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Hydrochlorothiazide / Triamterene

Pronunciation

Pronunciation: high-droe-klor-oh-THIGH-uh-zide/try-AM-tur-een
Class: Diuretic combination

Trade Names

Maxzide-25MG
- Tablets 37.5 mg triamterene/25 mg hydrochlorothiazide

Dyazide
- Capsules 37.5 mg triamterene/25 mg hydrochlorothiazide

Maxzide
- Tablets 75 mg triamterene/50 mg hydrochlorothiazide

Apo-Triazide (Canada)
Nu-Triazide (Canada)

Pharmacology

Hydrochlorothiazide inhibits reabsorption of sodium and chloride in ascending loop of Henle and early distal tubules. Triamterene interferes with sodium reabsorption at distal tubule. Combination provides additive diuretic activity and antihypertensive effects and minimizes potassium depletion.

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Indications and Usage

Treatment of edema or hypertension in patients who have or are at risk of developing hypokalemia.

Contraindications

Anuria; renal decompensation; severe hepatic disease; hypersensitivity to thiazides, triamterene, or sulfonamide-derived drugs; patients receiving spironolactone, amiloride, or potassium supplements; hyperkalemia; metabolic or respiratory acidosis.

Dosage and Administration

Adults

PO 1 to 2 tablets or capsules daily.

Storage/Stability

Store in tightly closed container at room temperature.

Drug Interactions

Angiotensin-converting enzyme inhibitors

May result in severely elevated serum potassium levels.

Allopurinol

May increase incidence of hypersensitivity reactions to allopurinol.

Amantadine

May increase amantadine plasma levels and risk for adverse reactions.

Anticoagulants

May diminish anticoagulant effects.

Bile acid sequestrants

May reduce thiazide absorption; give thiazide at least 2 h before sequestrant.

Diazoxide

May cause hyperglycemia.

Digitalis glycosides

Diuretic-induced hypokalemia and hypomagnesemia may precipitate digitalis-induced arrhythmias.

Indomethacin

May cause rapid progression into acute renal failure.

Lithium

May decrease renal excretion of lithium; monitor lithium levels.

Loop diuretics

May cause synergistic effects that may result in profound diuresis and serious electrolyte abnormalities.

Methenamines, NSAIDs

May decrease effectiveness of thiazide.

Potassium preparations

May severely increase serum potassium levels, possibly resulting in cardiac arrhythmias or cardiac arrest. Monitor serum potassium closely if potassium is coadministered.

Sulfonylureas, insulin

May decrease hypoglycemic effect of sulfonylureas. May need to adjust dosage of sulfonylureas or insulin.

Laboratory Test Interactions

May interfere with the fluorescent measurement of quinidine serum levels. May decrease serum protein-bound iodine levels without signs of thyroid disturbance.

Adverse Reactions

Cardiovascular

Orthostatic hypotension.

CNS

Dizziness; lightheadedness; vertigo; headache; paresthesias; weakness; restlessness; insomnia; fatigue.

Dermatologic

Purpura; photosensitivity; rash; urticaria; necrotizing angiitis, vasculitis, cutaneous vasculitis; alopecia; exfoliative dermatitis; toxic epidermal necrolysis; erythema multiforme; Stevens-Johnson syndrome.

EENT

Blurred vision; xanthopsia (yellow vision).

GI

Anorexia; gastric irritation; nausea; vomiting; abdominal pain or cramping; bloating; diarrhea; constipation; pancreatitis; sialadenitis; dry mouth.

Genitourinary

Impotence; reduced libido; interstitial nephritis; azotemia; elevated BUN and creatinine.

Hematologic

Leukopenia; thrombocytopenia; agranulocytosis; aplastic or hypoplastic anemia; hemolytic anemia; megaloblastic anemia.

Hepatic

Jaundice; liver enzyme abnormalities.

Metabolic

Hyperglycemia; glycosuria; hyperuricemia; hyperkalemia; electrolyte imbalance; hypochloremia; hyponatremia.

Miscellaneous

Muscle cramp or spasm; fever; anaphylactic reactions.

Precautions

Pregnancy

Category C .

Lactation

Excreted in breast milk.

Children

Safety and efficacy have not been established.

Hypersensitivity

May occur in patients with or without history of allergy or bronchial asthma; cross-sensitivity with sulfonamides may also occur.

Renal Function

May precipitate azotemia or hypermagnesemia; use drug with caution.

Hepatic Function

Minor alterations of fluid and electrolyte balance may precipitate hepatic coma; use drug with caution.

Electrolyte imbalances and BUN increase

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

Hematologic effects

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

Lipids

May affect total serum cholesterol, total triglycerides, and LDL in some patients.

Postsympathectomy

Antihypertensive effects may be enhanced.

Renal stones

Triamterene has been found in renal stones; use drug with caution in patients with histories of stone formation.

Overdosage

Symptoms

Orthostatic or general hypotension, tachycardia, syncope, electrolyte abnormalities, potassium deficiency, vomiting, nausea, shock, weakness, confusion, dizziness, cramps of calf muscles, thirst, polyuria, anuria, lethargy.

Patient Information

  • Instruct patient to take medication early in day to avoid diuretic effect at night.
  • Tell patient to take drug with food or milk and to report GI symptoms.
  • Advise patient to limit sodium intake for optimal drug effect.
  • Advise patient to limit exposure to sun and to use sunscreen or wear protective clothing to avoid photosensitivity reaction.
  • Instruct diabetic patients to report increased levels of blood glucose.
  • Caution patient to avoid sudden position changes to prevent orthostatic hypotension.
  • Tell patient to report these symptoms to health care provider: decrease in urinary output, jaundice, muscle cramps, weakness, nausea, blurred vision, dizziness.
  • Instruct patient to drink 2 to 3 L/day of water unless contraindicated.
  • Advise patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.

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