Grapefruit juice and cholesterol medication

My mother-in-law has been visiting with us for the past few weeks.  She remarked one day while peeling a mango how she felt as if she had a kindred spirit with citrus fruit, but was quick to also mention how disappointed she was to learn that she is no longer able to eat grapefruit.  When asked why, she simply replied, “I’m on cholesterol medication.”

That wonderful, thick skinned, tangy yet sweet fruit that is also known as the forbidden fruit of Barbados and grows in clusters like grapes is well known for its interactions with multiple medications.  Grapefruit contains certain chemical compounds called polyphenolics that inhibit the metabolism or break down of some medications, statins being one of the most notorious.  Statins are highly effective and one of the most commonly prescribed cholesterol lowering medicines.  This class of medication inhibits a liver enzyme and can lower LDL by ~50% and raise HDL.  Drugs in the statin class include lovastatin, pravastatin, simvastatin, fluvastatin, atorvastatin, and rosuvastatin.  Although generally safe, statins have the potential to cause serious side effects such as muscle injury and liver damage.

Enzymes called cytochromes metabolize many drugs such as statins.  Most of these enzymes are concentrated in the liver, but some of them are found else where in the body such as in the gut.  One cytochrome in particular called CYP3A4 is quite predominant in the small intestine and significantly participates in the breakdown of statins.  Grapefruit can inhibit the activity of this intestinal cytochrome thereby increasing the level of statins in the blood stream.  More drug can therefore lead to a higher risk of side effects.  As little as 8 oz. of grapefruit juice can have a significant effect on drug levels.  And, the effect of eating a single serving of grapefruit may last as long as 24 hours.

Fortunately, all is not lost for my mother-in-law.  Mangos, oranges, and orange juice do not effect statin levels.  Although other citrus fruits such as limes and Seville oranges (sour oranges) do contain some similar chemical compounds to grapefruits, there have been no significant reports of them leading to harm with statins.  Also, not all statins are subject to the effects of grapefruit.  Pravastatin undergoes little breakdown by the intestinal cytochrome and is safe to take with grapefruit juice.  Whether these alternatives will be satisfactory to my mother-in-law waits to be seen.  But it saddens me to see two kindred spirits separated by one cholesterol medicine.