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Active ingredient: Triamterene - Brands, Medical Use, Clinical Data

Brands, Medical Use, Clinical Data

Drug Category

  • Diuretics
  • Potassium-sparing Diuretics

Dosage Forms

  • Tablet

Brands / Synonyms

Ademin; Ademine; Diren; Ditak; Diucelpin; Diurene; Dyazide; Dyren; Dyrenium; Dytac; Jatropur; Maxzide; Maxzide-25; Noridil; Noridyl; Pterofen; Pterophene; Taturil; Teriam; Teridin; Tri-Span; Triampur; Triamteren; Triamterene and Hydrochlorothiazide; Triamteril; Triamteril Complex; Trispan; Triteren; Urocaudal

Indications

For the treatment of edema associated with congestive heart failure, cirrhosis of the liver, and the nephrotic syndrome; also in steroid-induced edema, idiopathic edema, and edema due to secondary hyperaldosteronism.

Pharmacology

Triamterene, a relatively weak, potassium-sparing distal tubule diuretic and antihypertensive, is used in the management of hypokalemia. Triamterene is similar in action to amiloride but, unlike amiloride, increases the urinary excretion of magnesium.

Mechanism of Action

Triamterene interferes with sodium reabsorption in the distal renal tubule by inhibiting sodium transport mechanisms directly. Specifically it inhibits the Na+/K+/2Cl- co-transporter. The result is an electrical-potential difference across the membrane that blocks the passive distal tubular secretion of potassium. Relative to other diuretics, triamterene has a unique mode of action as it inhibits the reabsorption of sodium ions in exchange for potassium and hydrogen ions at that segment of the distal tubule under the control of adrenal mineralocorticoids (especially aldosterone).

Absorption

Rapidly absorbed, with somewhat less than 50% of the oral dose reaching the urine.

Toxicity

Not Available

Biotrnasformation / Drug Metabolism

Triamterene is primarily metabolized to the sulfate conjugate of hydroxytriamterene. Both the plasma and urine levels of this metabolite greatly exceed triamterene levels.

Contraindications

Anuria, severe or progressive kidney disease or dysfunction with the possible exception of nephrosis. Severe hepatic disease. Hypersensitivity to the drug.

Triamterene should not be used in patients with preexisting elevated serum potassium, as is sometimes seen in patients with impaired renal function or azotemia, or in patients who develop hyperkalemia while on the drug. Patients should not be placed on dietary potassium supplements, potassium salts, or potassium-containing salt substitutes in conjunction with triamterene.

Triamterene should not be given to patients receiving other potassium-sparing agents such as spironolactone, amiloride hydrochloride, or other formulations containing triamterene. Two deaths have been reported in patients receiving concomitant spironolactone and triamterene or Dyazide. Although dosage recommendations were exceeded in one case and in the other serum electrolytes were not properly monitored, these two drugs should not be given concomitantly.

Drug Interactions

Caution should be used when lithium and diuretics are used concomitantly because diuretic-induced sodium loss may reduce the renal clearance of lithium and increase serum lithium levels with risk of lithium toxicity. Patients receiving such combined therapy should have serum lithium levels monitored closely and the lithium dosage adjusted if necessary.

A possible interaction resulting in acute renal failure has been reported in a few subjects when indomethacin, a nonsteroidal anti-inflammatory agent, was given with triamterene. Caution is advised in administering nonsteroidal anti-inflammatory agents with triamterene.

The effects of the following drugs may be potentiated when given together with triamterene: antihypertensive medication, other diuretics, preanesthetic and anesthetic agents, skeletal muscle relaxants (nondepolarizing).

Potassium-sparing agents should be used with caution in conjunction with angiotensin-converting enzyme (ACE) inhibitors due to an increased risk of hyperkalemia.

The following agents, given together with triamterene, may promote serum potassium accumulation and possibly result in hyperkalemia because of the potassium-sparing nature of triamterene, especially in patients with renal insufficiency: blood from blood bank (may contain up to 30 mEq of potassium per liter of plasma or up to 65 mEq per liter of whole blood when stored for more than 10 days); low-salt milk (may contain up to 60 mEq of potassium per liter); potassium-containing medications (such as parenteral penicillin G potassium); salt substitutes (most contain substantial amounts of potassium).

Triamterene may raise blood glucose levels; for adult-onset diabetes, dosage adjustments of hypoglycemic agents may be necessary during and after therapy; concurrent use with chlorpropamide may increase the risk of severe hyponatremia.

Drug/Laboratory Test Interactions

Triamterene and quinidine have similar fluorescence spectra; thus, triamterene will interfere with the fluorescent measurement of quinidine.

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