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Drug Interactions between elbasvir / grazoprevir and Tagamet HB

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

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Interactions between your drugs

Moderate

cimetidine grazoprevir

Applies to: Tagamet HB (cimetidine) and elbasvir / grazoprevir

MONITOR: Coadministration with inhibitors of CYP450 3A4 may increase the plasma concentrations of grazoprevir, which is a substrate of the isoenzyme. In 8 study subjects, administration of a single 100 mg dose of grazoprevir with the potent CYP450 3A4 inhibitor ketoconazole (400 mg once daily) increased grazoprevir peak plasma concentration (Cmax), systemic exposure (AUC) and trough plasma concentration (Cmin) by 13%, 200% and 100%, respectively, compared to administration of grazoprevir alone. High plasma levels of grazoprevir may increase the risk of adverse effects such as alanine aminotransferase (ALT) elevations. Ketoconazole also increased the Cmax, AUC and Cmin of a single 50 mg dose of elbasvir by 29%, 80% and 89%, respectively. The extent to which other, less potent inhibitors of CYP450 3A4 may interact with elbasvir and grazoprevir is unknown.

MANAGEMENT: Caution is advised if elbasvir-grazoprevir is prescribed in combination with CYP450 3A4 inhibitors. Patients should be monitored for increased adverse effects such as nausea, vomiting, and ALT elevations.

References

  1. (2016) "Product Information. Zepatier (elbasvir-grazoprevir)." Merck & Co., Inc

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Drug and food interactions

Minor

grazoprevir food

Applies to: elbasvir / grazoprevir

Food does not appear to have clinically significant effects on the pharmacokinetics of elbasvir and grazoprevir. When a single 50 mg-100 mg dose of elbasvir-grazoprevir was administered to healthy study subjects with a high-fat meal (900 kcal; 500 kcal from fat), elbasvir peak plasma concentration (Cmax) and systemic exposure (AUC) decreased by 15% and 11%, respectively, while grazoprevir Cmax and AUC increased by 2.8- and 1.5-fold, respectively, compared to administration under fasting conditions. According to the product labeling, elbasvir-grazoprevir may be administered with or without food.

References

  1. (2016) "Product Information. Zepatier (elbasvir-grazoprevir)." Merck & Co., Inc

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Minor

cimetidine food

Applies to: Tagamet HB (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 (1982) "Effects of cimetidine on the elimination and actions of ethanol." JAMA, 247, p. 2819-21
  2. Hansten PD (1992) "Effects of H2-receptor antagonists on blood alcohol levels." JAMA, 267, p. 2469

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Minor

cimetidine food

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

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Minor

cimetidine food

Applies to: Tagamet HB (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 (1990) "Effect of cimetidine and ranitidine on the hepatic and renal elimination of nicotine in humans." Eur J Clin Pharmacol, 38, p. 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.

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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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