Warfarin with Tinidazole Interaction Details
Brand Names Associated with Warfarin
- Coumadin®
- Jantoven®
- Warfarin
Brand Names Associated with Tinidazole
- Tindamax®
- Tinidazole
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 07, 2023
Interaction Effect
A prolongation of prothrombin time
Interaction Summary
Tinidazole, a nitroimidazole, is chemically-related to metronidazole. Concomitant administration of oral metronidazole and warfarin has resulted in an increase in prothrombin time (PT). Although not specifically studied with tinidazole, similar to metronidazole, concurrent administration of tinidazole and oral anticoagulants may enhance the anticoagulant effect, resulting in a prolongation of prothrombin time. Oral anticoagulant dosage may need to be adjusted during concurrent tinidazole therapy and up to 8 days after discontinuation of tinidazole . Close monitoring of the PT ratio or INR with the addition and withdrawal of treatment with tinidazole is recommended.
Severity
Moderate
Onset
Unspecified
Evidence
Theoretical
How To Manage Interaction
Oral anticoagulant dosage may need to be adjusted during concurrent tinidazole therapy and up to 8 days after discontinuation. Closely monitor the prothrombin time ratio or INR with the addition and withdrawal of treatment with tinidazole.
Mechanism Of Interaction
Enhanced anticoagulant effect
Literature Reports
A) Eight healthy subjects who were concomitantly treated with oral metronidazole 250 mg three times daily for eight days and a single dose of warfarin 1.5 mg/kg were studied. It was found that the combination of racemic warfarin with metronidazole resulted in an increase in the one stage prothrombin time expressed as a percent increase of area under the curve from 100 to 142 with a concomitant increase in mean plasma warfarin half-life of 35 hours to 46 hours. Subsequent studies indicate that the S(-) isomer of warfarin was the specific enantiomer most effected by metronidazole with an increase in prothrombin time from 100 to 196 and a concomitant increase in half-life from 32 hours to 50 hours .
Warfarin Overview
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Warfarin is used to prevent blood clots from forming or growing larger in your blood and blood vessels. It is prescribed for people with certain types of irregular heartbeat, people with prosthetic (replacement or mechanical) heart valves, and people who have suffered a heart attack. Warfarin is also used to treat or prevent venous thrombosis (swelling and blood clot in a vein) and pulmonary embolism (a blood clot in the lung). Warfarin is in a class of medications called anticoagulants ('blood thinners'). It works by decreasing the clotting ability of the blood.
Tinidazole Overview
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Tinidazole is used to treat trichomoniasis (a sexually transmitted disease that can affect men and women), giardiasis (an infection of the intestine that can cause diarrhea, gas, and stomach cramps), and amebiasis (an infection of the intestine that can cause diarrhea, gas, and stomach cramps and can spread to other organs such as the liver). Tinidazole is also used to treat bacterial vaginosis (an infection caused by an overgrowth of harmful bacteria in the vagina) in women. Tinidazole is in a class of medications called nitroimidazole antimicrobials. It works by killing the organisms that can cause infection.
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Antibiotics will not work for colds, flu, or other viral infections. Using antibiotics when they are not needed increases your risk of getting an infection later that resists antibiotic treatment.
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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.