Moduretic (Amiloride Hydrochloride / Hydrochlorothiazide) - Drug Interactions, Contraindications, Overdosage

DRUG INTERACTIONS

In some patients, the administration of a non-steroidal anti-inflammatory agent can reduce the diuretic, natriuretic, and antihypertensive effects of loop, potassium-sparing and thiazide diuretics. Therefore, when MODURETIC and non-steroidal anti-inflammatory agents are used concomitantly, the patient should be observed closely to determine if the desired effect of the diuretic is obtained. Since indomethacin and potassium-sparing diuretics, including MODURETIC, may each be associated with increased serum potassium levels, the potential effects on potassium kinetics and renal function should be considered when these agents are administered concurrently.

OVERDOSAGE

No data are available in regard to overdosage in humans. The oral LD₅₀ of the combination drug is 189 and 422 mg/kg for female mice and female rats, respectively.

It is not known whether the drug is dialyzable.

No specific information is available on the treatment of overdosage with MODURETIC, and no specific antidote is available. Treatment is symptomatic and supportive. Therapy with MODURETIC should be discontinued and the patient observed closely. Suggested measures include induction of emesis and/or gastric lavage.

Amiloride HCl: No data are available in regard to overdosage in humans.

The oral LD₅₀ of amiloride HCl (calculated as the base) is 56 mg/kg in mice and 36 to 85 mg/kg in rats, depending on the strain.

The most common signs and symptoms to be expected with overdosage are dehydration and electrolyte imbalance. If hyperkalemia occurs, active measures should be taken to reduce the serum potassium levels.

Hydrochlorothiazide: The oral LD₅₀ of hydrochlorothiazide is greater than 10.0 g/kg in both mice and rats.

The most common signs and symptoms observed are those caused by electrolyte depletion (hypokalemia, hypochloremia, hyponatremia) and dehydration resulting from excessive diuresis. If digitalis has also been administered, hypokalemia may accentuate cardiac arrhythmias.

CONTRAINDICATIONS

HYPERKALEMIA

MODURETIC should not be used in the presence of elevated serum potassium levels (greater than 5.5 mEq per liter).

ANTIKALIURETIC THERAPY OR POTASSIUM SUPPLEMENTATION

MODURETIC should not be given to patients receiving other potassium-conserving agents, such as spironolactone or triamterene. Potassium supplementation in the form of medication, potassium-containing salt substitutes or a potassium-rich diet should not be used with MODURETIC except in severe and/or refractory 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.

IMPAIRED RENAL FUNCTION

Anuria, acute or chronic renal insufficiency, and evidence of diabetic nephropathy are contraindications to the use of MODURETIC. Patients with evidence of renal functional impairment (blood urea nitrogen [BUN] levels over 30 mg per 100 mL or serum creatinine levels over 1.5 mg per 100 mL) or diabetes mellitus should not receive the drug without careful, frequent and continuing monitoring of serum electrolytes, creatinine, and BUN levels. Potassium retention associated with the use of an antikaliuretic agent is accentuated in the presence of renal impairment and may result in the rapid development of hyperkalemia.

HYPERSENSITIVITY

MODURETIC is contraindicated in patients who are hypersensitive to this product, or to other sulfonamide-derived drugs.