Pharmacology · Vasopressors and inotropes
Ephedrine !
A mixed-acting sympathomimetic given intravenously to treat low blood pressure during anaesthesia. Repeated doses lose effect (tachyphylaxis).
Updated 2026-11-01
Mechanism of action
Ephedrine acts in two ways: it stimulates alpha and beta adrenergic receptors directly, and it releases norepinephrine stored in sympathetic nerve endings. Heart rate, contractility and vascular tone rise. Because the indirect part depends on nerve stores, repeated doses work less and less (tachyphylaxis).
- Ephedrine stimulates alpha and beta receptors directly
- It also releases norepinephrine from nerve endings
- Heart rate, contractility and vascular tone rise
- Repeated doses deplete stores: tachyphylaxis
Pharmacokinetics
- Metabolism
- Partly converted to norephedrine
- Elimination
- Parent drug and metabolite in urine; slower in kidney impairment
- Half-life
- About 6 hours after oral use (label); longer effect in kidney impairment
Indications
- Clinically important hypotension in the setting of anaesthesia
Adverse effects
Common
- Nausea and vomiting
- Tachycardia
Contraindications
- None listed on the label; caution with other pressor drugs and in kidney impairment
Key interactions
- Oxytocin and other oxytocic drugs
- Pressor effect potentiated: severe postpartum hypertension has been described
- MAO inhibitors, clonidine, propofol and atropine
- Stronger pressor effect
- Alpha and beta blockers, reserpine, quinidine
- Weaker pressor effect
What is monitored
- Blood pressure and heart rate after each dose
- ECG during anaesthesia
- Response to repeated doses (tachyphylaxis)
Administration and safety
- Given intravenously by anaesthesia staff; concentrated products are diluted (normal saline or dextrose solution) before bolus injection: check the label.
- Ephedrine and epinephrine have look-alike names: read the label twice.
- Inspect the solution for particles and discolouration before use.
Nursing care
- Check blood pressure and heart rate after each dose.
- If the response fades after several doses, report it: tachyphylaxis may require another vasopressor.
- In obstetric patients, tell the team if oxytocic drugs have been or will be given.
Pregnancy and breastfeeding
Data from use in pregnant women have not shown a risk of major birth defects or adverse outcomes; maternal hypotension itself can cause fetal bradycardia, so it is treated.
Test yourself
Think of the answer, then tap the question to see it.
Why does ephedrine lose effect when doses are repeated?
Part of its action is indirect, releasing stored norepinephrine; repeated doses deplete the stores (tachyphylaxis).
Which combination with ephedrine can cause severe postpartum hypertension?
Oxytocic drugs such as oxytocin or ergot derivatives.
In what setting is intravenous ephedrine mainly used?
To treat clinically important hypotension during anaesthesia, for example spinal anaesthesia.
Related drugs
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - EPHEDRINE SULFATE injection (DailyMed (U.S. National Library of Medicine), 2020); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025); Farmacología básica y clínica (Katzung), cap. 9 (McGraw Hill, 2025).
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