Ranitidine (H2 Receptor Antagonist)

Ranitidine – Histamine H2-Receptor Antagonist for Gastric Acid-Related Disorders

Basic Information

• CAS Number (base): 66357-35-5

• CAS Number (hydrochloride): 66357-59-3

• Molecular Formula: C₁₃H₂₂N₄O₃S

• Molecular Weight: 314.40 g/mol (base); 350.86 g/mol (HCl salt)

• Synonyms: Zantac, Ranitidine hydrochloride

• Appearance: White to off-white crystalline powder

• Solubility: Freely soluble in water, soluble in methanol, sparingly soluble in ethanol, practically insoluble in chloroform

• Melting Point: 69–70°C (base); 133–134°C (hydrochloride)

Overview
Ranitidine is a potent, selective, competitive histamine H2-receptor antagonist that inhibits gastric acid secretion. It blocks the action of histamine on H2-receptors on parietal cells in the stomach, thereby suppressing both basal and meal-stimulated acid production. Ranitidine is widely used for the treatment of peptic ulcer disease (PUD), gastroesophageal reflux disease (GERD), and Zollinger-Ellison syndrome.

Applications

• Peptic ulcer disease: Treatment and prevention of gastric and duodenal ulcers.

• Gastroesophageal reflux disease (GERD): Symptom relief and healing of erosive esophagitis.

• Zollinger-Ellison syndrome: Control of gastric acid hypersecretion in this rare condition.

• Stress ulcer prophylaxis: Prevention of stress-related mucosal damage in critically ill patients.

• Other uses: As an adjunct in the treatment of urticaria and other histamine-mediated conditions.

Mechanism of Action
Ranitidine competitively and reversibly inhibits histamine H2-receptors on gastric parietal cells. This prevents histamine from stimulating acid secretion, reducing both the volume and concentration of gastric acid. Unlike first-generation H2 antagonists, ranitidine features a furan ring instead of an imidazole structure, which contributes to its improved selectivity and reduced side-effect profile.

Key Benefits

• Potent and selective H2-receptor blockade.

• Reduces gastric acid secretion and promotes ulcer healing.

• Well-absorbed after oral administration.

• Fewer cytochrome P450 interactions compared to cimetidine.

• Available in multiple formulations (tablets, injections, effervescent tablets).

Safety and Regulatory Considerations
Ranitidine has been associated with the presence of low levels of N-nitrosodimethylamine (NDMA), a probable human carcinogen, formed through degradation of the ranitidine molecule. This has led to restrictions on its use in some countries. Healthcare providers and patients are advised to consider alternative H2 antagonists (e.g., famotidine) or proton pump inhibitors where appropriate.

Handling and Storage

• Store in a cool, dry place, protected from light and moisture.

• Keep containers tightly sealed to prevent degradation.

• Use appropriate personal protective equipment (gloves, safety goggles) when handling in bulk quantities.

Packaging
Available in various pack sizes (e.g., 1 kg, 5 kg, 25 kg drums) and custom packaging upon request.

Quality Assurance
Each batch is tested for purity (by HPLC), moisture content, and residual solvents to ensure compliance with pharmaceutical standards.