Amiodarone is a drug for the treatment of atrial fibrillation, which is metabolized (broken down chemically) by a major liver enzyme that also metabolizes many anti-cancer drugs. Grapefruit juice is known to block this enzyme, resulting in failure of metabolism if amiodarone given at the same time. This combination can also result in very high blood levels of the drug that can lead to possible toxic effects.
The authors demonstrated the blockage of the enzyme by giving amiodarone to patients on the same day they drank three 300 ml. glasses of grapefruit juice. High blood levels of amiodarone in the patients resulted. The high doses could have been dangerous to the health of the patient simply because of drinking grapefruit juice.
CONCLUSION: People on pharmaceutical medications who consume grapefruit should be sure there is no conflict with their medication.
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