Potassium Chloride / Potassium Gluconate
Potassium is a critical intracellular electrolyte essential for life. It plays a vital role in maintaining cellular resting membrane potentials, particularly in excitable tissues like the heart, skeletal muscle, and smooth muscle. **Clinical Pearls:** * **Hypokalemia** (low potassium) is a common complication of chronic kidney disease (especially in cats), aggressive diuresis, diabetic ketoacidosis (DKA), and severe gastrointestinal losses. * **Potassium Gluconate** is typically preferred for oral supplementation as it is less irritating to the GI tract and provides a mild alkalinizing effect. * **Potassium Chloride (KCl)** is the standard for intravenous supplementation but must **always** be diluted prior to administration to prevent fatal arrhythmias. * Total body potassium depletion may be severe even if serum levels appear normal, especially in the presence of acid-base disturbances (acidosis shifts potassium extracellularly).
กลไกการออกฤทธิ์: Potassium is the principal intracellular cation in the body. It works primarily via the **Na+/K+ ATPase pump** to maintain the electrochemical gradient across cell membranes. * Maintains cellular tonicity and resting membrane potential → essential for nerve impulse transmission. * Regulates smooth, skeletal, and cardiac muscle contraction. * Acts as a crucial cofactor in carbohydrate utilization and protein synthesis. * Essential for the maintenance of normal renal function.
ขนาดยาตามชนิดสัตว์
- Treatment of chronic mild hypokalemia (3.0-3.5 mEq/L) · 0.5-1 mEq/kg mixed in food once or twice daily · PO · q12-24h
- Treatment of chronic mild hypokalemia (Tumil-K powder) · 1/4 teaspoonful (2 mEq) per 4.5 kg body weight in food twice daily; adjust as necessary · PO · q12h
- Moderate to severe (<3.0 mEq/L) or acute hypokalemia · Rate should not exceed 0.5 mEq/kg/hour. Under dire circumstances (serum K < 2.0 mEq/L), rate can be increased to 1.5 mEq/kg/hour along with close EKG monitoring. · IV · Continuous
- Subcutaneous fluid supplementation (<10 kg patients) · 150 mL SC every 12 hours of isotonic fluids containing 30-35 mEq/L KCl · SC · q12h
- Oral maintenance supplementation · 2-4 mEq/day · PO · Daily · Using potassium gluconate.
- Sliding scale IV supplementation based on Serum K+ · Serum K+ <2 mEq/L = 60 mEq/1000 mL IV fluid; Serum K+ 2-2.5 mEq/L = 40 mEq/1000 mL IV fluid; Serum K+ 2.5-3 mEq/L = 30 mEq/1000 mL IV fluid; Serum K+ 3-3.5 mEq/L = 20 mEq/1000 mL IV fluid. Infusion rates should generally not exceed 0.5 mEq/kg/hour. · IV · Continuous
- Hypokalemia in 'downer' cows · 80 grams sodium chloride and 20 grams potassium chloride in 10 liters of water via stomach tube. Provide a bucket containing similar solution for cow to drink and another containing fresh water. · PO · Once
- Hypokalemia maintenance/treatment · 50 grams PO daily; 1 mEq/kg/hour IV drip · PO/IV · Daily/Continuous
วิธีการให้ยา
ข้อห้ามใช้
- Hyperkalemia
- Renal failure or severe renal impairment
- Severe hemolytic reactions
- Untreated Addison's disease (hypoadrenocorticism)
- Acute dehydration
- GI motility impairment (for solid oral dosage forms)
อาการไม่พึงประสงค์
- Hyperkalemia (muscle weakness, cardiac conduction disturbances)
- Gastrointestinal distress (vomiting, diarrhea) with oral therapy
- Vein irritation and phlebitis with IV therapy
อันตรกิริยาระหว่างยา
- ACE Inhibitors (e.g., enalapril) · Potassium retention may occur; increased risk for hyperkalemia.
- Digoxin · In patients with severe or complete heart block receiving digitalis therapy, it is often recommended not to use potassium salts.
- NSAIDs · Oral potassium given with non-steroidal anti-inflammatory agents may increase the risk of gastrointestinal adverse effects.
- Potassium-Sparing Diuretics (e.g., spironolactone) · Potassium retention may occur; increased risk for hyperkalemia.
การติดตาม
- Serum potassium levels
- Other electrolytes (sodium, chloride, magnesium, calcium)
- Acid/base status
- Blood glucose
- ECG (especially during IV administration)
- CBC
- Urinalysis and renal function parameters
การได้รับยาเกินขนาด
Fatal hyperkalemia may develop if potassium salts are administered too rapidly IV or if potassium renal excretory mechanisms are impaired. **Clinical Signs of Hyperkalemia:** * Muscular weakness * Gastrointestinal disturbances * Severe cardiac conduction disturbances (bradycardia, atrial standstill, ventricular fibrillation, asystole) **Treatment of Hyperkalemia:** * Immediate discontinuation of the potassium supplement. * Continuous ECG, acid/base, and electrolyte monitoring. * **Medical interventions:** Glucose/insulin infusions (drives K+ into cells), sodium bicarbonate (alkalinization drives K+ into cells), calcium therapy (cardioprotective, antagonizes K+ effects on the heart), and polystyrene sulfonate resin (binds K+ in the GI tract).
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