Expert: Eric Brandt - 9/15/2006

Question
From where is the citrate part of this formulation derived?  Is it from natural sources, or can it be created chemically?  

I am asking this because I have been prescribed something which forbides any use of grapefruit.  The last time I took it I had a reaction and then found that my vitamin C contained bioflavanoids taken from grapefruit peels.

I am now taking powdered buffered C and am much happier with it.  Not only is it less expensive, but I can take more of it more easily.

I do have other forms of calcium, but since I have this bottle I am wondering if I can still use it.  

Answer
Hi Joan,
I do not know where the citrate in calcium citrate comes from. There are different brands and the source may be different. However, I would guess that the cirate is most likely synthetic as it would be cheaper to produce than extracting it from natural sources.
The interaction of drugs with grapefruit involves a chemical which inhibits the breakdown of the prescribed drug thus leading to an elevated blood level of the drug and an increased chance of developing side effects.
The citric acid is not involved in that interaction so I would say you would be safe taking calcium citrate as it is not expected to interact in the same way as grapefruit.
Thank you for using Allexperts
Sincerely,
Eric Brandt, B.Sc. Pharm