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Drug Interactions between dabrafenib and phenobarbital

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

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Interactions between your drugs

Moderate

PHENobarbital dabrafenib

Applies to: phenobarbital and dabrafenib

GENERALLY AVOID: Coadministration with potent inducers of CYP450 2C8 and/or 3A4 may decrease the plasma concentrations of dabrafenib, which is primarily metabolized by these isoenzymes. Administration of rifampin (600 mg once a day), a potent CYP450 3A4 and moderate CYP450 2C8 inducer, with dabrafenib (150 mg twice a day) for 10 days resulted in a decreased dabrafenib AUC (34%) and Cmax (27%). The AUC of the metabolite hydroxy-dabrafenib was not affected; however, the AUC increased by 73% for the metabolite carboxy-dabrafenib and decreased by 30% for desmethyl-dabrafenib.

MANAGEMENT: Concomitant use of dabrafenib with potent CYP450 2C8 or 3A4 inducers should generally be avoided. Otherwise, patients should be closely monitored for potential loss of efficacy of dabrafenib.

References (3)
  1. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  2. Cerner Multum, Inc. "Australian Product Information."
  3. (2013) "Product Information. Tafinlar (dabrafenib)." GlaxoSmithKline

Drug and food interactions

Major

PHENobarbital food

Applies to: phenobarbital

GENERALLY AVOID: Concurrent acute use of barbiturates and ethanol may result in additive CNS effects, including impaired coordination, sedation, and death. Tolerance of these agents may occur with chronic use. The mechanism is related to inhibition of microsomal enzymes acutely and induction of hepatic microsomal enzymes chronically.

MANAGEMENT: The combination of ethanol and barbiturates should be avoided.

References (5)
  1. Gupta RC, Kofoed J (1966) "Toxological statistics for barbiturates, other sedatives, and tranquilizers in Ontario: a 10-year survey." Can Med Assoc J, 94, p. 863-5
  2. Misra PS, Lefevre A, Ishii H, Rubin E, Lieber CS (1971) "Increase of ethanol, meprobamate and pentobarbital metabolism after chronic ethanol administration in man and in rats." Am J Med, 51, p. 346-51
  3. Saario I, Linnoila M (1976) "Effect of subacute treatment with hypnotics, alone or in combination with alcohol, on psychomotor skills related to driving." Acta Pharmacol Toxicol (Copenh), 38, p. 382-92
  4. Stead AH, Moffat AC (1983) "Quantification of the interaction between barbiturates and alcohol and interpretation of fatal blood concentrations." Hum Toxicol, 2, p. 5-14
  5. Seixas FA (1979) "Drug/alcohol interactions: avert potential dangers." Geriatrics, 34, p. 89-102
Moderate

dabrafenib food

Applies to: dabrafenib

ADJUST DOSING INTERVAL: Food may reduce as well as delay the absorption of dabrafenib. In study subjects, administration of dabrafenib with a high-fat meal decreased peak plasma concentration (Cmax) and systemic exposure (AUC) by 51% and 31%, respectively, and delayed median Tmax by approximately 3.6 hours compared to administration in the fasted state.

MANAGEMENT: Dabrafenib should be taken at least 1 hour before or 2 hours after a meal.

References (1)
  1. (2013) "Product Information. Tafinlar (dabrafenib)." GlaxoSmithKline

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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