PHILADELPHIA, Aug. 20 (UPI) -- A Canadian researcher warns grapefruit and other juices may cause drugs to be under-absorbed.
Dr. David Bailey of the University of Western Ontario in London, who 20 years ago discovered the "grapefruit juice effect" that an increased absorption of a drug that can result in a toxic overdose, has now found grapefruit as well as apple and orange juices can result in the opposite affect -- a decreased absorption of a drug.
The loss of as much as half of the drug's effect can pose a danger for someone in need of medication, Bailey says.
"Recently, we discovered that grapefruit and these other fruit juices substantially decrease the oral absorption of certain drugs undergoing intestinal uptake transport," Bailey said in a statement. "The concern is loss of benefit of medications essential for the treatment of serious medical conditions."
Bailey suggests an active ingredient of grapefruit juice -- naringin -- reduces absorption by blocking an uptake transporter -- OATP1A2 -- that shuttles some drugs from the small intestine to the bloodstream. By contrast, grapefruit can boost some drug levels by blocking a metabolizing enzyme -- CYP3A4 -- that breaks some drugs down.
Bailey's findings were presented at a meeting of the American Chemical Society in Philadelphia.