氯化鉀 / 葡萄糖酸鉀
鉀是維持生命不可或缺的關鍵細胞內電解質。它在維持細胞靜息膜電位方面扮演著至關重要的角色，特別是在心臟、骨骼肌和平滑肌等興奮性組織中。 **臨床要點：** * **低血鉀症**（鉀離子過低）是慢性腎病（尤其是貓）、積極利尿治療、糖尿病酮酸血症 (DKA) 以及嚴重胃腸道流失的常見併發症。 * **葡萄糖酸鉀**通常是口服補充的首選，因為它對胃腸道的刺激較小，並具有輕微的鹼化作用。 * **氯化鉀 (KCl)** 是靜脈補充的標準藥物，但在給藥前**必須**稀釋，以防止致命的心律不整。 * 即使血清鉀濃度看起來正常，全身鉀的消耗也可能很嚴重，特別是在存在酸鹼不平衡的情況下（酸中毒會使鉀離子轉移至細胞外）。
作用機制: 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.
各物種劑量
- 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
- Severe hypokalemia (<2.3 mEq/L) with severe muscle weakness or recumbency · Isotonic potassium chloride (11.5 grams of potassium chloride per 1 liter of sterile water) at a rate of 4 mL/kg/hour. Combined with large doses of oral potassium salts (i.e., 200 grams of KCl per day). · IV/PO · Continuous/Daily
劑量為合格獸醫專業人員的臨床參考。請務必對照最新藥品仿單及個別病患確認。
給藥途徑
禁忌症
- 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)
不良反應
- Hyperkalemia (muscle weakness, cardiac conduction disturbances)
- Gastrointestinal distress (vomiting, diarrhea) with oral therapy
- Vein irritation and phlebitis with IV therapy
藥物相互作用
- 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.
監測
- 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
過量
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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