First-Line H2 Blocker Treatment
Ranitidine is the first-line H2 blocker for patients requiring histamine-2 receptor antagonist therapy. 1, 2
Pharmacology and Mechanism of Action
- Ranitidine is a competitive, reversible inhibitor of histamine at H2 receptors on gastric cells, effectively reducing gastric acid secretion 2
- It is 4-10 times more potent than cimetidine in inhibiting stimulated gastric acid secretion 3
- Unlike cimetidine, ranitidine does not contain an imidazole group, resulting in fewer drug interactions and side effects 3
Dosing Recommendations
Standard Dosing
- For most indications: 150 mg twice daily orally 1, 2
- Alternative dosing: 150 mg once daily at bedtime for maintenance therapy 3
Hospital-Based Setting
- 1-2 mg/kg per dose, with maximum dose of 75-150 mg oral or IV 1
- For stress ulcer prophylaxis in critically ill patients: twice daily dosing 1
Special Populations
- Elderly patients: Dose adjustment may be needed due to prolonged half-life (3-4 hours vs 2.5-3 hours in younger adults) and reduced clearance 2
- Renal impairment: Dose adjustment recommended as elimination half-life increases proportionally to decrease in creatinine clearance 2
- Pediatric patients: 1-2 mg/kg dosing with similar bioavailability (48%) to adults 2
Clinical Applications
Stress Ulcer Prophylaxis
- Recommended for patients with sepsis or septic shock who have risk factors for GI bleeding 1
- Used as adjunctive treatment in hospital settings for critically ill patients 1
Gastrointestinal Reflux Disease (GERD)
- Effective for symptomatic treatment of intermittent or mild nonerosive GERD (>70% response rate) 4
- Less effective for erosive esophagitis (40-60% symptomatic improvement) where proton pump inhibitors may be preferred 4
Peptic Ulcer Disease
- Effective for healing both duodenal and gastric ulcers 3
- Single 150 mg dose at night decreases ulcer recurrence 3
Other Indications
- Used in management of food-induced anaphylactic reactions as part of discharge therapy 1
- Can be considered for dyspepsia in patients receiving chemotherapy 1
Comparison with Other H2 Blockers
- All four major H2 blockers (cimetidine, ranitidine, famotidine, nizatidine) have similar efficacy at recommended doses 4
- Famotidine is 8 times more potent than ranitidine on a weight basis 5
- Twice daily dosing of H2 blockers provides better 24-hour acid suppression than single daily dosing 6, 7
- Ranitidine has fewer drug interactions compared to cimetidine, which can alter hepatic metabolism of other medications 3, 5
Clinical Considerations and Cautions
- Absorption is not significantly impaired by food or antacids 2
- For stress ulcer prophylaxis, either H2 blockers or proton pump inhibitors may be used 1
- In systemic sclerosis with reflux, H2 antagonists are used as second-line therapy after proton pump inhibitors 1
- When used for NSAID-associated GI discomfort, H2 blockers can be combined with NSAIDs to reduce dyspepsia 1
- H2 blockers are generally very safe with minimal side effects compared to other acid-suppressing medications 4
Practical Prescribing Tips
- For most patients, start with ranitidine 150 mg twice daily 1, 2
- For maintenance therapy, consider once-daily bedtime dosing 3
- In hospital settings for stress ulcer prophylaxis, use ranitidine twice daily 1
- For patients with drug interactions or side effects from ranitidine, consider famotidine as an alternative H2 blocker 5