Hydrochlorothiazide and Triamterene

This fixed combination drug is not indicated for the initial therapy of edema or hypertension except in individuals in whom the development of hypokalemia cannot be risked. Triamterene and hydrochlorothiazide capsules are indicated for the treatment of hypertension or edema in patients who develop hypokalemia on hydrochlorothiazide alone. Triamterene and hydrochlorothiazide capsules are also indicated for those patients who require a thiazide diuretic and in whom the development of hypokalemia cannot be risked. Triamterene and hydrochlorothiazide capsules may be used alone or as an adjunct to other antihypertensive drugs, such as beta-blockers. Since triamterene and hydrochlorothiazide capsules may enhance the action of these agents, dosage adjustments may be necessary.

The usual dose of triamterene and hydrochlorothiazide capsules is 1 or 2 capsules given once daily, with appropriate monitoring of serum potassium and of the clinical effect.

Antikaliuretic Therapy and Potassium Supplementation Triamterene and hydrochlorothiazide capsules should not be given to patients receiving other potassium-sparing agents such as spironolactone, amiloride, or other formulations containing triamterene. Concomitant potassium-containing salt substitutes should also not be used. Potassium supplementation should not be used with triamterene and hydrochlorothiazide capsules except in severe cases of hypokalemia. Such concomitant therapy can be associated with rapid increases in serum potassium levels. If potassium supplementation is used, careful monitoring of the serum potassium level is necessary.

Hyperkalemia Abnormal elevation of serum potassium levels (greater than or equal to 5.5 mEq/liter) can occur with all potassium-sparing diuretic combinations, including triamterene and hydrochlorothiazide capsules. Hyperkalemia is more likely to occur in patients with renal impairment and diabetes (even without evidence of renal impairment) and in the elderly or severely ill. Diabetes Caution should be exercised when administering triamterene and hydrochlorothiazide capsules to patients with diabetes, since thiazides may cause hyperglycemia, glycosuria, and alter insulin requirements in diabetes. Also, diabetes mellitus may become manifest during thiazide administration. Impaired Hepatic Function Thiazides should be used with caution in patients with impaired hepatic function. They can precipitate hepatic coma in patients with severe liver disease.

Adverse effects are listed in decreasing order of severity. Hypersensitivity: Anaphylaxis, rash, urticaria, subacute cutaneous lupus erythematosus-like reactions, photosensitivity. Cardiovascular: Arrhythmia, postural hypotension. Metabolic: Diabetes mellitus, hyperkalemia, hypokalemia, hyponatremia, acidosis, hypercalcemia, hyperglycemia, glycosuria, hyperuricemia, hypochloremia. Gastrointestinal: Jaundice and/or liver enzyme abnormalities, pancreatitis, nausea and vomiting, diarrhea, constipation, abdominal pain. Renal: Acute renal failure (one case of irreversible renal failure has been reported), interstitial nephritis, renal stones composed primarily of triamterene, elevated BUN and serum creatinine, abnormal urinary sediment. Hematologic: Leukopenia, thrombocytopenia and purpura, megaloblastic anemia. Musculoskeletal: Muscle cramps.

Angiotensin-Converting Enzyme Inhibitors Potassium-sparing agents should be used with caution in conjunction with angiotensin-converting enzyme (ACE) inhibitors due to an increased risk of hyperkalemia. Oral Hypoglycemic Drugs Concurrent use with chlorpropamide may increase the risk of severe hyponatremia. Nonsteroidal Anti-inflammatory Drugs A possible interaction resulting in acute renal failure has been reported in a few patients on triamterene and hydrochlorothiazide capsules when treated with indomethacin, a nonsteroidal anti-inflammatory agent. Caution is advised in administering nonsteroidal anti-inflammatory agents with triamterene and hydrochlorothiazide capsules. Lithium Lithium generally should not be given with diuretics because they reduce its renal clearance and increase the risk of lithium toxicity.

Store at 20° to 25°C (68° to 77°F). Protect from light.