Understanding Anesthesiology - The Global Regional Anesthesia ...

MIDAZOLAM
Class
Short-acting benzodiazepine. Used for sedation or as
an adjunct during general anesthesia. Midazolam has
anxiolytic and sedative (but not analgesic) properties.
Mechanism of Action
Agonism at the inhibitory GABA receptor.
Dose
For sedation: 0.03-0.08 mg/kg IV
Can also be given intramuscularly, intranasally and
orally.
Onset
Within 3-5 minutes
CVS
In larger doses, in the presence of hypovolemia or
when used in combination with opioids, midazolam
can lead to decreased blood pressure and increased
heart rate. Cardiac output is unchanged.
Respiratory
Dose-related respiratory depression occurs. This response
is exaggerated in the elderly, in those with
COPD or when used in combination with opioids.
Misc.
Midazolam is water-soluble therefore the pain on injection
and phlebitis that are seen with diazepam are uncommon.
Duration
Elimination half-time is 1-4 hours, making midazolam
a much shorter acting agent than diazepam.
Elimination
Metabolized in the liver by microsomal enzymes and
excreted in the urine.
Effects
CNS
Induces anxiolysis, amnesia, hypnosis. Decreases cerebral
blood flow. Minimal effects on intracranial pressure.
May contribute to post-operative delirium in the
elderly.
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