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. 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, 7. Improvement of mucosal regeneration capacity, and 8. Replacement of prostaglandins that have been depleted as a result of various insults to the area. Misoprostol has also been shown to increase the amplitude and frequency of uterine contractions during pregnancy via selective binding to the EP-2/EP-3 prostanoid receptors. Misoprostol is indicated for the treatment of ulceration (duodenal, gastric and NSAID induced) and prophylaxis for NSAID induced ulceration. Misoprostol is also indicated for other uses that are not approved in Canada, including the medical termination of an intrauterine pregnancy used alone or in combination with methotrexate, as well as the induction of labour in a selected population of pregnant women with unfavourable cervices. This indication is avoided in women with prior uterine surgery or cesarean surgery due to an increased risk of possible uterine rupture. Misoprostol is also used for the prevention or treatment of serious postpartum hemorrhage. Misoprostol is sold under the brandname Cytotec among others.

Diflunisal is a salicylic acid derivative with analgesic and anti-inflammatory activity. It was developed by Merck Sharp & Dohme in 1971 after showing promise in a research project studying more potent chemical analogs of aspirin. Diflunisal is an aspirin-like nonsteroidal anti-inflammatory drug that inhibits cyclooxygenase-2 (COX-2), an enzyme involved in prostaglandin synthesis.In animals, prostaglandins sensitize afferent nerves and potentiate the action of bradykinin in inducing pain. Since prostaglandins are known to be among the mediators of pain and inflammation, the mode of action of diflunisal may be due to a decrease of prostaglandins in peripheral tissues.

(R)-Naproxen is an enantiomer of the more active (S)-Naproxen, the last belongs to the class of Non-Steroidal Anti-Inflammatory Drugs. (S)- and (R)-naproxen represent useful substrates to distinguish different glucuronosyl transferases isozymes.

Esomeprazole strontium is a proton pump inhibitor. It suppresses gastric acid secretion by specific inhibition H+/K+ ATPase in the gastric parietal cell. The S- and R-isomers of omeprazole are protonated and converted in the acidic compartment of the parietal cell forming the active inhibitor, the achiral sulphenamide. By acting specifically on the proton pump, esomeprazole blocks the final step in acid production, thus reducing gastric acidity. The drug is indicated for the treatment of gastroesophageal reflux disease, reduction the risk of NSAID-associated gastric ulcer, eradication of H.pylori, and pathological hypersecretory conditions.

Naproxen (naproxen sodium, NAPROSYN®) is a propionic acid derivative related to the arylacetic acid group of nonsteroidal anti-inflammatory drugs (NSAIDs). It is an anti-inflammatory agent with analgesic and antipyretic properties. Both the acid and its sodium salt are used in the treatment of rheumatoid arthritis and other rheumatic or musculoskeletal disorders, dysmenorrhea, and acute gout. The mechanism of action of the naproxen (naproxen sodium, NAPROSYN®), like that of other NSAIDs, is not completely understood but involves inhibition of cyclooxygenase (COX-1 and COX-2).

Naproxen (naproxen sodium, NAPROSYN®) is a propionic acid derivative related to the arylacetic acid group of nonsteroidal anti-inflammatory drugs (NSAIDs). It is an anti-inflammatory agent with analgesic and antipyretic properties. Both the acid and its sodium salt are used in the treatment of rheumatoid arthritis and other rheumatic or musculoskeletal disorders, dysmenorrhea, and acute gout. The mechanism of action of the naproxen (naproxen sodium, NAPROSYN®), like that of other NSAIDs, is not completely understood but involves inhibition of cyclooxygenase (COX-1 and COX-2).