Drug interactions
Isoflurane + Phenylephrine
Severity: Minor
Isoflurane and Phenylephrine: minor 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
Volatile halogenated anesthetics such as isoflurane sensitize the myocardium to catecholamines, although isoflurane does so less than halothane. Systemic phenylephrine may produce arrhythmias or exaggerated blood pressure changes, though it is routinely used during anesthesia for hypotension.
What this interaction means in plain words
Isoflurane and Phenylephrine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Isoflurane belongs to Central Nervous System; Phenylephrine belongs to Respiratory.
Why it happens
Volatile anesthetic myocardial sensitization to catecholamines, with vasodilation offset by vasoconstriction.
What to do
Titrate phenylephrine to effect with continuous ECG and blood pressure monitoring during anesthesia.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Phenylephrine
- Isocarboxazid + Phenylephrine Contraindicated
- Phenelzine + Phenylephrine Contraindicated
- Phenylephrine + Tranylcypromine Contraindicated
- Bromocriptine + Phenylephrine Major
- Cocaine + Phenylephrine Major
- Dihydroergotamine intranasal + Phenylephrine Major
Other interactions of Isoflurane
Frequently asked questions
Can I take Isoflurane with Phenylephrine?
MediHelp rates the interaction as minor. Isoflurane and Phenylephrine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Volatile halogenated anesthetics such as isoflurane sensitize the myocardium to catecholamines, although isoflurane does so less than halothane. Systemic phenylephrine may produce arrhythmias or exaggerated blood pressure changes, though it is routinely used during anesthesia for hypotension.
How serious is the interaction between Isoflurane and Phenylephrine?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Titrate phenylephrine to effect with continuous ECG and blood pressure monitoring during anesthesia.
What other medicines interact with Phenylephrine?
MediHelp also lists interactions of Phenylephrine with, for example, Isocarboxazid, Phenelzine, Tranylcypromine. The full list is on the Phenylephrine page.
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