Cholestyramine with Tinidazole Interaction Details

Brand Names Associated with Cholestyramine

Brand Names Associated with Tinidazole

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Feb 28, 2024

Interaction Effect

Decreased tinidazole effectiveness

Interaction Summary

Tinidazole, a nitroimidazole, is chemically-related to metronidazole. The bioavailability of metronidazole was decreased by 21% in a single dose study with healthy volunteers when oral metronidazole and cholestyramine are administered concomitantly[1]. Although not specifically studied with tinidazole, similar to metronidazole, concurrent administration of cholestyramine and tinidazole may result in decreased oral bioavailability and effectiveness of tinidazole. Therefore, the dosing regimens for these two drugs should be separated to minimize any potential effect on the oral bioavailability of tinidazole [2].

Severity

Moderate

Onset

Rapid

Evidence

Theoretical

How To Manage Interaction

Coadministration of cholestyramine with tinidazole may decrease the absorption of tinidazole, resulting in reduced tinidazole effectiveness. If concurrent use is required, separate the dosing regimens for these two drugs to minimize any potential effect on the oral bioavailability of tinidazole[2].

Mechanism Of Interaction

Decreased tinidazole absorption

References

1 ) Molokhia AM: Effect of concomitant oral administration of some adsorbing drugs on the bioavailabiity of metronidazole. Drug Dev Ind Pharm 1987; 13:1229.

2 ) Product Information: TINDAMAX(R) oral tablets, tinidazole oral tablets. Mission Pharmacal Company, San Antonio, TX, 2007.

Cholestyramine Overview

• Cholestyramine is used with diet changes (restriction of cholesterol and fat intake) to reduce the amount of cholesterol and certain fatty substances in your blood. Accumulation of cholesterol and fats along the walls of your arteries (a process known as atherosclerosis) decreases blood flow and, therefore, the oxygen supply to your heart, brain, and other parts of your body. Lowering your blood level of cholesterol and fats may help to prevent heart disease, angina (chest pain), strokes, and heart attacks.

• This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

Tinidazole Overview

• 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.

• 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:

• Gold Standard Drug Database
• Micromedex
• Lexicomp
• DrugBank

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.