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Pronunciation |
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(sye
MET i
deen) |
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U.S. Brand
Names |
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Tagamet®; Tagamet® HB
[OTC] |
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Generic
Available |
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No |
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Canadian Brand
Names |
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Apo®-Cimetidine; Novo-Cimetine; Nu-Cimet;
Peptol® |
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Pharmacological Index |
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Histamine H2 Antagonist |
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Use |
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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. |
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Pregnancy Risk
Factor |
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B |
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Contraindications |
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Hypersensitivity to cimetidine, other component, or other
H2-antagonists |
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Warnings/Precautions |
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Adjust dosages in renal/hepatic impairment or patients receiving drugs
metabolized through the P-450 system |
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Adverse
Reactions |
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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 |
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Overdosage/Toxicology |
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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. |
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Drug
Interactions |
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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 |
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Stability |
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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 |
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Mechanism of
Action |
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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 |
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Pharmacodynamics/Kinetics |
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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 |
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Usual Dosage |
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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 |
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Dietary
Considerations |
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Alcohol: Additive CNS effects, avoid or limit use |
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Monitoring
Parameters |
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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 |
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Test
Interactions |
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creatinine, AST, ALT,
creatinine
(S) |
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Mental Health: Effects
on Mental Status |
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May cause agitation or drowsiness; rare reports of
confusion |
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Mental Health:
Effects on Psychiatric
Treatment |
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Rare reports of agranulocytosis; use caution with clozapine and
carbamazepine; may inhibit the metabolism of TCAs and benzodiazepines; monitor
for adverse effects |
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Dental Health: Local
Anesthetic/Vasoconstrictor
Precautions |
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No information available to require special precautions |
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Dental Health:
Effects on Dental Treatment |
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No effects or complications reported |
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Patient
Information |
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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. |
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Nursing
Implications |
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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
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Dosage Forms |
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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 |
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References |
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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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