氨苯蝶啶
氨苯蝶啶是一種**保鋎利尿劑**，可作為螺內酯 (spironolactone) 的替代藥物，用於犬隻**充血性心臟衰竭 (CHF)** 的輔助治療。 * **臨床應用**：其在獸醫學中的使用經驗及藥代動力學數據有限。對於小動物，螺內酯通常仍是首選的保鋎利尿劑。 * **主要優勢**：它有助於控制水腫和體液過載，同時防止使用環利尿劑（如呅塞米）或噻嗪類利尿劑時常見的鋎離子過度流失。
作用機制: Triamterene exerts a direct effect on the **late distal convoluted tubule** and **collecting duct** of the kidneys. * **Mechanism**: It directly blocks **epithelial sodium channels (ENaC)** on the lumenal side of the kidney tubule → inhibits the reabsorption of sodium (Na+) → decreases the electrical gradient across the tubular membrane → reduces the driving force for the secretion and excretion of potassium (K+) and hydrogen (H+) ions. * **Aldosterone Independence**: Unlike spironolactone, triamterene does **not** competitively inhibit aldosterone. Its action is independent of endogenous aldosterone levels. * **Net Effect**: Increases urinary excretion of sodium, calcium, magnesium, and bicarbonate while retaining potassium and chloride. It has little effect on blood pressure when used alone but can slightly reduce Glomerular Filtration Rate (GFR).
各物種劑量
- Adjunctive treatment of recurrent heart failure associated with chronic mitral valve insufficiency · 1-2 mg/kg PO q12h · PO · q12h · Documentation of use is limited; spironolactone is drug of choice.
- As a diuretic for adjunctive treatment of CHF · 2-(4) mg/kg/day PO · PO · q24h
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
- Anuria
- Severe or progressive renal disease
- Severe hepatic disease
- Hypersensitivity to triamterene
- Preexisting hyperkalemia or history of triamterene-induced hyperkalemia
- Concurrent therapy with another potassium-sparing agent (e.g., spironolactone, amiloride)
- Concurrent potassium supplementation
不良反應
- Hyperkalemia (most significant risk)
- Gastrointestinal upset
- Hyponatremia
- Headache or dizziness (reported in humans)
- Increased sensitivity to sunlight
- Hypersensitivity reactions (rare)
- Nephrolithiasis (rare)
- Blood dyscrasias such as agranulocytosis, thrombocytopenia, or megaloblastosis (rare)
藥物相互作用
- ACE Inhibitors (e.g., enalapril, benazepril) · Increased risks for hyperkalemia.
- Antidiabetic Agents (insulin, oral hypoglycemics) · Triamterene may increase blood glucose levels.
- Antihypertensive Agents · Possible potentiation of hypotensive effects.
- Diuretics, Potassium-Sparing (spironolactone, amiloride) · Increased risk of hyperkalemia; concurrent use is contraindicated.
- Lithium · Triamterene may reduce lithium clearance, increasing the risk of lithium toxicity.
- NSAIDs (especially indomethacin) · May increase the risks of nephrotoxicity when used concurrently.
- Potassium Supplements or High Potassium Foods · Increased risk for hyperkalemia.
- Quinidine · Laboratory interaction: Triamterene may interfere with the fluorescent assay of quinidine.
監測
- Serum electrolytes (especially potassium)
- BUN and creatinine
- Hydration status
- Blood pressure, if indicated
- Signs of edema
- Patient weight, if indicated
過量
The oral LD50 for triamterene in mice is 380 mg/kg. * **Clinical Signs**: Fluid and electrolyte imbalance (especially hyperkalemia) is the most likely risk. Gastrointestinal effects or hypotension are also possible. * **Management**: Consider gut emptying protocols for very large or unknown quantity ingestions. Acute overdoses should generally be managed by observation, with rigorous fluid, electrolyte (especially serum potassium), and acid-base monitoring. Initiate supportive treatment as required.
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。