Pharmacological action Cimetidine
Cimetidine is a histamine blocker H2 receptors. It inhibits the production of hydrochloric acid stimulated food, gastrin, acetylcholine and histamine. Reducing the level of hydrochloric acid, the pH increases and decreases the activity of pepsin.
Cimetidine starts gastric mucosal defense mechanism, heals damage caused by the action of hydrochloric acid. It reduces the concentration of cytochrome P450. No effect on adrenergic receptors, has no anesthetic effect. Upon receiving Cimetidine inside therapeutic effect occurs after 1 hour and continues to act for 4-5 hours.
Cimetidine completely absorbed from the gastrointestinal tract. Metabolism occurs in the "first pass". Bioavailability - 60-70%. Maximum plasma concentration at admission on an empty stomach, is achieved after 1 hour, 3 hours later, the second peak may be observed. Cimetidine is distributed in body tissues. The level of binding to plasma proteins - 20%.
The half-life Tsimetidina - about 2 hours, with renal dysfunction may be increased. Write mainly unchanged in the urine. Clearance Cimetidine increased in patients who received burns.
Instruction Cimetidine recommended to set the dosage based on the patient's general condition. Adult patients a single dose of 100-800 mg.
When administered intravenously, Cimetidine single dose is 200 mg, intravenous infusion - 400 mg. The maximum permitted daily dose regardless of the method of administration should not exceed 2 years
The maximum allowable dose of Cimetidine for children from 1 year of age and older, regardless of the route of administration - 25-30 mg / kg / day in divided doses. Children under one year - 20 mg / kg / day.
Interaction with other drugs Cimetidine
Simultaneous treatment with aluminum hydroxide containing magnesium hydroxide antacids can reduce the absorption of Cimetidine. In combination with sulfonylureas - hypoglycemic agents - sometimes there is hypoglycemia.
Combinations with Cimetidine chlordiazepoxide, clorazepate, triazolam, alprazolam, diazepam, klobazamom, nitrazepama, flurazepama increases the concentration of benzodiazepines in blood plasma. May intensify sedation.
Simultaneous application increases the concentration of amiodarone in the blood due to slow its metabolism.
Cimetidine combination with atenolol in some cases cause severe bradycardia.
In simultaneous reception with benzylpenicillin increases its bioavailability.
Simultaneous treatment with vecuronium chloride, verapamil, gallopamilom enhances the action of these drugs.
Combination with indomethacin reduces its concentration in the blood plasma without affecting its anti-inflammatory effect.
The combination of ketoconazole and itraconazole reduces their absorption in the gastrointestinal tract.
Cimetidine reduces the clearance of lidocaine and increases its concentration in blood plasma may result in increased side effects of lidocaine.
Pregnancy and lactation
Due to the fact that cimetidine can penetrate the placental barrier and is excreted in breast milk, caution should be used the drug during pregnancy and breastfeeding.
Side effects Cimetidine
- when abrupt cancellation Cimetidine relapses of peptic ulcer disease;
- vomiting, pancreatitis, flatulence, hepatitis, nausea, diarrhea, jaundice;
- drowsiness, depression, fatigue, dizziness, emotional lability, hallucinations, agitation, anxiety, nervousness, psychosis, headache, hyperthermia, confusion, decreased libido;
- itching, skin rash, redness, exfoliative dermatitis, erythema multiforme, angioedema, Stevens-Johnson syndrome;
- possible in men (especially at higher doses) reduced potency, gynecomastia;
- rarely - thrombocytopenia, leukopenia, pancytopenia, neutropenia, agranulocytosis, aplastic and haemolytic anemia, eosinophilia;
- bradycardia, AV block, tachycardia, decreased blood pressure, vasculitis;
- interstitial nephritis, urinary retention;
- arthralgia, myalgia, polymyositis;
- hair loss.
- symptomatic ulcers;
- systemic mastocytosis;
- peptic ulcer exacerbation;
- multiple endocrine adenomatosis;
- prevention of relapse of peptic ulcer disease;
- heartburn (caused by hyperacidity);
- reflux esophagitis.
According to the instructions of cimetidine it can be used as adjunct therapy in pancreatic enzyme insufficiency, rheumatoid arthritis, urticaria (acute).
Hypersensitivity to cimetidine.
It should be used with caution in patients with cimetidine heart failure, chronic, diseases of the blood, liver cirrhosis, kidney or liver failure, immunosuppression, children and adolescents under 16 years.
Before the course, make sure that there are no patient of malignant diseases of the digestive system.
Patients with kidney or liver dysfunction requires specially adjusted dosing regimen.
With prolonged use is necessary to carry out systematic monitoring of the liver and blood. Instruction Cimetidine not recommended abruptly stop taking the drug because of the risk of recurrence of peptic ulcer.