H2 Receptor Antagonist — Aspiration Prophylaxis

Ranitidine / Famotidine (H2 Antagonist — Aspiration Prophylaxis)

Brand names: Famotidine (generic), Pepcid

Famotidine is an H2-receptor antagonist used perioperatively to reduce gastric acidity as aspiration prophylaxis (ranitidine has been withdrawn from UK use).

Dosing — not shown for this use

The product information we hold does not support a dose for this page's specific use, route or population, so none is shown. Follow your local or national guideline, and confirm against the product SmPC.

Clinical monograph

How it works

It competitively blocks histamine H2 receptors on gastric parietal cells, reducing the volume and acidity of gastric secretions.

Prescribing in practice

Ranitidine was withdrawn from the UK market over nitrosamine (NDMA) contamination, so famotidine or an alternative is used in current practice.
Reducing gastric acidity and volume before anaesthesia aims to lessen the consequences of aspiration in at-risk patients.
Dose adjustment may be needed in significant renal impairment; consult current prescribing references.

Monitoring

Routine monitoring is not generally required for short perioperative use; assess renal function where relevant.

Counselling the patient

This medicine reduces stomach acid before your operation.
Mention any kidney problems or other medicines you take.

Evidence & guidelines

H2-receptor antagonists are established for aspiration prophylaxis, and the MHRA withdrawal of ranitidine reflects the NDMA contamination concern.

Reference: MHRA Ranitidine Withdrawal 2019; AAGBI Preoperative Assessment Guidelines; Mendelson (1946) aspiration criteria; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways