces, there is definitely value starting the medication inpatient; just not in the emergency department most times. In a critically ill patient, you are likely not going to be able to give anything PO. Forcing enteral access for the purpose of potassium binder administration has no acute benefit. If we are considering the use of potassium binders in the acute setting, let's provide you with a general understanding of the available products.
Differences in Potassium Binders
Kayexylate [SPS] (sodium polystyrene sulfonate)
SPS was the first FDA approved potassium binder for treating chronic hyperkalemia in the setting of chronic kidney disease.
As a non-specific binder, you get some nasty electrolyte abnormalities, specifically hypocalcemia, hypomagnesaemia, and hypernatremia.
The sorbital in the formulation as well makes it really tough on the stomach. Not many patients are able to tolerate multiple doses.
Out of the available potassium binders, SPS was the only one shown to have a contraindication in the setting of obstructive bowel disease.
Not that the onset of action is more than up two hours. Always remember that pharmacokinetics listed on the package insert is in a controlled setting, normally in healthy patients.
Valtessa [PCS] (patiromer calcium sorbitex)
PCS was released shortly after the availability of SPS. We wouldn't be as concerned about electrolyte abnormalities as we would with SPS, but hypomagnesaemia should be on your radar.
The onset of action is 4 to 7 hours. Definitely not something I am even considering if its a part of my formulary in the emergency department.
Lokelma [SZC] (sodium zirconium cyclosilicate)
There has been optimism that SZC would provide an additional therapy in the acute setting. With a listed onset of action of one hour, seems reasonable to start if access is available.
SZC isn't known to be associated with significant electrolyte abnormalities, and appears to be better tolerated than SPS/PCS.
My perspective on the utility of potassium binders in the emergency department has been based on the ENERGIZE Trial.
Emergency Potassium Normalization Treatment Including Sodium Zirconium Cyclosilicate: A Phase II, Randomized, Double-blind, Placebo-controlled Study (ENERGIZE)
Peacock et al. AcadEmerg Med. 2020 Jun;27(6):475-486.
Lots of numbers if you aren't used to reading medical literature (speaking of validity of studies...). In summary, the study design seemed promising but unfortunately, they had difficulty collecting accurate/consistent data from participants. Even without a large patient population, we can probably safely assume we aren't getting any effect with SZC. At the same time, the study was pretty consistent with the low incidence of adverse drug reactions compared to placebo. These kinds of studies are great, in my opinion, because they generate thought provoking discussions and provide some insight on ADR.
Another promising emergency medicine tool that didn't quite make the impact we were hoping for.
Potassium binders aren't likely having benefit in the ED, but may be reasonable with anticipating SZC being continued. Be mindful that SPS and PCS are associated with electrolyte abnormalities. SZC had promising pharmcokinetics, but current literature indicates that we don't need to force potassium binders.
I hope you learned something new,
Mark Nguyen, PharmD
I do not have any relationships to report. This is for educational purposes only. This is not medical advice. As always, patient-centered care relies on your clinical judgement. Refer to institutional policies, guidelines, and standard operating manuals to abide by employer requirements. Emergency medicine pharmacist responsibilities referenced are within the context of writer’s practicing state; practice according to your state law. The content of this article are based on my views and personal experiences, and are not representative of any affiliation I am associated with.
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