Maxzide (Triamterene / Hydrochlorothiazide) - Drug Interactions, Contraindications, Overdosage, etc

DRUG INTERACTIONS

Thiazides may add to or potentiate the action of other antihypertensive drugs.

The thiazides may decrease arterial responsiveness to norepinephrine. This diminution is not sufficient to preclude effectiveness of the pressor agent for therapeutic use. Thiazides have also been shown to increase the responsiveness to tubocurarine.

Lithium generally should not be given with diuretics because they reduce its renal clearance and add a high risk of lithium toxicity. Refer to the package insert on lithium before use of such concomitant therapy.

Acute renal failure has been reported in a few patients receiving indomethacin and formulations containing triamterene and hydrochlorothiazide. Caution is therefore advised when administering nonsteroidal anti-inflammatory agents with MAXZIDE (triamterene and hydrochlorothiazide).

Potassium-sparing agents should be used very cautiously, if at all, in conjunction with angiotensin-converting enzyme (ACE) inhibitors due to a greatly increased risk of hyperkalemia. Serum potassium should be monitored frequently.

OVERDOSAGE

No specific data are available regarding MAXZIDE (triamterene and hydrochlorothiazide) overdosage in humans and no specific antidote is available.

Fluid and electrolyte imbalances are the most important concern. Excessive doses of the triamterene component may elicit hyperkalemia, dehydration, nausea, vomiting and weakness and possibly hypotension. Overdosing with hydrochlorothiazide has been associated with hypokalemia, hypochloremia, hyponatremia, dehydration, lethargy (may progress to coma) and gastrointestinal irritation. Treatment is symptomatic and supportive. Therapy with MAXZIDE (triamterene and hydrochlorothiazide) should be discontinued. Induce emesis or institute gastric lavage. Monitor serum electrolyte levels and fluid balance. Institute supportive measures as required to maintain hydration, electrolyte balance, respiratory, cardiovascular and renal function.

CONTRAINDICATIONS

HYPERKALEMIA

MAXZIDE (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.

ANTIKALIURETIC THERAPY OR POTASSIUM SUPPLEMENTATION

MAXZIDE should not be given to patients receiving other potassium-conserving agents such as spironolactone, amiloride HCl or other formulations containing triamterene. Concomitant potassium supplementation in the form of medication, potassium-containing salt substitute or potassium-enriched diets should also not be used.

IMPAIRED RENAL FUNCTION

MAXZIDE is contraindicated in patients with anuria, acute and chronic renal insufficiency or significant renal impairment.

HYPERSENSITIVITY

MAXZIDE should not be used in patients who are hypersensitive to triamterene or hydrochlorothiazide or other sulfonamide-derived drugs.