Triamterene
Triamterene is a **potassium-sparing diuretic** that may be considered as an alternative to spironolactone for the adjunctive treatment of **congestive heart failure (CHF)** in dogs. * **Clinical Utility**: There is limited clinical experience and pharmacokinetic data associated with its use in veterinary medicine. Spironolactone generally remains the preferred potassium-sparing diuretic for small animals. * **Key Advantage**: It can help manage edema and fluid overload while preventing the excessive potassium loss often seen with loop diuretics (like furosemide) or thiazide diuretics.
Mecanismo: 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).
Dosificación por especie
- 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
Las dosis son una referencia clínica para veterinarios colegiados. Confirme siempre con la ficha técnica vigente y el paciente individual.
Vías de administración
Contraindicaciones
- 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
Efectos adversos
- 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)
Interacciones farmacológicas
- 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.
Monitorización
- Serum electrolytes (especially potassium)
- BUN and creatinine
- Hydration status
- Blood pressure, if indicated
- Signs of edema
- Patient weight, if indicated
Sobredosis
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.
La referencia de fármacos de VetSheet está destinada a veterinarios colegiados como apoyo a la decisión clínica, no sustituye el juicio profesional ni la ficha técnica vigente del fabricante.