Saturday 23 July 2011

PHARMACOLOGICAL EFFECTS OF COMMON MEDICATIONS WITH GRAPEFRUIT JUICE




PHARMACOLOGICAL EFFECTS OF COMMON MEDICATIONS WITH GRAPEFRUIT JUICE
 
Grapefruit is a healthy addition to a well-balanced diet. However, the fruit or juice has been shown to affect the metabolism of many medications, increasing the risk of toxicity and adverse events. Characteristics of oral medications that may interact with grapefruit include extensive metabolism through the intestinal cytochrome P450 3A4 (CYP3A4) system, low bioavailability, and a narrow therapeutic index. Grapefruit juice interacts through the intestinal CYP3A4 system and can inhibit the concentration for 24–72 hours.1 This list is based on manufacturer's prescribing information and is not a complete list of medications that may interact with grapefruit. Caution should be taken by both patient and physician and monitor adverse reactions when taking medications that may interact with grapefruit or juice.
BrandGenericClinical Implications of Co-administration with Grapefruit or Grapefruit Juice
ANTIARRHYTHMICS
CordaroneamiodaroneInhibits CYP3A4-mediated metabolism of oral amiodarone resulting in increase plasma levels of amiodarone. Avoid co-administration.
MultaqdronedaroneModerate inhibitor of CYP3A, results in a 3-fold increase in dronedarone exposure and a 2.5-fold increase in Cmax. Avoid co-administration.
RanexaranolazineModerate CYP3A inhibitor. Limit dose of Ranexa to 500mg twice daily.
TikosyndofetilideInhibitor of the CYP3A4 isoenzyme, thus could increase systemic dofetilide exposure. If co-administration is necessary, use with caution.
ANTIMALARIAL
Coartemartemether/lumefantrineMay increase concentrations of artemether and/or lumefantrine and potentiate QT prolongation.
ANTIPSYCHOTIC
OrappimozideInhibits CYP3A4-mediated metabolism of pimozide. Avoid co-administration.
CALCIUM CHANNEL BLOCKERS
NimotopnimodipineElevates plasma concentrations and prolongs action of nimodipine due to a decreased first pass metabolism or reduced clearance. Avoid co-administration.
Plendilfelodipine2-fold increase in felodipine AUC and Cmax. Avoid co-administration prior to and during treatment.
Procardianifedipine2-fold increase in nifedipine AUC and Cmax with no change in half-life. Avoid co-administration.
Sularnisoldipine3-fold increase in nisoldipine Cmax and 2-fold increase in nisoldipine AUC. Avoid co-administration before and after dosing.
CHOLESTEROL-LOWERING MEDICATIONS
LipitoratorvastatinInhibits CYP3A4 and can increase plasma concentrations of atorvastatin, especially with excessive grapefruit juice consumption (>1.2 liters per day).
MevacorlovastatinInhibits CYP3A4 and can increase plasma concentrations of lovastatin. Avoid large quantities of grapefruit juice (>1 quart daily).
ZocorsimvastatinInhibits CYP3A4 and can increase plasma concentrations of simvastatin and may increase risk of myopathy. Avoid large quantities of grapefruit juice (>1 quart daily).
H1-RECEPTOR ANTAGONIST
AllegrafexofenadineMay reduce bioavailability and exposure of fexofenadine. In a bioequivalence study, the bioavailability of fexofenadine was reduced by 36%. Take with water.
IMMUNOSUPPRESSANTS
NeoralcyclosporineAffects metabolism and increases blood concentrations of cyclosporine. Avoid co-administration.
PrograftacrolimusAffects CYP3A-mediated metabolism and should be avoided.
ToriseltemsirolimusMay increase plasma concentrations of sirolimus, a major metabolite of temsirolimus, and should be avoided.
INTERMITTENT CLAUDICATION THERAPY
PletalcilostazolIncrease in the Cmax of cilostazol by ∼50%, but has no effect on AUC.
KINASE INHIBITORS
GleevecimatinibMay increase plasma concentrations of imatinib and should be avoided.
SpryceldasatinibMay increase plasma concentrations of dasatinib and should be avoided.
SutentsunitinibMay increase plasma concentrations of sunitinib and should be avoided.
TarcevaerlotinibDose reduction in 50mg decrements should be considered if severe adverse reactions occur. Use with caution.
TasignanilotinibMay increase plasma concentrations of nilotinib and should be avoided.
PSYCHOTROPIC AGENTS
BuSparbuspirone4.3 fold increase in Cmax; 9.2 fold increase in AUC. Avoid drinking large amounts (200mL double-strength three times daily) of grapefruit juice.
HalciontriazolamIncreases the Cmax of triazolam by 25%, increases AUC by 48%, and increases half-life by 18%. Use with caution.
TegretolcarbamazepineInhibits carbamazepine metabolism and may increase plasma carbamazepine levels. Use with caution.
VersedmidazolamCaution is advised when midazolam is administered concomitantly with drugs that are known to inhibit the P450-3A4 enzyme system

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