Isoproterenol and Entacapone: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Entacapone
Isoproterenol
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
An increased risk of tachycardia, hypertension, and arrhythmias
Interaction Deep Dive
A controlled study observed that coadministration of a single dose of entacapone followed by an intravenous infusion of isoproterenol may result in increased chronotropic and arrhythmogenic effects of isoproterenol. However, the conclusions were limited by the fact that the study was terminated after two subjects developed ventricular arrhythmias1. Drugs metabolized by catechol-o-methyltransferase (COMT) should be administered with caution to patients also receiving entacapone 2.
Why it happens (mechanism)
Inhibition of catechol-o-methyltransferase (COMT)
Literature reports
1 report — tap to read
a) In a controlled study, the interactions between entacapone with isoproterenol and epinephrine were examined. The study was originally designed to follow a placebo controlled, randomized crossover design. However, after two patients developed ventricular arrhythmia, the study was terminated before its completion. Six subjects completed the isoproterenol and epinephrine infusions while taking placebo and five subjects completed these infusions while taking a single dose of entacapone 400 mg. Four dosages of epinephrine and isoproterenol were given, ranging from 1.5 mcg/min to 12 mcg/min for epinephrine and from 0.5 mcg/min to 2 mcg/min for isoproterenol. The maximum increase in heart rate during the infusion of isoproterenol was statistically greater in the group taking entacapone (40 beats/min +/- 11 beats/min) compared to placebo (27 beats/min +/- 7 beats/min). The maximum increase in heart rate for epinephrine was also greater in the group taking entacapone (25 beats/min +/- 13 beats/min) compared to placebo (14 beats/min +/- 9 beats/min), but this difference was not statistically significant. During the isoproterenol infusion, two of six placebo subjects complained of palpitations while six of eight entacapone subjects complained of palpitations. During the epinephrine infusion, two of six placebo subjects reported palpitations while four of eight entacapone subjects reported palpitations. The authors suggested taking caution during coadministration of these two drugs, since entacapone may potentiate the chronotropic and arrhythmogenic effects of isoproterenol and epinephrine 1.
Common questions
Can I take Isoproterenol and Entacapone together?
An increased risk of tachycardia, hypertension, and arrhythmias Always confirm with your pharmacist or prescriber before making any change.
How serious is the Isoproterenol and Entacapone interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Isoproterenol or Entacapone need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (2)
- Illi A, Sundberg S, Ojala-Karlsson P, et al: The effect of entacapone on the disposition and hemodynamic effects of intravenous isoproterenol and epinephrine. Clin Pharmacol Ther 1995; 58:221-227. PubMed
- Product Information: Comtan(R), entacapone. Novartis Pharmaceuticals Corporation, East Hanover, NJ, 1999. DailyMed
Keep reading about Entacapone
Keep reading about Isoproterenol
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