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Drug Interactions between cimetidine and duloxetine

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

cimetidine DULoxetine

Applies to: cimetidine and duloxetine

MONITOR: Coadministration with inhibitors of CYP450 1A2 may increase the plasma concentrations of duloxetine, which is a substrate of the isoenzyme. In 14 male study subjects, coadministration with 100 mg fluvoxamine, a potent CYP450 1A2 inhibitor, resulted in a 2.5-fold increase in duloxetine peak plasma concentration (Cmax), a nearly 6-fold increase in duloxetine systemic exposure (AUC), and an approximately 3-fold increase in duloxetine half-life. The interaction has not been studied with less potent CYP450 1A2 inhibitors such as mexiletine, propafenone, and zileuton. Theoretically, high plasma levels of duloxetine may increase the risk of serious adverse effects such as hypertension, hypertensive crisis, increased heart rate, orthostatic hypotension, syncope, and serotonin syndrome. Serotonin syndrome is a rare but serious and potentially fatal condition thought to result from hyperstimulation of brainstem 5-HT1A and 2A receptors. Symptoms may include mental status changes such as irritability, altered consciousness, confusion, hallucinations, and coma; autonomic dysfunction such as tachycardia, hyperthermia, diaphoresis, shivering, blood pressure lability, and mydriasis; neuromuscular abnormalities such as hyperreflexia, myoclonus, tremor, and ataxia; and gastrointestinal symptoms such as abdominal cramping, nausea, vomiting, and diarrhea.

MANAGEMENT: Caution is advised if duloxetine is used in combination with CYP450 1A2 inhibitors. Pharmacologic response to duloxetine should be monitored more closely whenever a CYP450 1A2 inhibitor is added to or withdrawn from therapy, and the dosage adjusted as necessary.

References

  1. Brosen K, Skjelbo E, Rasmussen BB, Poulsen HE, Loft S "Fluvoxamine is a potent inhibitor of cytochrome P4501A2." Biochem Pharmacol 45 (1993): 1211-4
  2. Martinez C, Albet C, Agundez JA, et al. "Comparative in vitro and in vivo inhibition of cytochrome P450 CYP1A2, CYP2D6, and CYP3A by H2-receptor antagonists." Clin Pharmacol Ther 65 (1999): 369-76
  3. "Product Information. Cymbalta (duloxetine)." Lilly, Eli and Company (2004):
  4. Uwe F, Strobl G, Manaut F, et al. "Quinolone antibacterial agents: relationship between structure and in vitro inhibition of the human cytochrome P450 isofaorm CYP1A2." Mol Pharmacol 43 (1993): 191-9
View all 4 references

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Drug and food interactions

Moderate

DULoxetine food

Applies to: duloxetine

GENERALLY AVOID: Use of duloxetine in conjunction with chronic alcohol consumption may potentiate the risk of liver injury. Duloxetine alone can increase serum transaminase levels. In clinical trials, 0.3% of patients discontinued duloxetine due to liver transaminase elevations. The median time to detection was about two months. Three duloxetine-treated patients had liver injury as manifested by transaminase and bilirubin elevations, with evidence of obstruction. Substantial intercurrent ethanol use was present in each of these cases, which may have contributed to the abnormalities observed. Duloxetine does not appear to enhance the central nervous system effects of alcohol. When duloxetine and ethanol were administered several hours apart so that peak concentrations of each would coincide, duloxetine did not increase the impairment of mental and motor skills caused by alcohol.

MANAGEMENT: Due to the risk of liver injury, patients prescribed duloxetine should be counseled to avoid excessive use of alcohol. Duloxetine should generally not be prescribed to patients with substantial alcohol use.

References

  1. "Product Information. Cymbalta (duloxetine)." Lilly, Eli and Company (2004):

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Minor

cimetidine food

Applies to: cimetidine

Concurrent use of cimetidine and ethanol may result in increased ethanol concentrations. The mechanism appears to be due to inhibition of gastric alcohol dehydrogenase by cimetidine, leading to increased bioavailability of the alcohol and inhibition of hepatic metabolism of alcohol. The clinical significance of this interaction is limited. More importantly, patients requiring cimetidine for gastrointestinal disease should be counseled to avoid alcohol to prevent worsening of their disease. The other H-2 receptor antagonists appear to have minimal effects on the concentrations of alcohol.

References

  1. Feely J, Wood AJ "Effects of cimetidine on the elimination and actions of ethanol." JAMA 247 (1982): 2819-21
  2. Hansten PD "Effects of H2-receptor antagonists on blood alcohol levels." JAMA 267 (1992): 2469

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Minor

cimetidine food

Applies to: cimetidine

Caffeine effects may be increased in patients also taking cimetidine. The mechanism may be due to decreased caffeine metabolism induced by cimetidine. Although adequate clinical data are lacking, a reduction in dose or elimination of caffeine may be needed if excess CNS stimulation is observed.

References

  1. "Product Information. Tagamet (cimetidine)." SmithKline Beecham PROD (2001):
  2. Broughton LJ, Rodgers HJ "Decreased systenuc clearance of caffeine due to cimetidine." Br J Clin Pharmacol 12 (1981): 155-9

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Minor

cimetidine food

Applies to: cimetidine

H2 antagonists may reduce the clearance of nicotine. Cimetidine, 600 mg given twice a day for two days, reduced clearance of an intravenous nicotine dose by 30%. Ranitidine, 300 mg given twice a day for two days, reduced clearance by 10%. The clinical significance of this interaction is not known. Patients should be monitored for increased nicotine effects when using the patches or gum for smoking cessation and dosage adjustments should be made as appropriate.

References

  1. Bendayan R, Sullivan JT, Shaw C, Frecker RC, Sellers EM "Effect of cimetidine and ranitidine on the hepatic and renal elimination of nicotine in humans." Eur J Clin Pharmacol 38 (1990): 165-9

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Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

See also

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

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