Brands, Medical Use, Clinical Data
Drug Category
- Diuretics
- Potassium-sparing Diuretics
Dosage Forms
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.
|
