Drug interactions
Ritonavir + Theophylline
Severity: Moderate
Ritonavir and Theophylline: moderate interaction.
Last updated Sources: US FDA label
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
Ritonavir can change theophylline exposure, and theophylline concentrations have been reported to fall during ritonavir therapy. Subtherapeutic levels may lead to loss of bronchodilator control, while changes in either direction matter because theophylline has a narrow therapeutic index.
What this interaction means in plain words
Ritonavir 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.
Ritonavir belongs to Anti Virals; Theophylline belongs to Respiratory.
Why it happens
Ritonavir inhibits CYP3A4 and CYP1A2 but also induces CYP1A2 and other pathways, so the net effect on theophylline clearance is variable, with a reduction in levels most often reported.
What to do
Measure serum theophylline concentrations when ritonavir is started or stopped and adjust the theophylline dose accordingly. Monitor for both toxicity (tachycardia, tremor, nausea, seizures) and loss of asthma control.
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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References
- Ritonavir - FDA drug label (DailyMed) — openFDA / DailyMed
Other interactions of Theophylline
- Riociguat + Theophylline Contraindicated
- Adenosine + Theophylline Major
- Apalutamide + Theophylline Major
- Bupropion + Theophylline Major
- Carvedilol + Theophylline Major
- Cimetidine + Theophylline Major
Other interactions of Ritonavir
- Alfuzosin + Ritonavir Contraindicated
- Amiodarone + Ritonavir Contraindicated
- Avanafil + Ritonavir Contraindicated
- Colchicine + Ritonavir Contraindicated
- Dronedarone + Ritonavir Contraindicated
- Eletriptan + Ritonavir Contraindicated
Frequently asked questions
Can I take Ritonavir with Theophylline?
MediHelp rates the interaction as moderate. Ritonavir 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. Ritonavir can change theophylline exposure, and theophylline concentrations have been reported to fall during ritonavir therapy. Subtherapeutic levels may lead to loss of bronchodilator control, while changes in either direction matter because theophylline has a narrow therapeutic index.
How serious is the interaction between Ritonavir 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: Measure serum theophylline concentrations when ritonavir is started or stopped and adjust the theophylline dose accordingly. Monitor for both toxicity (tachycardia, tremor, nausea, seizures) and loss of asthma control.
What other medicines interact with Theophylline?
MediHelp also lists interactions of Theophylline with, for example, Riociguat, Adenosine, Apalutamide. The full list is on the Theophylline page.
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