Pharmacy Author: Omudhome Ogbru, PharmD
Medical Pharmacy Editor: Jay W. Marks, MD

GENERIC NAME: clopidogrel bisulfate

BRAND NAME: Plavix

DRUG CLASS AND MECHANISM: Clopidogrel bisulfate is an anti-platelet drug, that is, a drug that inhibits the ability of platelets to clump together as part of a blood clot. It is similar to ticlopidine (Ticlid) in chemical structure and in the way it works. Unlike ticlopidine, clopidogrel bisulfate does not cause serious reductions of white cells in the blood and, therefore, routine blood testing to determine if the white blood cell count is low is not necessary during treatment.

The risk of heart attacks and strokes (which usually are caused by blood clots) is increased in patients with a recent history of stroke or heart attack and patients with peripheral vascular disease. (Peripheral vascular disease is the same as atherosclerotic arterial disease or "hardening" of the arteries in which the arteries become narrowed. It frequently occurs in the legs and often causes claudication or pain in the legs upon walking). Clopidogrel bisulfate is used to reduce the risk of heart attacks and strokes in these patients. Clopidogrel bisulfate was approved by the FDA in 1997.

GENERIC AVAILABLE: No

PRESCRIPTION: Yes

PREPARATIONS: Tablets: 75mg.

STORAGE: Tablets should be stored at room temperature, 15-30 C (59-86 F).

PRESCRIBED FOR: Clopidogrel is used to prevent strokes and heart attacks in persons who are at high risk. In one large study, clopidogrel bisulfate was more effective than aspirin in reducing heart attacks. The frequency of side effects of clopidogrel bisulfate was similar to aspirin; however, stomach and intestinal bleeding probably occurs less often with clopidogrel bisulfate than with aspirin.

DOSING: Clopidogrel bisulfate usually is taken once daily. It can be taken with or without food.

DRUG INTERACTIONS: The combination of clopidogrel with nonsteroidal antiinflammatory drugs (NSAIDs) such as ibuprofen (Motrin, Advil, Nuprin), naproxen (Naprosyn, Aleve), diclofenac (Voltaren), etodolac (Lodine), nabumetone (Relafen), fenoprofen (Nalfon), flurbiprofen (Ansaid), indomethacin (Indocin), ketoprofen (Orudis; Oruvail), oxaprozin (), piroxicam (Feldene), sulindac (Clinoril), tolmetin (Tolectin), and mefenamic acid (Ponstel) may increase the risk of stomach and intestinal bleeding.

At high concentrations in the blood, clopidogrel inhibits the activity of the enzyme which metabolizes (eliminates) warfarin (Coumadin), a "blood thinner". This could lead to an increase in levels of warfarin and increase the risk of bleeding due to over-thinning of the blood. To date there have been no reports of an important interaction in humans between warfarin and clopidogrel. Nonetheless, because warfarin increases the risk of bleeding, blood tests to measure the degree to which the blood is anti-coagulated or thinned (prothrombin time; INR) may be ordered to assess the degree of blood-thinning when warfarin and clopidogrel are used together. The same enzyme also is responsible for the metabolism of phenytoin (Dilantin), tamoxifen (Nolvadex), tolbutamide (Orinase), torsemide (Demadex), and fluvastatin (Lescol). Although important interactions between clopidogrel and these drugs are unlikely, interactions should be looked for carefully.

Clopidogrel is converted to its active form by enzymes in the liver. Drugs that reduce the activity of these enzymes (for example, omeprazole [Prilosec, Zegerid], esomeprazole [Nexium]) may reduce the activity of clopidogrel and should not be used with clopidogrel. Other drugs that also may react with clopidogrel in a similar fashion include fluoxetine (Prozac, Sarafem), cimetidine (Tagamet), fluconazole (Diflucan), ketoconazole (Nizoral, Extina, Xolegel, Kuric), voriconazole (Vfend), ethaverine (Ethatab, Ethavex), felbamate (Felbatol), and fluvoxamine (Luvox).

PREGNANCY: There are no adequate studies of clopidogrel in pregnant women. Therefore, it can be used in pregnancy if the physician determines that it is needed.

NURSING MOTHERS: Studies in rats have shown that clopidogrel appears in breast milk; however, it is not known whether it also appears in human breast milk. Because of a potential for side effects in the nursing infant, the physician must weigh the potential benefits and possible risks before prescribing clopidogrel in nursing mothers.