triamterene(redirected from Apo-Trihex)
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Pharmacologic class: Potassium-sparing diuretic
Therapeutic class: Diuretic
Pregnancy risk category B
FDA Box Warning
• Abnormal serum potassium elevation may occur, and is more likely in patients with renal impairment or diabetes and in elderly or severely ill patients. As uncorrected hyperkalemia may be fatal, monitor serum potassium levels frequently, especially when dosage is changed or patient has an illness that may influence renal function.
Depresses sodium resorption and potassium excretion in renal distal tubule
Capsules: 50 mg, 100 mg
Indications and dosages
Adults: 100 mg P.O. b.i.d. Do not exceed 300 mg/day.
• Concurrent antihypertensive drug therapy
• Elderly patients
• Diabetes insipidus
• Hypersensitivity to drug
• Severe hepatic disease
• Anuria, severe renal dysfunction (except nephrosis)
• Concurrent use of other potassium-sparing diuretics or potassium supplements
Use cautiously in:
• hepatic dysfunction, renal insufficiency, diabetes mellitus
• history of gout or renal calculi
• elderly or debilitated patients
• pregnant or breastfeeding patients
• children (safety not established).
• Give after meals.
• Know that drug may be used alone or as adjunct to thiazide or loop diuretics.
• Make sure patient stops taking potassium supplements before starting triamterene.
CNS: headache, fatigue, asthenia, dizziness
GI: nausea, vomiting, diarrhea, dry mouth
GU: azotemia, renal calculi
Hematologic: megaloblastic anemia, thrombocytopenia
Metabolic: hyperglycemia, hyperkalemia, metabolic acidosis
Skin: rash, photosensitivity
Drug-drug. Amantadine: increased amantadine blood level, greater risk of toxicity
Angiotensin-converting enzyme inhibitors, cyclosporine, indomethacin, potassium-sparing diuretics, potassium supplements, other potassium-containing
preparations: increased risk of hyperkalemia
Antihypertensives, nondepolarizing muscle relaxants, other diuretics, preanesthetic and anesthetic agents: potentiated effects of these drugs
Chlorpropamide: increased risk of hyponatremia
Cimetidine: increased bioavailability and decreased renal clearance of triamterene
Indomethacin: increased risk of acute renal failure
Lithium: decreased lithium clearance, greater risk of lithium toxicity
Drug-diagnostic tests. Alkali reserves, hemoglobin, platelets: decreased values
Blood urea nitrogen (BUN), creatinine, glucose, hepatic enzymes, potassium: increased levels
Liver function tests: increased values
Quinidine blood level: interference with fluorescent measurement
Drug-food. Salt substitutes containing potassium: increased risk of hyperkalemia
Drug-herbs. Gossypol, licorice: increased risk of hypokalemia
• Monitor BUN, creatinine, and electrolyte levels. Stay alert for hyperkalemia.
• Assess CBC with white cell differential.
• Advise patient to take after meals to reduce nausea.
• Instruct patient to take last daily dose in early evening to avoid nocturia.
• Teach patient to recognize and report signs and symptoms of electrolyte imbalances.
• Tell patient to avoid salt substitutes. Advise him not to use herbs without consulting prescriber.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, and herbs mentioned above.