An Hreceptor antagonist drug that promotes healing of peptic ulcers and reduces inflammation of the oesophagus (oesophagitis) by suppressing acid production from the stomach. Side effects, which include headaches and dizziness, are uncommon.
Acute gastritis is an in?ammatory reaction of the gastric mucosa to various precipitating factors, ranging from physical and chemical injury to infections. Acute gastritis (especially of the antral mucosas) may well represent a reaction to infection by a bacterium called Helicobacter pylori. The in?ammatory changes usually go after appropriate antibiotic treatment for the H. pylori infection. Acute and chronic in?ammation occurs in response to chemical damage of the gastric mucosa. For example, REFLUX of duodenal contents may predispose to in?ammatory acute and chronic gastritis. Similarly, multiple small erosions or single or multiple ulcers have resulted from consumption of chemicals, especialy aspirin and antirheumatic NONSTEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS).
Acute gastritis may cause anorexia, nausea, upper abdominal pain and, if erosive, haemorrhage. Treatment involves removal of the o?ending cause.
Chronic gastritis Accumulation of cells called round cells in the gastric mucosal characterises chronic gastritis. Most patients with chronic gastritis have no symptoms, and treatment of H. pylori infection usually cures the condition.
Atrophic gastritis A few patients with chronic gastritis may develop atrophic gastritis. With or without in?ammatory change, this disorder is common in western countries. The incidence increases with age, and more than 50 per cent of people over 50 may have it. A more complete and uniform type of ATROPHY, called ‘gastric atrophy’, characterises a familial disease called PERNICIOUS ANAEMIA. The cause of the latter disease is not known but it may be an autoimmune disorder.
Since atrophy of the corpus mucosa results in loss of acid- and pepsin-secreting cells, gastric secretion is reduced or absent. Patients with pernicious anaemia or severe atrophic gastritis of the corpus mucosa may secrete too little intrinsic factor for absorption of vitamin B12 and so can develop severe neurological disease (subacute combined degeneration of the spinal cord).
Patients with atrophic gastritis often have bacterial colonisation of the upper alimentary tract, with increased concentration of nitrite and carcinogenic N-nitroso compounds. These, coupled with excess growth of mucosal cells, may be linked to cancer. In chronic corpus gastritis, the risk of gastric cancer is about 3–4 times that of the general population.
Postgastrectomy mucosa The mucosa of the gastric remnant after surgical removal of the distal part of the stomach is usually in?amed and atrophic, and is also premalignant, with the risk of gastric cancer being very much greater than for patients with duodenal ulcer who have not had surgery.
Stress gastritis Acute stress gastritis develops, sometimes within hours, in individuals who have undergone severe physical trauma, BURNS (Curling ulcers), severe SEPSIS or major diseases such as heart attacks, strokes, intracranial trauma or operations (Cushing’s ulcers). The disorder presents with multiple super?cial erosions or ulcers of the gastric mucosa, with HAEMATEMESIS and MELAENA and sometimes with perforation when the acute ulcers erode through the stomach wall. Treatment involves inhibition of gastric secretion with intravenous infusion of an H2-receptorantagonist drug such as RANITIDINE or FAMOTIDINE, so that the gastric contents remain at a near neutral pH. Despite treatment, a few patients continue to bleed and may then require radical gastric surgery.
Gastric ulcer Gastric ulcers were common in young women during the 19th century, markedly fell in frequency in many western countries during the ?rst half of the 20th century, but remained common in coastal northern Norway, Japan, in young Australian women, and in some Andean populations. During the latter half of this century, gastric ulcers have again become more frequent in the West, with a peak incidence between 55 and 65 years.
The cause is not known. The two factors most strongly associated with the development of duodenal ulcers – gastric-acid production and gastric infection with H. pylori bacteria – are not nearly as strongly associated with gastric ulcers. The latter occur with increased frequency in individuals who take aspirin or NSAIDs. In healthy individuals who take NSAIDs, as many as 6 per cent develop a gastric ulcer during the ?rst week of treatment, while in patients with rheumatoid arthritis who are being treated long term with drugs, gastric ulcers occur in 20–40 per cent. The cause is inhibition of the enzyme cyclo-oxygenase, which in turn inhibits the production of repair-promoting PROSTAGLANDINS.
Gastric ulcers occur especially on the lesser curve of the stomach. The ulcers may erode through the whole thickness of the gastric wall, perforating into the peritoneal cavity or penetrating into liver, pancreas or colon.
Gastric ulcers usually present with a history of epigastric pain of less than one year. The pain tends to be associated with anorexia and may be aggravated by food, although patients with ‘prepyloric’ ulcers may obtain relief from eating or taking antacid preparations. Patients with gastric ulcers also complain of nausea and vomiting, and lose weight.
The principal complications of gastric ulcer are haemorrhage from arterial erosion, or perforation into the peritoneal cavity resulting in PERITONITIS, abscess or ?stula.
Aproximately one in two gastric ulcers heal ‘spontaneously’ in 2–3 months; however, up to 80 per cent of the patients relapse within 12 months. Repeated recurrence and rehealing results in scar tissue around the ulcer; this may cause a circumferential narrowing – a condition called ‘hour-glass stomach’.
The diagnosis of gastric ulcer is con?rmed by ENDOSCOPY. All patients with gastric ulcers should have multiple biopsies (see BIOPSY) to exclude the presence of malignant cells. Even after healing, gastric ulcers should be endoscopically monitored for a year.
Treatment of gastric ulcers is relatively simple: a course of one of the H2 RECEPTOR ANTAGONISTS heals gastric ulcers in 3 months. In patients who relapse, long-term inde?nite treatment with an H2 receptor antagonist such as ranitidine may be necessary since the ulcers tend to recur. Recently it has been claimed that gastric ulcers can be healed with a combination of a bismuth salt or a gastric secretory inhibitor
for example, one of the PROTON PUMP INHIBITORS such as omeprazole or lansoprazole
together with two antibiotics such as AMOXYCILLIN and METRONIDAZOLE. The long-term outcome of such treatment is not known. Partial gastrectomy, which used to be a regular treatment for gastric ulcers, is now much more rarely done unless the ulcer(s) contain precancerous cells.
Cancer of the stomach Cancer of the stomach is common and dangerous and, worldwide, accounts for approximately one in six of all deaths from cancer. There are marked geographical di?erences in frequency, with a very high incidence in Japan and low incidence in the USA. In the United Kingdom around 33 cases per 100,000 population are diagnosed annually. Studies have shown that environmental factors, rather than hereditary ones, are mainly responsible for the development of gastric cancer. Diet, including highly salted, pickled and smoked foods, and high concentrations of nitrate in food and drinking water, may well be responsible for the environmental effects.
Most gastric ulcers arise in abnormal gastric mucosa. The three mucosal disorders which especially predispose to gastric cancer include pernicious anaemia, postgastrectomy mucosa, and atrophic gastritis (see above). Around 90 per cent of gastric cancers have the microscopic appearance of abnormal mucosal cells (and are called ‘adenocarcinomas’). Most of the remainder look like endocrine cells of lymphoid tissue, although tumours with mixed microscopic appearance are common.
Early gastric cancer may be symptomless and, in countries like Japan with a high frequency of the disease, is often diagnosed during routine screening of the population. In more advanced cancers, upper abdominal pain, loss of appetite and loss of weight occur. Many present with obstructive symptoms, such as vomiting (when the pylorus is obstructed) or di?culty with swallowing. METASTASIS is obvious in up to two-thirds of patients and its presence contraindicates surgical cure. The diagnosis is made by endoscopic examination of the stomach and biopsy of abnormal-looking areas of mucosa. Treatment is surgical, often with additional chemotherapy and radiotherapy.... stomach, diseases of
The drugs used in combination are:
The receptor antagonists, which reduce the output of gastric acid by histamine H2receptor blockade; they include CIMETIDINE, FAMOTIDINE and RANITIDINE.
ANTIBIOTICS to eradicate Helicobacter pylori infection, a major cause of peptic ulceration. They are usually used in combination with one of the PROTON-PUMP INHIBITORS and include clarithomycin, amoxacillin and metronidazole.
BISMUTH chelates.
The prostaglandin analogue misoprostol has antisecretory and protective properties.
Proton-pump inhibitors omeprazole, lansoprazole, pantaprazole and rabeprazole, all of which inhibit gastric-acid secretion by blocking the proton pump enzyme system.... ulcer healing drugs
Mild, temporary gynaecomastia can occur at birth as a result of maternal hormones, and it is common at puberty.
Gynaecomastia developing in later life may be due to chronic liver diseases such as cirrhosis. Hormone secreting tumours such as pituitary or testicular tumours may also be a cause.
Adult gynaecomastia, which sometimes occurs in only one breast, can also occur when synthetic hormones and some drugs, such as digoxin, spironolactone, and cimetidine, change the balance of sex hormones. Rarely, a discrete lump that develops on one breast may be due to a male breast cancer.
Investigation may involve blood tests. If cancer is suspected, a biopsy will be performed. Treatment depends on the cause. If a drug is responsible, an alternative will be prescribed if possible. If there is no underlying disease, swelling usually subsides without treatment. Cosmetic surgery may be considered in severe cases (see mammoplasty).
H2-receptor antagonists A common abbreviation for histamine2-receptor antagonists, a group of ulcer-healing drugs. (See also cimetidine; ranitidine; famotidine.) habituation The process of becoming accustomed to an experience. In general, the more a person is exposed to a stimulus, the less he or she is affected by it. People can become habituated to certain drugs and develop a reduced response to their effects (see tolerance).... gynaecomastia
H2 receptors are mainly found in the stomach, where stimulation by histamine causes secretion of acid gastric juice. H2-receptor antagonists (e.g. *cimetidine, *nizatidine, *ranitidine, and *famotidine) block these receptors and reduce gastric acid secretion; they are used in the treatment of functional dyspepsia, *peptic ulcers, and *gastro-oesophageal reflux disease. H3- and H4-receptor antagonists have yet to find a clinical role.... antihistamine
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