Metabolism
1. Decreases intestinal cytochrome P450 3A4
2. Effect onset: Within 4 hours of Grapefruit intake
3. Effect duration: May persist 24-72 hours
4. Increases level of drugs metabolized by CYP 3A4
Drug Interactions: Increased serum concentrations
1. Antiarrhythmics
  1. Agents affected
    1. Amiodarone
    2. Disopyramide
    3. Quinidine
  2. Alternative agents not affected by Grapefruit
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
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
References

Citrus paradisi (C0947567)
Definition (MSH)	A plant species of the genus CITRUS, family RUTACEAE that provides the familiar grapefruit. There is evidence that grapefruit juice inhibits CYTOCHROME P-450 isoform 3A4, 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
Russian	GREIPFRUT, ГРЕЙПФРУТ
Japanese	グレープフルーツ
English	paradisi, Citrus, paradisus, Citrus, Citrus paradisus, grapefruits, Citrus paradisi, Citrus x paradisi, grapefruit, citrus paradisi, Citrus sinensis x Citrus grandis, Citrus sinensis x Citrus maxima, Citrus x paradisi Macfad.
Polish	Grejpfrut
French	Citrus paradisi
German	Citrus paradisi
Italian	Citrus paradisi
Dutch	Citrus paradisi
Portuguese	Citrus paradisi, Toronja
Spanish	Citrus paradisi
Sources	Derived from the NIH UMLS (Unified Medical Language System)

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