Cimetidine injection

This product is a representative of a new class of drugs, namely histamine H2-receptor antagonists. This product was first used to block the effect of histamine on parietal cell H2-receptors through a competitive inhibition mechanism. This product does not have typical anticholinergic pharmacological effects. Studies have shown that this product inhibits basal gastric acid secretion during the day and at night. This product also inhibits gastric acid secretion caused by food, histamine, pentagastrin, caffeine and insulin. Animal pharmacology and toxicology: In vitro studies have shown that this product is a specific competitive H2-receptor antagonist with no significant interaction with catecholamine beta-receptors, histamine H1-receptors or muscarinic receptors. Depending on the dose administered, or more precisely the blood concentration achieved, the drug efficacy of this product for humans and experimental animals is very similar. In all species of animal studies, a blood concentration of about 2 mol/L can inhibit 50% of the maximum gastric acid secretion. For rats, dogs and mice, the median lethal dose for oral administration is about 2-3g/kg, and the median lethal dose for intravenous administration is 100-150mg/kg. In chronic toxicity experiments on dogs, some animals showed signs of liver and kidney damage after administration of 504mg/kg. For rats and dogs, this product shows anti-androgenic effects. After 12 months of administration of drugs at a dose level of 150-950mg/kg to rats, the prostate of male rats in each dose group shrank, and the testicles and seminal vesicles shrank in the high-dose group. After 12 months of administration of drugs at a dose level of 41-504mg/kg to dogs, the weight of the prostate was reduced. Studies have found that this product has no significant effect on fertility. In a 24-month toxicology study in rats, dose levels of 150, 378 and 950 mg/kg/day (approximately 4-24 times the recommended human dose) resulted in a statistically significant higher incidence of benign Leydig cell tumors in the treated groups compared with the control group. Tumors occurred in both the control and treated groups, and the difference became apparent only in older rats. In an intravenous study in dogs, tachycardia and hypotension were observed at a dose level of 25 mg/kg. Tachycardia occurred at an oral dose of 336 mg/kg. Propranolol prevented or reversed the increased heart rate. The pharmacokinetics of this product, as well as its absorption, metabolism and excretion, are essentially similar in humans, rats and dogs. Human Pharmacology: Effects on Basal (Non-Irritant) Gastric Acid Secretion: In a double-blind, placebo-controlled study in patients with duodenal ulcers, a single dose of cimetidine significantly and persistently reduced basal gastric acid secretion on an empty stomach during the day and at night, in a dose-dependent manner. The degree of inhibition is related to the blood drug level achieved. When the blood drug level exceeds 0.5 mg/L, the degree of inhibition can usually reach more than 80%. The duration of this level is different for different doses. A single dose of 200 mg disappears after 4-5 hours, and a dose of 300 mg disappears after 7-8 hours, but a dose of 400 mg still has an effect after 8 hours. The effect of cimetidine is not only due to a significant reduction in gastric acid concentration, but also a reduction in gastric juice secretion. When the effective blood drug concentration is reached, the gastric acid pH level is usually above 5.0, which means that pepsin will be inactivated during most of the treatment process. Effect on irritant gastric acid secretion: It is known that cimetidine is a powerful inhibitor of gastric acid secretion caused by histamine, pentagastrin, insulin, food or caffeine stimulation in normal people and patients with duodenal ulcers. When the blood drug concentration is 0.5mg/L, gastric acid secretion is inhibited by at least 50% or more, and when the blood drug concentration exceeds 1.0mg/L, gastric acid inhibition reaches 80-90%. The choice of administration time related to the experimental meal affects the pattern of blood drug levels. Data show that administration during meals can properly control gastric acid secretion. Studies have shown that daily doses of 800mg and 1g reduce 24-hour gastric acidity by 70% and 72%, respectively. In these studies, the effect of cimetidine on pepsin concentration is different, but the total amount of pepsin secretion is reduced as a result of reduced gastric juice volume. As mentioned above, when the pH exceeds 5, all secreted pepsin during this period is inactive. This product significantly inhibits the increase in intrinsic factor concentration caused by histamine stimulation, but does not affect the basal level of intrinsic factor. In studies detecting serum gastrin, as expected, increases caused by stimulants (food, etc.) can be observed. In these studies, when the pH of the stomach in the placebo group and the cimetidine group were controlled, there was no significant difference in gastrin levels between the two groups. However, without controlling the intragastric pH, gastrin levels were higher in the cimetidine group. This appears to be due to the higher intragastric pH levels caused by cimetidine. Cimetidine had no effect on gastric emptying rate or lower esophageal sphincter (LOS) pressure.

The main ingredient of this product is cimetidine.

This product is a colorless to light yellow clear liquid.

1. Treatment of duodenal ulcer and gastric ulcer that have been clearly diagnosed. 2. Patients with recurrence of duodenal ulcer after short-term treatment. 3. Patients with persistent gastroesophageal reflux disease who are ineffective in anti-reflux measures and single drug treatment such as antacids. 4. Prevention of stress ulcer and bleeding in critically ill patients. 5. Gastrinoma (Zollinger-Ellison syndrome).

This product can be administered by slow intravenous drip or intravenous injection when necessary, or it can be directly injected into the muscle without dilution. Intravenous administration: Intravenous interval drip: Intravenous administration can be intermittent administration, 200mg diluted with 100ml glucose injection (5%) or other compatible intravenous solution, drip for 15-20 minutes, and repeat every 4-6 hours. For some patients, if it is necessary to increase the dose, the number of doses needs to be increased, but it should not exceed 2g per day. Intravenous continuous drip: Continuous intravenous drip can also be used. Usually the normal drip rate should not exceed 75mg/hour within 24 hours. Intravenous injection: In some cases, intravenous injection is necessary. 200mg injection of this product should be diluted with 0.9% sodium chloride solution (or other compatible solutions, see compatible solutions-intravenous injection) to 20ml, slowly injected, the injection time should not be shorter than 2 minutes, and the 200mg dose can be repeated at intervals of 3-6 hours. This method of administration should be avoided for patients with cardiovascular disease (see Precautions-Intravenous Injection). After the bleeding stops, oral administration can be adopted, usually at a dose of 200 mg, 3 times a day, taken with meals and 400 mg before bedtime. If necessary, it can be increased to 400 mg, 4 times a day. Intramuscular injection: The dose for intramuscular injection is usually 200 mg, which can be repeated after 4-6 hours. Compatible solutions - intravenous injection: Although the physical and chemical stability of Taiwei injection and its following compatible solutions after dilution at 25°C for 48 hours has been confirmed, care should still be taken to reduce microbial contamination. After the injection is prepared, drip as soon as possible and complete within 24 hours, and discard any remaining injection. The compatible solutions of this product are as follows: sodium chloride injection, 5% and 10% glucose injection, lactated Ringer's solution, 5% sodium bicarbonate injection, 5% glucose plus 0.2% sodium chloride. Renal insufficiency: For patients with renal insufficiency, the dose should be reduced according to creatinine clearance. The following are recommended doses: Creatinine clearance (ml/min) Dose 0-15 200 mg twice a day 15-30 200 mg three times a day 30-50 200 mg four times a day 50 Normal dose: There is little experience with continuous intravenous infusion of this product for patients with impaired renal function. Therefore, continuous intravenous infusion of this product is not recommended for this type of patient. For patients undergoing hemodialysis, since the drug can be excreted by dialysis, dialysis is recommended before the next dose. If the condition requires an increase in dose, the drug should be taken multiple times at a dose of 200 mg. It is not meaningful to remove cimetidine through continuous peritoneal dialysis, and there is no need to adjust the dose range for patients with renal failure. Special cases: In some cases, such as patients with percutaneous gastrostomy, gastric acid secretion needs to be controlled. If intravenous administration is required, the method of administration should be the same as the above recommended method.

A review of patients undergoing short-term clinical studies found that this product is well tolerated. The most common adverse reactions are diarrhea, fatigue, rash, etc. The incidence of all adverse reactions is similar between the placebo and cimetidine treatment groups. Severe rash and reversible alopecia have been reported occasionally. When used in large doses, some patients develop gynecomastia and impotence. These adverse reactions may disappear after discontinuation of the drug, and the incidence of gynecomastia and impotence is related to the dose and treatment duration. Some articles report some increases in serum transaminases and plasma creatinine. When treating patients with renal and hepatic insufficiency, these conditions should be noted. In the first week of treatment, 11% of patients usually have increased creatinine. During treatment or one week after stopping treatment, this increase no longer progresses and returns to pre-treatment levels. The significance of these changes is unclear. In elderly patients with renal insufficiency and organic brain symptoms, mental disorders occasionally occur, which generally disappear within a few days after discontinuation of the drug. Hepatitis, fever, interstitial nephritis and pancreatitis are occasionally seen, and these adverse reactions can return to normal after discontinuation of the drug. Allergic vasculitis has also been reported occasionally. These symptoms will return to normal after discontinuation of the drug. Occasionally, sinus bradycardia, tachycardia, heart block and allergic reactions have also been reported when using this product for treatment. This product rarely causes leukopenia (including granulocytopenia), thrombocytopenia, reduction of various types of cells and aplastic anemia. However, when cimetidine is used in combination with drugs known to cause bone marrow suppression, the benefits and risks of the combined use should be evaluated.

It is contraindicated for those who are allergic to cimetidine.

Cimetidine can change the pharmacokinetic and pharmacodynamic responses of some drugs by changing their absorption, hepatic metabolism, and renal tubular secretion. Cimetidine can affect the hepatic cytochrome P-450 oxidase system and affect renal tubular secretion. It can delay the excretion of drugs, thereby increasing the plasma concentrations of some co-administered drugs. For drugs with a small therapeutic dose range, such as warfarin anticoagulants, phenytoin, theophylline, lidocaine, quinidine, procainamide, flecainide, and nifedipine, toxic reactions are occasionally seen. When warfarin anticoagulants are used, the prothrombin time should be closely checked. When used with cimetidine, the dose of the anticoagulant should be appropriately adjusted. For the following other drugs, when starting or stopping co-administration with cimetidine, the plasma levels of the drug should be closely monitored and the dose adjusted if necessary. These drugs affected by cimetidine include beta blockers, calcium channel blockers, tricyclic antidepressants, benzodiazepines, chloramphenicol, and metformin. Although these drugs increase their plasma levels when used in combination with cimetidine, clinically significant effects are rarely seen. Particular caution should be exercised in elderly patients with liver or kidney disease.

Sealed storage

2ml:0.2g

Fuzhou FU Yao Pharmaceutical Co., Ltd.

• Founded in:

  2001-06-07

• Address:

  No. 279, Zhongxia, Gushan Town, Jin'an District, Fuzhou City

• Tax NO.:

  91350100727934373D

• Registered Funds:

  30 million yuan

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