Damage and protection of the human gastric mucosa. A multiparameter assessment

Management of gastroduodenopathy associated with use of nonsteroidal anti-inflammatory drugs

Adverse events associated with the use of nonsteroidal anti-inflammatory drugs (NSAIDs) are reported more frequently to the Food and Drug Administration than are those associated with any other group of drugs. The absolute risk for serious gastrointestinal events--in particular, ulcer bleeding, perforation, and death--is controversial; some investigators believe that an epidemic of NSAID-related complications is being experienced, whereas others suggest that the risks are being overemphasized. The management of patients who take NSAIDs regularly also remains controversial. Key unresolved issues include how best to identify those patients at particularly high risk for the development of ulcer complications and whether such patients should receive prophylactic therapy in an attempt to prevent such problems. In this review, we critically evaluate the currently available literature and present a management algorithm for the treatment and prevention of NSAID-associated gastroduodenopathy.

Protective effect of propranolol on ethanol-induced gastric lesions in mice

The non-selective beta-adrenoceptor antagonist, propranolol, has a protective effect on ethanol-induced gastric haemorrhagic lesions in mice when given in doses of 2.5, 5.0 and 10 mg/kg either parenterally (i.p.) or orally. The effect was more marked after oral administration. Another non-selective beta-adrenoceptor antagonist, timolol, failed to protect against ethanol-induced gastric lesions. Thus, beta-adrenoceptor blockade does not seem to play a role in the gastroprotective effect of propranolol. Pretreatment with the cyclo-oxygenase inhibitor, indomethacin, abolished the protective effect of 2.5 and 5.0 mg/kg i.p. propranolol but only attenuated the effect of the higher i.p. dose (10 mg/kg) and the three oral doses. These results indicate that the gastroprotective effect of propranolol is mediated partly by the prostaglandin pathway and partly by another mechanism which, we suggest, may involve its membrane-stabilising action.

Role of H2-receptor blockers in the prevention of gastric injury resulting from nonsteroidal anti-inflammatory agents

Nonsteroidal anti-inflammatory drugs (NSAIDs) can produce injury to the gastric and duodenal mucosa. The histamine (H2)-receptor blocker cimetidine was studied to determine whether protection of the gastric mucosa of normal volunteers could be provided against a single dose of aspirin, 1,300 mg. Gastric mucosal injury was assessed with gastroscopy performed two hours after aspirin intake. Three liquid cimetidine doses were administered over 24 hours prior to the aspirin dose, the last dose one hour before the aspirin. The 200-mg and 400-mg doses of cimetidine protected a sufficient number of subjects to warrant further study. In the second study, these two doses were further examined to determine whether three doses were necessary and whether the final dose could be coadministered with the aspirin instead of one hour before. Concomitant administration of a single dose of cimetidine with aspirin was found to protect the gastric mucosa from aspirin damage as effectively as the other cimetidine regimens employed. A final, double-blind comparison of cimetidine, 200 mg, with placebo administered with the aspirin, 1,300 mg, confirmed that cimetidine protected the gastric mucosa from the hemorrhagic effects of aspirin.

Mechanisms of nonsteroidal anti-inflammatory drug-induced gastric damage. Actions of therapeutic agents

All nonsteroidal anti-inflammatory drugs (NSAIDs) used in the treatment of rheumatic diseases may cause gastric mucosal damage. Although the best-studied agent is aspirin, the mechanisms by which it damages the gastric mucosa are not fully understood. However, it is thought that the drug impairs mucosal defenses by penetrating the protective mucous and bicarbonate layers and damaging the epithelial lining cells. In turn, gastric acid is permitted to pour through the breached defenses. This "back-diffusion" of acid further injures cells and destroys capillaries and venules. This local damaging effect is pH dependent and is contributed to by the acid secretion of the stomach. Other mechanisms by which aspirin may induce or contribute to mucosal injury include inhibition of mucosal prostaglandin synthesis, reduction and alteration of mucus secretion, reduction of bicarbonate secretion, interference with cell turnover, as well as systemic effects such as platelet dysfunction. The mechanism by which nonaspirin NSAIDs cause gastrointestinal damage is uncertain. All are known to inhibit prostaglandin synthesis, which could contribute to their toxicity since prostaglandins found in the stomach both inhibit acid secretion and have mucosal defensive effects. Partial protections against aspirin-induced or other NSAID-induced gastric mucosal damage has been demonstrated, at least in some studies, by sucralfate, prostaglandins, omeprazole and histamine (H2)-receptor antagonists. Sucralfate appears to act primarily on local defensive mechanisms; its antisecretory effects are minimal. Prostaglandins exert a protective effect at both antisecretory and nonantisecretory (cytoprotective) doses, indicating that either or both mechanisms may be involved. The most recently studied agent, omeprazole, is the most potent of all acid inhibitors; it may also be cytoprotective, possibly as a result of its effects on sulfhydryl groups. Prostaglandins and omeprazole are not available in the United States and their potential side effects may limit their use in patients with chronic rheumatic diseases. Protection by H2-receptor antagonists is mostly related to reduction of acid secretion, though a cytoprotective effect may occur.