| Mechanism | Competitively inhibits histamine actions at all H2 receptors, mainly inhibiting gastric acid secretions from parietal cells |
| Typical Dose | 150-300mg BD for up to 4-8 weeks |
| Indications | * Benign gastric/duodenal ulcers * Chronic episodic dyspepsia * GORD |
| Contra-indications | |
| Side-effects | * Diarrhoea * GI/LFT disturbances * Headache/dizziness/fatigue * Rash * Rarely: pancreatitis, bradycardia, AV block |
| Interactions | (Cimetidine: inhibits cyto P450 enzymes, ↓ metabolism of oral Anticoagulants, Phenytoin, Carbamazepine, quinidine, nifedipine, theophylline, TCAs) |
| Elimination | |
| Additional Notes | Ranitidine has fewer side effects than cimetidine. Treatment should last for 4-8 weeks May mask symptoms of Gastric Cancer |