依那普利
依那普利 (Enalapril) 是獸醫學中廣泛使用的**血管收縮素轉化酶 (ACE) 抑制劑**。它作為一種平衡的血管擴張劑，能同時降低前負荷與後負荷，是治療犬貓充血性心臟衰竭 (CHF) 的基石，常與匹莫苯丹 (Pimobendan) 和呋塞米 (Furosemide) 併用。 除了心血管方面的應用，依那普利還具有極高的**腎臟保護特性**。透過降低腎絲球出球小動脈的阻力，它能有效降低腎絲球內壓及蛋白尿，使其成為慢性腎病 (CKD) 和蛋白質流失性腎病 (PLN) 的標準輔助療法。 > **臨床要點：** 依那普利是一種**前驅藥 (Prodrug)**，需要透過肝臟生物轉化為其活性代謝物**依那普利拉 (Enalaprilat)**。在患有嚴重肝功能障礙的病患中，此轉化過程可能受損，應考慮替代療法。由於它主要經由腎臟排泄，在有明顯腎功能不全的病患中通常需要調整劑量。
作用機制: Enalapril is a prodrug converted in the liver to the active compound **enalaprilat**. Enalaprilat competitively binds to and inhibits **Angiotensin-Converting Enzyme (ACE)**. * **RAAS Inhibition:** Prevents the conversion of inactive **Angiotensin-I** → active **Angiotensin-II** (a potent vasoconstrictor). * **Vasodilation:** Decreased Angiotensin-II leads to reduced total peripheral resistance, pulmonary vascular resistance, and blood pressure (↓ afterload and preload). * **Aldosterone Reduction:** Lower Angiotensin-II levels reduce the secretion of **aldosterone** from the adrenal cortex, leading to decreased sodium and water retention, while mildly increasing potassium retention. * **Renal Hemodynamics:** Preferentially dilates the **efferent arteriole** of the glomerulus. This reduces intraglomerular hydrostatic pressure, thereby decreasing the filtration of proteins into the urine (anti-proteinuric effect) and slowing the progression of glomerular disease.
各物種劑量
- For adjunctive treatment of heart failure due to hypertrophic cardiomyopathy · 1.25-2.5 mg (total dose) PO once daily (q24h). · PO · q24h
- For adjunctive treatment of heart failure due to hypertrophic cardiomyopathy · 0.25-0.5 mg/kg (roughly 1.25-2.5 mg per cat) PO once a day (q24h) · PO · q24h
- For adjunctive treatment of heart failure due to hypertrophic cardiomyopathy · 0.5 mg/kg PO once daily, twice daily if necessary · PO · once to twice daily
- For proteinuria, hypertension in chronic kidney disease · 0.25 mg/kg PO once daily to 0.5 mg/kg PO twice daily; rarely higher · PO · once to twice daily
- For systemic hypertension · As a 2nd step drug when systolic BP >160 mmHg, diastolic >120 mmHg: 1) amlodipine (0.625 mg per cat q24h, if cat greater then 6 kg, 1.25 mg/cat q24h), add ACE inhibitor if proteinuric; 2) ACE inhibitor (benazepril/enalapril 0.5 mg/kg q12h); 3) spironolactone (1-2 mg/kg twice daily); 4) hydralazine 0.5 mg/kg PO twice daily. Each step added (except when increasing amlodipine dose) if after 1-2 weeks systolic BP > 160 mmHg. · PO · q12h · Stepwise therapy protocol.
- For adjunctive therapy for heart failure · 0.5 mg/kg PO once every other day (q48h) initially and may be increased to once a day if tolerated. · PO · q48h to q24h · Dissolve tablet(s) in distilled water and add a methylcellulose suspending agent (e.g., Ora-Plus) and cherry syrup for flavor.
- For dilative cardiomyopathy · 0.25-0.5 mg/kg PO once a day to every other day · PO · q24h to q48h
給藥途徑
禁忌症
- Hypersensitivity to ACE inhibitors
- Pregnancy (Category C in first trimester, Category D in second/third trimesters due to fetal kidney developmental risks)
不良反應
- Anorexia
- Vomiting
- Diarrhea
- Weakness
- Hypotension
- Renal dysfunction
- Hyperkalemia
- Lethargy (especially in cats)
- Inappetence
藥物相互作用
- Antidiabetic agents (insulin, oral agents) · Possible increased risk for hypoglycemia; enhanced monitoring recommended
- Diuretics (e.g., furosemide, hydrochlorothiazide) · Potential for increased hypotensive effects; furosemide doses may need reduction (by 25-50%) when adding enalapril
- Potassium-sparing diuretics (e.g., spironolactone, triamterene) · Increased hyperkalemic effects; enhanced monitoring of serum potassium recommended
- Hypotensive agents · Potential for increased hypotensive effect
- Lithium · Increased serum lithium levels possible; increased monitoring required
- NSAIDs · May reduce the anti-hypertensive or positive hemodynamic effects of enalapril; may increase risk for reduced renal function
- Potassium supplements · Increased risk for hyperkalemia
監測
- Clinical signs of CHF (respiratory rate/effort, exercise tolerance)
- Serum electrolytes (especially potassium)
- Renal panel (creatinine, BUN)
- Urine protein (UPC ratio)
- CBC with differential (periodic)
- Blood pressure (especially if treating hypertension or if clinical signs of hypotension arise)
過量
In dogs, a dose of 200 mg/kg was lethal, but 100 mg/kg was not. * **Primary Concern:** Severe **hypotension**. * **Treatment:** Supportive treatment with volume expansion using normal saline is recommended to correct blood pressure. * **Monitoring:** Because of the drug's long duration of action, prolonged monitoring and treatment may be required. * **Decontamination:** Recent overdoses should be managed by using gut emptying protocols when warranted.
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