In this episode, I’ll discuss whether patiromer can be used for acute hyperkalemia.
In the treatment of acute hyperkalemia, IV calcium provides immediate cardioprotection and allows time for insulin to move potassium into the intracellular space and away from the heart. This is only a short term solution however, since potassium will re-equilibrate out of the intracellular space several hours after insulin is given. Another intervention is required to remove the excess potassium from the patient and provide a definitive solution to acute hyperkalemia.
Hemodialysis is an effective intervention to remove excess potassium from a patient, and although there are not universally agreed upon triggers for initiation of dialysis, it is the preferred option in severe hyperkalemia.
When dialysis is not immediately available, or if the hyperkalemia is not felt to be severe enough to justify the invasive procedure of dialysis, gastrointestinal ion exchange resins are used.
Sodium polystyrene sulfate (SPS) is the oldest and most common agent, however there is considerable controversy over its use in acute hyperkalemia.
The best evidence available suggests that SPS is no more effective than laxative use for lowering serum potassium levels.
While not common, this medication can cause intestinal necrosis, a potentially fatal complication. Certain conditions lead to a higher incidence of intestinal necrosis from SPS and should be considered absolute contraindications to use:
-Postoperative patients
-Patients with an ileus or who are receiving opioids
-Patients with a bowel obstruction
For these reasons, there is a strong desire to find an alternative to the use of sodium polystyrene sulfate for hyperkalemia. Of the newer oral ion exchange resins, only patiromer has been studied in the setting of acute hyperkalemia.
Article
Patiromer for Treatment of Hyperkalemia in the Emergency Department: A Pilot Study.
Lead author: Zubaid Rafique
Published in Academic Emergency Medicine January 2020
Methods
The study was a single-center, randomized, open-label pilot study. The authors used a convenience sample of adult patients with end-stage renal disease and a serum potassium level of ≥ 6.0 mEq/L. Patients were randomized between standard of care or one dose of 25.2 g oral patiromer plus standard of care. The primary outcome being studied was the difference in potassium between groups after 6 hours had elapsed post-treatment.
Results
Each group contained 15 patients. At 6 hours there was a numerical decrease in potassium of 0.5 mEq/L in the patiromer group however this did not reach statistical significance. At just 2 hours post-treatment, there was a statistically significant decrease in potassium of 0.61 mEq/L. Safety outcomes were no different between groups.
Conclusion
The authors concluded:
In this open-label pilot study of severe hyperkalemia, a single dose of 25.2 g of oral patiromer reduced serum potassium within 2 hours but did not show a difference at 6 hours.
Discussion
Being a small pilot study, the authors had no a priori power calculation, so only a large treatment effect would have been detected. A larger study is now justified based on these outcomes. The finding of a significant difference in favor of patiromer at 2 hours is somewhat surprising as the onset of action for this medication is reported as 7 hours in the prescribing information. It should be noted however that the dose used in this study was triple the usual starting dose of 8.4 grams, and this may explain the early difference between groups.
While this study was just published in print in January 2020, members of my Hospital Pharmacy Academy first heard about it in the October 14th 2019 literature digest when the study was released early online. Each week I keep Academy members up to date with the medical literature by summarizing key articles from over 20 sources and journals. Each digest includes video and audio of my commentary on the new articles and how they apply to clinical practice. Get all the details about the practical resources the Hospital Pharmacy Academy offers and join today by going to pharmacyjoe.com/academy.
If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.
I wish the study specified if standard of care included SPS, in which case, were they adding Patiromer to SPS? Also, when looking at some of their graphs, the 2 hour patient graph (fig 3) stands out since the patiromer group was statistically significant at that point, but it looks like that may have been dominated by a single patient who’s potassium level drop by 3. Makes me wonder if a lab error occurred.