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Drug Interactions between AccessPak for HIV PEP Expanded with Viracept and Acid Reducer-Cimetidine

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

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Interactions between your drugs

Moderate

cimetidine tenofovir

Applies to: Acid Reducer-Cimetidine (cimetidine) and AccessPak for HIV PEP Expanded with Viracept (emtricitabine / nelfinavir / tenofovir)

MONITOR: Coadministration of tenofovir with other drugs that are also eliminated by active tubular secretion may result in increased plasma concentrations of tenofovir and/or the coadministered drug(s) due to competition for renal excretion. Drugs that are thought to undergo active tubular secretion include acyclovir, amiloride, cidofovir, cimetidine, flecainide, ganciclovir, metformin, midodrine, procainamide, quinidine, ranitidine, triamterene, valacyclovir, and valganciclovir.

MANAGEMENT: Patients receiving tenofovir in combination with other drugs that undergo active tubular secretion should be monitored for excessive pharmacologic effects of all drugs, and the dosages adjusted as necessary. Because tenofovir is associated with dose-related nephrotoxicity, especially proximal renal tubulopathy, renal function tests including serum creatinine, serum phosphorous, estimated creatinine clearance, urine glucose, and urine protein should be performed prior to and during therapy. Patients with renal insufficiency at baseline or during treatment may require dosage adjustment in accordance with the manufacturer's product labeling. Persistent or worsening bone pain, pain in extremities, fractures, and/or muscular pain or weakness may also be manifestations of proximal renal tubulopathy and should prompt an evaluation of renal function in at-risk patients.

References

  1. "Product Information. Viread (tenofovir)." Gilead Sciences (2001):
  2. "Product Information. Vemlidy (tenofovir)." Gilead Sciences (2017):

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Minor

cimetidine nelfinavir

Applies to: Acid Reducer-Cimetidine (cimetidine) and AccessPak for HIV PEP Expanded with Viracept (emtricitabine / nelfinavir / tenofovir)

There is currently no information in the medical literature regarding a potential interaction between nelfinavir and H2-receptor antagonists. Nelfinavir peak plasma concentration (Cmax), systemic exposure (AUC) and trough plasma concentration (Cmin) decreased by 37%, 36% and 39%, respectively, when nelfinavir (1250 mg twice daily) was coadministered with omeprazole (40 mg once daily 30 minutes before nelfinavir) for 4 days, presumably due to decreased solubility of nelfinavir as gastric pH increased. Although theoretically possible, it is not certain to what extent such an interaction may occur with H2-receptor antagonists, or whether it is clinically relevant. Caution may be advisable during coadministration.

References

  1. "Product Information. Viracept (nelfinavir)." Agouron Pharma Inc PROD (2001):

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Drug and food interactions

Minor

tenofovir food

Applies to: AccessPak for HIV PEP Expanded with Viracept (emtricitabine / nelfinavir / tenofovir)

Food enhances the oral absorption and bioavailability of tenofovir, the active entity of tenofovir disoproxil fumarate. According to the product labeling, administration of the drug following a high-fat meal increased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of tenofovir by approximately 14% and 40%, respectively, compared to administration in the fasting state. However, administration with a light meal did not significantly affect the pharmacokinetics of tenofovir compared to administration in the fasting state. Food delays the time to reach tenofovir Cmax by approximately 1 hour. Tenofovir disoproxil fumarate may be administered without regard to meals.

References

  1. "Product Information. Viread (tenofovir)." Gilead Sciences (2001):

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Minor

cimetidine food

Applies to: Acid Reducer-Cimetidine (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: Acid Reducer-Cimetidine (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: Acid Reducer-Cimetidine (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

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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