Midazolam Intramuscular for acutely disturbed behaviour

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Key information

Midazolam is an alternative intramuscular benzodiazepine that may be used for managing acutely disturbed behaviour in the event of a shortage of intramuscular lorazepam. It has a rapid onset and brief effect.

Key prescribing information for intramuscular midazolam


5 - 7.5mg by deep IM injection repeated after 2 hours

Maximum dose

15mg/ 24 hours

Dosing in special circumstance:

In elderly (>60), physically ill or debilitated patients, individuals with renal, hepatic or cardiac function or chronic respiratory insufficiency

¼- ½ adult dose



Absorption after IM injection is rapid and complete

Maximum plasma concentration in 30 minutes

Elimination half life - 1.5-2 .5 hours (In adults over 60 years of age, the elimination half-life may be prolonged up to four times)


Monitor for excessive sedation, respiratory depression, hypotension for at least 4 hours after last dose


10mg/2ml ampoules should be used for this indication


Midazolam 10mg/2ml is a controlled drug (CD). It must be ordered in the ward CD order book, stored in CD cupboard and receipt/administration recorded in the CD register.


No dilution of ampoule required


IM midazolam may be painful

Do not give IM midazolam within 1 hour of IM olanzapine

IM flumazenil should always be available when administering IM benzodiazepines.

Editorial Information

Last reviewed: 16 July 2020

Next review: 01 June 2023

Author(s): PMG-MH

Version: 1

Approved By: PMG-MH

Reviewer Name(s): Andrew Walker, Suzanne Burke