Table 2.
Comparison of potassium exchange resins for the treatment of hyperkalemia
| Drug name | Sodium polystyrene sulfonate (SPS) | Patiromer | Sodium zirconium cyclosilicate (SZC) |
|---|---|---|---|
| Trade name | Kayexalate®, Kionex® | Veltessa® | Lokelma® |
| FDA approval | 1958 (prior to drug regulation laws) | 2015 | 2018 |
| Onset of action | 2–24 h | 2 h | 1 h |
| Mode of action | The sulfonate molecule exists as sulfonic acid in its ionic state and allows for interaction with a Na+ counterion. In this method, Na+ is exchanged for K+ within the gastrointestinal tract | Utilizes the high colonic K+ concentration and exchanges its Ca2+ counterion for it. The attached fluorine atom at the alpha-carbon position of patiromer causes electron-withdrawing effects and generates a lower pKa compared to colonic pH. This allows the resin to exist in an ionized state and bind K+ effectively | Selectively binds to K+ throughout the length of the gastrointestinal tract. SZC mimics physiological K+ ion channels by utilizing a thermodynamically favorable binding pocket unique to the size of K+ |
| Degree of K+ lowering | 1.04 mEq/La | 0.6 mEq/Lb | 0.4 mEq/Lc |
| Location of efficacy | Large intestine | Distal colon | Small intestine and large intestine |
| Toxicity | Na+ loading/fluid overload, hypomagnesemia, hypocalcemia, colonic necrosis | Hypomagnesemia | Edema |
| Side effects | Nausea, vomiting, diarrhea, constipation, abdominal pain | Mild-severe constipation, abdominal pain | Constipation, abdominal pain |
| Exchange ion | Na+ | Ca2+ | H+, Na+ |
| Selectivity | Non-specific, K+, Ca2+, Mg2+ | Specific, K+ (low specificity, Mg2+) | Highly specific, K+ and ammonium |
| Resin size | ~ 11–124 µm | ~ 100 µm | > 3 µm (non-absorbed) |
| Molecular composition | Polymer resin consisting of sulfonate and attached vinylbenzene (styrene) R group | Polymer resin with attached carboxylic acid and fluorine atom at alpha carbon position | Three-dimensional, seven-member ring lattice made up of alternating zirconium and silicate atoms with adjoining oxygen atoms |
a1.04 mEq/L mean decrease of serum K+ compared to placebo treatment; SPS was given at a dosage of 30 g/day for 7 days [18]
b0.6 mEq/L decrease of serum K+ 2 h post-treatment with a single dosage of 25.2 g [19]
c0.4 mEq/L decrease of serum K+ at 2 h post-treatment with dosage of 10 g 3 times daily; clinically significant decrease of K+ observed at 1 h [21]