Cimetidine is used to treat gastrointestinal disorders. The H2 antihistamine is used to dampen gastric juice production.
What is cimetidine?
Cimetidine is used to treat gastrointestinal disorders. The H2 antihistamine is used to dampen gastric juice production. Cimetidine is a gastrointestinal agent. It belongs to the group of H2 receptor antagonists. The drug can thus inhibit the effects of the tissue hormone histamine. For this reason, it is suitable for the treatment of gastritis, stomach ulcers, heartburn, inflammation of the esophagus, and duodenitis. Cimetidine was among 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, known in modern times as GlaxoSmithKline. In 1976, the drug was launched under the name Tagamet. Tagamet advanced to become a sought-after success drug on the pharmacological market. Cimetidine was developed by the British chemists John Colin Emmett, Graham J. Durant and Robin Ganellin. For their achievement, they found induction into the National Inventors Hall of Fame.
Pharmacological action
The mode of action of cimetidine is based on the drug blocking an H2 receptor (binding site) of the tissue hormone histamine on gastric mucosal occupancy cells. Histamine is an important neurotransmitter (messenger substance). It forms gastric acid from the occupant cells and releases it. The blockade of the histamine receptors by cimetidine means that the hormone is no longer able to dock to the receptors, causing it to lose its effect. In this way, there is a reduced release of gastric acid. Cimetidine also has the property of limiting the activity of the gastric gastric epithelial cells. The occupant cells produce hydrochloric acid, which is responsible for breaking down the food that enters the stomach. However, excessive release of gastric acid can result in heartburn. Cimetidine ensures that the stomach cells do not produce too much acid. For the active ingredient to exert its positive effects, its dose must be high enough. After oral absorption of cimetidine into the organism, the gastrointestinal drug is rapidly absorbed within the gastrointestinal tract. Thus, it takes only 90 to 120 minutes for 50 percent of the H2 antihistamine to leave the body. This process takes place through the kidneys and urine.
Medical use and application
For use, cimetidine is used in the treatment and prevention of conditions in which it is important to decrease stomach acid production. These include acid-related stomach disorders, heartburn, inflammation of the esophagus, reflux esophagitis (abnormal reflux of stomach acid), and gastritis and duodenitis. Another area of application is Zollinger-Ellison syndrome, in which there is a pathological overproduction of gastric acid due to hormonal overstimulation of the occupant cells. Cimetidine is usually administered in tablet form. In addition, the drug can be injected directly into a vein. The dose of the gastrointestinal drug varies from person to person and depends on the 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. In this case, it is taken at night, since the production of gastric acid occurs especially during the night hours. However, the patient must not exceed a maximum dose of two grams of cimetidine daily.
Risks and side effects
Taking cimetidine may sometimes result in side effects. However, they do not occur in every person. Most patients experience itching|itching]], joint pain, muscle discomfort, headache, dizziness, gastrointestinal discomfort, and fatigue. Just under one percent of all users also experience temporary skin rashes, sleep problems, changes in blood count, enlargement of the male mammary gland (gynecomastia), cardiac arrhythmias, and impotence. In some cases, depression, confusion, and hallucinations have also been reported.Cimetidine should not be used at all in the case of an already existing hypersensitivity to the active substance. If the patient suffers from restrictions of his kidney function, it is advisable to reduce the dose. Prior to cimetidine therapy, it is also necessary to undergo a medical examination for malignant ulcers or infestation with the bacterium Helicobacter pylori. There would have to be a change in drug treatment in the corresponding case. Taking cimetidine during pregnancy should be subject to a thorough risk-benefit assessment. The reason for this is insufficient information on how the gastrointestinal drug works during this period. Possible adverse effects during breastfeeding cannot be ruled out due to the transfer of cimetidine into breast milk. For this reason, the drug should not be taken 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 within the realm of possibility. These include primarily the local anesthetic lidocaine, the antiepileptic anticonvulsant phenytoin, benzodiazepines, anticoagulants of the warfarin type, tricyclic antidepressants, which include imipramine in particular, beta-blockers such as metoprolol and propranolol, and alcohol. Thus, concomitant administration of these agents can increase or prolong both effects and side effects. In addition, because the pH in the stomach changes, this leads to absorption of other drugs into the bloodstream. These include absorption of the antifungal drug ketoconazole. Furthermore, cimetidine increases the concentration of glipizide, which has a blood sugar-lowering effect. This increases the effect of lowering blood glucose.
