KAYEXALATE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for KAYEXALATE (KAYEXALATE).
Kayexalate (sodium polystyrene sulfonate) is a cation-exchange resin that exchanges sodium ions for potassium ions in the gastrointestinal tract, primarily in the colon, thereby reducing serum potassium levels.
| Metabolism | Kayexalate is not metabolized; it acts locally in the gastrointestinal tract and is excreted unchanged in feces. |
| Excretion | Primarily fecal elimination of bound potassium; minimal renal elimination as the resin is not absorbed. |
| Half-life | Not applicable; the drug acts locally in the gastrointestinal tract and is not systemically absorbed. |
| Protein binding | 0% (not systemically absorbed). |
| Volume of Distribution | Not applicable as the drug is not absorbed. |
| Bioavailability | 0% (orally and rectally); acts locally without systemic absorption. |
| Onset of Action | Oral: 2-24 hours; Rectal enema: 30-60 minutes. |
| Duration of Action | 4-6 hours after oral administration; prolonged with repeated dosing; effects persist as long as resin remains in contact with colonic contents. |
15-30 g orally once daily to four times daily as a suspension in water, or as a retention enema (30-50 g every 6 hours) if oral administration is not feasible.
| Dosage form | POWDER |
| Renal impairment | No specific GFR-based dose adjustment is recommended; however, monitor serum potassium closely in patients with severe renal impairment due to risk of hypokalemia. |
| Liver impairment | No specific Child-Pugh based adjustment is required; use with caution in patients with hepatic impairment due to potential electrolyte disturbances. |
| Pediatric use | Oral: 1 g/kg/dose once daily to four times daily; retention enema: 0.5-1 g/kg/dose every 2-6 hours. Maximum single dose: 30 g for oral, 50 g for enema. |
| Geriatric use | Initiate at lower end of dosing range (e.g., 15 g orally once daily) and titrate based on serum potassium levels; monitor for electrolyte imbalances and bowel function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for KAYEXALATE (KAYEXALATE).
| Breastfeeding | Kayexalate is not absorbed systemically, so excretion into breast milk is negligible. The M/P ratio is not applicable. It is considered compatible with breastfeeding, but monitor infant for electrolyte disturbances if maternal use is prolonged or high-dose. |
| Teratogenic Risk | Kayexalate (sodium polystyrene sulfonate) is not absorbed systemically; thus, it is not expected to pose a direct teratogenic risk. However, the potential for maternal electrolyte disturbances (e.g., hypokalemia, hypernatremia) secondary to its use could indirectly affect fetal development. No human studies have evaluated teratogenic effects; animal reproduction studies are not available. Use during pregnancy only if clearly needed and with careful monitoring of maternal electrolytes. |
■ FDA Black Box Warning
Warning: Intestinal necrosis and other serious gastrointestinal adverse events (e.g., bleeding, ischemic colitis, perforation) have been reported, particularly when used with sorbitol.
| Serious Effects |
["Hypersensitivity to sodium polystyrene sulfonate or any component","Obstructive bowel disease","Neonates with reduced gut motility (risk of impaction)"]
| Precautions | ["Risk of intestinal necrosis, especially when co-administered with sorbitol.","Monitor serum potassium, calcium, and magnesium levels.","Use with caution in patients with gastrointestinal disorders or history of bowel surgery.","Sodium overload may occur, especially in patients with heart failure or renal impairment.","May bind to oral medications, reducing their absorption."] |
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| Fetal Monitoring | Monitor maternal serum potassium, sodium, calcium, and magnesium levels regularly. Assess for signs of hypokalemia (e.g., muscle weakness, cardiac arrhythmias, ECG changes) and hypernatremia (e.g., thirst, hypertension, seizures). In the fetus, monitor for potential effects of maternal electrolyte imbalances, such as fetal arrhythmias or growth disturbances via ultrasound and fetal heart rate monitoring. |
| Fertility Effects | No studies have assessed the effect of Kayexalate on fertility. Systemic absorption is minimal, so direct reproductive toxicity is unlikely. However, electrolyte imbalances induced by the drug could theoretically affect ovulatory function or spermatogenesis. |