II. Metabolism

  1. Decreases intestinal Cytochrome P450 3A4
    1. Increases level of drugs metabolized by CYP 3A4
    2. Drugs most affected are those with low oral absorption
  2. Small Grapefruit exposure can lead to Clinically SignificantDrug Interaction
    1. Single Grapefruit
    2. One cup of Grapefruit juice
  3. Effect onset: Within 4 hours of Grapefruit intake
  4. Effect duration: May persist 24-72 hours
    1. Grapefruit permanently binds and inactivates CYP 3A4 enzymes
    2. Enzymes replaced every 48-72 hours

III. Drug Interactions: Increased serum concentrations

  1. Antiarrhythmics
    1. Agents affected
      1. Amiodarone
      2. Disopyramide
      3. Quinidine
    2. Alternative agents not affected by Grapefruit
      1. Digoxin
      2. Diltiazem
      3. Verapamil
      4. Beta Blockers
  2. Calcium Channel Blockers
    1. Agents affected
      1. Felodipine
      2. Nicardipine
      3. Nifedipine (Procardia)
      4. Nimodipine
      5. Nisoldipine
    2. Alternative agents not affected by Grapefruit
      1. Diltiazem
      2. Verapamil
      3. Beta Blockers
  3. Statins
    1. Agents affected
      1. Atorvastatin (Lipitor)
      2. Lovastatin (Mevacor)
      3. Simvastatin (Zocor)
    2. Alternative agents not affected by Grapefruit
      1. Fluvastatin (Lescol)
      2. Pravastatin (Pravachol)
      3. Rosuvastatin (Crestor)
      4. Fibric Acids
      5. Niacin
      6. Bile acid sequestrants
  4. Immunosuppressants
    1. Agents affected
      1. Cyclosporine
      2. Tacrolimus
  5. Protease Inhibitors
    1. Agents affected
      1. Saquinavir
    2. Alternative agents not affected by Grapefruit
      1. Amprenavir
      2. Atazanavir
      3. Fosamprenavir
      4. Indinavir
      5. Lopinavir with Ritonavir
      6. Ritonavir
      7. Nelfinavir
  6. Miscellaneous agents
    1. Versed
    2. Estrogens
    3. Caffeine
    4. Ticagrelor (Brilanta)
      1. Increased Gastrointestinal Bleeding risk
    5. Dronedarone (Multaq)
      1. Increased Arrhythmia risk
    6. Eplerenone (Inspra)
      1. Increased Hyperkalemia risk
    7. Terfenadine (Seldane)
      1. Not available in United States since 1998
      2. Can aggravate QT Prolongation

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Related Studies

Ontology: Citrus paradisi (C0947567)

Definition (MSH) A plant species of the genus CITRUS, family RUTACEAE that produces the familiar grapefruit. There is evidence that grapefruit inhibits CYTOCHROME P-450 CYP3A4, resulting in delayed metabolism and higher blood levels of a variety of drugs.
Definition (ALT) Grapefruit.
Concepts Plant (T002)
MSH D032083
Swedish Grapefrukt
Czech Citrus paradisi
Finnish Citrus paradisi
Japanese グレープフルーツ
English grapefruit, grapefruits, Citrus paradisi, Citrus x paradisi Macfad., Citrus x paradisi, citrus paradisi, Citrus sinensis x Citrus grandis, Citrus sinensis x Citrus maxima
Polish Grejpfrut
Norwegian Citrus paradisi
Portuguese Toronja, Citrus paradisi
French Citrus paradisi
German Citrus paradisi
Italian Citrus paradisi
Dutch Citrus paradisi
Spanish Citrus paradisi