Does Haloperidol Lactate Interact with Quinidine?
Haloperidol Lactate and Quinidine have a moderate drug interaction according to U.S. FDA drug labeling data. Class 1A antiarrhythmic that prolongs QTc interval and inhibits CYP2D6; caution advised due to risk of QT prolongation and increased haloperidol levels. The mechanism involves additive qtc interval prolongation and cyp2d6 inhibition. Patients taking both medications should consult their healthcare provider before starting, stopping, or changing the dosage of either drug. This information is based on official FDA drug labeling sourced from OpenFDA and the NIH National Library of Medicine.
- Severity
- Moderate
- Management
- Monitor for effects
- Data Source
- U.S. FDA via OpenFDA
How This Interaction Works
The interaction between Haloperidol Lactate and Quinidine occurs because additive qtc interval prolongation and cyp2d6 inhibition. Clinically, this means class 1a antiarrhythmic that prolongs qtc interval and inhibits cyp2d6; caution advised due to risk of qt prolongation and increased haloperidol levels. This is classified as a moderate interaction. While it may not require stopping either medication, your healthcare provider should be aware you are taking both so they can monitor for potential effects and adjust treatment if necessary.
What To Tell Your Doctor or Pharmacist
If you are taking Haloperidol Lactate and your doctor is considering prescribing Quinidine (or vice versa), make sure to:
- Inform your doctor and pharmacist of all current medications, including over-the-counter drugs and supplements
- Ask whether the benefits of combining these medications outweigh the risks for your specific situation
- Ask what symptoms to watch for that would indicate the interaction is causing problems
- Ask whether any dosage adjustments are needed
- Never stop or change either medication without first consulting your healthcare provider