TRIAMTERENE

TRIAMTERENE (trye-am'ter-een) Dyrenium Classifications: electrolyte and water balance agent; potassium-sparing diuretic; Therapeutic: potassium-sparing diuretic Prototype: Spironolactone Pregnancy Category: D

Availability

50 mg, 100 mg capsules

Action

Structurally related to folic acid. Like spironolactone, has weak diuretic action and a potassium-sparing effect. Promotes excretion of sodium, chloride (to lesser extent), and carbonate. Unlike spironolactone, blocks potassium excretion by direct action on distal renal tubule rather than by inhibiting aldosterone. Decreased glomerular filtration rate and elevated BUN are associated with daily administration.

Therapeutic Effect

Has a diuretic action and a potassium-sparing effect.

Uses

Adjunct in the management of edema associated with CHF, hepatic cirrhosis, nephrotic syndrome, idiopathic edema, steroid-induced edema, and edema due to secondary hyperaldosteronism. Also alone or in conjunction with a thiazide or loop diuretic in patients with hypertension because of its potassium-sparing activity.

Contraindications

Hypersensitivity to drug; anuria, severe or progressive kidney disease or dysfunction; severe liver disease; diabetic neuropathy; elevated serum potassium; severe electrolyte or acid-base imbalance; pregnancy (category D).

Cautious Use

Impaired kidney or liver function; gout; history of gouty arthritis; diabetes mellitus, older adults; history of kidney stones; lactation.

Route & Dosage

Edema Adult: PO 100 mg b.i.d. (max: 300 mg/d), may be able to decrease to 100 mg/d or q.o.d. Geriatric: PO 50 mg/d (max: 100 mg/d in 1–2 divided doses) Child: PO 2–4 mg/kg/d in divided doses or q.o.d. (max: 300 mg/d)

Administration

Oral

• Empty capsule and give with fluid or mix with food, if patient cannot swallow capsule.
• Give drug with or after meals to prevent or minimize nausea.
• Schedule doses to prevent interruption of sleep from diuresis (e.g., with or after breakfast if a single dose is taken, or no later than 6 p.m. if more than one dose is prescribed). Consult physician.
• Withdraw drug gradually in patients on prolonged or high-dose therapy in order to prevent rebound increased urinary excretion of potassium.
• Store in tight, light-resistant containers at 15°–30° C (59°–86° F) unless otherwise directed.

Adverse Effects (≥1%)

GI: Diarrhea, nausea, vomiting, and other GI disturbances. CNS: Dizziness, headache, dry mouth, anaphylaxis, weakness, muscle cramps. Skin: Pruritus, rash, photosensitivity. CV: Hypotension (large doses). Metabolic: Hyperkalemia and other electrolyte imbalances, elevated BUN, elevated uric acid (patients predisposed to gouty arthritis), hyperchloremic acidosis. Hematologic: Blood dyscrasias: granulocytopenia, eosinophilia, megaloblastic anemia in patients with reduced folic acid stores (e.g., hepatic cirrhosis).

Diagnostic Test Interference

Pale blue fluorescence in urine interferes with fluorometric assay of quinidine and lactic dehydrogenase activity. Triamterene may cause increases in blood glucose levels (diabetic patients), BUN, serum potassium, magnesium, and uric acid and urinary calcium excretion.

Interactions

Drug: May increase lithium levels, thus increasing its toxicity; indomethacin may decrease renal elimination of triamterene; angiotensin-converting enzyme (ace) inhibitors, other potassium-sparing diuretics may cause hyperkalemia. Food: High potassium foods may increase risk of hyperkalemia.

Pharmacokinetics

Absorption: Rapidly but variably from GI tract. Onset: 2–4 h. Duration: 7–9 h. Metabolism: In liver to active and inactive metabolites. Elimination: In urine. Half-Life: 100–150 min.

Nursing Implications

Assessment & Drug Effects

• Monitor BP during periods of dosage adjustment. Hypotensive reactions, although rare, have been reported. Take care with ambulation, particularly for older adults.
• Weigh patient under standard conditions, prior to drug initiation and daily during therapy.
• Diuretic response usually occurs on first day of therapy; maximum effect may not occur for several days.
• Monitor and report oliguria and unusual changes in I&O ratio. Consult physician regarding allowable fluid intake.
• Be alert for S&S of kidney stone formation; reported in patients taking high doses or who have low urine volume and increased urine acidity.
• Lab tests: Obtain baseline and periodic determinations of serum potassium and other electrolytes. Obtain periodic kidney function (BUN, serum creatinine) in patients with known or suspected renal insufficiency. Obtain periodic blood studies in patients on prolonged therapy or with cirrhosis since both are prone to develop megaloblastic anemia.
• Observe for S&S of hyperkalemia (see Appendix F), particularly in patients with renal insufficiency, on high-dose or prolonged therapy, older adults, and those with diabetes.
• Do not give to a diabetic patient unless blood glucose is controlled because triamterene may increase blood glucose. Monitor patients closely.

Patient & Family Education

• Do not take potassium supplements, potassium-rich diet, and salt substitutes; unlike most diuretics, triamterene promotes potassium retention.
• Do not restrict salt; there is a possibility of low-salt syndrome (hyponatremia). Consult physician.
• Report overpowering fatigue or weakness, malaise, fever, sore throat, or mouth (possible symptoms of granulocytopenia) and unusual bleeding or bruising (thrombocytopenia) to physician.
• Be aware that drug may cause photosensitivity; avoid exposure to sun and sunlamps.
• Drug may impart a harmless pale blue fluorescence to urine.

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Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug