Moxifloxacin with Rifampin Interaction Details

Brand Names Associated with Moxifloxacin

Brand Names Associated with Rifampin

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Jan 04, 2024

Interaction Effect

Decreased moxifloxacin exposure and plasma concentrations

Interaction Summary

An open-label, multiple-dose, pharmacokinetic study in tuberculosis patients (n=19) demonstrated reductions in moxifloxacin exposure and plasma levels when used concomitantly with rifampin. Therefore, caution is warranted when moxifloxacin and rifampin are used concomitantly.

Severity

Moderate

Onset

Unspecified

Evidence

Established

How To Manage Interaction

Rifampin reduced the exposure and plasma concentrations of moxifloxacin. Therefore, caution is warranted when moxifloxacin and rifampin are used concomitantly.

Mechanism Of Interaction

Induction of uridine diphosphate glucuronosyltransferase and sulfotransferase metabolism of moxifloxacin by rifampin

Literature Reports

A) The AUC and Cmax of moxifloxacin decreased by 31% and 32%, respectively, when moxifloxacin was combined with intermittently administered rifampin and isoniazid in 19 Indonesian patients with tuberculosis (TB) in an open-label, multiple-dose, pharmacokinetic study. The mean weight of the patients was 55 kg (range, 38 to 80 kg). During their last month of treatment with 600 mg of isoniazid and 450 mg of rifampin (both 3 times per week), moxifloxacin 400 mg once daily for 5 days was added (phase I). After a 1-month washout, patients received 400 mg of oral moxifloxacin alone every day for another 5 days (phase II). The following are the geometric means (range) of moxifloxacin for phase I and phase II, respectively, for: AUC (0 to 24 hour (hr)), 33.3 milligrams x hour/liter (mg x hr/L) (25.1 to 55.5 mg x hr/L) and 48.2 mg x hr/L (37.2 to 60.5 mg x hr/L); Cmax, 3.2 mg/L (2.5 to 4.5 mg/L) and 4.7 mg/L (3.4 to 6 mg/L); total clearance, 12 L/hr (7.2 to 16 L/hr) and 8.3 L/hr (6.6 to 10.8 L/hr); and half-life, 7.1 hr (5 to 9.6 hr) and 9.9 hr (7.4 to 14 hr). The corresponding geometric ratios (90% confidence interval) between the 2 phases were 0.69 (0.65 to 0.74) for AUC, 0.68 (0.64 to 0.73) for Cmax, 1.45 (1.35 to 1.54) for total clearance, and 0.72 (0.68 to 0.75) for half-life. Additionally, moxifloxacin Tmax was prolonged when combined with rifampin and isoniazid (2.5 hr vs 1 hr; p=0.003). The geometric mean values for AUC (0 to 24 hr):minimum inhibitory concentration (MIC) and Cmax:MIC for moxifloxacin in phase II were significantly higher (p less than 0.01) and approached the desired value compared with phase I. The AUC(0 to 24 hr):MIC was greater than 100 (target ratio) in 47% of patients in the phase II compared with 5% of patients in phase I .

Moxifloxacin Overview

• Moxifloxacin is used to treat certain infections caused by bacteria such as pneumonia, and skin, and abdominal (stomach area) infections. Moxifloxacin is also used to prevent and treat plague (a serious infection that may be spread on purpose as part of a bioterror attack. Moxifloxacin may also be used to treat bronchitis or sinus infections but should not be used for these conditions if there are other treatment options available. Moxifloxacin is in a class of antibiotics called fluoroquinolones. It works by killing the bacteria that cause infections.

• Antibiotics such as moxifloxacin 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.

Rifampin Overview

• Rifampin is used with other medications to treat tuberculosis (TB; a serious infection that affects the lungs and sometimes other parts of the body). Rifampin is also used to treat some people who have Neisseria meningitidis (a type of bacteria that can cause a serious infection called meningitis) infections in their noses or throats. These people have not developed symptoms of the disease, and this treatment is used to prevent them from infecting other people. Rifampin should not be used to treat people who have developed symptoms of meningitis. Rifampin is in a class of medications called antimycobacterials. It works by killing the bacteria that cause infection.

• Antibiotics such as rifampin 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.