Brands, Medical Use, Clinical Data
- Anti-ulcer Agents
- Abortifacient Agents
Brands / Synonyms
Arthrotec; Cytotec; Misoprostol; Misoprostol 1:100; Misoprostol [Usan:Ban:Inn:Jan]; Misoprostolum [Inn-Latin]
Indicated for the treatment of ulceration (duodenal, gastric and NSAID induced) and prophylaxis for NSAID induced ulceration.
Misoprostol is a prostaglandin E1 (PGE1) analogue used for the treatment and prevention of stomach ulcers. When administered, misoprostol stimulates increased secretion of the protective mucus that lines the gastrointestinal tract and increases mucosal blood flow, thereby increasing mucosal integrity. It is sometimes co-prescribed with non-steroidal anti-inflammatory drugs (NSAIDs) to prevent the occurrence of gastric ulceration, a common adverse effect of the NSAIDs.
Mechanism of Action
Misoprostol seems to inhibit gastric acid secretion by a direct action on the parietal cells through binding to the prostaglandin receptor. The activity of this receptor is mediated by G proteins which normally activate adenylate cyclase. The indirect inhibition of adenylate cyclase by Misoprostol may be dependent on guanosine-5’-triphosphate (GTP). The significant cytoprotective actions of misoprostol are related to several mechanisms. These include: 1. Increased secretion of bicarbonate, 2. Considerable decrease in the volume and pepsin content of the gastric secretions, 3. It prevents harmful agents from disrupting the tight junctions between the epithelial cells which stops the subsequent back diffusion of H+ ions into the gastric mucosa, 4. Increased thickness of mucus layer, 5. Enhanced mucosal blood flow as a result of direct vasodilatation, 6. Stabilization of tissue lysozymes/vascular endothelium, and 7. Improvement of mucosal regeneration capacity.
Misoprostol is extensively absorbed.
Biotrnasformation / Drug Metabolism
Rapidly de-esterified to misoprostol acid. The de-esterified metabolite undergoes further metabolism by beta and omega oxidation; oxidation is followed by reduction of the ketone to yield prostaglandin F analogs.
Misoprostol should not be taken by anyone with a history of allergy to prostaglandins.
Misoprostol has not been shown to interfere with the beneficial effects of aspirin on signs and symptoms of rheumatoid arthritis. Misoprostol does not exert clinically significant effects on the absorption, blood levels, and anti-platelet effects of therapeutic doses of aspirin. Misoprostol has no clinically significant effect on the kinetics of diclofenac or ibuprofen.