Mechanism of Action
Cimetidine is a histamine H2 receptor antagonist that competitively blocks histamine from stimulating the H2 receptors located on the gastric parietal cells. This action reduces gastric acid secretion, regardless of the stimulus, including histamine, food, caffeine, and insulin. By inhibiting these receptors, cimetidine decreases the volume of gastric acid secretion, the concentration of hydrogen ions, and pepsin output.
Uses
Cimetidine injection is indicated for:
- Short-term treatment of active duodenal ulcers.
- Maintenance therapy for duodenal ulcer patients after healing of active ulcers.
- Short-term treatment of active benign gastric ulcers.
- Erosive gastroesophageal reflux disease (GERD) (oral solution only).
- Prevention of upper gastrointestinal bleeding in critically ill patients (injection only).
- Treatment of pathological hypersecretory conditions, such as Zollinger-Ellison syndrome.
Dosage and Administration
Adults:
- For active duodenal ulcers: 800 mg orally each evening, or 400 mg orally every 12 hours, or 300 mg orally every 6 hours.
- For maintenance therapy: 400 mg per day.
- For erosive GERD: 800 mg orally each evening, or 400 mg orally every 12 hours.
- Pediatric Patients:
- Neonates (under 28 days old): 5-20 mg/kg/day intravenously or orally, divided every 8-12 hours.
- Infants: 10-20 mg/kg/day intravenously or orally, divided every 6-12 hours.
- Children under 16 years of age: Use only if the benefit outweighs risks.
- Geriatric Patients:
Cimetidine is not the drug of choice in the elderly due to the increased potential for confusion and drug interactions. - Administration:
Cimetidine can be administered orally or intravenously. The injection form is available in strengths such as 150 mg/ml, 200 mg/2ml, and 300 mg/2ml. For intravenous administration, it is recommended to dilute the injection in a suitable solution and administer slowly.
Storage
Cimetidine injection should be stored at room temperature, typically between 15°C and 30°C (59°F to 86°F), and protected from light.
