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Grapefruit juice can interact with a number of therapeutically important drugs that could lead to the possibility of toxicity.
This finding was published in the August 2001 issue of the Journal of Clinical Psychopharmacology, based on work at the Tufts University School of Medicine that was supported in part by grants from the Department of Health and Human Services.
Many drugs are metabolized, or broken down, by a family of chemicals called cytochrome P450 enzymes. Grapefruit...
Grapefruit juice can interact with a number of therapeutically important drugs that could lead to the possibility of toxicity.
This finding was published in the August 2001 issue of the Journal of Clinical Psychopharmacology, based on work at the Tufts University School of Medicine that was supported in part by grants from the Department of Health and Human Services.
Many drugs are metabolized, or broken down, by a family of chemicals called cytochrome P450 enzymes. Grapefruit juice inhibits the activity of one of these, CYP3A, which is found both in cells that line the small intestine and in the liver. Grapefruit juice primarily affects CYP3A in the small intestine but has little or no affect on liver CYP3A. It may take as long as 48 to 72 hours for CYP3A to become active again after being inhibited by the last exposure to grapefruit juice.
The degree of a drug interaction will vary from drug to drug. Some drugs within a therapeutic class may be affected, while others may not be. For example, the cholesterol lowering “statin” drugs simvastatin (ZOCOR) and lovastatin (MEVACOR) interact significantly with grapefruit juice, while pravastatin (PRAVACHOL) and fluvastatin (LESCOL) are hardly affected at all. The degree of interaction will also vary depending on the amount of CYP3A found in an individual’s small intestine, which is unpredictable.
The table below lists drugs known to interact with a single eight-ounce glass of grapefruit juice. The degree or magnitude of interaction is rated as large, moderate, small or negligible. The drugs are listed by generic name with brand names in parenthesis.
What You Can Do
If grapefruit juice is a favorite breakfast beverage of yours and you are taking one of the drugs that interacts with it, you should consider a substitute juice with your morning meal. Needless to say substituting a half grapefruit doesn’t do the trick.
|
Calcium Channel Blockers |
||
|---|---|---|
|
Moderate |
Small or Negligible |
|
|
Statins |
||
|
Large |
Moderate |
Small or Negligible |
|
Immunosuppressants |
||
|
Moderate |
||
|
Sleeping Pills and Tranquilizers |
||
|
Large |
Moderate |
Small or Negligible |
|
Other Mind Drugs |
||
|
Moderate |
Small or Negligible |
|
|
Antihistamines |
||
|
Moderate |
Small or Negligible |
|
|
AIDS Drugs |
||
|
Moderate |
Small or Negligible |
|
|
Hormones |
||
|
Moderate |
||
|
Steroids |
||
|
Moderate |
Small or Negligible |
|
|
Other Drugs |
||
|
Large |
Moderate |
Small or Negligible |
