Cimetidine Injection

Representatives of this product is a kind of new drugs, namely, histamine H2 receptor antagonist, the product through the competitive inhibition mechanism first used for blocking the role of histamine H2 receptors on the wall cells. This product does not appear typical anticholinergic pharmacological effects. Studies have shown that this product based gastric acid secretion inhibition of day and night. This product also inhibit by food, histamine, pentagastrin, caffeine and insulin caused by gastric acid secretion. Animal pharmacology and toxicology: in vitro studies have shown that this product is a kind of specific competitive H2 receptor antagonist, and catecholamine receptors, histamine H1 receptor or a toadstool receptors are no obvious interaction. According to the dose of drug, more specifically, based on the blood concentration, this product is very similar to the effects of the human and experimental animals. In the study of all animal species, 2 mol/L about blood drug concentration can inhibit the maximum number of secretion of gastric acid 50%. For dogs, rats and mice, and the median lethal dose of oral medicine is about 2 to 3 g/kg, intravenous dosing of median lethal dose is 100-150 mg/kg, chronic toxicity experiments of the dog, after a dose of 504 mg/kg, some animals showed there were signs of liver and kidney damage. For dogs and rats, this article shows with androgen deprivation. Dose levels of 150-950 mg/kg of administered in rats after 12 months, each dose group of the prostate gland in the male rat narrowed, and in high dose group of seminal vesicle gland and testis. Dose levels of 41-504 mg/kg of drugs to give the dog after 12 months, lead to prostate weight. The study found that this product has no significant effect on fertility. For 24 months of toxicology studies in rats, the dose level of 150378 and 950 mg/kg/day (about 4 to 24 times the recommended dose for human body), compared with control group, the drug therapy group of benign Leydig (Leydig cell tumor incidence is higher, has significance in statistics. In the control group and treatment group had cancer, and only in older rats the differences became apparent. Intravenous drug research, for dogs, dose levels for 25 mg/kg can be observed when tachycardia, and hypotension. When an oral dose of 336 mg/kg when tachycardia. Propranolol can prevent or reverse heart rate speed up. For humans, rats and dogs, the product of the pharmacokinetic and its absorption, metabolism and excretion are basically similar. Human pharmacology: the base (not irritating) of gastric acid secretion function: for patients with duodenal ulcer, double-blind, placebo-controlled study, a single dose of cimetidine can obviously reduce fasting during the day and night of hydrochloric acid in gastric juice secretion, related to the dose. With the blood drug level associated with the degree of suppression, when the blood drug level of more than 0.5 mg/L, the degree of inhibition can usually reach more than 80%. Different doses, the duration of this level is not the same, a single dose of 200 mg dose, 4 to 5 hours after its role disappeared, 300 mg dose effect disappeared after 7 to 8 hours, however 400 mg dose still have a role after eight hours. The effect of cimetidine is not only due to obviously reduce stomach acid concentration, but also can reduce gastric juice secretion. When reach the effective blood drug concentration, hydrochloric acid in gastric juice pH levels are often more than 5.0, it shows that, in the treatment of most of the time in the process of pepsin will be inactivated. Influence on stimulating gastric acid secretion, we known cimetidine for normal people and patients with duodenal ulcer by histamine, pentagastrin, insulin, caused by food or caffeine to stimulate the secretion of gastric acid is a potent inhibitor. When the blood drug concentration of 0.5 mg/L, the inhibition of gastric acid secretion of 50% less or more than 50%, and when the blood concentrations greater than 1.0 mg/L, gastric acid suppression of 80-90%. With the related experimental drug delivery timing affect blood drug level model, data show that eating drug can properly control the secretion of gastric acid. Studies have shown that 800 mg daily 24 hours and 1 g dose respectively to reduce stomach acidity of 70% and 72% in these studies, the effect of cimetidine on the concentration of pepsin is different, but because of the result of the decrease of gastric juice and pepsin secretion volume decreases. As mentioned above, when the pH of more than 5, during this period all the secretion of pepsin were inactive. This product significantly inhibited histamine stimulation caused by internal factor to the increase of the concentration, but does not affect the factor of the basic level. The detection of serum gastric secrete element in the study, as expected, that can be observed by the stimulus (food, etc.) caused by the rise. In these studies, while the placebo group and pH of the stomach cimetidine group were controlled, and gastric secrete element level has no obvious difference between the two groups. However, such as pH does not control the stomach, cimetidine group stomach secrete hormone level is high. This seems to be caused by cimetidine and gastric pH level is higher. Cimetidine on gastric emptying rate and lower esophageal sphincter (LOS) pressure has no effect.