H2 Receptor Antagonists Flashcards
Give 2 examples of H2 receptor antagonists?
- Ranitidine
- Cimetidine
What is the action of H2 receptor antagonists?
Reduce gastric acid production by binding to H2 receptors and blocking them
How are H2 receptor antagonists administered?
Oral
What are the indications for H2 receptor antagonists?
- Peptic ulcers
- Duodenal ulcers
- GORD
What are the cautions for the use of H2 receptor antagonists?
Renal impairment
When should the dose of a H2 receptor antagonist be halved?
eGFR <50 ml/min
What drugs can cimetidine interact with?
- Warfarin
- Phenytoin
- Theophylline
- Carbamazepine
- Sodium valproate
- Clopidogrel
How does cimetidine interact with clopidogrel?
Reduces its antiplatelet effects
How does cimetidine interact with warfarin, phenytoin, theophylline, carbamazepine and sodium valproate?
By inhibiting the CYP450 enzymes and reducing their metabolism
What is the effect on the drugs metabolised by CYP450 enzymes of cimetidine?
Increases their effects
When should investigations be undertaken before starting H2 receptor antagonists?
When suspicious symptoms for gastric cancer
What are the commons side-effects of H2 receptor antagonists?
- Headache
- Dizziness
- Diarrhoea
What are the less common side-effects of H2 receptor antagonists?
- Rashes
- Confusion
- Depression
- Bleeding disorders
- Gynaecomastia
What mnemonic can be used to remember drugs that can cause gynaecomastia?
DISCO
What does DISCO stand for?
- Digoxin
- Isoniazid
- Spironolactone
- Cimetidine
- Oestrogens
