Drug interactions
Isoproterenol + Penbutolol
Severity: Major
Isoproterenol and Penbutolol: major interaction.
Last updated Sources: US FDA label
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
Penbutolol is a nonselective beta-blocker that blocks the receptors isoproterenol stimulates, reducing or abolishing its effect. Isoproterenol may be ineffective for bradycardia or bronchospasm, and unopposed responses may occur if the blocker is overcome.
What this interaction means in plain words
Isoproterenol and Penbutolol 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.
Why it happens
Competitive pharmacodynamic antagonism at beta-1 and beta-2 adrenergic receptors.
What to do
Avoid the combination where possible; choose an alternative such as glucagon or other agents for beta-blocker related bradycardia or bronchospasm. If isoproterenol is used, higher doses may be needed with close hemodynamic monitoring.
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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References
Other interactions of Isoproterenol
Frequently asked questions
Can I take Isoproterenol with Penbutolol?
MediHelp rates the interaction as major. Isoproterenol and Penbutolol 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. Penbutolol is a nonselective beta-blocker that blocks the receptors isoproterenol stimulates, reducing or abolishing its effect. Isoproterenol may be ineffective for bradycardia or bronchospasm, and unopposed responses may occur if the blocker is overcome.
How serious is the interaction between Isoproterenol and Penbutolol?
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 where possible; choose an alternative such as glucagon or other agents for beta-blocker related bradycardia or bronchospasm. If isoproterenol is used, higher doses may be needed with close hemodynamic monitoring.
What other medicines interact with Isoproterenol?
MediHelp also lists interactions of Isoproterenol with, for example, Adrenaline-articaine, Bisoprolol, Budesonide-formoterol. The full list is on the Isoproterenol page.
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