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 Dr. Lee is the founder and owner of Regrowth LLC, a company based in Los Angeles and dedicated to the treatment of hair loss. He has been developing innovative products and treating hair loss sufferers for the past 16 years. Dr. Lee is the creator of the Xandrox line of hair loss treatments.
Important Note: Due a busy schedule, Dr. Lee cannot answer any new questions at this time; however, he will be providing high quality answers to questions he receives from his own practice exclusively to Morphollica.com regularly
anonymous
2005-05-15
Can grapefruit juice alter absorption of Propecia?
Can drinking grapefruit juice alter the absorption or serum levels of
finasteride (Propecia or Proscar)?
Strangely enough, yes, it can. Drinking grapefruit juice to wash down the
oral doses of finasteride can raise the blood concentrations of the drug
beyond what the dosage has been known to do. Unlike other citrus juices,
grapefruit juice inhibits one of the body's intestinal enzyme systems and can
result in marked increases in absorption of the drugs. Within the liver, the
grapefruit juice competes with finasteride in its metabolic pathways and may
further increase the serum levels of many prescription drugs. Studies show that the interaction of grapefruit juice with drugs involves the
compounds in grapefruit juice, called furanocoumarins (e.g. bergamottin),
which block the enzymes in the intestines that normally break down many drugs,
allowing more of the drug to be absorbed into the bloodstream. In addition, grapefruit juice is one of the foods most likely to cause
problems with drugs, because it is metabolized by the same enzyme in the liver
that breaks down many drugs, including finasteride. The cytochrome P-450 3A4
enzyme breaks down grapefruit juice into useful components for the body, just
like it breaks down dozens of medications. But, if the grapefruit juice can
overload the system, keeping the liver busy and blocking it from breaking down
drugs and other substances, the blood levels of the affected medication may
remain too high. Some sources recommend not ingesting grapefruit juice within 2 hours before
and 5 hours after a drug, which may interact with it. Others contend that one
glass of grapefruit juice could elicit the maximum blocking effect, and that
the effect may persist for longer than 24 hours. Therefore, a safer approach
would be to substitute another citrus juice, such as orange juice, which has
the same vitamins but has not
demonstrated the drug interactions. Richard Lee, M.D.
Regrowth, LLC,
www.Minoxidil.com
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