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/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. Since uncorrected hyperkalemia may be fatal, serum potassium levels must be monitored at frequent intervals especially in patients first receiving triamterene/hydrochlorothiazide capsules, when dosages are changed or with any illness that may influence renal function.
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WARNINGS 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/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. Since uncorrected hyperkalemia may be fatal, serum potassium levels must be monitored at frequent intervals especially in patients first receiving triamterene/hydrochlorothiazide capsules, when dosages are changed or with any illness that may influence renal function. If hyperkalemia is suspected (warning signs include paresthesias, muscular weakness, fatigue, flaccid paralysis of the extremities, bradycardia and shock), an electrocardiogram (ECG) should be obtained. However, it is important to monitor serum potassium levels because hyperkalemia may not be associated with ECG changes. If hyperkalemia is present, triamterene/hydrochlorothiazide capsules should be discontinued immediately and a thiazide alone should be substituted. If the serum potassium exceeds 6.5 mEq/liter more vigorous therapy is required. The clinical situation dictates the procedures to be employed. These include the intravenous administration of calcium chloride solution, sodium bicarbonate solution and/or the oral or parenteral administration of glucose with a rapid-acting insulin preparation. Cationic exchange resins such as sodium polystyrene sulfonate may be orally or rectally administered. Persistent hyperkalemia may require dialysis. The development of hyperkalemia associated with potassium-sparing diuretics is accentuated in the presence of renal impairment ( see CONTRAINDICATIONS section ). Patients with mild renal functional impairment should not receive this drug without frequent and continuing monitoring of serum electrolytes. Cumulative drug effects may be observed in patients with impaired renal function. The renal clearances of hydrochlorothiazide and the pharmacologically active metabolite of triamterene, the sulfate ester of hydroxytriamterene, have been shown to be reduced and the plasma levels increased following triamterene/hydrochlorothiazide capsules administration to elderly patients and patients with impaired renal function. Hyperkalemia has been reported in diabetic patients with the use of potassium-sparing agents even in the absence of apparent renal impairment. Accordingly, serum electrolytes must be frequently monitored if triamterene/hydrochlorothiazide capsules are used in diabetic patients. Metabolic or Respiratory Acidosis Potassium-sparing therapy should also be avoided in severely ill patients in whom respiratory or metabolic acidosis may occur. Acidosis may be associated with rapid elevations in serum potassium levels. If triamterene/hydrochlorothiazide capsules are employed, frequent evaluations of acid/base balance and serum electrolytes are necessary.
ADVERSE REACTIONS Adverse effects are listed in decreasing order of frequency; however, the most serious adverse effects are listed first regardless of frequency. The serious adverse effects associated with triamterene/hydrochlorothiazide capsules have commonly occurred in less than 0.1% of patients treated with this product. Hypersensitivity anaphylaxis, rash, urticaria, photosensitivity. Cardiovascular arrhythmia, postural hypotension. Metabolic diabetes mellitus, hyperkalemia, hyperglycemia, glycosuria, hyperuricemia, hypokalemia, hyponatremia, acidosis, 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. Central Nervous System weakness, fatigue, dizziness, headache, dry mouth. Miscellaneous impotence, sialadenitis. Thiazides alone have been shown to cause the following additional adverse reactions: Central Nervous System paresthesias, vertigo. Ophthalmic xanthopsia, transient blurred vision. Respiratory allergic pneumonitis, pulmonary edema, respiratory distress. Other necrotizing vasculitis, exacerbation of lupus. Hematologic aplastic anemia, agranulocytosis, hemolytic anemia. Neonate and infancy thrombocytopenia and pancreatitis — rarely, in newborns whose mothers have received thiazides during pregnancy.