Drug interactions
Efavirenz + Pimavanserin
Severity: Major
Efavirenz and Pimavanserin: major 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
Pimavanserin prolongs the QT interval, and efavirenz may add to this effect, increasing the risk of arrhythmia. Efavirenz may also lower pimavanserin levels through CYP3A4 induction.
What this interaction means in plain words
Efavirenz and Pimavanserin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Efavirenz belongs to Anti Virals; Pimavanserin belongs to Central Nervous System.
Why it happens
Additive QT prolongation, plus CYP3A4 induction reducing pimavanserin exposure.
What to do
Avoid the combination if possible. If used, obtain an ECG, correct electrolytes, and monitor for reduced antipsychotic effect, adjusting the pimavanserin dose as needed.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Efavirenz
- Cobimetinib + Efavirenz Contraindicated
- Dienogest / estradiol valerate + Efavirenz Contraindicated
- Dihydroergotamine intranasal + Efavirenz Contraindicated
- Dihydroergotamine + Efavirenz Contraindicated
- Doravirine + Efavirenz Contraindicated
- Efavirenz + Elbasvir / grazoprevir Contraindicated
Other interactions of Pimavanserin
- Lefamulin + Pimavanserin Contraindicated
- Pimavanserin + Pimozide Contraindicated
- Pimavanserin + Vandetanib Contraindicated
- Adagrasib + Pimavanserin Major
- Amiodarone + Pimavanserin Major
- Amisulpride + Pimavanserin Major
Frequently asked questions
Can I take Efavirenz with Pimavanserin?
MediHelp rates the interaction as major. Efavirenz and Pimavanserin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Pimavanserin prolongs the QT interval, and efavirenz may add to this effect, increasing the risk of arrhythmia. Efavirenz may also lower pimavanserin levels through CYP3A4 induction.
How serious is the interaction between Efavirenz and Pimavanserin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination if possible. If used, obtain an ECG, correct electrolytes, and monitor for reduced antipsychotic effect, adjusting the pimavanserin dose as needed.
What other medicines interact with Efavirenz?
MediHelp also lists interactions of Efavirenz with, for example, Cobimetinib, Dienogest / estradiol valerate, Dihydroergotamine intranasal. The full list is on the Efavirenz page.
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