Ranitidine with Theophylline Interaction Details

Brand Names Associated with Ranitidine

Brand Names Associated with Theophylline

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Nov 25, 2023

Interaction Effect

Theophylline toxicity (nausea, vomiting, palpitations, seizures)

Interaction Summary

In patients with compromised theophylline metabolism (eg, the elderly, cirrhosis, pulmonary edema), the concurrent use of ranitidine may further decrease theophylline metabolism. When both drugs are required in this type of patient population, monitor theophylline levels more closely.

Severity

Minor

Onset

Delayed

Evidence

Probable

How To Manage Interaction

Theophylline serum concentrations should be closely monitored when ranitidine is added, discontinued, or when dosing changes occur. Dosing adjustments of theophylline may be necessary.

Mechanism Of Interaction

Decreased hepatic metabolism

Literature Reports

A) In some reports, concomitant ranitidine and theophylline therapy has not affected the pharmacokinetics of theophylline and dosage alterations were not required. This was attributed to a lack of inhibition of the hepatic microsomal enzyme system by ranitidine . However, case reports have demonstrated increased theophylline serum levels and/or clinical theophylline toxicity after co-administration with ranitidine . Furthermore, an idiosyncratic drug interaction was documented in a case in which theophylline toxicity recurred following an unintended rechallenge . Retrospective analysis of hospitalized patients with elevated serum theophylline concentrations could not find differences between those patients concomitantly treated with ranitidine or cimetidine in either the occurrence of elevated theophylline concentrations nor clinical toxicity . In pharmacokinetic studies involving H2 antagonists with theophylline , substantial interpatient and intrapatient variation in theophylline clearance has been noted both at basal measurement and after the addition of the H2 antagonist. This would suggest the need to closely monitor theophylline therapy regardless of which concomitant H2 antagonist might be chosen, a view supported by a recent review .

Ranitidine Overview

• Ranitidine is used to treat ulcers; gastroesophageal reflux disease (GERD), a condition in which backward flow of acid from the stomach causes heartburn and injury of the food pipe (esophagus); and conditions where the stomach produces too much acid, such as Zollinger-Ellison syndrome. Over-the-counter ranitidine is used to prevent and treat symptoms of heartburn associated with acid indigestion and sour stomach. Ranitidine is in a class of medications called H₂ blockers. It decreases the amount of acid made in the stomach.

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.

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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.