II. Mechanism
- Inhibits histamine action at parietal cell H2 receptor
- Decreases basal and food stimulated acid secretion
- Inhibits 50-80% of daily gastric acid secretion
III. Preparations: Adult
- Ranitidine (Zantac)
- Removed from U.S. market in 2020 due to NDMA contaminant (see adverse effects below)
- Bolus IV Dosing: 50 mg IV q6-8h
- Continuous IV Dosing: 6.25 mg/h IV
- Oral Dosing: 150 mg orally twice daily
- Cimetidine (Tagamet)
- Bolus Parenteral dosing: 300 mg IV or IM q6h
- Continuous IV Dosing: 37.5 mg/h IV
- Oral Dosing: 400-800 mg orally twice daily
- Famotidine (Pepcid)
- Oral dosing: 20 to 40 mg orally twice daily
- Nizatidine (Axid)
- Oral dosing: 150 mg orally twice daily
IV. Preparations: Children
- Ranitidine (Zantac) 15 mg/ml oral syrup
- Removed from U.S. market in 2020 due to NDMA contaminant (see adverse effects below)
- Age <16 years old
- Dose: 5-10 mg/kg/day (max 300 mg) divided every 12 hours
- Adult dosing for over age 16 years old
- Dose: 150 mg twice daily
- Cimetidine (Tagamet) 300 mg/ml oral solution
- Newborns
- Dose: 5-10 mg/kg/day divided every 8-12 hours
- Infants
- Dose: 10-20 mg/kg/day divided every 6-12 hours
- Children <12 years old
- Dose: 20-40 mg/kg/day divided every 6 hours
- Adult dosing for over age 12 years old
- Dose: 800 mg orally twice daily
- Newborns
- Famotidine (Pepcid) 40 mg/5ml oral suspension
- Age 0-3 months
- Dose: 0.5 mg/kg/day orally daily
- Age 3 months to 16 years old
- Dose: 0.5 mg/kg orally twice daily
- Age 0-3 months
- Nizatidine (Axid) 15 mg/ml
- Age 6 months to 11 years old
- Dose: 5-10 mg/kg/day divided every 12 hours
- Adult dosing over age 12 years old
- Dose: 150 mg orally twice daily
- Age 6 months to 11 years old
- References
V. Precautions: Impaired Renal Function
-
Creatinine Clearance <30 ml/min
- Give Cimetidine at half dose
-
Creatinine Clearance <50 ml/min
- Give all H2 Blockers (except Cimetidine) at half dose
VI. Efficacy
- Similar efficacy among all 4 agents
- H2 Blockers are not as effective in Tobacco Abuse
- Carafate and Prilosec preferred in this population
- Symptomatic relief of GERD in weeks in 70% of cases
VII. Disadvantages
- Even generic costs still approch Proton Pump Inhibitors
- (2003) Red Book, Medical Economics Data, Montvale, NJ
VIII. Adverse Effects
- Ranitidine (Zantac) was removed from U.S. market in 2020 due to NDMA contaminant
- NDMA has been associated with several cancers
- NDMA was found both as a manufacturing contaminant
- NDMA also appears to form in vivo with Ranitidine use
- Resulted in the complete withdrawal of Ranitidine from U.S. market
- In-vivo NDMA formation does not appear to occur with other H2 Blockers
- FDA Recall Information
- Cimetidine has more Drug Interactions and side effects
- Confusion
- Avoid H2 Blockers in Cognitive Impairment (Dementia, Delirium)
IX. References
- (2012) Presc Lett, 19(7): 38
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