H-2 ANTAGONISTS
CIMETIDINE / RANITIDINE AND/OR FAMOTIDINE
Guidelines for Use
It is considered appropriate to use an H-2 Antagonist in the following circumstances:
1. Short-term treatment of active duodenal ulcer.
2. Maintenance therapy to prevent recurrence of duodenal ulcer.
3. Pathological GI hypersecretory conditions.
4. Short-term treatment of active, benign gastric ulcer.
5. Gastroesophageal reflux and esophagitis with documented lack of response to more conventional therapy.
6. Treatment of GI bleeding.
7. Treatment or prophylaxis of stress ulcers.
8. Pre-operative dose to raise gastric pH for surgery to prevent acid aspiration pneumonitis.
Oral therapy is indicated in all cases where the patient is receiving medications or substance by mouth or enteral feedings.
Parenteral therapy is indicated only when the patient cannot take oral medications or due to some medical conditions cannot absorb oral medications.
Monitor:
1. Serum levels of theophylline, phenytoin, phenobarbital.
2. Prothrombin time for concurrent warfarin therapy.
3. Dosage adjustment for renal failure.
Dose:
Parenteral Dose of Cimetidine is 300 mg every 6 to 8 hours. A continuous infusion may be utilized for cimetidine. Normal dose is 900 to 1200 mg/24 hours.
Parenteral Dose of Ranitidine is 50 mg every 6 to 8 hours.
Parenteral Dose of Famotidine is 20 mg every 12 hours.
Oral Doses of Cimetidine — 300 mg every 6 hours.
400 mg every 8 hours.
800 mg at bedtime.
Oral Doses of Ranitidine/Nizatidine — 150 mg twice a day.
300 mg at bedtime.
Oral Doses of Famotidine — 20 mg every 12 hours.
If creatinine clearance is less than 50 ml/min the dose should be adjusted appropriately. Refer to the literature.
PARENTERAL H-2 ANTAGONISTS
STRESS ULCER PROPHYLAXIS
Cimetidine, Ranitidine, and Famotidine
Guidelines for Use
It is considered appropriate to use an H-2 Antagonist for stress ulcer prophylaxis in the following conditions:
1. Shock defined as systolic BP < 90 mmHg
2. Sepsis/Severe infection
3. Organ failure (renal/hepatic failure, CHF/MI)
4. Mechanical ventilation > 24 hours
5. Burns > 30% BSA
6. Multiple trauma, including closed head injury
7. Major surgery
8. History of ulcer disease
9. Organ Transplantation (including bone marrow)
10. High dose steroids (as in cancer chemotherapy)
11. Nausea/vomiting 7 days or greater post chemotherapy (for suspected gastritis)
Oral therapy should be the route of choice if the patient is not in an intensive care unit. Parenteral therapy may be acceptable in the ICU even if the patient is receiving some or all oral meds.
Monitor:
1. Serum levels of theophylline, phenytoin, phenobarbital, antiarrhythmics, and cyclosporine.
2. Prothrombin time for concurrent warfarin therapy
3. Dosage adjustment for renal failure
4. Patient response to: benzodiazepines, tricyclic antidepressants, beta blockers, calcium channel blockers, ACE inhibitors, NSAIDS, narcotics, carbamazepine, ketoconazole
Dose:
Listed below are the standard doses for treatment of duodenal ulcer. However, the goal in stress ulcer prophylaxis is to maintain gastric pH > 4. Thus, the doses may be inadequate in critically ill patients and should therefore be titrated to response.
|
Oral |
Intermittent Infusion |
Continuous Infusion* |
Renal Impairment |
|
|
Cimetidine
Ranitidine
Famotidine |
300mg QID
150mg BID
20mg BID |
300mg q6h
50mg q8h
20mg q12 |
900-1200mg
150mg
40mg |
ClCr <30ml/min
300mg q12h
ClCr <50ml/min
150mg po q24h
50mg IV q24h
ClCr <10ml/min
40mg QOD |
|
*Recommended for patients receiving TPN
Outcome: No development of ulceration.
