Oral Gastro-oesophageal reflux disease Adult: 20 mg bid for 6-12 wk or up to 40 mg bid if there is oesophageal ulceration. Maintenance: 20 mg bid to prevent recurrence. Child: ❤ mth 0.5 mg/kg once daily; 3 mth to 1 yr 0.5 mg/kg bid; >1-16 yr 0.5 mg/kg bid up to max 40 mg bid. Renal impairment:CrCl (ml/min)Dosage Recommendation<50Reduce the dose by half or increase dosing interval to 36-48 hr.
Oral Zollinger-Ellison syndrome Adult: Initially, 20 mg 6 hrly, up to 800 mg/day if necessary. Renal impairment:CrCl (ml/min)Dosage Recommendation<50Reduce the dose by half or increase dosing interval to 36-48 hr.
Oral Non-ulcer dyspepsia Adult: 10 mg once or bid. Renal impairment:CrCl (ml/min)Dosage Recommendation<50Reduce the dose by half or increase dosing interval to 36-48 hr.
Oral Heartburn Adult: 10 mg once or bid. Renal impairment:CrCl (ml/min)Dosage Recommendation<50Reduce the dose by half or increase dosing interval to 36-48 hr.
Intravenous Gastro-oesophageal reflux disease Adult: 20 mg 12 hrly, as an inj over at least 2 min or as an infusion over 15-30 min. Child: 1-16 yr 0.25 mg/kg 12 hrly, an inj over at least 2 min or as infusion over 15 min. Max: 40 mg/day. Renal impairment:CrCl (ml/min)Dosage Recommendation<50Reduce the dose by half or increase dosing interval to 36-48 hr.
Intravenous Benign gastric and duodenal ulceration Adult: 20 mg 12 hrly, as an inj over at least 2 min or as an infusion over 15-30 min. Child: 1-16 yr 0.25 mg/kg 12 hrly, an inj over at least 2 min or as infusion over 15 min. Max: 40 mg/day. Renal impairment:CrCl (ml/min)Dosage Recommendation<50Reduce the dose by half or increase dosing interval to 36-48 hr.
Reconstitution: For IV inj: Famotidine 20 mg is diluted to a total of 5 or 10 mL w/ NaCl 0.9% inj or dextrose 5% or 10% inj, lactated Ringer’s, water for inj soln to provide a soln containing approx 4 or 2 mg/mL, respectively. For intermittent IV infusion: Famotidine 20 mg is added to dextrose 5% inj 100 mL or NaCl 0.9% inj, lactated Ringer’s soln, water for inj soln to provide a soln containing approximately 0.2 mg/mL. Incompatibility: Y-site admin: Amphotericin B cholesteryl sulfate complex, piperacillin/tazobactam, sulfamethoxazole/trimethoprim cefepime, azithromycin. Syringe: Ceftriaxone, dexamethasone Na phosphate.AdministrationMay be taken with or without food. Special PrecautionsIncreased risk of community-acquired pneumonia. Possibility of malignancy should be excluded prior to therapy as the drug may mask symptoms and delay diagnosis of gastric malignancy. Renal impairment. Pregnancy and lactation.Adverse Drug ReactionsHeadache, dizziness, constipation, diarrhoea, acne, pruritus, urticaria, dry skin, fever, hypertension, flushing, musculoskeletal pain, arthralgia, tinnitus, increases in BUN or serum creatinine concentrations and proteinuria. Rarely, leukopenia, leukocytosis, neutropenia, increases in total serum bilirubin and cholestatic jaundice.Drug InteractionsAntacids slightly decrease the bioavailability of famotidine. May reduce serum concentration of ketoconazole and itraconazole. Food InteractionAlcohol may cause gastric mucosal irritation.Pregnancy Category (US FDA)Category BStorageIntravenous: Concentrate for inj: Store between 2-8°C. Oral: Tab: Store between 15-30°C.Mechanism of ActionFamotidine competitively blocks histamine at H2-receptors thus reducing basal, nocturnal and stimulated gastric acid secretion. Pepsin secretion is reduced resulting in decreased peptic activity. Onset: W/in 1 hr (oral); w/in 30 min (IV). Duration: 10-12 hr. Absorption: Readily but incompletely absorbed from the GI tract. Bioavailability: Approx 40-45%. Time to peak plasma concentration: 1-3 hr. Distribution: Enters the breast milk. Plasma protein binding: Approx 15-20%. Metabolism: Converted to famotidine S-oxide by hepatic metabolism (small portion). Excretion: Via urine by active tubular secretion approx 25-30% (oral) and 65-70% (IV) both as unchanged drug. Elimination half-life: Approx 3 hr.