ICD-10 Specific code K21: Gastro-oesophageal reflux disease

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.

Cisapride is a substituted piperidinyl benzamide prokinetic agent. Cisapride facilitates release of acetylcholine from the myenteric plexus, resulting in increased gastrointestinal motility. In addition, cisapride has been found to act as a serotonin agonist, stimulating type 4 receptors, and a serotonin 5-HT₃ receptor antagonist.

Esomeprazole is the S-isomer of omeprazole and reduces gastric acid secretion through a specific targeted mechanism of action. Esomeprazole is a weak base and is concentrated and converted to the active form in the highly acidic environment of the secretory canaliculi of the parietal cell, where it inhibits the enzyme H+ K+ -ATPase – the acid pump and inhibits both basal and stimulated acid secretion.

Pantoprazole is a substituted benzimidazole which inhibits the secretion of hydrochloric acid in the stomach by specific blockade of the proton pumps of the parietal cells.

Ranitidine is a specific rapidly acting histamine H₂-antagonist. It inhibits basal and stimulated secretion of gastric acid, reducing both the volume and the acid and pepsin content of the secretion. Ranitidine has a relatively long duration of action and so a single 150 mg dose effectively suppresses gastric acid secretion for twelve hours.