Ethinyl Estradiol; Norethindrone with Theophylline Interaction Details

Brand Names Associated with Theophylline

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Nov 12, 2023

Interaction Effect

Increased theophylline exposure and theophylline toxicity (nausea, vomiting, palpitations, seizures)

Interaction Summary

Combination oral/hormonal contraceptives containing some synthetic estrogens (ethinyl estradiol) may inhibit the metabolism of theophylline and may increase the plasma concentrations of theophylline . Combination contraceptives have been reported to decrease theophylline clearance by 34% and increase the half-life by 33% (7.9 vs 5.4 hr) . The distribution of theophylline has not been reported to change. A longer dosing interval may be possible while on combination contraceptives .

Severity

Major

Onset

Delayed

Evidence

Theoretical

How To Manage Interaction

Combination oral contraceptives (COCs) containing ethinyl estradiol may inhibit the metabolism of theophylline and may increase the plasma concentrations of theophylline.

Mechanism Of Interaction

Inhibition of theophylline metabolism

Literature Reports

A) Low-dose oral contraceptives do not appear to influence single-dose (intravenous) theophylline pharmacokinetics in adolescents . No differences were found in theophylline distribution volume, elimination half-life, or total body clearance between control subjects (n=10) and subjects who received 3 to 9 months of low-dose oral contraceptives (n=10).

Theophylline Overview

• Theophylline is used to prevent and treat wheezing, shortness of breath, and chest tightness caused by asthma, chronic bronchitis, emphysema, and other lung diseases. It relaxes and opens air passages in the lungs, making it easier to breathe.

Return To Our Drug Interaction Homepage

Feedback, Question Or Comment About This Information?

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.