Statins and Grapefruit

grapefriut

If you’re taking a statin medication for your cholesterol, you have undoubtedly heard the warning against consuming grapefruits or grapefruit juice. This restriction also applies to a number of other medications including certain cardiovascular medications, anti-cancer agents, antibiotics, antidepressants and others. For a more detailed list and approximations about the extent of the interaction with particular medications click on to the following site: http://www.cmaj.ca/content/suppl/2012/11/26/cmaj.120951.DC1/grape-bailey-1-at.pdf.

The discovery of the interaction was serendipitous. Researchers noticed a higher drug concentration in certain test subjects than others when a medication was initially being tested. Those with an elevated drug level were eventually found to have also consumed grapefruit. Pomelo, lime and marmalade can also produce the same effects.

The compounds in grapefruit responsible for the effect are called furanocoumarins and act by blocking the enzymes in the intestines responsible for the degradation of certain medications. It only takes one glass of grapefruit juice to produce the maximum effect, an effect that persists for longer than 24 hours. Therefore, taking grapefruit juice at a time well-separated from the medication dose is ineffective in solving the problem.

How big an issue does this represent? That depends on a number of factors, particularly on how dependent the medication is on the enzyme that is blocked by the juice. Some medications have a wide “therapeutic range.” In other words, increased blood levels don’t represent much of a concern. On the other hand, some medications have a narrow therapeutic range, with increased concentrations causing serious problems.

Although most statins should not be taken in combination with grapefruit products Crestor (rosuvastatin) and Pravachol (pravastatin) are exceptions since they are not significantly metabolized by the enzyme blocked by grapefruit.

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Aspirin and Disease Prevention

AspirinRecently the New York Times ran an op-ed entitled “The 2,000-Year-Old Wonder Drug” extolling the benefits of aspirin for a number of illnesses including cardiovascular disease and cancer. Although quite enthused about aspirin as a disease preventive, the author does advise medical consultation about the risks versus the benefits.

Is aspirin usually a good idea for middle-aged American? For those with known cardiovascular disease it usually is. However, one year ago a large study in the Archives of Internal Medicine did not show a reduction in cardiovascular or cancer deaths in patients without prior cardiovascular disease taking low-dose aspirin. A reduction in non-fatal heart attacks was noted. This benefit, however, was associated with a 30% increased risk of significant bleeding. The authors conclude against the routine use of aspirin for patients at low risk for cardiovascular disease.

More concerning, than the well-known risk of bleeding from the stomach or intestines, is the possibility of bleeding in the brain. Although the absolute risk of intracranial vessel bleeding is small (two hemorrhagic strokes per 10,000 patients taking aspirin) the consequences can be devastating.

Also, does aspirin prevent cancer? The evidence suggests that it is effective in preventing colon cancer and might be effective in preventing other cancers, although the evidence for the latter is less clear. The dose necessary to produce a statistically significant reduction in colon cancer is not certain, but some suggest that a full aspirin (325 mg) rather than low-dose aspirin (81 mg) might be needed.

The increased risk of bleeding associated with any dose of aspirin, and the possibility of greater risk with a higher dose, along with the very useful colon cancer prevention strategy of colonoscopy now in place caused the American Cancer Society not to recommend the routine use of daily aspirin to prevent colon cancer.

Patients at low risk for cardiovascular disease should consult their doctor before committing to a lifetime of daily low-dose aspirin. Low risk is defined as a patient whose 10-year absolute risk of a first coronary disease event is less than 10%. The doctor can calculate the risk by using a formula derived from the Framingham study of cardiovascular disease.

Aspirin is the wonder drug touted in the New York Times but, as usual in medical matters, every situation is different.