Cimetidinum

Pharmacological action of Cimetidinum

Cimetidinum is the lock histamine H2 receptors. Suppresses production of hydrochloric acid, stimulated food, gastrin, a histamine and acetylcholine. Reducing the level of hydrochloric acid, increases the pH level and lowers activity of pepsin.

Cimetidinum starts the protective mechanism mucous a stomach, heals the damages caused by effect of hydrochloric acid. Reduces concentration of P450 cytochrome. Does not exert impact on adrenoceptors, has no anesthetic effect. After reception of Cimetidinum in inside therapeutic effect comes in 1 hour and 4-5 hours continue to work.

Pharmacokinetics

Cimetidinum is completely soaked up from digestive tract. Metabolism happens at "the first passing". Bioavailability of drug – 60-70%. The maximum concentration in a blood plasma, at reception next the heart, is reached in 1 hour, in 3 hours the second peak can be observed. Cimetidinum is distributed in body tissues. Level of linkng with proteins of plasma – 20%.

Cimetidinum elimination half-life – about 2 hours, at dysfunction of kidneys can increase. It is removed generally in an invariable view with urine. The clearance of Cimetidinum increases at the patients who got burns.

Cimetidinum dosage

The instruction of Cimetidinum recommends to establish a dosage proceeding from the general condition of the patient. To adult patients the single dose makes 100-800 mg.

At intravenous administration of Cimetidinum the single dose is equal to 200 mg, at intravenous infusion – 400 mg. The most admissible daily dose irrespective of a method of introduction should not exceed 2 g.

The most admissible dose of Cimetidinum for children of 1 year is also more senior irrespective of a way of introduction – 25-30 mg/kg/days separate doses. To children is younger than one year – 20 mg/kg/days.

Interaction of Cimetidinum with other drugs

The concomitant use with the antacids containing aluminum hydroxide and magnesium hydroxide can lead to decrease in absorption of Cimetidinum. At a combination to sulphonylurea derivatives – hypoglycemic means – sometimes observe a hypoglycemia.

Cimetidinum combinations to chlordiazepoxide, clorazepate, triazolamy, alprazolamy, diazepam, klobazamy, nitrazepam, flurazepam leads to increase in concentration of benzodiazepines in a blood plasma. Can strengthen sedative action.

Simultaneous use increases concentration of Amiodaronum in blood, because of delay of his metabolism.

Cimetidinum combination with atenololy in certain cases causes the expressed bradycardia.

At a concomitant use with benzylpenicillin increases its bioavailability.

The concomitant use with a vekuroniya chloride, verapamil, gallopamily strengthens effect of these drugs.

The combination to indometacin leads to decrease in its concentration in a blood plasma, without influence on its antiinflammatory effect.

The combination with ketokonazoly and itrakonazoly reduces their absorption in digestive tract.

Cimetidinum reduces clearance of lidocaine and increases its concentration in a blood plasma, can lead to strengthening of side effects of lidocaine.

Pregnancy and lactation

Because Cimetidinum can get through a placental barrier and be allocated with breast milk, it is necessary to use with care drug at pregnancy and breastfeeding.

Side effects of Cimetidinum

• at sharp cancellation of Cimetidinum a recurrence of a peptic ulcer is possible;
• vomiting, pancreatitis, meteorism, hepatitis, nausea, diarrhea, jaundice;
• drowsiness, depression, increased fatigue, dizziness, emotional lability, hallucinations, excitement, concern, nervousness, psychosis, headache, hyperthermia, confusion of consciousness, decrease in a libido;
• itch, skin rash, hyperemia, exfoliative dermatitis, mnogoformny erythema, Quincke's disease, Stephens-Johnson's syndrome;
• are possible at men (especially at high doses): decrease in a potentiality, gynecomastia;
• seldom - thrombocytopenia, a leukopenia, a pancytopenia, a neutropenia, an agranulocytosis, aplastic and hemolitic anemia, an eosinophilia;
• bradycardia, AV blockade, tachycardia, decrease in the ABP, vasculitis;
• intersticial nephrite, urination delay;
• arthralgia, mialgiya, polymiositis;
• hair loss.

Indications to use of Cimetidinum

• symptomatic ulcers;
• system mastocytosis;
• peptic ulcer in an aggravation phase;
• polyendocrine adenomatosis;
• prevention of aggravations of a peptic ulcer;
• the heartburn (caused by a hyperacidity);
• reflux esophagitis.

According to the instruction Cimetidinum can be applied as auxiliary therapy at insufficiency of enzymes of a pancreas, a pseudorheumatism, a small tortoiseshell (in an acute form).

Contraindications

Hypersensitivity to Cimetidinum.

Special instructions

It is necessary to apply with care Cimetidinum to patients with heart failure in a chronic form, diseases of bodies of a hemopoiesis, cirrhosis, a renal or liver failure, immunity oppression, to children and teenagers 16 years are younger.

Prior to the beginning of a course it is necessary to be convinced of absence at the patient of malignant diseases of the digestive device.

Patients with dysfunction of kidneys or a liver need specially corrected dosing mode.

At prolonged use it is necessary to carry out systematic control of a condition of a liver and blood. The instruction of Cimetidinum does not recommend to stop sharply administration of drug in connection with danger of a recurrence of a peptic ulcer.