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Look Up > Drugs > Cimetidine
Cimetidine
Pronunciation
U.S. Brand Names
Generic Available
Canadian Brand Names
Pharmacological Index
Use
Pregnancy Risk Factor
Contraindications
Warnings/Precautions
Adverse Reactions
Overdosage/Toxicology
Drug Interactions
Stability
Mechanism of Action
Pharmacodynamics/Kinetics
Usual Dosage
Dietary Considerations
Monitoring Parameters
Test Interactions
Mental Health: Effects on Mental Status
Mental Health: Effects on Psychiatric Treatment
Dental Health: Local Anesthetic/Vasoconstrictor Precautions
Dental Health: Effects on Dental Treatment
Patient Information
Nursing Implications
Dosage Forms
References

Pronunciation
(sye MET i deen)

U.S. Brand Names
Tagamet®; Tagamet® HB [OTC]

Generic Available

No


Canadian Brand Names
Apo®-Cimetidine; Novo-Cimetine; Nu-Cimet; Peptol®

Pharmacological Index

Histamine H2 Antagonist


Use

Short-term treatment of active duodenal ulcers and benign gastric ulcers; long-term prophylaxis of duodenal ulcer; gastric hypersecretory states; gastroesophageal reflux; prevention of upper GI bleeding in critically ill patients.


Pregnancy Risk Factor

B


Contraindications

Hypersensitivity to cimetidine, other component, or other H2-antagonists


Warnings/Precautions

Adjust dosages in renal/hepatic impairment or patients receiving drugs metabolized through the P-450 system


Adverse Reactions

1% to 10%:

Central nervous system: Dizziness, agitation, headache, drowsiness

Gastrointestinal: Diarrhea, nausea, vomiting

<1%: Bradycardia, hypotension, tachycardia, confusion, fever, rash, gynecomastia, edema of the breasts, decreased sexual ability, neutropenia, agranulocytosis, thrombocytopenia, increased AST/ALT, myalgia, elevated creatinine


Overdosage/Toxicology

Treatment is primarily symptomatic and supportive. No experience with intentional overdose; reported ingestions of 20 g have had transient side effects seen with recommended doses; animal data have shown respiratory failure, tachycardia, muscle tremors, vomiting, restlessness, hypotension, salivation, emesis, and diarrhea.


Drug Interactions

CYP3A3/4 enzyme substrate; CYP1A2, 2C9, 2C18, 2C19, 2D6, and 3A3/4 enzyme inhibitor

Inhibition of warfarin metabolism, tricyclic antidepressant metabolism, diazepam elimination and cyclosporine elimination


Stability

Intact vials of cimetidine should be stored at room temperature and protected from light; cimetidine may precipitate from solution upon exposure to cold but can be redissolved by warming without degradation

Stability at room temperature:

Prepared bags: 7 days

Premixed bags: Manufacturer expiration dating and out of overwrap stability: 15 days

Stable in parenteral nutrition solutions for up to 7 days when protected from light

Physically incompatible with barbiturates, amphotericin B, and cephalosporins


Mechanism of Action

Competitive inhibition of histamine at H2-receptors of the gastric parietal cells resulting in reduced gastric acid secretion, gastric volume and hydrogen ion concentration reduced


Pharmacodynamics/Kinetics

Onset of action: 1 hour

Peak serum concentrations: ~1 hour after oral dose

Duration: 6 hours

Distribution: Crosses the placenta; appears in breast milk

Protein binding: 20%

Bioavailability: 60% to 70%

Half-life: Neonates: 3.6 hours; Children: 1.4 hours; Adults (with normal renal function): 2 hours

Time to peak serum concentration: Oral: Within 1-2 hours

Elimination: Principally as unchanged drug by the kidney; some excretion in bile and feces


Usual Dosage

Children: Oral, I.M., I.V.: 20-40 mg/kg/day in divided doses every 6 hours

Adults: Short-term treatment of active ulcers:

Oral: 300 mg 4 times/day or 800 mg at bedtime or 400 mg twice daily for up to 8 weeks

I.M., I.V.: 300 mg every 6 hours or 37.5 mg/hour by continuous infusion; I.V. dosage should be adjusted to maintain an intragastric pH greater than or equal to 5

Patients with an active bleed: Administer cimetidine as a continuous infusion (see above)

Duodenal ulcer prophylaxis: Oral: 400-800 mg at bedtime

Gastric hypersecretory conditions: Oral, I.M., I.V.: 300-600 mg every 6 hours; dosage not to exceed 2.4 g/day

Dosing adjustment/interval in renal impairment: Children and Adults:

Clcr 20-40 mL/minute: Administer every 8 hours or 75% of normal dose

Clcr 0-20 mL/minute: Administer every 12 hours or 50% of normal dose

Hemodialysis: Slightly dialyzable (5% to 20%)

Dosing adjustment/comments in hepatic impairment: Usual dose is safe in mild liver disease but use with caution and in reduced dosage in severe liver disease; increased risk of CNS toxicity in cirrhosis suggested by enhanced penetration of CNS


Dietary Considerations

Alcohol: Additive CNS effects, avoid or limit use


Monitoring Parameters

Blood pressure with I.V. push administration, CBC, gastric pH, signs and symptoms of peptic ulcer disease, occult blood with GI bleeding, monitor renal function to correct dose; monitor for side effects


Test Interactions

creatinine, AST, ALT, creatinine (S)


Mental Health: Effects on Mental Status

May cause agitation or drowsiness; rare reports of confusion


Mental Health: Effects on Psychiatric Treatment

Rare reports of agranulocytosis; use caution with clozapine and carbamazepine; may inhibit the metabolism of TCAs and benzodiazepines; monitor for adverse effects


Dental Health: Local Anesthetic/Vasoconstrictor Precautions

No information available to require special precautions


Dental Health: Effects on Dental Treatment

No effects or complications reported


Patient Information

Take with meals. Limit xanthine-containing foods and beverages which may decrease iron absorption. To be effective, continue to take for the prescribed time (possibly 4-8 weeks) even though symptoms may have improved. Smoking decreases the effectiveness of cimetidine; stop smoking if possible. Avoid use of caffeine or aspirin products. Report diarrhea, black tarry stools, coffee ground like emesis, dizziness, confusion, rash, unusual bleeding or bruising, sore throat, and fever.


Nursing Implications

Modify dosage in patients with renal impairment; can be administered as a slow I.V. push over a minimum of 15 minutes at a concentration not to exceed 15 mg/mL; or preferably as an I.V. intermittent or I.V. continuous infusion. Intermittent infusions are administered over 15-30 minutes at a final concentration not to exceed 6 mg/mL; for patients with an active bleed, preferred method of administration is continuous infusion

Monitor blood pressure with I.V. push administration; CBC


Dosage Forms

Infusion, as hydrochloride, in NS: 300 mg (50 mL)

Injection, as hydrochloride: 150 mg/mL (2 mL, 8 mL)

Liquid, oral, as hydrochloride (mint-peach flavor): 300 mg/5 mL with alcohol 2.8% (5 mL, 240 mL)

Tablet: 100 mg, 200 mg, 300 mg, 400 mg, 800 mg


References

Burkhart KK, Janco N, Kulig KW, et al, "Cimetidine as Adjunctive Treatment for Acetaminophen Overdose," Hum Exp Toxicol, 1995, 14(3):299-304.

Garcia Rodriguez LA and Jick H, "Risk of Gynaecomastia Associated With Cimetidine, Omeprazole, and Other Antiulcer Drugs," BMJ, 1994, 308(6927):503-6.

Inoue A, Teramae H, Hisa T, et al, "Fixed Drug Eruption Due to Cimetidine," Acta Derm Venereol, 1995, 75(3):250.

Koren G and Zemlickis DM, "Outcome of Pregnancy After First Trimester Exposure to H2-Receptor Antagonists," Am J Perinatol, 1991, 8(1):37-8.

Krenzelok EP, Litovitz T, Lippold KP, et al, "Cimetidine Toxicity: An Assessment of 881 Cases," Ann Emerg Med, 1987, 16(11):1217-21.

Lambert J, Mobassaleh M, and Grand RJ, "Efficacy of Cimetidine for Gastric Acid Suppression in Pediatric Patients," J Pediatr, 1992, 120(3):474-8.

Lloyd CW, Martin WJ, and Taylor BD, "The Pharmacokinetics of Cimetidine and Metabolites in a Neonate," Drug Intell Clin Pharm, 1985, 19(3):203-5.

Lloyd CW, Martin WJ, Taylor BD, et al, "Pharmacokinetics and Pharmacodynamics of Cimetidine and Metabolites in Critically Ill Children," J Pediatr, 1985, 107(2):295-300.

Mogelnicki SR, Waller JL, and Finlayson DC, "Physostigmine Reversal of Cimetidine-Induced Mental Confusion," JAMA, 1979, 241(8):826-7.

Penston J and Wormsley G, "Adverse Reactions and Interactions With H2-Receptor Antagonists," Med Toxicol Adverse Drug Exp, 1986, 1(3):192-216.

Sawyer D, Conner CS, and Scalley, "Cimetidine: Adverse Reactions and Acute Toxicity," Am J Hosp Pharm, 1981, 38(2):188-97.

Somogyi A and Gugler R, "Clinical Pharmacokinetics of Cimetidine," Clin Pharmacokinet, 1983, 8(6):463-95.

Somogyi A and Muirhead M, "Pharmacokinetic Interactions of Cimetidine 1987," Clin Pharmacokinet, 1987, 12(5):321-66.


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