1. Clinical & Scientific Overview
Famotidine (TIP-MED-000073, Reference Code [5.5]) is classified under
Gastrointestinal & Hepatobiliary Medicines (Ch 05) as a Histamine H2-Receptor Antagonist (H2 Blocker).
Within the Indian regulatory and compendial framework, it is governed under Schedule H Prescription Drug (To be sold by retail on the prescription of a Registered Medical Practitioner only — Drugs Rules 1945).
Representative Indian Market Examples (Edition 2.7 Ch 05 [5.5], p. 62): Famocid (Sun Pharma), Topcid (Torrent), Facid (Intas), Famtac (Zydus) — Strengths & Dosage Forms: Oral Film-Coated Tablets: 20 mg, 40 mg
Oral Film-Coated Tablets: 20 mg, 40 mg
3. Mechanism of Action & Pharmacodynamics
Histamine H2-Receptor Antagonist (H2 Blocker) acting on target receptor/enzyme pathways in Gastrointestinal & Hepatobiliary Medicines (Ch 05): clinical efficacy is mediated via Histamine H2-Receptor Antagonist (H2 Blocker) for Mild-to-moderate gastro-oesophageal reflux disease (GERD); nocturnal acid breakthrough; peptic ulcer disease; episodic heartburn and non-ulcer dyspepsia; step-down therapy when discontinuing chronic PPIs..
4. Therapeutic Indications & Evidence-Supported Uses
- Mild-to-moderate gastro-oesophageal reflux disease (GERD)
- nocturnal acid breakthrough
- peptic ulcer disease
- episodic heartburn and non-ulcer dyspepsia
- step-down therapy when discontinuing chronic PPIs
🇮🇳 Jurisdiction & Indication Note: Indications and schedules reflect Indian compendial and regulatory records (CDSCO / Indian Pharmacopoeia & NFI / NLEM 2022). Where international reference labels (US FDA DailyMed / NCBI StatPearls) are cited for pharmacokinetic or mechanistic parameters, international approvals do not automatically imply CDSCO approval in India.
5. Educational Dosage Context, Formulations & Administration
Educational Dosing & Regimen Summary: General Adult Reference: 20 mg twice daily (morning and bedtime) or 40 mg once daily at bedtime for acute ulcer/GERD; 20 mg once daily at bedtime for maintenance or nocturnal acid suppression. Dosing strictly depends on renal function! Follow physician prescription.
Administration & Meal Timing: With or without food (for prevention of meal-induced heartburn, take 15–60 minutes before eating; for nocturnal acid suppression, take at bedtime). | At bedtime (if OD) or morning and bedtime (if BD).
6. Pharmacokinetics, Metabolism & Renal/Hepatic Adjustment
Absorption, distribution, metabolism, and excretion follow class pharmacokinetic profile; verify patient renal/hepatic function.
Renal: Strictly renal-function dependent (~70% excreted unchanged in urine)! • CrCl ≥50 mL/min: Standard dose (20–40 mg/day). • CrCl <50 mL/min: Reduce dose by 50% (maximum 20 mg once daily at bedtime, or 20 mg every 36–48 hours in severe CKD) to prevent CNS accumulation and delirium. Hepatic: No adjustment required.
Renal: Strictly renal-function dependent (~70% excreted unchanged in urine)! • CrCl ≥50 mL/min: Standard dose (20–40 mg/day). • CrCl <50 mL/min: Reduce dose by 50% (maximum 20 mg once daily at bedtime, or 20 mg every 36–48 hours in severe CKD) to prevent CNS accumulation and delirium. Hepatic: No adjustment required.
Renal: Strictly renal-function dependent (~70% excreted unchanged in urine)! • CrCl ≥50 mL/min: Standard dose (20–40 mg/day). • CrCl <50 mL/min: Reduce dose by 50% (maximum 20 mg once daily at bedtime, or 20 mg every 36–48 hours in severe CKD) to prevent CNS accumulation and delirium. Hepatic: No adjustment required.
7. Contraindications, Precautions & High-Risk Warnings
- Exclude gastric malignancy if alarm symptoms exist. Cross-sensitivity with other H2 blockers. Note: Ranitidine was scrutinised/removed from NLEM in India due to NDMA impurity concerns, making Famotidine the standard H2-receptor antagonist.
Key Clinical Precautions: Renal: Strictly renal-function dependent (~70% excreted unchanged in urine)! • CrCl ≥50 mL/min: Standard dose (20–40 mg/day). • CrCl <50 mL/min: Reduce dose by 50% (maximum 20 mg once daily at bedtime, or 20 mg every 36–48 hours in severe CKD) to prevent CNS accumulation and delirium. Hepatic: No adjustment required.
8. Adverse Effects Profile
- Headache, dizziness, constipation or mild diarrhoea.
- Delirium, confusion, agitation, and hallucinations in elderly patients with renal impairment (when dose is not reduced for CrCl), rare thrombocytopenia/agranulocytosis, QT prolongation (rare, in renal failure).
- Monitor for severe hypersensitivity, organ toxicity, or dose-limiting adverse events.
9. Major Drug–Drug, Drug–Food & Drug–Herb Interactions
- Unlike cimetidine, famotidine does NOT inhibit hepatic CYP450 enzymes—therefore it has no CYP interaction with warfarin, phenytoin, theophylline, or clopidogrel! However, by raising gastric pH, it reduces absorption of cefpodoxime, cefuroxime axetil, itraconazole, ketoconazole, and dasatinib
- Tizanidine levels may be mildly increased
10. Clinical Monitoring, Patient Counselling & Storage
Clinical & Laboratory Monitoring: Monitor clinical response, baseline renal/hepatic parameters, and relevant serum biomarkers.
Pharmacist Patient Counselling Points:
- Patient Counselling Checklist: Ideal for step-down therapy when weaning off long-term PPIs (prevents rebound acid hypersecretion) and safe with clopidogrel. Take at bedtime for night-time acid reflux.
- Meal & Clock Timing Instruction: With or without food (for prevention of meal-induced heartburn, take 15–60 minutes before eating; for nocturnal acid suppression, take at bedtime). (At bedtime (if OD) or morning and bedtime (if BD).)
- Missed Dose Protocol: Take as soon as remembered; skip if close to the next scheduled dose.
- Geriatric Dispensing Pearl: Always check renal function in patients ≥65 years—standard 40 mg/day famotidine in an elderly patient with CrCl <50 mL/min can trigger acute night-time confusion and delirium.
Storage, Stability & Dispensing Safeguards: Store below 25°C–30°C in original moisture- and light-resistant packaging out of reach of children. Available forms: Oral Film-Coated Tablets: 20 mg, 40 mg
11. Visual Pharmacology & Mechanism Diagram (svg-v339-01-adme-12-step-journey)
12. Authoritative References, Regulatory Sources & Editorial Disclaimer
Primary Compendial & Guideline Reference: Indian Pharmacist Desk Reference — Professional Edition 2.7 (2026–27) • Ch 05 [5.5] (p. 62)
Official Verification Portals: Indian Pharmacopoeia Commission (IPC) & National Formulary of India (NFI) • Central Drugs Standard Control Organization (CDSCO) • Ministry of Health & Family Welfare — NLEM 2022 • NCBI Bookshelf / StatPearls Pharmacology Reference • DailyMed (US FDA Official Prescribing Reference)
Last Medically & Pharmaceutically Reviewed: 2026-11-10 • Verification Status: HANDBOOK_SOURCE_CONTENT
Educational & Clinical Disclaimer: This reference profile is published solely for pharmacy education, academic study, and professional clinical reference. It does not substitute for patient-specific clinical judgement, qualified specialist oncology/medical supervision, or official CDSCO/IP prescribing information. Never self-medicate with prescription, Schedule H/H1/X, NDPS, or oncology medicines.
13. Related Reference Monographs, Educational Guides & Visual Concept
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