Drug interactions
Methacholine + Theophylline
Severity: Moderate
Methacholine and Theophylline: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Theophylline is a bronchodilator and can blunt the bronchoconstrictor response to methacholine. This may produce a false-negative challenge test result and lead to underdiagnosis of airway hyperresponsiveness.
What this interaction means in plain words
Methacholine and Theophylline can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Methacholine belongs to Respiratory; Theophylline belongs to Respiratory.
Why it happens
Theophylline relaxes airway smooth muscle by phosphodiesterase inhibition and adenosine antagonism, which functionally opposes methacholine-induced bronchoconstriction.
What to do
Withhold theophylline for the interval stated in the test protocol or label before methacholine challenge, if clinically safe. Document any medications that could not be withheld when interpreting results.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Methacholine
Other interactions of Theophylline
- Riociguat + Theophylline Contraindicated
- Adenosine + Theophylline Major
- Apalutamide + Theophylline Major
- Bupropion + Theophylline Major
- Carvedilol + Theophylline Major
- Cimetidine + Theophylline Major
Frequently asked questions
Can I take Methacholine with Theophylline?
MediHelp rates the interaction as moderate. Methacholine and Theophylline can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Theophylline is a bronchodilator and can blunt the bronchoconstrictor response to methacholine. This may produce a false-negative challenge test result and lead to underdiagnosis of airway hyperresponsiveness.
How serious is the interaction between Methacholine and Theophylline?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Withhold theophylline for the interval stated in the test protocol or label before methacholine challenge, if clinically safe. Document any medications that could not be withheld when interpreting results.
What other medicines interact with Methacholine?
MediHelp also lists interactions of Methacholine with, for example, Cromolyn sodium. The full list is on the Methacholine page.
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