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Drug Interactions between atazanavir and carbamazepine

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

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Interactions between your drugs

Moderate

carBAMazepine atazanavir

Applies to: carbamazepine and atazanavir

MONITOR: Coadministration with drugs that are inducers of CYP450 3A4 may decrease the plasma concentrations of protease inhibitors (PIs), which are primarily metabolized by the isoenzyme.

MANAGEMENT: Given the risk of reduced viral susceptibility and resistance development associated with subtherapeutic antiretroviral drug levels, protease inhibitors should be used cautiously with agents that induce CYP450 3A4, particularly if only one PI is used in the antiretroviral regimen. Coadministration of atazanavir without ritonavir and carbamazepine, phenobarbital, or phenytoin is not recommended. Antiretroviral response should be monitored more closely whenever a CYP450 3A4 inducer is added to or withdrawn from therapy, and the antiretroviral regimen adjusted as necessary.

References

  1. (2001) "Product Information. Invirase (saquinavir)." Roche Laboratories
  2. (2001) "Product Information. Crixivan (indinavir)." Merck & Co., Inc
  3. (2001) "Product Information. Viracept (nelfinavir)." Agouron Pharma Inc
  4. Brooks J, Daily J, Schwamm L (1997) "Protease inhibitors and anticonvulsants." AIDS Clin Care, 9, 87,90
  5. Barry M, Gibbons S, Back D, Mulcahy F (1997) "Protease inhibitors in patients with HIV disease. Clinically important pharmacokinetic considerations." Clin Pharmacokinet, 32, p. 194-209
  6. (2001) "Product Information. Agenerase (amprenavir)." Glaxo Wellcome
  7. Acosta EP, Henry K, Baken L, Page LM, Fletcher CV (1999) "Indinavir concentrations and antiviral effect." Pharmacotherapy, 19, p. 708-12
  8. Sommadossi JP (1999) "HIV protease inhibitors: pharmacologic and metabolic distinctions." AIDS, 13, s29-40
  9. Hugen PWH, Burger DM, Brinkman K, terHofstede HJM, Schuurman R, Koopmans PP, Hekster YA (2000) "Carbamazepine-indinavir interaction causes antiretroviral therapy failure." Ann Pharmacother, 34, p. 465-70
  10. Durant J, Clevenbergh P, Garraffo R, Halfon P, Icard S, DelGiudice P, Montagne N, Schapiro JM, Dellamonica P (2000) "Importance of protease inhibitor plasma levels in HIV-infected patients treated with genotypic-guided therapy: pharmacological data from the Viradapt Study." Aids, 14, p. 1333-9
  11. (2001) "Product Information. Fortovase (saquinavir)." Roche Laboratories
  12. (2003) "Product Information. Reyataz (atazanavir)." Bristol-Myers Squibb
  13. (2003) "Product Information. Lexiva (fosamprenavir)." GlaxoSmithKline
  14. Liedtke MD, Lockhart SM, Rathbun RC (2004) "Anticonvulsant and antiretroviral interactions." Ann Pharmacother, 38, p. 482-9
  15. (2005) "Product Information. Aptivus (tipranavir)." Boehringer-Ingelheim
  16. (2006) "Product Information. Prezista (darunavir)." Ortho Biotech Inc
  17. Canadian Pharmacists Association (2006) e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink
View all 17 references

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Drug and food interactions

Moderate

carBAMazepine food

Applies to: carbamazepine

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of carbamazepine. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

In a small, randomized, crossover study, the administration of carbamazepine with grapefruit juice (compared to water) increased plasma drug concentrations by approximately 40%. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits.

MANAGEMENT: Patients receiving carbamazepine should be advised to avoid or limit consumption of alcohol. Given the drug's narrow therapeutic index, patients receiving carbamazepine therapy should preferably avoid the regular consumption of grapefruits and grapefruit juice to prevent any undue fluctuations in plasma drug levels. Patients should be advised to report signs of carbamazepine toxicity (nausea, visual disturbances, dizziness, or ataxia) to their physicians.

References

  1. (2002) "Product Information. Tegretol (carbamazepine)." Novartis Pharmaceuticals
  2. Garg SK, Kumar N, Bhargava VK, Prabhakar SK (1998) "Effect of grapefruit juice on carbamazepine bioavailability in patients with epilepsy." Clin Pharmacol Ther, 64, p. 286-8
  3. Bailey DG, Dresser GR, Kreeft JH, Munoz C, Freeman DJ, Bend JR (2000) "Grapefruit-felodipine interaction: Effect of unprocessed fruit and probable active ingredients." Clin Pharmacol Ther, 68, p. 468-77

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Moderate

atazanavir food

Applies to: atazanavir

ADJUST DOSING INTERVAL: Administration of atazanavir with food enhances oral bioavailability and reduces pharmacokinetic variability. According to the manufacturer, administration with a light meal increased the peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of a single 400 mg dose of atazanavir by 57% and 70%, respectively, relative to the fasting state. Administration with a high-fat meal resulted in a mean increase of 35% in atazanavir AUC and no change in Cmax compared to fasting. The coefficient of variation of AUC and Cmax decreased by approximately one-half when given with either a light or high-fat meal compared to the fasting state.

MANAGEMENT: To ensure maximal oral absorption, atazanavir should be administered with or immediately after a meal.

References

  1. (2003) "Product Information. Reyataz (atazanavir)." Bristol-Myers Squibb

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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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