Some medications directly treat an illness; others are used to prevent illness or injury. Plavix is an oral medication given to prevent another heart attack or stroke in people who have already had one. Plavix is also prescribed for patients who have unstable angina or poor circulation in the legs because these patients have increased risk for a heart attack or stroke. Plavix is also given to patients before percutaneous coronary intervention, a hospital procedure in which blood vessels in the heart are cleared of blockages and a stent is placed to prevent future blocks.
Plavix's Action In the Blood
Heart attacks and most strokes are caused by a blood clot blocking a blood vessel. Platelets are one of the components of blood that play a role in the normal clotting process. Platelets stick together, or aggregate, to form a platelet plug, the first stage in developing a blood clot. Plavix changes the chemistry of platelets, reducing their ability to aggregate and therefore reducing the likelihood that blood clots will form inside a blood vessel.
Timing Plavix's Effects
Platelets live only about seven days, and new platelets are being made all the time. Even though Plavix's effects begin within two hours of the first dose, it takes from three to seven days to reach maximal effect. After stopping Plavix, it takes seven to 10 days for the blood's clotting ability to go back to normal.
Risks of Plavix
Because Plavix reduces the blood's ability to clot, anyone taking Plavix has an increased risk of bleeding either internally or when cut. Patients may bruise more easily, and even minor breaks in the skin, as with shaving, may take longer than usual to stop bleeding. The risk of increased bleeding is even greater for patients taking other blood-thinning medications, such as aspirin, warfarin or heparin.
Side Effects of Plavix
Other than the risk of bleeding, side effects of Plavix are few. A small number (4 percent to 6 percent) of people on Plavix experience stomach pain, upset stomach, diarrhea or rash. In an extremely rare but dangerous side effect, micro-clots can form blocks throughout all the blood vessels.
Not Effective for Everyone
In March 2010, the FDA issued a warning (see Resources) that Plavix may not be fully effective for a small percentage of the population that is missing a specific enzyme in the liver. A genetic test can indicate whether a person has the enzyme that will activate Plavix. For patients who do not have it, Plavix may not provide enough protection from harmful blood clots.
References
- "Pharmacology for Nursing Care"; Richard A. Lehne, PhD.; 2006
- FDA: Drug Safety Communication
- Mayo Clinic: Clopidogrel
Member Comments