Key points
- Posaconazole can interact with other medicines, although its interaction pattern is often a little simpler than itraconazole or voriconazole.
- It mainly interacts through CYP3A4 inhibition.
- Important interaction groups include immunosuppressants, steroids, blood thinners, and some heart medicines.
- Some medicines can reduce posaconazole levels and make treatment less effective.
- Tablets and oral suspension are not interchangeable in the same way.
What is posaconazole?
Posaconazole is an azole antifungal used in aspergillosis and in some high-risk patients for prevention of fungal infection. It is often seen as somewhat easier to manage than some older azoles, but important interactions still exist.
Why posaconazole interacts with other medicines
Posaconazole mainly affects CYP3A4, a key liver enzyme involved in handling many medicines. This means some drugs can become stronger, while some combinations can lower posaconazole levels and make it less effective.
The interaction groups most likely to matter
Steroids
Posaconazole can increase exposure to some steroids, including inhaled or oral steroids, which may increase the risk of steroid side effects.
Immunosuppressants
Medicines such as tacrolimus and ciclosporin can rise significantly with posaconazole and usually need close specialist monitoring.
Blood thinners
Some blood thinners may become stronger, increasing bleeding risk.
Statins
Some statins can rise in level, increasing the risk of muscle problems.
Heart rhythm medicines
Some combinations can increase the risk of heart rhythm problems and need careful review.
Medicines that reduce posaconazole effectiveness
Some medicines, including rifampicin-type antibiotics and certain anti-seizure drugs, can lower posaconazole levels and may make treatment less effective.
Posaconazole formulations and absorption
Posaconazole comes in different forms, including tablets, oral suspension, and infusion. The oral suspension and tablets are not handled identically by the body and should not be assumed to be interchangeable dose-for-dose without clinical advice.
In practice, the tablets tend to be more predictable than the suspension.
What patients should do in practice
- Tell your pharmacist or clinician if you are taking posaconazole.
- Ask about new medicines, especially blood thinners, steroids, statins, and heart medicines.
- If your formulation changes, ask whether there are any special instructions.
- Do not stop or swap medicines without advice.
When to seek medical advice
Seek medical advice urgently for severe bleeding, fainting, major palpitations, severe muscle pain, or rapid worsening after a medicine change.
Important
This page does not list every interaction. For a full check, use the BNF interaction checker or speak to a pharmacist or clinician.
References
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