Clopidogrel Bisulfate: uses, dosing, side effects & brands

Plavix (Clopidogrel Bisulfate) is a p2y12 platelet inhibitor.

The FDA classifies clopidogrel bisulfate as a p2y12 platelet inhibitor. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.

The elimination half-life of clopidogrel bisulfate is about 6 hours — that is how long the body takes to clear half of a dose. Clopidogrel is a prodrug, and its half-life says little about how long it works. The active metabolite that actually blocks platelets has an even shorter half-life — about 30 minutes — but it binds the platelet P2Y12 receptor irreversibly, so every platelet it touches stays blocked for the rest of that platelet's life (roughly 7 to 10 days). The label states platelet aggregation and bleeding time return to baseline generally about 5 days after the last dose, which is the number that matters before surgery, not the 6-hour half-life. The label reports these half-lives after a single 75 mg dose and does not give separate half-life values for older adults or for kidney or liver impairment; it does note that people with moderate to severe renal impairment show markedly less platelet inhibition (about 25%), while severe hepatic impairment gave inhibition similar to healthy subjects. Clopidogrel is sold only as immediate-release tablets in the US — there is no extended-release form. CYP2C19 poor metabolizers form less active metabolite and get less platelet inhibition. Half-life is not the same as how long a drug test can detect the drug, and it varies with age, kidney and liver function.

It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run clopidogrel bisulfate against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.

We track 2 clopidogrel bisulfate-containing products in the U.S.: Plavix and Clopidogrel Bisulfate. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.

Across the brands we track, clopidogrel bisulfate is currently marketed as tablet, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.

Yes. Our catalog lists 1 generic clopidogrel bisulfate product alongside the brand versions. A generic has the same active ingredient and must meet the FDA's bioequivalence standard; it usually costs less. Ask your pharmacist which one your plan covers.

In the everyday sense, yes — clopidogrel is an antiplatelet, one of the two main kinds of 'blood thinner.' It keeps platelets from clumping (unlike anticoagulants such as warfarin or apixaban, which act on clotting factors). It is used to prevent clots after stents and certain heart events; do not stop it without medical advice.

Bleeding, and a rare blood disorder called thrombotic thrombocytopenic purpura. (This answers for clopidogrel 75 mg film-coated tablets, sold as Plavix and as generics — the form almost everyone means.) Clopidogrel keeps platelets from clumping, so cuts bleed longer and internal bleeding is possible: watch for bleeding that won't stop, unusual bruising, red, pink or brown urine, red or black tarry stools, vomiting blood or coffee-ground material, or a sudden severe headache or weakness. TTP is listed in the label's warnings and is a medical emergency — it can cause low platelets, anemia with fatigue and paleness, fever, confusion or other neurological changes, and small purple or red skin spots. Get emergency care rather than waiting for a routine appointment. The label also warns about cross-reactivity among thienopyridines, so a past reaction to ticlopidine or prasugrel matters here.

Because in some people the drug barely works. Clopidogrel is a prodrug: it only becomes active after the body's cytochrome P450 system, principally the enzyme CYP2C19, converts it. People who carry two nonfunctional copies of the CYP2C19 gene — 'CYP2C19 poor metabolizers' — form less of the active metabolite at normal doses and get a reduced effect on platelet activity, which means less protection against heart attack and stent thrombosis than they and their doctor believe they are getting. The boxed warning states that tests are available to identify poor metabolizers, and that another platelet P2Y12 inhibitor should be considered in anyone identified as one. The label gives the prevalence: approximately 2 percent of White and 4 percent of Black patients are poor metabolizers, and it is higher in Asian patients — for example 14 percent of Chinese patients. If you have had a stent thrombosis or a repeat event while taking clopidogrel faithfully, ask about CYP2C19 testing.

Two contraindications on the label, meaning do not use rather than use with care. First, active pathological bleeding, such as a bleeding peptic ulcer or intracranial hemorrhage. Second, hypersensitivity — for example anaphylaxis — to clopidogrel or to any component of the product. Beyond those, a history of reaction to another thienopyridine such as ticlopidine or prasugrel should be raised with your prescriber, because the label warns about cross-reactivity among thienopyridines.

Omeprazole and esomeprazole, most importantly. The label says to avoid concomitant use of Plavix with omeprazole or esomeprazole because both significantly reduce clopidogrel's antiplatelet activity — they inhibit CYP2C19, the enzyme that activates the drug, producing the same blunted effect the boxed warning describes for poor metabolizers. This matters because these two are sold over the counter for heartburn, so people start them without telling anyone. If you need stomach acid protection while on clopidogrel, ask your prescriber which acid-reducing option to use instead. Also tell your prescriber about NSAIDs, anticoagulants and other antiplatelet drugs, which add to bleeding risk.

Only when your prescriber says so, and the timing is specific. The label warns that discontinuing Plavix increases the risk of cardiovascular events, so stopping it early — especially in the months after a stent — can cause the exact heart attack or stent thrombosis it was prescribed to prevent. When surgery requires stopping it, the label says to interrupt therapy for five days before the surgery where possible, and to resume as soon as hemostasis is achieved. Tell the surgeon, dentist and anesthesiologist you take clopidogrel well before the procedure date, and have the cardiologist who prescribed it weigh in rather than letting the proceduralist decide alone.