Cimetidine is used to treat gastrointestinal diseases. The H2 antihistamine is used to dampen gastric juice production.
What is cimetidine?
Cimetidine is an active ingredient in the gastrointestinal tract. It belongs to the group of H2 receptor antagonists. The agent can inhibit the effects of the tissue hormone histamine. For this reason, it is suitable for treating gastric inflammation, stomach ulcers, heartburn, inflammation of the esophagus and duodenitis.
Cimetidine was one of the first H2 antagonists to be marketed for the treatment of gastrointestinal ulcers and heartburn. The drug was developed in the 1960s by the pharmaceutical company SmithKline and French, now known as GlaxoSmithKline. In 1976 the product was launched under the name Tagamet®. Tagamet advanced to become a popular drug for success in the pharmacological market.
Cimetidine was developed by British chemists John Colin Emmett, Graham J. Durant and Robin Ganellin. They were inducted into the National Inventors Hall of Fame for their achievements.
Pharmacological effect
The mode of action of cimetidine is based on the fact that the drug blocks an H2 receptor (binding site) of the tissue hormone histamine on the gastric mucosal cells. Histamine is an important neurotransmitter (messenger substance). It forms gastric acid from the parietal cells and releases it. The blockage of the histamine receptors by cimetidine causes the hormone to no longer be able to dock with the receptors, which makes it less effective. In this way there is a reduced secretion of gastric acid.
Cimetidine also has the property of restricting the activities of the gastric parietal cells. The parietal cells produce hydrochloric acid, the task of which is to break up the food that has entered the stomach. However, an excessive release of stomach acid can lead to heartburn. Cimetidine now ensures that the parietal cells do not produce too much acid. In order for the active ingredient to develop its positive effects, the dose must be high enough.
After oral ingestion of cimetidine into the organism, the gastrointestinal agent is rapidly absorbed within the gastrointestinal tract. It only takes 90 to 120 minutes for 50 percent of the H2 antihistamine to leave the body. This process takes place through the kidneys and the urine.
Medical application & use
Cimetidine is used in the therapy and prevention of diseases in which a reduction in gastric acid production is important. These include acid-related stomach problems, heartburn, inflammation of the esophagus, reflux esophagitis (pathological reflux of gastric acid) as well as stomach and duodenitis.
Another area of application is the Zollinger-Ellison syndrome, in which there is a pathological overproduction of gastric acid due to hormonal parietal cell overstimulation.
Cimetidine is usually administered in the form of tablets. In addition, the drug can be injected directly into a vein. The dose of the gastrointestinal agent varies from person to person and depends on the particular clinical picture. The function of the kidneys also plays a role. In the case of a gastrointestinal ulcer, it is possible to prescribe 800 to 1000 milligrams of cimetidine over a period of four to eight weeks. It is taken at night, as stomach acid is produced, especially at night. However, the patient must not exceed a maximum dose of two grams of cimetidine per day.
Risks & side effects
Taking cimetidine can sometimes cause side effects. However, they do not occur in every person. Most patients suffer from itching itching]], joint pain, muscle discomfort, headache, dizziness, gastrointestinal complaints and fatigue.
In almost one percent of all users, skin rashes, sleep problems, changes in the blood count, an enlargement of the male mammary gland (gynecomastia), cardiac arrhythmias and impotence appear temporarily. In some cases, depression, confusion, and hallucinations are also recorded.
Cimetidine must not be used at all in the event of an already existing hypersensitivity to the active ingredient. If the patient suffers from impaired kidney function, it is advisable to reduce the dose. Before starting cimetidine therapy, it is also necessary to conduct a medical examination for malignant ulcers or an infection with the Helicobacter pylori bacterium. In the appropriate case, a change in drug treatment would have to take place.
The use of cimetidine during pregnancy should be carefully weighed against risk. The reason for this is insufficient information on how the gastrointestinal agent works during this period. If cimetidine passes into breast milk, possible impairments during breastfeeding cannot be ruled out. For this reason, it is important to stop taking the drug during this period. In children and adolescents, too, there is insufficient knowledge about the effects of cimetidine during growth.
Interactions between cimetidine and other drugs are possible. These include primarily the local anesthetic lidocaine, the antiepileptic anticonvulsant phenytoin, benzodiazepines, anticoagulants of the warfarin type, tricyclic antidepressants, which primarily include imipramine, beta blockers such as metoprolol and propranolol, and alcohol. Thus, both the effect and the side effects can be increased or prolonged by the simultaneous administration of these agents.
Because the pH in the stomach also changes, this leads to the absorption of other drugs into the bloodstream. This includes u. a. ingesting the antifungal agent ketoconazole. Cimetidine also increases the concentration of glipizide, which has a blood sugar-lowering effect. This increases the effect of lowering blood sugar.
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