- Antihistamines: how to neutralize the negative effects of histamine?
- Blockers of histamine H2-receptor
- Nizatidine and ranitidine
- Side effects when taking H2-blockers of histamine receptors
- Antagonists of histamine H2 receptor
Antagonists of histamine H2 receptor
H2 antagonists, antagonists or histamine H2 receptor were discovered for many years later H1-antagonists. The first drug based on them began cimetidine, ranitidine was followed, famotidine, and nizatidine.
H2 antagonists inhibit histamine H2-receptor. The main result is the inhibition of gastric acid secretion. Subject to the recommended dosage antisecretory effect of different H2 antagonists alike.
The biological value of H2 antagonists varies from 50% for ranitidine
Ranitidine - help in the prevention of relapse of peptic ulcer
famotidine and about 90% to nizatidine and is taken into account when assigning dose. Most often they are advised to take at night to reduce the acidity of gastric juice at night. They are derived primarily through the kidneys.
We have especially cimetidine. While the remaining H2-antagonists have little effect on cytochrome P450, cimetidine inhibits it and also increases the concentration and enhances the effect of many other drugs.
Since gastric acid causes aggravation of ulcer and slows scarring ulcer, H2-antagonists are used for treating ulcer of the esophagus, stomach and duodenum, and also bleeding esophageal ulcer origin. In the latter case, commonly used H2-antagonists in injectable form.
H2 antagonists cimetidine, ranitidine, famotidine, and nizatidine may also be used for the treatment of gastroduodenal ulcer, but there is another option - proton pump inhibitors, with whom, for the elimination of Helicobacter pylori, appointed by antibiotics.
All H2 antagonists can cause bradycardia due to suppression of the positive chronotropic effect of histamine, and other side effects are usually not severe.
Cimetidine has endocrine side effects
: Increases the concentration of prolactin
Prolactin - effect on the body is not fully known
in blood plasma, and may induce gynecomastia
Gynecomastia - known since ancient times
and galaktoreyu. It also possesses antiandrogenic action, displacing dihydrotestosterone and thus, in some cases, can cause impotence
Impotence - a female perspective on the problem
. By inhibiting cytochrome P450 hepatic cimetidine may slow the biotransformation of various drugs, such as oral anticoagulants, benzodiazepines, beta-adrenergic antagonists, tacrolimus, theophylline concentrations due to this exceeds the normal.