Achy Legs & Grapefruit Juice

Grapefruit and grapefruit products, as well as some other citrus fruits such as pomelos, interact with a number of medications. Because they can increase the amount of medication you absorb, they can also increase the side effects you experience from a drug. Grapefruit interferes with metabolism of many statins, a category of drug used to treat high cholesterol levels. Statins can cause muscle aches and, in some cases, a more severe muscle disorder called rhabdomyolysis.

ACTIONS

Grapefruit contains ingredients that inhibit the action of an enzyme, CYP 3A4. This enzyme breaks down drugs so that some of the drug passes through the body unabsorbed. As a consequence, you absorb more of the medication than you normally would if you drink grapefruit juice and take certain medications. Grapefruit affects only medications metabolized by CYP 3A4. Of the medications affected by grapefruit juice, statin drugs are the drugs most often associated with muscle aches and the possibility of rhabdomyolysis, severe muscle breakdown.

AFFECTED STATINS

Not all statin medications undergo metabolism by CYP 3A4. The statins most affected by grapefruit products include atorvastatin, sold under the brand name Lipitor; lovastatin, sold under the brand name Mevacor; and simvastatin, sold under the brand name Zocor. Pravastatin, sold as Pravochol; fluvastatin, sold as Lescol; and rosuvastatin, sold as Crestor, are metabolized by different pathways and don't have the same risk.

RISKS

Muscle aches are annoying but not dangerous. However, in some cases, a serious disorder called rhabdomyolysis can develop in anyone taking statin drugs, especially if you take more than one statin drug or take other medications, including the immunosuppressant cyclosporine or gemfibrozil, sold as Lopid, another cholesterol-lowering agent. Signs of rhabdomyolysis include severe muscle aching and muscle weakness. Your urine may turn dark and urine production may decrease. Rhabdomyolysis can cause severe and sometimes permanent kidney damage. Seek medical attention immediately if you develop these symptoms while taking any statin drug, even if you haven't consumed any grapefruit.

TIMING

Grapefruit can interfere with statins and some other medications for as long as 72 hours, pharmacist Amy Stump of the University of Alabama School of Medicine warns in the August issue of "American Family Physician." CYP 3A4 levels in the intestine may decrease by as much as 47 percent within four hours of grapefruit consumption. Because of the long effect, simply consuming grapefruit products at a different time than your statin drug may not lessen the risks. Avoid grapefruit products altogether if you take statins; discuss the possible effects with your doctor.