ATC Group: A02B DRUGS FOR PEPTIC ULCER AND GASTRO-OESOPHAGEAL REFLUX DISEASE (GORD)

Alginic acid is a polysaccharide distributed widely in the cell walls of brown algae which is hydrophilic and forms a viscous gum when hydrated. Its salts with metals such as sodium and calcium are known as alginates. It is a significant component of the biofilms produced by the bacterium Pseudomonas aeruginosa, a major pathogen found in the lungs of some people who have cystic fibrosis. The biofilm and P. aeruginosa have a high resistance to antibiotics and are susceptible to inhibition by macrophages.

Under the effect of gastric acid, a precipitate is formed from bismuth subcitrate, which adheres primarily to the ulcerated area and inhibits the activity of pepsin. Bismuth subcitrate contributes to the healing of a high percentage of gastric and duodenal ulcers.

Carbenoxolone is a glycyrrhetinic acid derivative with a steroid-like structure, similar to substances found in the flavor-ful root of the licorice plant. It influences endogenous glucocorticoids by potently inhibiting 11β-hydroxysteroid dehydrogenase. Electrolyte imbalance is a serious side effect of carbenoxolone when used systemically. Carbenoxolone is best known in cellular physiology as a modestly potent, reasonably effective, water-soluble blocker of gap junctions. It exerts anti-inflammatory activity. Carbenoxolone has used orally in the clinical treatment of peptic ulcers, now it is used topically for the treatment of lip sores and mouth ulcers.

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.

Dexlansoprazole belongs to a class of antisecretory compounds, the substituted benzimidazoles, that suppress gastric acid secretion by specific inhibition of the (H+, K+)-ATPase at the secretory surface of the gastric parietal cell.

Dexrabeprazole belongs to the class of antisecretory compounds, the substituted benzimidazoles, that do not exhibit anticholinergic or H₂ histamine antagonist properties, but suppress gastric acid secretion by the specific inhibition of the H+/K+- ATPase enzyme at the secretory surface of the gastric parietal cell. This enzyme system is regarded as the acid (proton) pump, and therefore dexrabeprazole is classified as a gastric proton-pump inhibitor blocking the final step of acid production.

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.

Famotidine is a potent competitive H₂-receptor antagonist. Famotidine has a rapid onset of action and, at the recommended doses, has a long duration of action and is highly effective at relatively low blood concentrations.

Lansoprazole is a gastric proton pump inhibitor. It inhibits the final stage of gastric acid formation by inhibiting the activity of H+/K+ ATPase of the parietal cells in the stomach. The inhibition is dose-dependent and reversible, and the effect applies to both basal and stimulated secretion of gastric acid.

Misoprostol is an analogue of naturally occurring prostaglandin E1 which promotes peptic ulcer healing and symptomatic relief. Misoprostol protects the gastroduodenal mucosa by inhibiting basal, stimulated and nocturnal acid secretion and by reducing the volume of gastric secretions, the proteolytic activity of the gastric fluid, and increasing bicarbonate and mucus secretion.

Nizatidine is a potent, selective, competitive and fully reversible histamine H₂-receptor antagonist. Nizatidine significantly decreased basal and stimulated gastric acid and pepsin concentration, in addition to the volume of gastric secretion.

Omeprazole, a racemic mixture of two enantiomers reduces gastric acid secretion through a highly targeted mechanism of action. It is a specific inhibitor of the acid pump in the parietal cell. It is rapidly acting and provides control through reversible inhibition of gastric acid secretion with once daily dosing.

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.

Rabeprazole belongs to the class of anti-secretory compounds, the substituted benzimidazoles, that do not exhibit anticholinergic or H₂ histamine antagonist properties, but suppress gastric acid secretion by the specific inhibition of the H+/K+ -ATPase enzyme (the acid or proton pump).

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.

Rebamipide, a gastroprotective drug, is a compound selected from over 500 amino acid analogs of 2(1H)-quinolinone. Rebamipide stimulates prostaglandin generation in gastric mucosa and improves not only the speed but also the quality of ulcer healing. Rebamipide works by enhancing mucosal defense, scavenging free radicals and temporarily activating genes encoding cyclooxygenase-2.

Roxatidine is a competitive histamine H2 receptor antagonist. Roxatidine is a potent and selective inhibitor of basal and stimulated gastric acid secretion through competitive blockade of H2-receptors. Total pepsin secretion is reduced in a dose-dependent manner. There is an independent mucosal protection action. Roxatidine is indicated for the treatment of peptic ulcer, gastro-oesophageal reflux disease, gastritis, upper gastrointestinal haemorrhage and Zollinger-Ellison syndrome also it can be used as a premedication before anaesthesia. Roxatidine possessed a robust estrogenic activity.

Sucralfate forms an ulcer adherent complex with the proteinaceous exudate of the ulcer site. This property enables sucralfate to form a protective barrier over the ulcer lesion giving sustained protection against the penetration and action of gastric acid, pepsin and bile.

Tripoxide is a gastric cytoprotective agent used for the treatment of gastritis and gastric uclers. Troxipide has a mode of action different from that for other anti-gastric agents: it does not inhibit acid secretion and does not have acid neutralizing activity. It exerts its activity by increasing mucus production, cytoprotective prostaglandin secretion, regeneration of collagen fibers, reducing inflammatory mediator induced neutrophil migration and reactive oxygen species generation in gastric mucosa, enhancing gastric mucosal metabolism and microcirculation.

Vonoprazan suppresses basal and stimulated gastric acid secretion at the secretory surface of the gastric parietal cell through inhibition of the H+, K+-ATPase enzyme system in a potassium competitive manner. Because this enzyme is regarded as the acid (proton) pump within the parietal cell, vonoprazan has been characterized as a type of gastric proton-pump inhibitor, in that it blocks the final step of acid production. Vonoprazan does not require activation by acid. Vonoprazan may selectively concentrate in the parietal cells in both the resting and stimulated states. Vonoprazan binds to the active pumps in a noncovalent and reversible manner.