Thursday, 19 November 2009

Aspergillus provides a solution to grapefruit juice interacting with medications

Grapefruit juice has been shown to interfere with absorbtion and/or metabolism of several prescription drugs with potentially hazardous consequences in some cases. The effect can be either to increase or lower the amount of the drug circulating in the blood of the patient, so if a drug such as one meant to lower blood pressure was taken with grapefruit juice the effect could be to reduce blood pressure too much (see here for more examples).

The aim of drug management is to find a dosage level which causes blood levels to stay within a useful range for each patient. It is not hard to imagine a patient unaware of the interaction between grapefruit juice and their medication might take a glass of grapefruit juice with their drug causing drug blood levels to increase. When the juice carton is empty they might use a different drink causing levels to drop again resulting in much confusion on the part of their doctor over what the right dose for them is!

There is clearly some benefit to understanding what component of grapefruit juice is important for this interaction and in removing it from grapefuit juice offered for comsumption. It is already known that one factor is furanocomarins (FC) which inhibit the enzymatic activity in the liver of patients that activates some drugs, so one aim is to remove FC's from grapefruit juice.
The United States Department of Agriculture (USDA) have made some progress in this regard. They have identified fungi that can remove or inactivate FC's from grapefruit juice and are in the process of finding out how the fungus does that.

It is ironic to note that the fungus used at the USDA is Aspergillus niger. Aspergillus (more usually fumigatus) causes a serious infection known as aspergillosis. The infections are treated with antifungal drugs in an attempt to eradicate the fungus. Once such antifungal is itraconazole and itraconazole is one of those drugs that interact with grapefruit juice, enhancing the effective dose.One species of Aspergillus is helping counteract the pathogenicity of another!

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