Allopurinol with Theophylline Interaction Details

Brand Names Associated with Allopurinol

Brand Names Associated with Theophylline

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Feb 27, 2024

Interaction Effect

Theophylline toxicity (nausea, vomiting, palpitations, seizures)

Interaction Summary

Large doses of allopurinol (ie, 300 mg twice daily) have been shown to reduce theophylline clearance by approximately 20%. The onset of this interaction takes from two to four weeks[1]. Monitor theophylline levels two to three weeks after adding or deleting allopurinol to theophylline therapy and adjust theophylline dose if required.

Severity

Moderate

Onset

Delayed

Evidence

Theoretical

How To Manage Interaction

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

Mechanism Of Interaction

Decreased theophylline metabolism

Literature Reports

A) Although early reports indicated that the pharmacokinetics and disposition of theophylline were not significantly affected by concomitant allopurinol administration [2][3], a more recent study [1] reported that allopurinol 300 mg administered q12h for 14 to 28 days inhibited theophylline metabolism, with a corresponding reduction in the mean clearance and an increase in the half-life, despite failure of allopurinol in smaller doses given for only 7 days to alter theophylline disposition. When allopurinol is given in these doses, theophylline dose reductions should be initiated to avoid toxicity.

References

1 ) Manfredi RL & Vesell ES: Inhibition of theophylline metabolism by long-term allopurinol administration. Clin Pharmacol Ther 1981; 29:224-228.

2 ) Vozeh S, Powell JR, Cupit GC, et al: Influence of allopurinol on theophylline disposition in adults. Clin Pharmacol Ther 1980; 27:194-197.

3 ) Grygiel JJ, Wing LMH, Farkas J, et al: Effects of allopurinol on theophylline metabolism and clearance. Clin Pharmacol Ther 1979; 26:660-667.

Allopurinol Overview

• Allopurinol is used to treat gout (a type of arthritis in which uric acid, a naturally occurring substance in the body, builds up in the joints and causes sudden attacks of redness, swelling, pain, and heat in one or more joints). Allopurinol is also used to treat high levels of uric acid that builds up in the blood as tumors break down in people with certain types of cancer who are being treated with chemotherapy medications. It is also used to treat kidney stones that have come back in people who have high levels of uric acid in their urine. Allopurinol is in a class of medications called xanthine oxidase inhibitors. It works by reducing the production of uric acid in the body. High levels of uric acid may cause gout attacks or kidney stones. Allopurinol is used to prevent gout attacks, not to treat them once they occur.

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.