[.
]Action/Kinetics:
Acts directly on the distal tubule to promote the excretion of sodium--which is exchanged for potassium or hydrogen ions--bicarbonate, chloride, and fluid. It increases urinary pH and is a weak folic acid antagonist. Onset: 2-4 hr. Peak effect: 6-8 hr. Duration: 7-9 hr. t1/2: 3 hr. From one-half to two-thirds of the drug is bound to plasma protein. Metabolized to hydroxytriamterene sulfate, which is also active. About 20% is excreted unchanged through the urine.
Uses:
Edema due to CHF, hepatic cirrhosis, nephrotic syndrome, steroid therapy, secondary hyperaldosteronism, and idiopathic edema. May be used alone or with other diuretics. Investigational: Prophylaxis and treatment of hypokalemia, adjunct in the treatment of hypertension.
Contraindications:
Hypersensitivity to drug, severe or progressive renal insufficiency, severe hepatic disease, anuria, hyperkalemia, hyperuricemia, gout, history of nephrolithiasis. Lactation.
Special Concerns:
Safety and efficacy have not been determined in children.
Side Effects:
Electrolyte: Hyperkalemia, electrolyte imbalance. GI: Nausea, vomiting (may also be indicative of electrolyte imbalance), diarrhea, dry mouth. CNS: Dizziness, drowsiness, fatigue, weakness, headache. Hematologic: Megaloblastic anemia, thrombocytopenia. Renal: Azotemia, interstitial nephritis. Miscellaneous: Anaphylaxis photosensitivity, hypokalemia, jaundice, muscle cramps, rash.
Laboratory Test Alterations:
Triamterene may impart blue fluorescence to urine, interfering with fluorometric assays (e.g., lactic dehydrogenase, quinidine). 
BUN, creatinine. Serum uric acid in clients predisposed to gouty arthritis.
Overdose Management:
Symptoms: Electrolyte imbalance, especially hyperkalemia. Also, nausea, vomiting, other GI disturbances, weakness, hypotension, reversible acute renal failure. Treatment: Immediately induce vomiting or perform gastric lavage. Evaluate electrolyte levels and fluid balance and treat if necessary. Dialysis may be beneficial.
Drug Interactions:
- Amantadine / Toxic amantadine effects R/T
renal excretion
- Angiotensin-converting enzyme inhibitors / Significant hyperkalemia
- Antihypertensives / Potentiated by triamterene
- Captopril / Risk of significant hyperkalemia
- Cimetidine / Bioavailability and clearance of triamterene
- Digitalis / Inhibited by triamterene
- Indomethacin / Risk of nephrotoxicity and acute renal failure
- Lithium / Chance of toxicity R/T renal clearance
- Potassium salts / Additive hyperkalemia
- Spironolactone / Additive hyperkalemia
How Supplied:
Capsule: 50 mg, 100 mg
Dosage
•Capsules.
Diuretic.
Adults, initial: 100 mg b.i.d. after meals; maximum daily dose: 300 mg.
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