INTERACTIONS OF GRAPEFRUIT WITH MEDICATIONS

Revelation - Conclusion

The ability of a dietary component to interact with a pharmaceutical is not new. The interaction between Vitamin K in leafy vegetables, e.g. cabbage, broccoli, brussel sprouts, etc. and the blood thinning medication, warfarin (Coumadin), has been known for decades. However, the potential for adverse drug interactions with a single glass of grapefruit juice, is unprecedented with respect to the number of drugs affected and the magnitude of the response. 

Many health food supplements contain "citrus bioflavinoids" as one of their ingredients, but source of the bioflavinoid was not disclosed. You should be very careful if you are taking any prescription medications and contemplate consuming any of the health foods that has unidentified citrus bioflavinoids. These supplements may not be as "safe" as promoted.

Grapefruit's effect on medications is unpredictable. It may enhance the desired effect of the drug in some instances (so that we can take a lower amount of the drug and still get the effectiveness). It also means that if you take the suggested dose of the drug, our system gets a higher than expected concentration of the drug, resulting in amplification of the side effects of the drug and sometimes resulting in dangerous situations that was unforeseen at the time of the introduction of the drug in question.  The same dose of drug could produce blood levels in different individuals ranging in concentration from normal to very toxic. Depending on the individual and the drug in question, dangerously high levels of the drug could enter the systemic circulation. 

With further research, it should be possible to eventually harness this drug enhancing effect of grapefruit juice to our advantage. However, at the present time, it would be more prudent to avoid drinking grapefruit juice when taking any medications that utilize cytochrome P450 3A4 isoenzymes for any of the steps in their respective metabolic pathways. 

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