Avanafil and Trospium / Xanomeline: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Avanafil
Trospium / Xanomeline
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
Here's what's going on. Avanafil (Stendra) is broken down in your body by an enzyme called CYP3A4. The medication Cobenfy contains xanomeline, which can briefly slow down that enzyme in your gut. When it slows down, your body clears avanafil a little more slowly, so more of it can build up.
In plain terms, you might feel avanafil's side effects more strongly, like headache, flushing, a stuffy nose, or dizziness. This concern is theoretical, meaning it's based on how the drugs work rather than confirmed reports. The good news is your care team can easily manage this by keeping an eye on how you feel and adjusting things if needed. Let them know if side effects feel stronger than usual.
Mechanism: Xanomeline (in Cobenfy) transiently inhibits intestinal CYP3A4 without meaningful systemic inhibition. Avanafil is a sensitive oral CYP3A4 substrate, so co-administration may increase avanafil exposure (AUC/Cmax) and thereby the frequency/severity of dose-related adverse effects.
- Direction: increased avanafil effect (neither drug is a prodrug here).
- Magnitude: not quantified; gut-limited inhibition.
- Onset: unspecified.
- Evidence: theoretical.
- Management: monitor for PDE5-inhibitor adverse effects (hypotension, headache, flushing, priapism, visual changes). Dose may be individualized by the care team.
What happens
Increased oral sensitive CYP3A4 substrate exposure and an increased risk on severity and frequency of sensitive CYP3A4 substrate-related adverse reactions
Interaction Deep Dive
In the gut, xanomeline produces a temporary, local inhibition of CYP3A4, though this effect does not extend systemically. When xanomeline is taken alongside oral medications that are sensitive CYP3A4 substrates, the exposure to those oral sensitive CYP3A4 substrates can rise. As a result, adverse reactions attributable to these substrates may occur more often and/or with greater severity. During such concurrent use, patients should be observed for any increase in the frequency and/or severity of adverse reactions associated with oral drugs that are sensitive substrates of CYP3A41.
Why it happens (mechanism)
Inhibition of CYP3A4-substrate metabolism by xanomeline
How to manage this interaction
What your care team may do:
- Watch you more closely for stronger avanafil side effects such as headache, flushing, nasal congestion, dizziness, or low blood pressure.
- Individualize and adjust your avanafil dose if needed to keep you comfortable.
What you can do:
- Keep taking both medications exactly as prescribed unless your prescriber tells you otherwise.
- Tell your pharmacist or doctor if avanafil's effects feel stronger than usual, or if you notice a prolonged or painful erection, chest pain, fainting, or vision changes.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Avanafil and Trospium / Xanomeline together?
Cobenfy (xanomeline) may briefly raise avanafil levels in your gut, so avanafil side effects could feel a bit stronger; keep taking both as prescribed and tell your care team if side effects increase. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Avanafil and Trospium / Xanomeline interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Avanafil and Trospium / Xanomeline interaction managed?
What your care team may do: Watch you more closely for stronger avanafil side effects such as headache, flushing, nasal congestion, dizziness, or low blood pressure. Individualize and adjust your avanafil dose if needed to keep you comfortable. What you can do: Keep taking both medications exactly as prescribed unless your prescriber tells you otherwise. Tell your pharmacist or doctor if avanafil'… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Avanafil or Trospium / Xanomeline need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (1)
- Citation #1
Keep reading about Avanafil
Keep reading about Trospium / Xanomeline
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