Risk of acid aspiration (Mendelson's Syndrome) before general anaesthesia

Indication for Cimetidine

Population group: Suitable for both men and women, only adults (18 years old or older)

Cimetidine is recommended before general anaesthesia in patients thought to be at risk of acid aspiration (Mendelson’s Syndrome), particularly obstetric patients during labour.

For this indication, competent medicine agencies globally authorize below treatments:

400-2,400 mg in 1-6 divided doses

Route of admnistration


Defined daily dose

400 - 2,400 mg

Dosage regimen

From 66.667 To 400 mg 6 time(s) per day every day

Detailed description

In patients thought to be at risk of acid aspiration syndrome, an oral dose of 400mg can be given 90-120 minutes before induction of general anaesthesia or, in obstetric practice, at the start of labour. While such a risk persists, a dose of up to 400mg may be repeated (parenterally if appropriate) at four hourly intervals as required up to the usual daily maximum of 2.4g.

Active ingredient

Cimetidine is a histamine H2-receptor antagonist which rapidly inhibits both basal and stimulated gastric secretion of acid and reduces pepsin output. It is a reversible, competitive antagonist, and is used as an anti-ulcer drug.

Read more about Cimetidine

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