檸檬酸鹽（檸檬酸鉀、檸檬酸鈉、檸檬酸）
檸檬酸鹽在獸醫學中主要用作**尿液鹼化劑**，並用於治療與慢性腎病（CKD）或腎小管酸中毒相關的**慢性代謝性酸中毒**。 **檸檬酸鉀**特別適用於預防犬貓的**草酸鈣結石**。由於它適口性較佳且能補充鉀離子（許多慢性腎病患畜容易出現低血鉀），因此通常比碳酸氫鈉更受青睞。 *臨床要點*：雖然對預防草酸鈣結石非常有效，但必須避免過度鹼化尿液，因為過高的尿液 pH 值可能會意外促進磷酸鈣結石的形成。
作用機制: Citrate salts are absorbed from the gastrointestinal tract and **oxidized in the liver** to produce **bicarbonate** (HCO3-), which acts as a systemic alkalinizing agent, raising blood pH and subsequently urine pH. In the urinary tract, the mechanism is twofold: 1. **Alkalinization**: The resulting alkaline urine increases the solubility of calcium oxalate. 2. **Chelation**: Excreted citrate directly **complexes with calcium** in the urine → decreases the concentration of free calcium available to bind with oxalate → inhibits the formation and growth of calcium oxalate crystals.
各物種劑量
- Adjunctive therapy to inhibit calcium oxalate formation · Initially 50-100 mg/kg PO q12h · PO · q12h · Goal is to achieve a urine pH of approximately 7.5.
- Decrease possibility of calcium oxalate stone formation (Nutrived Potassium Citrate Granules) · 1 scoop mixed or sprinkled on food per day · PO · q24h
- Adjunctive therapy to inhibit calcium oxalate formation · 100-150 mg/kg/day PO · PO · q24h · It is unclear whether this dose will actually increase urinary citrate in cats.
- Adjunctive therapy of chronic renal failure as a potassium supplement and alkalinizing agent · Initially, 75 mg/kg PO q12h · PO · q12h
- Significantly acidemic chronic renal failure · 2.5 mEq (total dose) potassium or 15-30 mg/kg as potassium citrate PO q12h · PO · q12h
- Hypokalemic chronic renal failure · 2-4 mEq (total dose) of potassium per day as potassium citrate or potassium gluconate · PO · q24h
- Adjunctive therapy to inhibit calcium oxalate crystal formation (hypocitraturia) · 40-75 mg/kg PO q12h · PO · q12h · Avoid overzealous urinary alkalinization as calcium phosphate uroliths may form.
- Adjunctive therapy to inhibit calcium oxalate crystal formation · Initially 50 mg/kg PO q12h · PO · q12h · Monitor urine pH; goal is to obtain values of 7-7.5.
- Decrease possibility of calcium oxalate stone formation (Nutrived Potassium Citrate Granules) · 1 scoop mixed or sprinkled on food per 10 lb. body weight per day · PO · q24h
- Persistent calcium oxalate crystalluria/uroliths (after diet and hydrochlorothiazide) · 50-75 mg/kg PO q12h · PO · q12h · Give to effect to achieve a urine pH of 6.5-7. If urine pH already above 7-7.5, do not use. Monitor serum potassium monthly.
- Adjunctive therapy of chronic renal failure as a potassium supplement and alkalinizing agent · Initially, 75 mg/kg PO q12h · PO · q12h
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給藥途徑
禁忌症
- Heart failure
- Severe renal impairment (with azotemia or oliguria)
- Urinary tract infections (UTI) associated with calcium or struvite stones
- Aluminum toxicity
- Hyperkalemia or conditions predisposing to it (adrenal insufficiency, acute dehydration, uncontrolled diabetes mellitus) - for potassium citrate
- Peptic ulcer disease
- Delayed gastric emptying, esophageal compression, or intestinal obstruction (specifically for tablet formulations)
不良反應
- Gastrointestinal distress (nausea, vomiting, diarrhea)
- Hyperkalemia (specifically with potassium citrate)
- Fluid retention (specifically with sodium citrate)
- Metabolic alkalosis (rare)
藥物相互作用
- Amphetamines · Alkalinized urine can decrease excretion, potentially increasing toxicity.
- Pseudoephedrine / Ephedrine · Alkalinized urine can decrease excretion.
- Antacids · May cause systemic alkalosis. Aluminum-containing antacids may cause aluminum toxicity, especially in renal insufficiency. Sodium bicarbonate combinations may cause hypernatremia.
- Aspirin (Salicylates) · Alkalinized urine can increase the excretion of salicylates, decreasing their efficacy.
- Fluoroquinolones (e.g., ciprofloxacin, enrofloxacin) · Solubility is decreased in an alkaline environment; monitor for signs of crystalluria.
- Lithium · Alkalinized urine can decrease excretion.
- Methenamine · Concurrent use is not recommended as methenamine requires an acidic urine for efficacy.
- Quinidine · Alkalinized urine can decrease excretion.
- Tetracyclines · Alkalinized urine can decrease excretion.
- ACE Inhibitors (e.g., enalapril, lisinopril) · May lead to increases in serum potassium levels (hyperkalemia) when used with potassium citrate.
- Cyclosporine · May increase serum potassium levels when used with potassium citrate.
- Digoxin · May increase serum potassium levels when used with potassium citrate.
監測
- Serum potassium, sodium, bicarbonate, chloride
- Acid/base status
- Urine pH
- Urinalysis (monitor for crystalluria)
- Serum creatinine and CBC (particularly in chronic renal failure)
過量
Overdosage and acute toxicity generally fall into 4 categories: 1. **Gastrointestinal distress and ulceration** 2. **Metabolic alkalosis** 3. **Hypernatremia** (with sodium citrate) 4. **Hyperkalemia** (with potassium citrate) **Treatment**: If an overdose occurs and preventing absorption is reasonable (especially with tablets), employ gut-emptying protocols if not contraindicated. Treat GI effects with intravenous fluids or supportive care. Hyperkalemia, hypernatremia, and metabolic alkalosis should be treated symptomatically. Contact an animal poison control center for specific treatment modalities.
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