Action

Inhibits sodium and chloride reabsorption from ascending loop of Henle and distal renal tubule; increases renal excretion of water, sodium, chloride, magnesium, calcium, and hydrogen. Also may exert renal and peripheral vasodilatory effects. Net effect is natriuretic diuresis.

Availability

Injection: 10 mg/ml

Tablets: 5 mg, 10 mg, 20 mg, 100 mg

Indications and dosages

➣ Heart failure

Adults: 10 to 20 mg P.O. or I.V. daily. If response inadequate, double dosage until desired response occurs. Don't exceed 200 mg as a single dose.

➣ Hypertension

Adults: 5 mg P.O. daily. May increase to 10 mg daily after 4 to 6 weeks; if drug still isn't effective, additional antihypertensives may be prescribed.

➣ Chronic renal failure

Adults: 20 mg P.O. or I.V. daily. If response inadequate, double dosage until desired response occurs. Don't exceed 200 mg as a single dose.

➣ Hepatic cirrhosis

Adults: 5 or 10 mg P.O. or I.V. daily, given with aldosterone antagonist or potassium-sparing diuretic. If response inadequate, double dosage. Don't exceed 40 mg as a single dose.

Contraindications

• Hypersensitivity to drug, thiazides, or sulfonylureas

• Anuria

Precautions

Use cautiously in:

• severe hepatic disease accompanied by cirrhosis or ascites, preexisting uncorrected electrolyte imbalances, diabetes mellitus, worsening azotemia

• elderly patients

• pregnant or breastfeeding patients

• children younger than age 18.

Administration

• Give I.V. by direct injection over at least 2 minutes or by continuous I.V. infusion.

• Flush I.V. line with normal saline solution before and after administering.

Adverse reactions

CNS: dizziness, headache, asthenia, insomnia, nervousness, syncope

CV: hypotension, ECG changes, chest pain, volume depletion, atrial fibrillation, ventricular tachycardia, shunt thrombosis

EENT: rhinitis, sore throat

GI: nausea, diarrhea, vomiting, constipation, dyspepsia, anorexia, rectal bleeding, GI hemorrhage

GU: excessive urination

Metabolic: hyperglycemia, hyperuricemia, hypokalemia

Musculoskeletal: joint pain, myalgia

Respiratory: increased cough

Skin: rash

Other: edema

Interactions

Drug-drug. Aminoglycosides, cisplatin: increased risk of ototoxicity

Amphotericin B, corticosteroids, mezlocillin, piperacillin, potassium-wasting diuretics, stimulant laxatives: additive hypokalemia

Antihypertensives, nitrates: additive hypotension

Lithium: increased lithium blood level and toxicity

Neuromuscular blockers: prolonged neuromuscular blockade

Nonsteroidal anti-inflammatory drugs, probenecid: inhibited diuretic response

Sulfonylureas: decreased glucose tolerance, hyperglycemia in patients with previously well-controlled diabetes

Drug-diagnostic tests. Glucose, uric

acid: increased levels

Potassium: decreased level

Drug-herbs. Dandelion: interference with diuresis

Ephedra (ma huang): reduced hypotensive effect of torsemide

Geranium, ginseng: increased risk of diuretic resistance

Licorice: rapid potassium loss

Drug-behaviors. Acute alcohol ingestion: additive hypotension

Patient monitoring

• Monitor vital signs, especially for hypotension.

• Assess ECG for arrhythmias and other changes.

• Monitor weight and fluid intake and output to assess drug efficacy.

• Monitor electrolyte levels, particularly potassium. Stay alert for signs and symptoms of hypokalemia.

• Assess hearing for signs and symptoms of ototoxicity.

• Monitor blood glucose level carefully in diabetic patient.

Patient teaching

• Advise patient to take in morning with or without food.

• Instruct patient to move slowly when sitting up or standing, to avoid dizziness from sudden blood pressure drop.

• Tell patient to monitor weight and report sudden increases.

• Instruct diabetic patient to monitor blood glucose level carefully.

• Caution patient to avoid alcohol during drug therapy.

• Advise patient to consult prescriber before using herbs.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, herbs, and behaviors mentioned above.