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H2 Receptor Antagonist

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H2 Receptor Antagonist, H2 Antagonist, H2 Blocker, Ranitidine, Zantac, Cimetidine, Tagamet, Nizatidine, Axid, Famotidine, Pepcid

  • Mechanism
  1. Inhibits histamine action at parietal cell H2 receptor
  2. Decreases basal and food stimulated acid secretion
  3. Inhibits 50-80% of daily gastric acid secretion
  • Preparations
  • Adult
  1. Ranitidine (Zantac)
    1. Bolus IV Dosing: 50 mg IV q6-8h
    2. Continuous IV Dosing: 6.25 mg/h IV
    3. Oral Dosing: 150 mg orally twice daily
  2. Cimetidine (Tagamet)
    1. Bolus parenteral dosing: 300 mg IV or IM q6h
    2. Continuous IV Dosing: 37.5 mg/h IV
    3. Oral Dosing: 400-800 mg orally twice daily
  3. Famotidine (Pepcid)
    1. Oral dosing: 20 to 40 mg orally twice daily
  4. Nizatidine (Axid)
    1. Oral dosing: 150 mg orally twice daily
  • Preparations
  • Children
  1. Ranitidine (Zantac) 15 mg/ml oral syrup
    1. Age <16 years old
      1. Dose: 5-10 mg/kg/day (max 300 mg) divided every 12 hours
    2. Adult dosing for over age 16 years old
      1. Dose: 150 mg twice daily
  2. Cimetidine (Tagamet) 300 mg/ml oral solution
    1. Newborns
      1. Dose: 5-10 mg/kg/day divided every 8-12 hours
    2. Infants
      1. Dose: 10-20 mg/kg/day divided every 6-12 hours
    3. Children <12 years old
      1. Dose: 20-40 mg/kg/day divided every 6 hours
    4. Adult dosing for over age 12 years old
      1. Dose: 800 mg orally twice daily
  3. Famotidine (Pepcid) 40 mg/5ml oral suspension
    1. Age 0-3 months
      1. Dose: 0.5 mg/kg/day orally daily
    2. Age 3 months to 16 years old
      1. Dose: 0.5 mg/kg orally twice daily
  4. Nizatidine (Axid) 15 mg/ml
    1. Age 6 months to 11 years old
      1. Dose: 5-10 mg/kg/day divided every 12 hours
    2. Adult dosing over age 12 years old
      1. Dose: 150 mg orally twice daily
  5. References
    1. Baird (2015) Am Fam Physician 92(8): 705-14 [PubMed]
  1. Creatinine Clearance <30 ml/min
    1. Give Cimetidine at half dose
  2. Creatinine Clearance <50 ml/min
    1. Give all H2 Blockers (except Cimetidine) at half dose
  • Efficacy
  1. Similar efficacy among all 4 agents
  2. H2 Blockers are not as effective in Tobacco abuse
    1. Carafate and Prilosec preferred in this population
  3. Symptomatic relief of GERD in weeks in 70% of cases
    1. Devault (1999) Am J Gastroenterol 94:1434-42 [PubMed]
  • Disadvantages
  1. Even generic costs still approch Proton Pump Inhibitors
    1. (2003) Red Book, Medical Economics Data, Montvale, NJ
  • Adverse Effects
  1. Cimetidine has more Drug Interactions and side effects
  2. Confusion
    1. Avoid H2 Blockers in cognitive Impairment (Dementia, Delirium)
  • References
  1. (2012) Presc Lett, 19(7): 38