Furosemide with Phenprocoumon Interaction Details
Brand Names Associated with Furosemide
- Furosemide
- Lasix®
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 10, 2023
Interaction Effect
Altered protein binding of phenprocoumon and furosemide
Interaction Summary
Various studies have reported different results following the coadministration of phenprocoumon and furosemide. These include no changes in the plasma protein binding of phenprocoumon, decreased phenprocoumon protein binding, or slightly decreased furosemide protein binding.
Severity
Minor
Onset
Rapid
Evidence
Theoretical
How To Manage Interaction
Although various results have been reported following coadministration with phenprocoumon and furosemide, anticoagulation control should be monitored regardless of concomitant therapy. Any dosing adjustments which may be necessary should be based on the level of anticoagulation that is desired.
Mechanism Of Interaction
Displacement from protein binding sites
Literature Reports
A) One study has suggested that furosemide may reduce the percentage of phenprocoumon that is protein bound. In therapeutic concentrations (5 mcg/mL (20 mcmol/L)), phenprocoumon was 99.9% bound. When the furosemide concentration was increased from 0 to 400 mcg/mL (1200 mcmol/L) in a Krebs-Henseleit solution, the bound fraction of phenprocoumon was reduced to 25%. The reduction in the percent of phenprocoumon bound was significant only at furosemide concentrations at and above 250 mcg/mL (760 mcmol/L). The decreased binding of phenprocoumon in the presence of furosemide is suggestive that displacement may also occur in vivo .
B) Seven elderly patients (ages 60 to 84 years) were treated with furosemide 40 mg intravenously, followed in four days by phenprocoumon 0.3 mg/kg intravenously. Another dose of furosemide 40 mg was immediately given to determine the free and bound furosemide in the serum. At a therapeutic furosemide concentration (5 mcg/mL (20 mcmol/L)), the average percentage binding in the serum was 96.5% in the elderly subjects and 97.7% in the serum of younger (ages 20-45 years) patients. This difference between older and younger patients is attributed to the fact that elderly patients have reduced concentrations of albumin. During the coadministration of phenprocoumon in concentrations not exceeding 6.2 mcg/mL (22 mcmol/L), the binding of furosemide decreased to 95.8%. This modest decrease in furosemide binding was not considered to be significant .
C) Furosemide was safely administered to 8 patients receiving phenprocoumon. Phenprocoumon was administered in a dose of 0.22 mg/kg daily for seven days. Following a wash-out period of three weeks, the phenprocoumon dosing was resumed together with furosemide 40 mg twice daily for seven days. During coadministration of these two agents, the plasma half-life, area under the concentration-time curve (AUC), and apparent volume of distribution of phenprocoumon were not altered. There was a slight increase in the renal excretion of unconjugated and conjugated phenprocoumon, suggesting incomplete excretion of these compounds during the control phase. Plasma protein binding of phenprocoumon was 98.3% before and after furosemide. Prothrombin time was not altered with the coadministration of furosemide and phenprocoumon. The authors concluded that furosemide may be safely administered to patients receiving phenprocoumon therapy .
Furosemide Overview
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Furosemide is used alone or in combination with other medications to treat high blood pressure. Furosemide is used to treat edema (fluid retention; excess fluid held in body tissues) caused by various medical problems, including heart, kidney, and liver disease. Furosemide is in a class of medications called diuretics ('water pills'). It works by causing the kidneys to get rid of unneeded water and salt from the body into the urine.
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High blood pressure is a common condition and when not treated, can cause damage to the brain, heart, blood vessels, kidneys and other parts of the body. Damage to these organs may cause heart disease, a heart attack, heart failure, stroke, kidney failure, loss of vision, and other problems. In addition to taking medication, making lifestyle changes will also help to control your blood pressure. These changes include eating a diet that is low in fat and salt, maintaining a healthy weight, exercising at least 30 minutes most days, not smoking, and using alcohol in moderation.
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Definitions
Severity Categories
Contraindicated
These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.
Major
This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.
Moderate
This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.
Minor
While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.
Onset
Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.
Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.
Evidence
Level of documentation of the interaction.
Established: The interaction is documented and substantiated in peer-reviewed medical literature.
Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.
How To Manage The Interaction
Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.
It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.
Mechanism Of Interaction
The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.
Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.
Where Does Our Information Come From?
Information for our drug interactions is compiled from several drug compendia, including:
The prescribing information for each drug, as published on DailyMED, is also used.
Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.
The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.