Midazolam

Question 1

Midazolam Mechanism of Action

Answer 1

• Midazolam is a benzodiazepine.
• Midazolam enhances the activity of gamma-aminobutyric acid (GABA) at GABA receptors within the central nervous system, resulting in anticonvulsant
activity, sedation, amnesia, anxiolysis and muscle relaxation.

Question 2

Midazolam Indications

Answer 2

Prolonged seizures.
Agitated delirium causing a mild to moderate risk to safety and droperidol is unavailable or ineffective.
Pain associated with severe muscle spasm. ICP
Sedation, for example for joint relocation. ICP
Sedation post intubation. ICP
Severe anxiety associated with COPD. ICP

Question 3

Midazolam Contraindications

Answer 3

Known severe allergy

Question 4

Midazolam Cautions

Answer 4

Concurrent administration of opiates, ketamine or other sedatives. This will increase and prolong the effects.
Intoxication. This will increase and prolong the effects.
Elderly and/or frail. These will increase and prolong the effects.

Question 5

Midazolam Use during pregnancy/breastfeeding

Answer 5

Safety has not been demonstrated during pregnancy, but midazolam should be administered if indicated.
May be administered if the patient is breastfeeding. Advise the patient to stop breastfeeding and seek further advice from their lead maternity carer or GP.

Question 6

Midazolam Common adverse effects

Answer 6

• Sedation.
• Respiratory depression.
• Hypotension.
• Amnesia.

Question 7

Midazolam Onset of effect

Answer 7

• IV: 2-3 minutes.

* IM: 3-5 minutes.

Question 8

Midazolam Duration of effect

Answer 8

30-60 minutes. The sedative effect may be longer, particularly in the elderly.

Question 9

Midazolam Pharmacokinetics

Answer 9

• Midazolam is predominantly metabolised by the liver.

* There are no significant effects from liver impairment on acute administration.

Question 10

Midazolam Common interactions

Answer 10

• The effects will be increased and prolonged in the presence of other sedatives or pain relieving medicines (for example other benzodiazepines, opiates, ketamine and alcohol).

Question 11

Midazolam Additional Information

Answer 11

When administering midazolam for sedation or analgesia the patient must be able to obey commands at all times.

Question 12

Midazolam GABA explanation

Answer 12

• GABA is an inhibitory neurotransmitter
• It changes uptake of chloride ions (complex and varied)
• Midazolam potentiates the activity of GABA, binding to GABA receptors and increasing its effect (increased chloride ion opening)
• Results in hyper-polarisation of the post synaptic neuron -> signals are transmitted across the synaptic cleft but “bounce off” the post-synaptic cell