Ranitidine

Ranitidine is an antiulcer drug and belongs to the category of histamine H2 receptor antagonists.

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Indications Ranitidine

Among the indications:

• aggravated ulcer of the duodenum or stomach;
• prophylactic agent against ulcer exacerbation;
• ulcers of a symptomatic nature (ulcerative lesions (rapidly developing) of the stomach or duodenum, which appear under the influence of stress, taking various medications or pathologies of nearby internal organs);
• erosive form of esophagitis (an inflammatory process in the esophagus, in which the integrity of its mucous membrane is destroyed), as well as reflux esophagitis (an inflammatory process in the esophagus, provoked by the reflux of stomach contents into it);
• gastrinoma (a combination of ulcerative lesion of the stomach and a benign tumor formed in the pancreas);
• prevention of the development of disorders in the upper gastrointestinal tract, as well as in the period after surgery;
• prevention of possible penetration of gastric juice into the respiratory system in patients undergoing surgery under anesthesia.

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Release form

It is produced in the form of tablets and injection solution. The tablets have a volume of 0.15 and 0.3 g; one pack contains 20, 30 or 100 tablets. The solution is contained in ampoules of 2 ml.

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Pharmacodynamics

The drug selectively blocks histamine H2 receptors in the parietal cells of the gastric mucosa and also suppresses the secretion of hydrochloric acid. Ranitidine's effect also reduces the total secretory volume, which reduces the concentration of pepsin in the gastric contents.

The antisecretory properties of the drug create conditions in which ulcerative lesions of the duodenum and stomach heal faster. Ranitidine enhances the protective properties of the tissues of the gastroduodenal region: improves microcirculation processes, enhances the restorative effect, and also increases the secretion of mucous elements.

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Pharmacokinetics

After oral administration, it is rapidly absorbed from the gastrointestinal tract. The peak concentration is 440-545 ng/ml. It is reached 2-3 hours after taking the drug at a dosage of 150 mg. The bioavailability is approximately 50% (this is due to the "first pass" effect in the liver). Food intake does not affect the absorption of the substance.

It binds to plasma proteins by 15%. It can penetrate histohematic barriers (also through the placenta), but it passes poorly through the BBB. The distribution volume is approximately 1.4 l/kg. Partial biotransformation occurs in the liver. As a result, the main decay product is formed - N-oxide, and with it S-oxide, and then their demethylation occurs.

The half-life period with a normal creatinine clearance rate is 2-3 hours. In case of decreased clearance, this period is extended. The renal clearance rate is approximately 410 ml/min (this is a sign of an active process of tubular secretion).

Excretion occurs mainly with urine - during the following 24 hours after administration (unchanged substance) approximately 30% (oral administration) or 70% (intravenous administration) of the drug is excreted. It is also excreted as N-oxide (less than 4% of the total dose), and in addition S-oxide with desmethylranitidine (1% each).

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Dosing and administration

The dosage is selected individually. For an adult, it is usually 0.15 g twice a day (morning and evening) or a single dose of 0.3 g at night. The duration of the treatment course is 1-2 months.

As a preventative measure against ulcer exacerbation, 0.15 g should be taken at night. The duration of such a course can be up to 1 year (regular endoscopic monitoring is also necessary (every four months) - examination of the gastric mucosa using a special device used for visual examination).

For gastrinoma, you need to take 0.15 g of the medicine three times a day. If necessary, the daily dosage can be increased to 0.6-0.9 g.

As a preventative measure against the occurrence of bleeding or ulceration (due to stress), the medicine should be administered intravenously or intramuscularly, at a dosage of 0.05-0.1 g every 6-8 hours.

For children aged 14-18 years, the dosage is 0.15 g twice a day.

Patients with renal failure (creatinine level in blood serum is more than 3.3 mg/100 ml) should take the medicine twice a day at a dosage of 0.075 g.

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Use Ranitidine during pregnancy

The drug is prohibited during pregnancy and lactation.

Contraindications

Among the contraindications:

• individual intolerance to the components of the drug;
• children under 14 years of age.

Caution should be exercised when prescribing the drug to patients with impaired renal excretory function.

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Side effects Ranitidine

Side effects include:

• nervous system: dizziness with headaches, feeling of fatigue or anxiety, depression, feeling of drowsiness, as well as vertigo and insomnia. In rare cases, reversible loss of visual acuity, ocular accommodation disorder, confusion, and the appearance of hallucinations are observed;
• cardiovascular and hematopoietic system organs: AV block, bradycardia or tachycardia, and in addition arrhythmia, thrombocytopenia, leukopenia and granulocytopenia. In rare cases, agranulocytosis, aplastic anemia and pancytopenia (in some situations with bone marrow hypoplasia) may develop. Isolated cases - IHA;
• Gastrointestinal organs: vomiting with nausea, diarrhea or constipation, abdominal pain syndrome. Pancreatitis may occasionally develop. Single cases - cholestatic, hepatocellular or mixed form of hepatitis (sometimes it can occur against the background of jaundice) - in this case, it is necessary to immediately stop using the drug. Such reactions are usually reversible, but can occasionally be fatal. In extremely rare cases, liver failure has occurred;
• musculoskeletal system organs: isolated – pain in the joints or muscles;
• allergy: skin rash, bronchospasm, eosinophilia or fever. Isolated cases – erythema multiforme, anaphylaxis and Quincke’s edema;

Others: Vasculitis or hair loss are occasionally observed. Single cases – decreased libido or potency, as well as gynecomastia. Long-term use may provoke anemia due to B12 deficiency.

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Overdose

Manifestations of overdose include convulsions, as well as the development of bradycardia and ventricular arrhythmia.

Therapy involves inducing vomiting or rinsing the patient's stomach, followed by symptomatic treatment. In the event of seizures, diazepam should be administered intravenously; atropine is administered to eliminate bradycardia, and lidocaine is administered to eliminate ventricular arrhythmia.

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Interactions with other drugs

In case of combination of Ranitidine with antacid drugs, an interval should be made between the use of these drugs (at least 1-2 hours), since the latter can have a negative effect on the absorption of ranitidine.

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Storage conditions

The medicine should be kept in standard conditions for medicines - a dark, dry place, inaccessible to small children. The temperature regime is within 15-30°C.

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Shelf life

Ranitidine is permitted to be used for 3 years from the date of manufacture of the drug.

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