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 Tablets are indicated for the treatment of hypertension or edema in patients who develop hypokalemia on hydrochlorothiazide alone. Triamterene and hydrochlorothiazide is also indicated for those patients who require a thiazide diuretic and in whom the development of hypokalemia cannot be risked (e.g., patients on concomitant digitalis preparations, or with a history of cardiac arrhythmias, etc.). Triamterene and hydrochlorothiazide may be used alone or in combination with other antihypertensive drugs such as beta-blockers.Since triamterene and hydrochlorothiazide may enhance the actions of these drugs, dosage adjustments may be necessary.
Triamterene and hydrochlorothiazide should not be used in the presence of elevated serum potassium levels (greater than or equal to 5.5 mEq/liter).If hyperkalemia develops, this drug should be discontinued and a thiazide alone should be substituted.
Abnormal elevation of serum potassium levels (greater than or equal to 5.5 mEq/liter) can occur with all potassium-conserving diuretic combinations, including triamterene and hydrochlorothiazide.
Hyperkalemia is more likely to occur in patients with renal impairment, diabetes (even without evidence of renal impairment) or elderly or severely ill patients.
Since uncorrected hyperkalemia may be fatal, serum potassium levels must be monitored at frequent intervals especially in patients first receiving triamterene and hydrochlorothiazide, 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 mild hyperkalemia may not be associated with ECG changes. If hyperkalemia is present, triamterene and hydrochlorothiazide should be discontinued immediately and a thiazide only 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 injection, sodium bicarbonate injection 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 (seeCONTRAINDICATIONS).
Patients with mild renal function 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 and hydrochlorothiazide administration to elderly patients and patients with impaired renal function. Hyperkalemia has been reported in diabetic patients with the use of potassium-conserving agents even in the absence of apparent renal impairment.
Accordingly, triamterene and hydrochlorothiazide should be avoided in diabetic patients.If it is employed, serum electrolytes must be frequently monitored. Because of the potassium-sparing properties of angiotensin-converting enzyme (ACE) inhibitors, triamterene and hydrochlorothiazide should be used cautiously, if at all, with these agents (seePRECAUTIONS, Drug Interactions).