Cimetidine

General

• Type: H2 blocker
• Dosage Forms: 200, 300, 400, 800mg
• Common Trade Names: Tagamet HB 200

Adult Dosing

Duodenal Ulcer, Active

• 800mg PO QHS x 4-8 weeks

Duodenal Ulcer, Maintenance

• 400mg PO QHS

Gastric Ulcer, active benign

• 800mg PO QHS x 6 weeks

H. Pylori Infection

• 400mg PO BID x 10-28 days

Pediatric Dosing

GERD/PUD

• Neonates: 5- 10mg/kg/day PO divided q8-12h
• Infants: 10-20mg/kg/day PO divided q8-12h
• Children: 20-40mg/kg/day PO divided q6H

Special Populations

• Pregnancy Rating: B (animal studies show no risk for adverse fetal effects, human fetal harm possible but unlikely)
• Lactation: Probably Safe
• Renal Dosing
  • Adult: CrCL 10-50: decrease dose 50%, CrCl <10, decrease dose 75%
  • Pediatric: CrCl 20-40, decrease dose 25% or give q8h, CrCL <20: decrease dose 50%
• Hepatic Dosing
  • Adult: Not Defined
  • Pediatric not defined

Contraindications

• Allergy to class/drug
• caution if renal impairment
• caution if hepatic impairment
• caution in elderly patients
• caution if chronic pulmonary disease
• caution if DM
• caution if immunocompromised

Adverse Reactions

Serious

• Anticholinergic toxicity
• neutropenia
• thrombocytopenia
• agranulocytosis
• aplastic anemia
• pneumonia
• depression
• psychosis
• hallucinations
• pancreatitis
• interstital nephritis
• bradycardia
• tachycardia
• AV block
• skin reaction

Common

• headache
• diarrhea
• dizziness
• gynecomastia
• nausea
• vomiting
• confusion
• agitation
• drowsiness
• rash
• ALT,AST elevation

Pharmacology

• Half-life: 2H
• Metabolism: Liver; CYP450, 1A2, 2C19, 2D6 Inhibitor
• Excretion: urine
• Mechanism of Action: Histamine H2 Receptor blocker

See Also

• Antihistamines
• Anticholinergic toxicity

References

• 2019 American Geriatrics Society Beers Criteria Update Expert Panel. American Geriatrics Society 2019 Updated AGS Beers Criteria for Potentially Inappropriate Medication Use in Older Adults. J Am Geriatr Soc. 2019;67(4):674-694. doi: 10.1111/jgs.15767. [PubMed 30693946]
• American Society of Anesthesiologists Task Force on Obstetric Anesthesia. Practice guidelines for obstetric anesthesia: an updated report by the American Society of Anesthesiologists Task Force on Obstetric Anesthesia. Anesthesiology. 2007;106(4):843-863. [PubMed 17413923]
• Andreev E, Koopman M, Arisz L. A rise in plasma creatinine that is not a sign of renal failure: which drugs can be responsible? J Intern Med. 1999;246(3):247-252. [PubMed 10475992]
• ASHP Therapeutic Guidelines on Stress Ulcer Prophylaxis. ASHP Commission on Therapeutics and approved by the ASHP Board of Directors on November 14, 1998. Am J Health Syst Pharm. 1999;56(4):347-379. [PubMed 10690219]
• Aronoff GR, Bennett WM, Berns JS, et al, eds. Drug Prescribing in Renal Failure: Dosing Guidelines for Adults and Children. 5th ed. Philadelphia, PA: American College of Physicians; 2007.