LOOP DIURETIC DOSING

• ACRONYMS AND DEFINITIONS

• CrCl - Creatinine clearance
• P = Drugs with approved pediatric dosing

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• Kidney disease dosing
• Patients with significant kidney disease need diuretics to help increase fluid elimination
• Loop diuretics are the most effective class of diuretics for eliminating fluid
• Loop diuretics maintain their effectiveness once the CrCl falls below 30 ml/min, where thiazide diuretics do not

• Liver disease dosing
• Cirrhosis (Child-Pugh C)
• Patients with cirrhosis often need diuretics to control fluid retention
• Loop diuretics and spironolactone are preferred in these patients
• See cirrhosis treatment recommendations for more
• Mild to moderate liver disease (Child-Pugh A/B)
• Dosage adjustments are not typically needed

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• DRUG INTERACTIONS

• NOTE: Drug interactions presented here are NOT all-inclusive. Other interactions may exist. The interactions presented here are meant to encompass commonly prescribed medications and/or interactions that are well-documented. Always consult your physician or pharmacist before taking medications concurrently. CLICK HERE for more information on drug interactions.


• All loop diuretics
• Aminoglycoside antibiotics (gentamicin, etc) - Loop diuretics and aminoglycoside antibiotics both have the potential to cause ototoxicity (hearing loss). The risk may be increased when they are taken together.
• Bile Acid Sequestrants (Questran®, Welchol®, etc) - Bile acid sequestrants may decrease the absorption of loop diuretics. Loop diuretics should be taken one hour before or 4 hours after bile acid sequestrants.
• Cisplatin - Loop diuretics and cisplatin both have the potential to cause ototoxicity (hearing loss). The risk may be increased when they are taken together. Loop diuretics may also increase the risk of kidney damage from cisplatin.
• Cyclosporine - Loop diuretics and cyclosporine both increase the risk of gout. When taken together, the risk may be compounded.
• Ethacrynic acid - Loop diuretics and ethacrynic acid both have the potential to cause ototoxicity (hearing loss). The risk may be increased when they are taken together.
• Lithium - Loop diuretics may reduce the clearance of lithium. Loop diuretics should not be taken with lithium if possible. Lithium levels should be monitored closely in patients taking loop diuretics.
• Methotrexate - Loop diuretics may increase blood levels of methotrexate and vice versa.
• NSAIDS (Advil®, ibuprofen, naprosyn, etc.) - NSAIDS can block the therapeutic effect of all diuretics. Patients should monitor for decreased effectiveness of diuretics when taking NSAIDS for extended periods.
• Probenecid - Probenecid may inhibit the action of loop diuretics
• Salicylates (Aspirin, etc.) - In patients receiving high doses of salicylates, loop diuretics may block their clearance and increase the risk of salicylate toxicity.
• Thyroid hormone (Synthroid®, levothyroxine, etc.) - high doses of furosemide (> 80 mg) may inhibit binding of thyroid hormone to thyroxine-binding globulin (TBG). This can increase free levels of thyroid hormone and subsequently lead to a decrease in total (free and bound) thyroid.


• Furosemide
• Sucralfate (Carafate®) - Sucralfate may inhibit the effects of furosemide. Intake should be separated by 2 hours.
• Cephalosporin antibiotics (Keflex®, Rocephin®, etc) - Furosemide may potentiate the risk of cephalosporin-induced kidney damage
• Phenytoin (Dilantin®) - Phenytoin may inhibit the diuretic effect of furosemide

• Metabolism and clearance
• Furosemide
• Furosemide does not undergo extensive liver metabolism
• Bumetanide
• The liver metabolism of bumetanide is not well-defined
• Torsemide
• CYP2C9 - substrate
• CYP2C8 - substrate

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• PHARMACOKINETICS

Drug	Peak effect	Duration of effect
Furosemide	1 - 2 hours	6 - 8 hours
Bumetanide	1 - 2 hours	4 - 6 hours
Torsemide	1 - 2 hours	6 - 8 hours

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• PRICE ($) INFO

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• BIBLIOGRAPHY

• 1 - Manufacturer's package insert
• 2 - PubMed ID 8971430