Sodium polystyrene sulfonate is a medication used to treat high levels of potassium in the blood, a condition known as hyperkalemia. It works by binding to potassium in the intestines, thereby reducing its absorption and promoting its elimination through the feces. This medication is typically administered orally or rectally. It's often used in emergency situations when hyperkalemia is severe and requires rapid reduction of potassium levels. However, it's important to note that sodium polystyrene sulfonate should be used cautiously and under medical supervision due to the potential for side effects and interactions with other medications.

Kayexalate (sodium polystyrene sulfonate) powder is used to treat high potassium in the blood. It is a cation-binding exchange resin that inhibits the absorption of potassium from the gastrointestinal tract (along with other cations)

Sodium polystyrene sulfonate (Kayexalate) Uses:

• Hyperkalemia:
  • It is used in the maintenance treatment of hyperkalemia.
  • Limitations of use:
    • Sodium polystyrene sulfonate should not be used as an emergency treatment for life-threatening hyperkalemia due to delayed onset of action.

Other novel drugs used to treat hyperkalemia include sodium zirconium cyclosilicate (Lokelma) and Patiromer (Veltassa). Some of the important differences between Sodium polystyrene sulfonate (Kayexalate) powder and Lokelma (Sodium zirconium cyclosilicate) are highlighted in the article: Lokelma vs Kayexalate for the treatment of Hyperkalemia.

Sodium polystyrene sulfonate (Kayexalate) Dose in Adults

Sodium polystyrene sulfonate (Kayexalate) Dose in the treatment of Hyperkalemia:

• Orally: 15 grams, which could be taken 1 to 4 times a day.
• Rectally: 30 to 50 grams, every 6 hours.

Sodium polystyrene sulfonate (Kayexalate) Dose in Children

Sodium polystyrene sulfonate (Kayexalate) Dose in the treatment of Hyperkalemia:  

For treating high potassium levels (hyperkalemia) in infants, children, and adolescents, the doses of sodium polystyrene sulfonate are:

Weight-based dosing:

• Oral or through a tube into the stomach: 1 gram per kilogram of body weight, given every 6 hours. The maximum dose per time is 15 grams. Oral is preferred over rectal administration.
• Rectal: 1 gram per kilogram of body weight, given every 2 to 6 hours. The maximum dose range per time is between 30 to 50 grams. The medication should be retained for at least 15 to 60 minutes. Sorbitol-free preparations are preferred.

Exchange-ratio based dosing for infants and small children:

• Both oral, through a tube into the stomach, and rectal administration: Use 1 milliequivalent (mEq) of potassium per gram of sodium polystyrene sulfonate resin for calculation.

Sodium polystyrene sulfonate (Kayexalate) for the pretreatment of formula or expressed breast milk to decrease potassium load for renal failure patients:

For reducing the potassium content in infant formula or expressed breast milk for patients with kidney problems, sodium polystyrene sulfonate can be added:

Infant/Enteral formula:

• Add 0.5 to 2.6 grams per 100 milliliters of formula, or 0.25 to 1 gram per milliequivalent (mEq) of potassium in the formula. Adjust the dose based on the patient's potassium levels in the blood.
• After adding the medication, shake the formula vigorously, then let it sit in the refrigerator for 30 to 60 minutes. Afterward, pour off the liquid for feeding, leaving the solid part at the bottom. The effectiveness of potassium reduction depends on the formula used.

Expressed breast milk:

• Typically, add around 1 gram per 100 milliliters of expressed breast milk. Adjust the dose according to the patient's blood potassium levels.
• After adding the medication, shake the milk well, then let it sit in the refrigerator for about an hour. Afterward, pour off the liquid for feeding, leaving the solid part at the bottom. This helps reduce the potassium content in the milk.
• Besides reducing potassium, other electrolytes like calcium, magnesium, copper, and zinc may also decrease, while sodium levels may increase. Close monitoring of patients is essential.

Pregnancy Risk Factor C

• Sodium polystyrene sulfonate has a Pregnancy Risk Factor C classification.
• This means that there haven't been studies specifically on its effects during pregnancy in animals.
• However, because it's not absorbed into the bloodstream after being taken orally or rectally, it's not expected to have a significant impact on the fetus if used during pregnancy.

Sodium polystyrene sulfonate use during breastfeeding:

• Since sodium polystyrene sulfonate isn't absorbed into the bloodstream, it's unlikely to pass into breast milk significantly.
• Therefore, breastfeeding while using this medication isn't expected to expose the nursing baby to it in significant amounts.

Sodium polystyrene sulfonate (Kayexalate) Dose in Kidney Disease:

• The manufacturer's instructions don't include specific dosage adjustments.
• However, it's important to be cautious when using sodium polystyrene sulfonate, especially in patients with kidney problems.
• These patients are at higher risk of experiencing gastrointestinal side effects.

Sodium polystyrene sulfonate (Kayexalate) Dose in Liver disease:

• The manufacturer's instructions do not contain specific dosage adjustments for individuals with liver problems.

Side effects of Sodium polystyrene sulfonate (Kayexalate):

• Endocrine & Metabolic:
  • Hypernatremia
  • Hypocalcemia
  • Hypokalemia
  • Hypomagnesemia
  • Sodium Retention
• Gastrointestinal:
  • Anorexia
  • Constipation
  • Diarrhea
  • Fecal Impaction
  • Nausea
  • Vomiting

Contraindications to Sodium polystyrene sulfonate (Kayexalate):

Sodium polystyrene sulfonate should not be used if someone is:

• Allergic to sodium polystyrene sulfonate, polystyrene sulfonate resins, or any ingredient in the medication.
• Experiencing low potassium levels, except if they're using a brand called Kayexalate.
• Dealing with bowel obstruction.
• A newborn with slow gut movement, especially if given orally or rectally with formulations containing sorbitol.

Warnings and precautions

Aspiration:

• There have been reports of people developing acute bronchitis and bronchopneumonia from inhaling particles of sodium polystyrene sulfonate.
• This risk is higher for patients with a weakened gag reflex, altered consciousness, or those prone to regurgitation.
• It's recommended to give the medication while the patient is sitting or standing upright to minimize this risk.

Electrolyte disturbances:

• Sodium polystyrene sulfonate can cause significant low potassium levels (hypokalemia).
• It's important to monitor blood potassium levels regularly, preferably multiple times a day.
• Some patients, especially those with certain risk factors, may need an electrocardiogram (ECG) monitoring.
• Additionally, this medication may also affect other electrolytes like magnesium and calcium, potentially lowering their levels as well.

Impaction of the fecal feces:

• Taking high doses of sodium polystyrene sulfonate by mouth, especially in older adults, can lead to fecal impaction.
• In children, using it rectally has also been linked to fecal impaction.

Intestinal necrosis:

• There have been reports of intestinal necrosis, which is severe damage or death of intestinal tissue (including some cases resulting in death), and other serious gastrointestinal issues such as bleeding, ischemic colitis, and perforation, particularly when sodium polystyrene sulfonate is given with sorbitol.
• It's best not to use sorbitol alongside this medication.
• The risk is higher for those with a history of intestinal problems or surgery, low blood volume, prematurity, and kidney issues.
• Only use it in patients with normal bowel function.
• Avoid giving it to postoperative patients at risk of constipation or impaction until their bowel function returns to normal.
• If constipation occurs, stop using it.

Cardiovascular disease

• Sodium polystyrene sulfonate should be used cautiously in patients with severe heart failure and/or high blood pressure (hypertension).
• The extra sodium it contains could worsen these conditions.

Edema

• If someone has edema (swelling due to fluid retention), they should be cautious when using sodium polystyrene sulfonate.
• The extra sodium it contains could make the edema worse.

Renal impairment

• If someone has kidney problems, they should use sodium polystyrene sulfonate with caution.

Sodium polystyrene sulfonate: Drug Interaction

Note: Drug Interaction Categories:

• Risk Factor C: Monitor When Using Combination
• Risk Factor D: Consider Treatment Modification
• Risk Factor X: Avoid Concomitant Use

Monitoring parameters:

• Serum Electrolytes: Keep an eye on levels of potassium, sodium, calcium, and magnesium in the blood.
• ECG Monitoring: Consider electrocardiogram (ECG) tests for certain patients.
• Signs/Symptoms of Fluid Overload: Watch for signs of fluid buildup in patients who are sensitive to sodium intake, such as those with heart failure, hypertension, or edema.

How to administer Sodium polystyrene sulfonate (Kayexalate)?

Oral or NG Administration:

• Administer orally or through a nasogastric (NG) tube while the patient is sitting upright.
• Give it at least 3 hours before or after other medications. For patients with gastroparesis, allow a 6-hour gap.
• Do not mix with orange juice or any fruit juice containing potassium.
• Shake the suspension well before giving it. Cooling it can make it taste better.
• You can also mix the suspension into the patient's food, except for foods high in potassium like bananas and orange juice.

Rectal Administration:

• Before giving the medication rectally, use a cleansing enema first.
• Administer sodium polystyrene sulfonate as a warm emulsion, at body temperature.
• Gently agitate the solution during administration.
• Keep the enema in the colon for at least 30 to 60 minutes, and ideally for several hours.
• After the recommended retention time, flush the colon with a solution that doesn't contain sodium to remove the resin.

Mechanism of action of Sodium polystyrene sulfonate (Kayexalate):

• Sodium polystyrene sulfonate works by swapping sodium ions for potassium ions in the intestine, particularly in the large intestine, before being excreted from the body.
• In practical terms, it can remove about 1 milliequivalent (mEq) of potassium per gram of resin in the body, but in laboratory conditions, it can remove up to 3.1 mEq of potassium per gram of resin.
• Because of this variability, it's crucial to closely monitor the levels of electrolytes in the blood.

The onset of action:

• It takes hours to days for sodium polystyrene sulfonate to start working.

Absorption:

• It's not absorbed into the bloodstream at all.

Excretion:

• The medication is entirely removed from the body through feces, primarily in the form of potassium polystyrene sulfonate.

International Brands of Sodium polystyrene sulfonate:

• Kalexate
• Kayexalate
• Kionex
• SPS
• Kexelate
• Kuzem
• Resinokaten
• Resinsodio
• Resonium
• Resonium A

Sodium polystyrene sulfonate Brand Names in Pakistan:

Kayexalate Powder (100 gms, 450 gms)