Torsemide
Indication
Torsemide is most commonly used in the management of edema during CHF and hepatic or renal disease. It may also be used in the treatment of hypertensive patients alone or in combination with other antihypertensive medications.
Mechanism of Action
Torsemide is a loop diuretic and functions through inhibition of reabsorption of sodium and chloride from the ascending loop of Henle. It interferes with the chloride-binding cotransport system (Na+-K+-2C1~ symporter) and halts salt transport in this segment. This action causes increased excretion of water, sodium, chloride, and potassium. The drug also inhibits calcium and magnesium reabsorption in the ascending limb by eliminating the transepithelial potential difference.
Dosing
Neonates, infants, and children: no data is available Adults:
Oral I.V.:
Edema: 10 to 20 mg once daily. Titrate up to maximum dose of 200mg/day
Hypertension: 5mg once daily initially, then increase to 10 mg once daily, if needed, after 4 to 6 weeks
Pharmacokinetics
Rapidly absorbed; bioavailability, 80 to 90%. Peak serum concentrations are reached in 1 hour. Torsemide is metabolized by cytochrome P450. The half-life of torsemide is normally 2 to 4 hours, but is increased to 7 to 8 hours in cirrhosis. Of the total dose, 20% is excreted unchanged in the urine.
Monitoring parameters: serum electrolytes, renal function, blood pressure
Contraindications: anuria
Precautions/Adverse Effects
Warning: loop diuretics are potent agents. Excess amounts may lead to profound diuresis with fluid and electrolyte loss. Close medical supervision and dose evaluation is required.
Adverse effects that may occur with torsemide use include hypotension, chest pain, dizziness, headache, prerenal azotemia, and rashes. Other effects may include hypokalemia, nausea, pancreatitis, photosensitivity, diarrhea, dehydration, and decreased uric acid excretion. Hyponatremia, hypochloremia, arthritic pain, metabolic alkalosis, hypercalciuria, agranulocytosis, anemia, hyperuricemia, and cramps have also been reported.
Drug-Drug Interactions
Increased potassium losses with torsemide increase the risk of digoxin toxicity. Use of torsemide with aminoglycosides or ethacrynic acid increases risk of ototoxicity. Torsemide use increases the anticoagulant effects of warfarin. NSAIDs decrease the diuretic effect of torsemide. Torsemide decreases lithium excretion; and decreased glucose tolerance with torsemide may increase requirements of oral antidiabetic agents.
Poisoning Information
Symptoms of torsemide overdose may include acute and profound water loss, volume and electrolyte depletion, dehydration, reduction of blood volume, and circulatory collapse. Electrolyte depletion maybe manifested by weakness, dizziness, mental confusion, anorexia, lethargy, vomiting, and cramps. Decontamination using activated charcoal is recommended and other treatment is supportive and symptomatic. Replacement of fluid and electrolyte losses maybe necessary.
Compatible Diluents/Administration
Administer torsemide undiluted by direct I.V. injection over at least 2 minutes; torsemide maybe diluted in D5W orNS to concentrations of 0.1,0.2,0.4, or 0.8 mg/ mL for continuous infusion, and is stable for 24 hours at room temperature.
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