Ephedrine
(generic)
Indirect + direct mixed alpha + beta sympathomimetic
Indirect-acting sympathomimetic — promotes release of stored norepinephrine from presynaptic vesicles AND has direct alpha + beta receptor agonism. Mixed action → increases HR (β1) + contractility (β1) + SVR (α1). Tachyphylaxis develops with repeated dosing (depleted NE stores).
Indications
- •Hypotension during anesthesia, especially with bradycardia (treats both HR + BP)
- •Hypotension after spinal/epidural anesthesia (alternative to phenylephrine, especially in non-OB)
- •Symptomatic hypotension in cardiac surgery (vasoconstrictor + inotropic support)
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Hypotension bolus | 5-10 mg IV; can repeat q3-5 min | — |
| Pediatric hypotension | 0.1-0.2 mg/kg IV | |
| Maximum total typical session | ~50 mg before considering other agents (tachyphylaxis) | — |
Pharmacokinetics
Onset 1-2 min IV. Duration 10-15 min. Renal excretion (~95% unchanged). Half-life 3-6 h. Crosses placenta (use during cesarean — historical concern about fetal acidemia at high doses, but practically OK at standard doses).
Hemodynamic effects
↑HR, ↑contractility, ↑SVR → ↑BP. Useful for hypotension + bradycardia (in contrast to phenylephrine which is pure alpha → may cause reflex bradycardia).
Side effects
- !Tachycardia (problematic in CAD, AS)
- !Tachyphylaxis (depletion of stored norepinephrine)
- !Hypertension overshoot if dosed too aggressively
- !Catecholamine-like effects: tremor, anxiety in awake patient
- !Possible MI in susceptible patients (catecholamine-driven)
Contraindications
- ×Tachyarrhythmia
- ×Severe HTN, pheochromocytoma (uncontrolled catecholamine surge)
- ×Concurrent MAOI use (severe HTN crisis)
Clinical pearls
- ★FIRST-LINE for hypotension WITH BRADYCARDIA in non-OB cases — treats both HR + BP. If hypotension WITHOUT bradycardia or with tachycardia, phenylephrine is preferred.
- ★Cesarean spinal hypotension: PHENYLEPHRINE infusion is preferred over ephedrine boluses (Ngan Kee Anesth Analg 2010 — less fetal acidemia). Ephedrine has fallen from first-line in OB.
- ★TACHYPHYLAXIS: after 3-4 boluses, switch to phenylephrine or norepinephrine (works on different mechanism — direct receptor agonism unaffected by NE depletion).
- ★MAOI patients: indirect-acting sympathomimetics → catecholamine SURGE (norepinephrine pool not metabolized normally) → severe HTN crisis. Use direct-acting (phenylephrine, norepinephrine) instead.
- ★Standard concentration: 50 mg/mL ampoule; dilute to 5 mg/mL in saline (1 mL bolus) for routine intraop use.
Education only — confirm against current package inserts and institutional protocols. Doses assume normal organ function unless otherwise noted.