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Triamterene

Pronunciation

Pronunciation: try-AM-tur-een
Class: Potassium-sparing diuretic

Trade Names

Dyrenium
- Capsules 50 mg
- Capsules 100 mg

Pharmacology

Interferes with sodium reabsorption at distal renal tubule, resulting in increased excretion of sodium and water and decreased excretion of potassium.

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Pharmacokinetics

Absorption

C max is 30 ng/mL and T max is 3 h. Triamterene is rapidly absorbed; max effect is seen in several days.

Distribution

Triamterene crosses the placental barrier.

Metabolism

Triamterene is primarily metabolized to sulfate conjugate of hydroxytriamterene.

Elimination

Less than 50% of triamterene is excreted in urine.

Onset

Onset of action is 2 to 4 h after ingestion.

Peak

Time to peak effect is 3 h.

Duration

Duration of diuresis depends on several factors, especially renal function, but generally it tapers off 7 to 9 h after administration.

Indications and Usage

Treatment of edema associated with CHF, hepatic cirrhosis, and nephrotic syndrome; treatment of steroid-induced edema, idiopathic edema, and edema caused by secondary hyperaldosteronism; management of hypertension in patient with diuretic-induced hypokalemia or at risk of hypokalemia.

Contraindications

Treatment with spironolactone or amiloride; anuria; severe hepatic disease; hyperkalemia; severe or progressive kidney disease or dysfunction, with exception of nephrosis.

Dosage and Administration

Adults

PO 100 mg twice daily after meals (max, 300 mg/day).

Children

PO 2 to 4 mg/kg/day given in 1 dose or 2 divided doses (max, 300 mg/day).

Storage/Stability

Store at room temperature in tight, light resistant container.

Drug Interactions

ACE inhibitors

May result in severely elevated serum potassium levels.

Indomethacin

May cause rapid progression into acute renal failure.

Potassium preparations and salt substitutes

May severely increase serum potassium levels, possibly resulting in cardiac arrhythmias or cardiac arrest. Do not take with potassium preparations.

Laboratory Test Interactions

May interfere with fluorometry such as quinidine serum levels and LDH determination.

Adverse Reactions

Cardiovascular

Hypotension.

CNS

Weakness; fatigue; dizziness; headache.

Dermatologic

Photosensitivity; rash.

GI

Diarrhea; nausea; vomiting; dry mouth.

Genitourinary

Azotemia; elevated BUN and creatinine; renal stones; bluish discoloration to urine; interstitial nephritis.

Hepatic

Jaundice; liver enzyme abnormalities.

Hematologic

Thrombocytopenia; megaloblastic anemia.

Metabolic

Hyponatremia; hyperchloremic metabolic acidosis; hyperkalemia.

Miscellaneous

Anaphylaxis; muscle cramps.

Precautions

Pregnancy

Category B .

Lactation

Undetermined.

Renal Function

Use drug with caution; monitor renal function.

Adult-onset diabetes mellitus

Blood glucose levels may be increased; dosage adjustments of hypoglycemic agents may be needed.

Concurrent diuretic therapy

Dosage reduction may be necessary.

Electrolyte imbalances and BUN increase

Hyperkalemia (serum potassium greater than 5.5 mEq/L), hyponatremia, hyperchloremia, and increases in BUN may occur. Monitor serum electrolytes and BUN levels.

Hematologic effects

Triamterene is weak folic acid antagonist and may contribute to appearance of megaloblastosis.

Metabolic acidosis

May decrease alkali reserve with possibility of metabolic acidosis.

Renal stones

Triamterene has been found in renal stones. Use drug with caution in patients with history of stone formation.

Overdosage

Symptoms

Hypotension, hyperkalemia, metabolic acidosis, nausea, vomiting, weakness, acute renal failure.

Patient Information

  • Tell patient to avoid salt substitutes and limit potassium-rich foods.
  • Inform patients taking antihypertensives that additive effects are possible; identify signs and symptoms of hypotension and precautions to be taken.
  • Advise patient that medication may cause urine to become blue tinged.
  • Explain potential GI adverse reactions and to take medication after meals.
  • Tell patient that drug may cause weakness, headache, nausea, vomiting, or dry mouth and to notify health care provider if they become severe or persistent.
  • Instruct patient to report these symptoms to health care provider: fever, sore throat, mouth sores, unusual bleeding or bruising.
  • Caution patient to avoid intake of alcoholic beverages or other CNS depressants.
  • Advise patient to use caution while driving or performing other tasks requiring mental alertness.
  • Caution patient to avoid exposure to sunlight or ultraviolet light and to use sunscreen or wear protective clothing to prevent photosensitivity reaction.

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