Ranitidine

An H₂-receptor blocker that reduces stomach acid secretion.

What is Ranitidine?

Ranitidine is a histamine H₂-receptor antagonist that works by reducing the amount of acid produced by the stomach.

It was widely used before the introduction of proton pump inhibitors.

History & Background

Ranitidine became one of the most prescribed acid-reducing drugs worldwide due to its effectiveness and lower side effects compared to earlier agents.

Chemical Structure & Properties

• IUPAC name: N-[2-[[[5-[(dimethylamino)methyl]furan-2-yl]methyl]thio]ethyl]-N′-methyl-2-nitroethene-1,1-diamine
• Molecular formula: C₁₃H₂₂N₄O₃S
• Molar mass: 314.40 g/mol
• Functional groups: Nitro group, thioether, amine

Mechanism of Action

Ranitidine selectively blocks H₂ receptors on gastric parietal cells, leading to:

• Reduced basal acid secretion
• Reduced stimulated acid release
• Relief from heartburn and ulcer pain

Pharmacokinetics

• Absorption: Well absorbed orally
• Peak plasma time: 1–3 hours
• Metabolism: Partial hepatic metabolism
• Half-life: 2–3 hours
• Excretion: Urine

Medical Uses

• Peptic ulcer disease
• Gastroesophageal reflux disease (GERD)
• Zollinger–Ellison syndrome
• Stress ulcer prophylaxis

Dosage Guidelines

Adults: 150 mg twice daily or 300 mg at bedtime

Injection: Used in hospital settings

⚠️ Dosage adjustment required in kidney disease.

Side Effects

• Headache
• Dizziness
• Constipation or diarrhea
• Fatigue

Warnings & Precautions

• Withdrawn in many countries due to NDMA impurity concerns
• Use safer alternatives when available
• Consult physician before use

Drug Interactions

• Warfarin
• Ketoconazole
• Procainamide

Frequently Asked Questions

Is ranitidine still safe? – Restricted in many regions.

Is it a PPI? – No, it is an H₂ blocker.

Does it work fast? – Yes, within hours.

Alternatives? – Famotidine, PPIs.

⚠️ Educational content only. Not a substitute for professional medical advice.