💊 Famotidine

H₂ Receptor Antagonist

Generic Name	Famotidine
Drug Class	H₂ Receptor Antagonist (H₂RA)
Indications	Gastro-esophageal reflux disease (GERD) Peptic ulcer disease (gastric and duodenal) Zollinger–Ellison syndrome Prevention of stress-related mucosal bleeding
Mechanism of Action	Selective histamine H₂ receptor antagonist → decreases gastric acid secretion by parietal cells.
Available Forms & Strengths	• Tablet: 20 mg, 40 mg • Oral suspension: 40 mg/5 mL • IV injection: 20 mg/mL
Dosage	Adults: 20–40 mg once or twice daily Children: 0.5–1 mg/kg/day divided doses (max 40 mg/day)
Route	Oral, IV
Common Side Effects	Headache Dizziness Constipation or diarrhea Fatigue
Serious Adverse Effects	Arrhythmias (rare), hepatotoxicity (rare), confusion (especially elderly)
Contraindications	Hypersensitivity to famotidine or other H₂ receptor antagonists
Precautions	• Renal impairment (dose adjustment required) • Elderly patients • Pregnancy & lactation: use if benefit outweighs risk
Drug Interactions	• Drugs requiring gastric pH-dependent absorption (e.g., ketoconazole, atazanavir) • Cimetidine (rare additive effects)
Pregnancy & Lactation	Pregnancy: Generally considered safe Lactation: Use with caution
Storage	Store below 30°C, protect from moisture
References	BNF \| BNF for Children \| Goodman & Gilman

⚠️ Clinical note: Dose adjustment required in renal impairment. Monitor for CNS effects in elderly patients.