Pimozide and Propafenone interaction
Pimozide and Propafenone: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Propafenone (propafenone hydrochloride) label · effective 2026-01-29
• Avoid use with other antiarrhythmic agents or drugs that prolong the QT interval.
It may also worsen premature ventricular contractions or supraventricular arrhythmias, and it may prolong the QT interval.
Use with Drugs that Prolong the QT Interval and Antiarrhythmic Agents The use of propafenone hydrochloride extended-release capsules in conjunction with other drugs that prolong the QT interval has not been extensively studied.
From the Pimozide label · effective 2026-08-12
Concomitant use of pimozide with paroxetine and other strong CYP 2D6 inhibitors is contraindicated (See PRECAUTIONS – DRUG INTERACTIONS ).
Concomitant use of pimozide and paroxetine or other strong CYP 2D6 inhibitors are contraindicated (see CONTRAINDICATIONS ).
DRUG INTERACTIONS Because pimozide prolongs the QT interval of the electrocardiogram, an additive effect on QT interval would be anticipated if administered with other drugs, such as phenothiazines, tricyclic antidepressants or antiarrhythmic agents, which prolong the QT interval.
CYP 2D6 inhibitors: In healthy subjects, co-administration of pimozide 2 mg (single dose) and paroxetine 60 mg resulted in a 151% increase in pimozide AUC and a 62% increase in pimozide C max compared to pimozide administered alone.
The concentrations observed in poor CYP 2D6 metabolizers are similar to those seen with strong CYP 2D6 inhibitors such as paroxetine.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.