Grapefruit

Aka: Grapefruit, Grapefruit Drug Interaction

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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

IV. References

  1. (1995) Medical Letter 37(955):73
  2. (2013) Prescr Lett 20(1): 1
  3. Stump (2006) Am Fam Physician 605-11 [PubMed]
  4. Dahan (2004) Eur J Clin Nutr 58:1-9 [PubMed]
  5. Kane (2000) Mayo Clin Proc 75:933-42 [PubMed]

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