Drug interactions
Norepinephrine + Phentolamine
Severity: Moderate
Norepinephrine and Phentolamine: moderate 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
Phentolamine blocks the alpha-mediated vasoconstriction of norepinephrine, reducing its pressor effect. This is used therapeutically to treat norepinephrine extravasation but can cause hypotension and tachycardia if given systemically together.
What this interaction means in plain words
Norepinephrine and Phentolamine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Alpha-adrenergic blockade by phentolamine antagonizes norepinephrine vasoconstriction.
What to do
Monitor blood pressure and heart rate continuously and titrate norepinephrine to effect. Anticipate higher vasopressor requirements.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Phentolamine
Frequently asked questions
Can I take Norepinephrine with Phentolamine?
MediHelp rates the interaction as moderate. Norepinephrine and Phentolamine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Phentolamine blocks the alpha-mediated vasoconstriction of norepinephrine, reducing its pressor effect. This is used therapeutically to treat norepinephrine extravasation but can cause hypotension and tachycardia if given systemically together.
How serious is the interaction between Norepinephrine and Phentolamine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood pressure and heart rate continuously and titrate norepinephrine to effect. Anticipate higher vasopressor requirements.
What other medicines interact with Phentolamine?
MediHelp also lists interactions of Phentolamine with, for example, Alfuzosin, Avanafil, Doxazosin. The full list is on the Phentolamine page.
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