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Drug Interactions between darunavir and fosphenytoin

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

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Interactions between your drugs

Major

fosphenytoin darunavir

Applies to: fosphenytoin and darunavir

GENERALLY AVOID: Coadministration with carbamazepine, phenobarbital, phenytoin, or primidone may significantly reduce the plasma concentrations of darunavir. The proposed mechanism is induction of CYP450 3A4, the isoenzyme responsible for the metabolic clearance of darunavir.

MANAGEMENT: Given the risk of reduced viral susceptibility and resistance development associated with subtherapeutic antiretroviral drug levels, darunavir should not be used in combination with carbamazepine, phenobarbital, phenytoin, or primidone.

References (4)
  1. 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
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  3. (2006) "Product Information. Prezista (darunavir)." Ortho Biotech Inc
  4. Canadian Pharmacists Association (2006) e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink

Drug and food interactions

Moderate

darunavir food

Applies to: darunavir

ADJUST DOSING INTERVAL: Food enhances the absorption and oral bioavailability of darunavir administered in combination with low-dose ritonavir. The mechanism is unknown. When administered with food, the peak plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC) of darunavir were approximately 30% higher than when administered in the fasting state. Darunavir exposure was similar for the range of meals studied. The total caloric content of the various meals evaluated ranged from 240 Kcal (12 grams fat) to 928 Kcal (56 grams fat).

MANAGEMENT: To ensure maximal oral absorption, darunavir coadministered with ritonavir should be taken with food. The type of food is not important.

References (1)
  1. (2006) "Product Information. Prezista (darunavir)." Ortho Biotech Inc

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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