Triamterene
2,4,7-triamino-6-phenylpteridine
Also known as: Dyrenium · Dytac · Dyazide · Maxzide · Triteren · NSC-77625 · KF-8542 · FI-6143 · triamteren · trimaterenum · triamtereen
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Adjunctive treatment of recurrent heart failure associated with chronic mitral valve insufficiency | 1-2 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| As a diuretic for adjunctive treatment of CHF | 2-(4) mg/kg/day PO | PO | q24h | — | 🌎 NA |
- Adjunctive treatment of recurrent heart failure associated with chronic mitral valve insufficiency: Documentation of use is limited; spironolactone is drug of choice.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
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.
Mechanism of action
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).
Safety & warnings
Contraindications
- 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
Adverse effects
- 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)
Precautions
Warning: Hyperkalemia is a definite possibility. Monitoring of electrolytes and renal function is strictly necessary.
- Renal Function: May slightly reduce GFR (reversible upon discontinuation). Use with caution in patients with compromised renal blood flow.
- Pregnancy: Crosses the placental barrier. Animal studies (rats) at 6-20X human dose showed no adverse fetal effects, but adequate studies are lacking. Weigh potential benefits against risks.
- Lactation: Distributed into milk. Safety during nursing cannot be assured.
Drug interactions
Increased risks for hyperkalemia.
Triamterene may increase blood glucose levels.
Possible potentiation of hypotensive effects.
Increased risk of hyperkalemia; concurrent use is contraindicated.
Triamterene may reduce lithium clearance, increasing the risk of lithium toxicity.
May increase the risks of nephrotoxicity when used concurrently.
Increased risk for hyperkalemia.
Laboratory interaction: Triamterene may interfere with the fluorescent assay of quinidine.
Monitoring
- Serum electrolytes (especially potassium)
- BUN and creatinine
- Hydration status
- Blood pressure, if indicated
- Signs of edema
- Patient weight, if indicated
Pharmacokinetics
Absorption
In humans, rapidly absorbed after oral administration with an oral bioavailability of about 85%. Onset of diuresis occurs in 2-4 hours and diminishes after about 8 hours.
Distribution
Crosses the placental barrier and is distributed into milk.
Metabolism
Metabolized in the liver to 6-p-hydroxytriamterine and its sulfate conjugate.
Elimination
Metabolites are eliminated in the bile/feces and urine.
Overdose
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.
Available products
Formulations
- Capsules
- Tablets (typically in combination with hydrochlorothiazide)
Veterinary
- None
Human-labeled
- Triamterene Capsules: 50 mg & 100 mg (Dyrenium)
- Triamterene 37.5 mg / Hydrochlorothiazide 25 mg Tablets and Capsules (Dyazide, Maxzide-25MG, generic)
- Triamterene 50 mg / Hydrochlorothiazide 25 mg Capsules (generic)
- Triamterene 75 mg / Hydrochlorothiazide 50 mg Tablets (Maxzide, generic)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Triamterene capsules should be stored between 15-30°C (59-86°F) in tight, light-resistant containers.
Client information
- Administration: Give this medication with food to help prevent stomach upset.
- Urine Color: Your pet's urine may develop a bluish hue while taking this medication; this is a normal and harmless effect.
- Monitoring: Because this medication has not been used extensively in dogs or cats, closely observe your pet and report any unusual effects (such as severe lethargy, weakness, or vomiting) to your veterinarian immediately.
- Dietary Restrictions: Do not give your pet potassium supplements or high-potassium foods/treats unless specifically directed by your veterinarian.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.