Cimetidine Dosage

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Usual Adult Dose for Duodenal Ulcer

Parenteral: 300 mg IV or IM every 6 to 8 hours. Alternatively, a continuous IV infusion may be administered at a rate of 37.5 to 50 mg/hour, or up to a maximum rate of 100 mg/hour (2.4 g/day).

Oral: 800 mg to 1600 mg once a day at bedtime. Alternatively, dosage regimens of 300 mg four times per day, with meals and at bedtime, or 400 mg twice daily, in the morning and at bedtime, have shown to be effective.

Usual Adult Dose for Duodenal Ulcer Prophylaxis

Parenteral: 300 mg IV or IM once or twice a day.

Oral: 400 mg once a day at bedtime.

Usual Adult Dose for Erosive Esophagitis

Parenteral: 300 mg IV or IM every 6 hours. Alternatively, a continuous IV infusion may be administered at a rate of 50 mg/hour initially, with 25 mg/hour incremental increases up to a maximum rate of 100 mg/hour (2.4 g/day).

Oral: 800 mg twice a day, or alternatively, 400 mg four times a day.

Usual Adult Dose for Stress Ulcer Prophylaxis

Parenteral: 300 mg IV or IM every 6 hours. Alternatively, a continuous IV infusion may be administered at a rate of 50 mg/hour.

Usual Adult Dose for Upper GI Hemorrhage

Continuous IV infusion at a rate of 50 mg/hour preceded by an IV bolus dose of 150 mg. Maximum daily dose should not exceed 2.4 g.

Usual Adult Dose for Zollinger-Ellison Syndrome

Parenteral: 300 mg IV or IM every 6 hours. Alternatively, a continuous IV infusion may be administered at a rate of 50 mg/hour initially. Infusion rates have ranged from 40 to 600 mg/hour, but should not exceed a daily total of 2.4 g.

Oral: 300 mg 4 times a day with meals and at bedtime.

Usual Adult Dose for Gastric Ulcer

Parenteral: 300 mg IV or IM every 6 hours. Alternatively, a continuous IV infusion may be administered at a rate of 50 mg/hour.

Oral: 800 mg once a day at bedtime, or 300 mg 4 times a day.

Usual Adult Dose for Gastroesophageal Reflux Disease

Parenteral: 300 mg IV or IM every 6 hours. Alternatively, a continuous IV infusion may be administered at a rate of 50 mg/hour. Maximum daily dose should not exceed 2.4 g.

Oral: 800 mg twice a day, or 400 mg 4 times a day.

Usual Adult Dose for Dyspepsia

200 mg orally right before (or up to 30 minutes) eating. Maximum per 24 hours: 2 doses.

Usual Pediatric Dose for Gastroesophageal Reflux Disease

Neonatal: 5 to 10 mg/kg/day administered IV or IM in divided doses every 8 to 12 hours.

Infants: 10 to 20 mg/kg/day administered IV, IM, or oral in divided doses every 6 to 12 hours.

Children: 20 to 40 mg/kg/day administered IV, IM, or oral in divided doses every 6 hours.

Usual Pediatric Dose for Dyspepsia

Greater than or equal to 12 years: 200 mg up to twice daily; may take 30 minutes prior to eating foods or beverages expected to cause heartburn or indigestion.

Renal Dose Adjustments

CrCl <30 mL/min: Give 50% of the recommended dose to patients being treated for prevention of upper GI bleeding.

The initial recommended dosage for patients with severely impaired renal function is 300 mg orally or injectable, given every 12 hours, and if needed, the frequency may be increased to every 8 hours with caution.

Liver Dose Adjustments

Dosage adjustments should be considered for patients with severe liver disease.

Dose Adjustments

Dosage adjustments are based on patient's individual needs. In adults with normal renal and liver function, the maximum oral or injectable dosage in a 24 hour period should not exceed 2.4 g.

Dosage adjustments may be necessary to maintain an intragastric acid secretory rate at 10 mEq/hr or less.

Precautions

Symptomatic response to cimetidine does not rule out the possibility of gastrointestinal malignancy.

Dialysis

Slightly dialyzable (5% to 20%). Schedule the dose to begin at the end of the hemodialysis session.

Other Comments

A total of 6 to 8 weeks is usually sufficient for ulcer healing. Gastroesophageal reflux disease usually requires 8 to 12 weeks for healing. Erosive esophagitis therapy generally should not exceed 12 weeks.

Agents in this class of drugs (H2 antagonists) have not demonstrated unequivocal efficacy in the treatment of upper gastrointestinal hemorrhage, nor are they approved by the FDA for use in this setting. However, some clinicians use intravenous H2 antagonists as part of the therapeutic approach to treating upper gastrointestinal hemorrhage. Drug has not been studied beyond 7 days.

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