Famotidine
Class: Histamine H2-receptor antagonist
Indications: reduction of gastric acid secretion in gastric/duodenal ulcers, reflux disease and malignant bowel obstruction
Contraindications/cautions: hypersensitivity to other H2-receptor antagonists/ H2-receptor antagonists may mask symptoms of gastric cancer; particular care is required in patients presenting with ‘alarm features’, in such cases gastric malignancy should be ruled out before treatment; increased risk of CNS adverse effects
Adverse reactions: common: diarrhoea, constipation, headache, dizziness. less common: dry mouth, nausea, vomiting, flatulence, taste disorders, anorexia, fatigue
Metabolism/clearance: 25 to 30% metablolised by CYP450 in the liver – first pass metabolism. Minimal inhibitory effect on other drugs. 70% eliminated renally
Interactions: No significant interactions known with common palliative care drugs
| Dosing: | ||
|---|---|---|
| oral: | Oesophageal reflux | 20 mg bd |
| Severe oesophagitis | 40 mg bd | |
| Peptic ulcer or peptic ulcer prevention | 20 mg bd or 40 mg nocte | |
| Paraneoplastic sweating | 20 to 40 mg once daily (benefit within 2 to 3 days) | |
Syringe driver: Malignant bowel obstruction 40 mg/24 hours via syringe driver – WFI or NaCl 0.9% as diluent
Mechanism of action: inhibits acid concentration and volume of gastric secretion as well as basal and nocturnal gastric acid secretion
Peak effect: 1 to 3 hours after oral dose
Onset: onset of action 1 hour orally
Duration: 6 to 10 hours after single dose
Notes:
- reduce dose in hepatic and renal impairment
- famotidine injection must be stored in the fridge until added to a syringe driver