Lasix (Furosemide) - Drug Interactions, Contraindications, Overdosage

DRUG INTERACTIONS

Drug Interactions

LASIX may increase the ototoxic potential of aminoglycoside antibiotics, especially in the presence of impaired renal function. Except in life-threatening situations, avoid this combination.

LASIX should not be used concomitantly with ethacrynic acid because of the possibility of ototoxicity. Patients receiving high doses of salicylates concomitantly with LASIX, as in rheumatic disease, may experience salicylate toxicity at lower doses because of competitive renal excretory sites.

LASIX has a tendency to antagonize the skeletal muscle relaxing effect of tubocurarine and may potentiate the action of succinylcholine.

Lithium generally should not be given with diuretics because they reduce lithium's renal clearance and add a high risk of lithium toxicity.

LASIX may add to or potentiate the therapeutic effect of other antihypertensive drugs. Potentiation occurs with ganglionic or peripheral adrenergic blocking drugs.

LASIX may decrease arterial responsiveness to norepinephrine. However, norepinephrine may still be used effectively.

Simultaneous administration of sucralfate and LASIX tablets may reduce the natriuretic and antihypertensive effects of LASIX. Patients receiving both drugs should be observed closely to determine if the desired diuretic and/or antihypertensive effect of LASIX is achieved. The intake of LASIX and sucralfate should be separated by at least two hours.

One study in six subjects demonstrated that the combination of furosemide and acetylsalicylic acid temporarily reduced creatinine clearance in patients with chronic renal insufficiency. There are case reports of patients who developed increased BUN, serum creatinine and serum potassium levels, and weight gain when furosemide was used in conjunction with NSAIDs.

Literature reports indicate that coadministration of indomethacin may reduce the natriuretic and antihypertensive effects of LASIX (furosemide) in some patients by inhibiting prostaglandin synthesis. Indomethacin may also affect plasma renin levels, aldosterone excretion, and renin profile evaluation. Patients receiving both indomethacin and LASIX should be observed closely to determine if the desired diuretic and/or antihypertensive effect of LASIX is achieved.

OVERDOSAGE

The principal signs and symptoms of overdose with LASIX are dehydration, blood volume reduction, hypotension, electrolyte imbalance, hypokalemia and hypochloremic alkalosis, and are extensions of its diuretic action.

The acute toxicity of LASIX has been determined in mice, rats and dogs. In all three, the oral LD₅₀exceeded 1000 mg/kg body weight, while the intravenous LD₅₀ranged from 300 to 680 mg/kg. The acute intragastric toxicity in neonatal rats is 7 to 10 times that of adult rats.

The concentration of LASIX in biological fluids associated with toxicity or death is not known.

Treatment of overdosage is supportive and consists of replacement of excessive fluid and electrolyte losses. Serum electrolytes, carbon dioxide level and blood pressure should be determined frequently. Adequate drainage must be assured in patients with urinary bladder outlet obstruction (such as prostatic hypertrophy).

Hemodialysis does not accelerate furosemide elimination.

CONTRAINDICATIONS

LASIX is contraindicated in patients with anuria and in patients with a history of hypersensitivity to furosemide.