2. CIMETIDINE
• H2 Antagonist
• Reduced gastric acid secretion, gastric volume, hydrogen ion
concentration
• Hepatic metabolism
• Urinary excretion
• 80% gastric acid ↓ for 4-5 hrs. after 300mg dose
• Elimination half life ~ 2hrs (adults), 1.4 (children), 3.6hrs (neonates)
• Caution in patient with severe renal failure (drug accumulation)
• Administer with meals
3. Indications
• Short term treatment for active benign gastric and duodenal ulcers
• Gastroesophageal reflux disease
• Hypersecretory conditions (Zollinger-Ellison syndrome, systemic
mastocytosis, multiple endocrine adenomas)
• Heartburn (OTC only)
4. Dosing
• Duodenal ulcer, active: Oral: 300 mg 4 times daily or 800 mg at bedtime or 400
mg twice daily for up to 8 weeks
• Note: Higher doses of 1600 mg at bedtime for 4 weeks may be beneficial for a
subpopulation of patients with larger duodenal ulcers (>1 cm defined
endoscopically) who are also heavy smokers (≥1 pack/day).
• Duodenal ulcer, prophylaxis: Oral: 400 mg at bedtime
• Gastric ulcer, active: Oral: 300 mg 4 times daily or 800 mg at bedtime for up to 8
weeks
• Gastroesophageal reflux disease: Oral: 400 mg 4 times daily or 800 mg twice
daily for 12 weeks
• Pathological hypersecretory conditions: Oral: 300 mg 4 times daily; adjust dose
to patient response; maximum 2.4 g/day
• Heartburn (OTC) 200mg daily 30 min prior to irritating food. Max. 400 dose/day
5. Dose adjustment
• Severe renal impairment: 300 mg every 12 hours; may increase frequency
with caution. When hepatic impairment is also present, further reductions
in dosage may be necessary
• Alternate recommendation
• GFR >50 mL/minute: No dosage adjustment necessary.
• GFR 10 to 50 mL/minute: Administer 50% of normal dose
• GFR <10 mL/minute: 300 mg every 8 to 12 hours
• Hemodialysis: Dose after dialysis
• CCRT: Administer 50% of normal dose
• Peritoneal dialysis: 300 mg every 8 to 12 hours
• Geriatric patients ≥65 years: CrCl <50 mL/minute: Reduce the dose because
of risk of mental status changes
