1. Dosage
Histamine H2-receptor antagonists (H2RAs) are FDA-approved for use in gastric ulcer, duodenal ulcer, gastroesophageal reflux disease (GERD), esophagitis, hypersecretory conditions, and non-ulcer indigestion/heartburn.
In April 2020, the Food and Drug Administration requested that manufacturers remove all prescription and over-the-counter (OTC) formulations of ranitidine from the market. The request for removal was precipitated by the discovery of N-nitrosodimethylamine (NDMA), a probable human carcinogen, in various ranitidine products. Zantac® is one of several trade names for ranitidine, and in June 2021, Sanofi Pharmaceuticals released Zantac 360°® as an OTC product. However, this new formulation contains famotidine rather than ranitidine.
1.1. Adults
The maximum adult H2RA daily doses when prescribed for acute and maintenance FDA-approved conditions are summarized in Table 1 and Table 2. Dosage regimens exceeding these maximum recommended values will be reviewed.
Drug Name | Dosage Form/Strength | Treatment Indication | Maximum Recommended Dosage |
---|---|---|---|
cimetidine (generics) | 200 mg, 300 mg, 400 mg, 800 mg tablets; 300 mg/5 mL oral solution | duodenal ulcer | 1200 mg/day ^ |
gastric ulcer | 1200 mg/day | ||
gastroesophageal reflux disease (GERD) - nonerosive | 1600 mg/day | ||
heartburn | 400 mg/day | ||
hypersecretory conditions | 2400 mg/day | ||
famotidine (Pepcid, Zantac 360°, generics) | 10 mg, 20 mg, 40 mg tablets; 40 mg/5 mL oral suspension | duodenal ulcer | 40 mg/day |
erosive esophagitis (EE) | 80 mg/day | ||
gastric ulcer | 40 mg/day | ||
GERD - nonerosive | 40 mg/day | ||
heartburn | 40 mg/day | ||
hypersecretory conditions | 640 mg/day | ||
nizatidine (generics) | 150 mg, 300 mg capsules; 15 mg/mL oral solution | duodenal ulcer | 300 mg/day in single or divided doses |
gastric ulcer | 300 mg/day in single or divided doses | ||
GERD - nonerosive | 300 mg/day in single or divided doses |
Legend:
- ^ Patients who are heavy smokers with duodenal ulcers greater than 1 cm may benefit from cimetidine 1600 mg at bedtime.
Drug Name | Dosage Form/Strength | Treatment Indication | Maximum Recommended Dosage |
---|---|---|---|
cimetidine (generics) | 200 mg, 300 mg, 400 mg, 800 mg tablets; 300 mg/5 mL oral solution | duodenal ulcer | 400 mg/day |
hypersecretory conditions | 2400 mg/day | ||
famotidine (Pepcid®, generics) | 10 mg, 20 mg, 40 mg tablets; 40 mg/5 mL oral suspension | duodenal ulcer | 20 mg/day |
hypersecretory conditions | 640 mg/day | ||
nizatidine (generics) | 150 mg, 300 mg capsules; 15 mg/mL oral solution | duodenal ulcer | 150 mg/day at bedtime |
Current American College of Gastroenterology guidelines recommend the use of a proton pump inhibitor over H2RAs for Helicobacter pylori treatment regimens13.
Currently, famotidine is available as a combination product with ibuprofen, and it is marketed under the trade name Duexis®. Duexis® is FDA approved for the prophylaxis against upper gastrointestinal ulcers in adult patients with osteoarthritis or rheumatoid arthritis.14 Dosing for this agent is provided in Table 3.
Drug Name | Dosage Form/Strength | Treatment Indication | Maximum Recommended Dosage |
---|---|---|---|
famotidine/ ibuprofen (Duexis®, generics) | 26.6 mg/ 800 mg oral tablets | gastric ulcer prophylaxis in osteoarthritis or rheumatoid arthritis | 79.8 mg / 2400 mg/day in three divided doses |
1.2. Pediatrics
Maximum recommended pediatric H2RA daily doses for acute and maintenance therapy are summarized in Table 4. Dosages exceeding these recommendations will be reviewed.
Drug Name | Patient Characteristics | Treatment Indication | Maximum Recommended Dosage |
---|---|---|---|
cimetidine (generics) | Greater than or equal to 16 years of age | duodenal ulcer | 1200 mg/day ^ |
Greater than or equal to 16 years of age | gastric ulcer | 1200 mg/day | |
Greater than or equal to 16 years of age | gastroesophageal reflux disease (GERD) - nonerosive | 1600 mg/day | |
Greater than or equal to 12 years of age | heartburn | 400 mg/day | |
Greater than or equal to 16 years of age | hypersecretory conditions | 2400 mg/day | |
famotidine (Pepcid®, generics) | 1 to 17 years of age | duodenal ulcer | tablet: 40 mg/day* suspension: 40 mg/day |
1 to 17 years of age | erosive esophagitis (EE) | tablet: 80 mg/day* suspension: 80 mg/day |
|
1 to 17 years of age | gastric ulcer | tablet: 40 mg/ day* suspension: 40 mg/day |
|
1 to 16 years of age | GERD - nonerosive | tablet: 40 mg/day* suspension: 80 mg/day |
|
3 months to 1 year of age | GERD - nonerosive | suspension: 1 mg/kg twice daily (maximum of 40 mg daily) | |
Less than 3 months of age | GERD - nonerosive | suspension: 1 mg/kg once daily | |
famotidine (Pepcid®, Zantac 360°, generics) | Greater than or equal to 12 years of age | heartburn | 40 mg/day |
nizatidine (generics) | Greater than or equal to 12 years of age | EE | 300 mg/day in single or divided doses |
Greater than or equal to 12 years of age | GERD - nonerosive | 300 mg/day in single or divided doses |
Legend:
- ^ Patients who are heavy smokers with duodenal ulcers greater than 1 cm may benefit from cimetidine 1600 mg at bedtime
- * dosing for pediatric patients weighing greater than or equal to 40 kg
Drug Name | Patient Characteristics | Treatment Indication | Maximum Recommended Dosage |
---|---|---|---|
cimetidine (generics) | Greater than or equal to 16 years of age | duodenal ulcer | 400 mg at bedtime |
Greater than or equal to 16 years of age | hypersecretory conditions | 2400 mg/day |
1.3. Dosage in Renal Impairment
H2RAs are primarily renally excreted. Dosage modifications for H2RA use in renal impairment are summarized in Table 6.
Drug Name | Dosage Adjustments in Renal Impairment |
---|---|
cimetidine |
|
famotidine |
|
nizatidine |
active treatment:
maintenance therapy:
|