Polystyrene sulfonate (Kayexalate) is used in renal failure to:

RUHS, Jaipur, PB B.Sc Nursing Entrance-2020

Pharmacology

Easy

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2020

Explanation

Sodium polystyrene sulfonate (Kayexalate) is classified as a cation-exchange resin.
Its primary function is to treat hyperkalemia, which is a high level of potassium in the blood, commonly seen in renal failure.
The resin works in the intestines by trading sodium ions for potassium ions.
This process binds the potassium, which is then removed from the body through the feces, effectively lowering the serum potassium level.

Option A: Kayexalate does not correct acidosis. Metabolic acidosis, common in renal failure, is typically managed with an alkalizing agent like sodium bicarbonate.
Option B: Kayexalate does not reduce phosphate levels. Hyperphosphatemia in renal failure is treated with phosphate binders, such as sevelamer or calcium acetate, which bind to phosphate in the gut.
Option D: This statement reverses the relationship and is outdated. Sorbitol, a laxative, was historically co-administered with Kayexalate to induce diarrhea and prevent constipation caused by the resin. However, this combination is now warned against due to a high risk of intestinal necrosis.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pharmacological management of hyperkalemia in renal failure as background academic context rather than a clinical decision trigger.
Nurses must closely monitor serum potassium levels in patients with renal failure, as hyperkalemia can lead to life-threatening cardiac dysrhythmias.
When administering Kayexalate, the nurse should assess for normal bowel function, as the drug is contraindicated in patients with an ileus or recent abdominal surgery due to the risk of intestinal necrosis.
Monitor for adverse effects such as hypernatremia, fluid overload (due to sodium absorption), hypocalcemia, and hypomagnesemia.

How to Approach the Question

First, identify the drug mentioned in the question: Polystyrene sulfonate (Kayexalate).
Recall the drug's classification and primary purpose. Kayexalate is a potassium-binding, cation-exchange resin.
Think about the pathophysiology of renal failure. The kidneys fail to excrete potassium, leading to hyperkalemia.
Connect the drug's purpose to the disease process. Kayexalate is given to remove excess potassium.
Evaluate each option based on the drug's mechanism of action. The only option that describes removing potassium is 'Exchange potassium for sodium'.
Eliminate the other options by recalling the standard treatments for other renal failure complications like acidosis (bicarbonate) and hyperphosphatemia (phosphate binders).

Concept Tested & Keywords

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E6 Pharmacology Nursing Lilley 11e Part 2 pp. 166-168, 170-172