Famotidine

Intravenous
Benign gastric ulcer, Duodenal ulcer

Intravenous
Hypersecretory conditions

Intravenous
Gastro-oesophageal reflux disease

Oral
Duodenal ulcer

Oral
Gastro-oesophageal reflux disease

Oral
Hypersecretory conditions

Oral
Benign gastric ulcer

CrCl (mL/min)	Dosage
<10 to <50	Reduce dose to half of the recommended dose or prolong the dosing interval to 36-48 hours based on clinical response.

May be taken with or without food.

Powder for oral susp: Reconstitute bottle containing 400 mg famotidine with 46 mL water to provide a suspension containing 40 mg/5 mL. Shake vigorously (for 5-10 seconds) until suspended. IV inj: Dilute 2 mL (20 mg) with 0.9% NaCl inj or other compatible IV solution to a total volume of either 5 mL or 10 mL. IV infusion: Dilute 2 mL (20 mg) with 100 mL of 5% dextrose in water or other compatible solution.

Hypersensitivity to famotidine or other H₂-receptor antagonists.

Patient with chronic lung disease and diabetes. Immunocompromised or intubated (in ICU setting) patient. May mask symptoms of gastric malignancy. Renal impairment. Children and elderly. Pregnancy and lactation.

Significant: CNS effects including confusion, disorientation, hallucinations, delirium, agitation, lethargy and seizure (particularly in elderly and patients with renal impairment); may increase the risk of developing community-acquired pneumonia; may decrease the absorption of vitamin B₁₂.
Blood and lymphatic system disorders: Rarely, thrombocytopenia, pancytopenia, leucopenia.
Cardiac disorders: Arrhythmia, atrioventricular block, palpitations.
Gastrointestinal disorders: Constipation, diarrhoea, dry mouth, nausea, vomiting, dysgeusia, flatulence, abdominal discomfort or distension.
General disorders and administration site conditions: Fever, fatigue, asthenia; transient irritation at inj site (IV).
Hepatobiliary disorders: Rarely, cholestatic jaundice, hepatitis.
Immune system disorders: Rarely, hypersensitivity reaction (e.g. anaphylaxis, angioedema).
Investigations: Rarely, increased liver enzymes.
Metabolism and nutrition disorders: Anorexia.
Musculoskeletal and connective tissue disorders: Rarely, musculoskeletal pain, arthralgia, muscle cramps.
Nervous system disorders: Headache, dizziness. Rarely, somnolence.
Psychiatric disorders: Rarely, insomnia.
Skin and subcutaneous tissue disorders: Rash, pruritus, dry skin, urticaria. Very rarely, alopecia, Stevens-Johnson syndrome, toxic epidermal necrolysis.

IV/Parenteral/PO: B

Rule out the presence of gastric malignancy before initiating therapy. Monitor gastric pH and occult blood with gastrointestinal bleeding; CBC and liver function (prolonged use with high doses).

May decrease the serum concentrations of atazanavir, delavirdine, rilpivirine, ketoconazole, itraconazole, cefditoren, nilotinib, erlotinib, ledipasvir, and fosamprenavir. May reduce the absorption of dasatinib. Probenecid may delay the excretion of famotidine. Antacids may reduce the absorption of famotidine.

Description:
Mechanism of Action: Famotidine competitively blocks histamine at H₂-receptors of the gastric parietal cells, resulting in the inhibition of gastric acid secretion and reduction of gastric volume.
Onset: Antisecretory effect: Within 1 hour (oral).
Duration: Antisecretory effect: 10-12 hours (oral, IV).
Pharmacokinetics:
Absorption: Incompletely absorbed from the gastrointestinal tract. Bioavailability: Approx 40-45% (oral). Time to peak plasma concentration: Approx 1-3 hours (oral).
Distribution: Crosses the placenta and enters breast milk. Volume of distribution: 1.3 ± 0.2 L/kg (IV). Plasma protein binding: Approx 15-20%.
Metabolism: Metabolised in the liver (up to 30-35%) to form famotidine S-oxide. Undergoes minimal first-pass metabolism.
Excretion: Via urine (approx 25-30% [oral], 65-70% [IV]) as unchanged drug. Elimination half-life: 2.5-3.5 hours.

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 5702160. https://pubchem.ncbi.nlm.nih.gov/compound/5702160. Accessed June 28, 2022.

Tab: Store between 15-30°C. Protect from light. Oral susp: Store at 25°C. Do not freeze. Solution for inj: Store between 2-8°C.

Antacids, Antireflux Agents & Antiulcerants

A02BA03 - famotidine ; Belongs to the class of H2-receptor antagonists. Used in the treatment of peptic ulcer and gastro-oesophageal reflux disease (GERD).

Anon. Famotidine. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 05/04/2022.

Anon. Famotidine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 05/04/2022.

Buckingham R (ed). Famotidine. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 05/04/2022.

Douglas Pharmaceuticals Ltd. Pepzan 20 mg and 40 mg Tablet data sheet 11 February 2019. Medsafe. http://www.medsafe.govt.nz. Accessed 15/06/2022.

Famotidine 40 mg Film-coated Tablets (Teva UK Limited). MHRA. https://products.mhra.gov.uk. Accessed 05/04/2022.

Famotidine Injection, Solution (Fresenius Kabi USA, LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 05/04/2022.

Famotidine Powder for Suspension (Zydus Pharmaceuticals USA Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 05/04/2022.

Famotidine Tablet (Alembic Pharmaceuticals Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 05/04/2022.

Famotin Tablets (Teva Pharmaceutical Investments Singapore Pte. Ltd.). MIMS Singapore. http://www.mims.com/singapore. Accessed 05/04/2022.

Joint Formulary Committee. Famotidine. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 05/04/2022.

Sunpepcin Tablet (Sunward Pharmaceutical Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 05/04/2022.