Adverse Reactions with Medications and Grapefruit [posted 7/24/98]
Question: I recently read an article regarding the adverse affects of grapefruit and certain medications (i.e. high blood medicine). Could you tell me more about this?

Answer: Looks like procardia is the only one affected by this interaction. However, some wonder whether other drugs of the procardia class, calcium channel blockers, might have effects and research in progress. However, just don't take them concurrently and there is no problem. The affect is blocking absorption.

Grapefruit Juice
Question: My computer software issued a warning on seldane and on procardia not to take within one hour of consumption of grapefruit juice. While I have heard that this will increase the blood levels of seldane, I have not been able to find any information on the mechanism or any studies done on the combined use. I have been asked by a patient the mechanism and whether fresh or concentrate juice makes a difference.

Answer: I know of no appreciable clinical effect. I suspect there are theoretical reasons, but I think this obfuscates the issue. That is, although there may be theoretical considerations there is no practical problem. However, check with the companies. Seldane is Marion-Merrell Dow and the is telephone number 800-633-1610. Procardia is Pfizer and the telephone number is 800-438-1985.
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