Triamterene
Triamterene (Dyrenium)
Triamterene
(try- AM-ter-een)
Pregnancy Category: B Dyrenium (Rx)

Classification: Diuretic, potassium-sparing

See Also: See also Diuretics .

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. t 1/2: 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.