Normo-K

Approved Indications:

• Hyperkalemia (elevated serum potassium):
• Used to treat hyperkalemia, especially in patients with renal failure who are unable to adequately excrete potassium.
• Employed when rapid correction is not immediately necessary or in conjunction with other agents like insulin, glucose, or bicarbonate for faster reduction.

Off-label / Clinically Accepted Uses:

• Chronic Kidney Disease (CKD)-associated hyperkalemia:
• Used intermittently or regularly in patients with CKD or ESRD (end-stage renal disease) to maintain potassium within a safe range.
• Digoxin toxicity management (adjunct):
• Occasionally used in patients with hyperkalemia during digoxin toxicity, although not a first-line option.

Route: Oral or Rectal (enema)

Adults:

• Oral:
• Initial dose: 15 g to 60 g per day in divided doses.
• Maintenance: 15 g once or twice daily based on serum potassium levels.
• Rectal (enema):
• Initial dose: 30 g to 50 g suspended in 100 mL to 200 mL of 20% sorbitol or water, retained for at least 30–60 minutes.
• May be repeated every 4–6 hours as needed.

Pediatric:

• Oral:
• 1 g/kg/day in divided doses.
• Rectal:
• 0.5–1 g/kg/dose every 6 hours if needed; retention time should be 30–60 minutes.

Geriatric:

• Same adult dosing, but increased caution due to higher risk of gastrointestinal effects and fluid/electrolyte imbalance.

Renal Impairment:

• No dose adjustment required, but monitor closely for hypokalemia, sodium overload, and constipation.

Hepatic Impairment:

• No specific adjustments, but monitor electrolyte shifts closely.

Duration:

• Use until serum potassium normalizes; long-term use requires regular monitoring of electrolytes and bowel function.

Sodium polystyrene sulfonate is a cation-exchange resin that functions primarily in the large intestine. It exchanges sodium ions for potassium ions within the intestinal lumen, particularly the colon. Each gram of resin can exchange approximately 1 mEq of potassium. The exchanged potassium is then excreted in the feces, resulting in a net reduction of serum potassium levels. The drug is not systemically absorbed and works locally within the gastrointestinal tract.

• Absorption: Not systemically absorbed.
• Distribution: Acts locally in the gut; no systemic distribution.
• Metabolism: Not metabolized; remains chemically unchanged.
• Excretion: Excreted in feces as a complex bound to potassium.
• Onset of Action:
• Oral: Typically within 2 to 6 hours.
• Rectal: Faster onset, often within 1 hour.
• Duration of Action: Up to 6 hours or longer depending on bowel transit time.
• Half-life: Not applicable due to lack of systemic absorption.

• Pregnancy:
• FDA Pregnancy Category C. Animal studies are lacking; use only if clearly needed.
• Not systemically absorbed, thus presumed to have minimal fetal risk. Caution advised in severe maternal constipation or fluid overload.
• Lactation:
• Not expected to be excreted into breast milk due to lack of systemic absorption.
• Considered likely safe during breastfeeding.

• Therapeutic Class: Potassium Binder / Electrolyte-modifying Agent
• Subclass: Cation-exchange resin
• Generation: First-generation potassium binder

• Known hypersensitivity to sodium polystyrene sulfonate or excipients
• Neonates with reduced gut motility (e.g., post-surgery or ileus)
• Bowel obstruction or risk of fecal impaction
• Severe hypokalemia
• Patients on sorbitol-containing enema preparations (risk of colonic necrosis)
• History of intestinal perforation or necrotizing enterocolitis

• Colonic necrosis: Rare but serious, especially with rectal use and sorbitol combinations.
• Gastrointestinal obstruction or perforation risk: Avoid in patients with compromised bowel motility or post-operative ileus.
• Electrolyte imbalance: Monitor sodium, calcium, magnesium, and potassium regularly.
• Fluid overload: Sodium content may worsen congestive heart failure, edema, or hypertension.
• Constipation risk: May cause or exacerbate constipation, especially in elderly or immobilized patients.
• Pediatric use: Caution due to increased risk of bowel complications.
• Avoid concurrent use of aluminum hydroxide or magnesium-containing laxatives.

Common:

• Gastrointestinal:
• Constipation
• Anorexia
• Nausea
• Vomiting
• Metabolic:
• Hypokalemia
• Hypernatremia
• Hypocalcemia

Serious/Rare:

• Intestinal necrosis (especially with sorbitol)
• Gastrointestinal obstruction or perforation
• Fecal impaction
• Seizures (from severe hypocalcemia or hypokalemia)
• Electrolyte imbalance leading to cardiac arrhythmia

Onset:

• Gastrointestinal effects may appear within hours to days.
• Electrolyte imbalances may occur early or accumulate with prolonged use.

• Aluminum hydroxide or magnesium-containing antacids/laxatives:
• Risk of intestinal obstruction or systemic toxicity.
• Lithium:
• Reduced efficacy due to binding in the gut.
• Thyroxine:
• May reduce absorption and therapeutic effect of levothyroxine.
• Digoxin:
• Electrolyte imbalance may increase digoxin toxicity risk.
• Food interactions:
• Best taken away from meals to enhance efficacy.
• Enzyme interactions:
• Not applicable (not systemically absorbed; no CYP450 involvement).

• FDA Black Box Warning:
• Updated to highlight the risk of intestinal necrosis with concomitant sorbitol use, especially in pediatric and post-surgical patients.
• Guideline shifts:
• Newer potassium binders (e.g., patiromer, sodium zirconium cyclosilicate) are preferred in chronic hyperkalemia due to better safety profiles; sodium polystyrene sulfonate still in use when cost/access is a concern.
• Clinical monitoring emphasized:
• Updated recommendations for electrolyte and ECG monitoring during use.

• Temperature: Store at 20°C to 25°C (68°F to 77°F).
• Excursions permitted from 15°C to 30°C.
• Humidity: Keep tightly closed in a dry place.
• Light Protection: No special requirements.
• Handling:
• Shake suspensions well before use.
• For rectal use, ensure proper warming and mixing to avoid precipitation.
• Reconstitution:
• Mix with water or sorbitol suspension as directed for oral or rectal administration.
• Use immediately after reconstitution; do not store.