Drug interactions
Efavirenz + Vandetanib
Severity: Major
Efavirenz and Vandetanib: 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
Both drugs prolong the QT interval, which raises the risk of torsades de pointes with vandetanib, a drug with a boxed warning for QT prolongation. Efavirenz may also lower vandetanib exposure through enzyme induction.
What this interaction means in plain words
Efavirenz and Vandetanib 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; Vandetanib belongs to Oncology.
Why it happens
Additive QT prolongation plus CYP3A4 induction by efavirenz, which lowers vandetanib levels.
What to do
Avoid the combination and use a non-QT-prolonging antiretroviral. If unavoidable, monitor ECG, potassium, magnesium and calcium closely.
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 Vandetanib
- Amiodarone + Vandetanib Contraindicated
- Amisulpride + Vandetanib Contraindicated
- Amitriptyline + Vandetanib Contraindicated
- Anagrelide + Vandetanib Contraindicated
- Asenapine + Vandetanib Contraindicated
- Chloroquine + Vandetanib Contraindicated
Frequently asked questions
Can I take Efavirenz with Vandetanib?
MediHelp rates the interaction as major. Efavirenz and Vandetanib 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. Both drugs prolong the QT interval, which raises the risk of torsades de pointes with vandetanib, a drug with a boxed warning for QT prolongation. Efavirenz may also lower vandetanib exposure through enzyme induction.
How serious is the interaction between Efavirenz and Vandetanib?
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 and use a non-QT-prolonging antiretroviral. If unavoidable, monitor ECG, potassium, magnesium and calcium closely.
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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