Famotidine

A potent and selective H₂-receptor antagonist for acid suppression.

What is Famotidine?

Famotidine is a histamine H₂-receptor blocker that decreases acid secretion from gastric parietal cells.

It is considered safer and more potent than older H₂ blockers.

History & Background

Famotidine was developed as a next-generation H₂ blocker, offering stronger acid suppression with fewer side effects.

Chemical Structure & Properties

• IUPAC name: 3-[(2-[(diaminomethylene)amino]-4-thiazolyl)methylthio]-N′-sulfamoylpropanimidamide
• Molecular formula: C₈H₁₅N₇O₂S₃
• Molar mass: 337.45 g/mol
• Functional groups: Thiazole, sulfonamide, amine

Mechanism of Action

Famotidine selectively blocks H₂ receptors in the stomach, causing:

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

Pharmacokinetics

• Absorption: Moderate oral absorption
• Peak plasma time: 1–3 hours
• Metabolism: Minimal hepatic metabolism
• Half-life: 2.5–3.5 hours
• Excretion: Urine (unchanged)

Medical Uses

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

Dosage Guidelines

Adults: 20–40 mg once or twice daily

IV use: Hospital settings only

⚠️ Dose adjustment needed in kidney disease.

Side Effects

• Headache
• Dizziness
• Constipation or diarrhea
• Fatigue

Warnings & Precautions

• Generally safer than ranitidine
• Use caution in renal impairment
• Do not exceed prescribed dose

Drug Interactions

• Ketoconazole (reduced absorption)
• Iron supplements

Frequently Asked Questions

Is famotidine safer than ranitidine? – Yes.

Is it a PPI? – No, H₂ blocker.

Does it work fast? – Yes, within hours.

Can it be taken daily? – Yes, if prescribed.

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