Understanding Anesthesiology - The Global Regional Anesthesia ...

EPHEDRINE SULFATE
Class
Sympathomimetic (indirect-acting); vasopressor. Used in
the treatment of hypotension.
Mechanism of Action
Ephedrine causes more norepinephrine to be released
from the storage vesicles in the terminal of neurons
thus increasing the amount of norepinephrine in the
synaptic space. Ephedrine is (mostly) an “indirectacting”
catecholamine because it doesn’t act at the
post-synaptic norepinephrine receptors.
Dose
5-20 mg IV (adults)
25-50 mg IM (adults)
Onset
IV: immediate
IM: minutes
Duration
IV: 10-minutes
IM: 60 minutes
Elimination
Hepatic, renal
Effects
CNS
Increases MAC of volatile anesthetics
Respiratory
Bronchodilator
CVS
Increases heart rate, contractility and therefore cardiac
output (through its & adrenergic effect). Overall effect is
to increase systemic vascular resistance through its #-
adrenergic effect. May cause arrhythmias especially
when used with volatile anesthetics. As the mechanism
of action involves the release of intracellular catecholamines,
there is an unpredictable effect in patients with
depleted endogenous catecholamines.
Misc.
Excessive catecholamine effects may lead to hypertension,
tachycardia, arrhythmias, pulmonary edema, anxiety,
tremors, hyperglycemia and transient hyperkalemia
followed by hypokalemia. Skin necrosis may occur at
site of injection.
Contraindications
Ephedrine should not be used in patients on monoamine
oxidase inhibitors (MAOIs) or those using cocaine. In
these patients, phenylephrine is a safer choice for raising
blood pressure. Ephedrine should be used with caution
in patients who take SSRIs (serotonin-norepinephrine
re-uptake inhibitors), as it may increase the risk of “serotonin
syndrome”.
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