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Prescribing information: Plavix (clopidogrel bisulfate)
DESCRIPTION |
CLINICAL PHARMACOLOGY
| CLINICAL STUDIES DESCRIPTION PLAVIX (clopidogrel bisulfate)
is an inhibitor of ADP-induced platelet aggregation acting by direct inhibition
of adenosine diphosphate (ADP) binding to its receptor and of the subsequent
ADP-mediated activation of the glycoprotein GPIIb/IIIa complex. Chemically
it is methyl (+)-(S)- The structural formula is as follows:
Clopidogrel bisulfate is a white to off-white powder. It is practically insoluble in water at neutral pH but freely soluble at pH 1. It also dissolves freely in methanol, dissolves sparingly in methylene chloride, and is practically insoluble in ethyl ether. It has a specific optical rotation of about +56°. PLAVIX for oral administration is provided as pink, round, biconvex, debossed film-coated tablets containing 97.875 mg of clopidogrel bisulfate which is the molar equivalent of 75 mg of clopidogrel base. Each tablet contains hydrogenated castor oil, hydroxypropylcellulose, mannitol, microcrystalline cellulose and polyethylene glycol 6000 as inactive ingredients. The pink film coating contains ferric oxide, hydroxypropyl methylcellulose 2910, lactose monohydrate, titanium dioxide and triacetin. The tablets are polished with Carnauba wax. Mechanism of Action Clopidogrel is an inhibitor of platelet aggregation. A variety of drugs that inhibit platelet function have been shown to decrease morbid events in people with established cardiovascular atherosclerotic disease as evidenced by stroke or transient ischemic attacks, myocardial infarction, unstable angina or the need for vascular bypass or angioplasty. This indicates that platelets participate in the initiation and/or evolution of these events and that inhibiting them can reduce the event rate.Pharmacodynamic Properties Clopidogrel selectively inhibits the binding of adenosine diphosphate (ADP) to its platelet receptor and the subsequent ADP-mediated activation of the glycoprotein GPIIb/IIIa complex, thereby inhibiting platelet aggregation. Biotransformation of clopidogrel is necessary to produce inhibition of platelet aggregation, but an active metabolite responsible for the activity of the drug has not been isolated. Clopidogrel also inhibits platelet aggregation induced by agonists other than ADP by blocking the amplification of platelet activation by released ADP. Clopidogrel does not inhibit phosphodiesterase activity. Clopidogrel acts by irreversibly modifying the platelet ADP receptor. Consequently, platelets exposed to clopidogrel are affected for the remainder of their lifespan. Dose dependent inhibition of platelet aggregation can be seen 2 hours after single oral doses of PLAVIX. Repeated doses of 75 mg PLAVIX per day inhibit ADP-induced platelet aggregation on the first day, and inhibition reaches steady state between Day 3 and Day 7. At steady state, the average inhibition level observed with a dose of 75 mg PLAVIX per day was between 40% and 60%. Platelet aggregation and bleeding time gradually return to baseline values after treatment is discontinued, generally in about 5 days. Pharmacokinetics and Metabolism After repeated 75-mg oral doses of clopidogrel (base), plasma concentrations of the parent compound, which has no platelet inhibiting effect, are very low and are generally below the quantification limit (0.00025 mg/L) beyond 2 hours after dosing. Clopidogrel is extensively metabolized by the liver. The main circulating metabolite is the carboxylic acid derivative, and it too has no effect on platelet aggregation. It represents about 85% of the circulating drug-related compounds in plasma. Following an oral dose of 14C-labeled clopidogrel in humans, approximately 50% was excreted in the urine and approximately 46% in the feces in the 5 days after dosing. The elimination half-life of the main circulating metabolite was 8 hours after single and repeated administration. Covalent binding to platelets accounted for 2% of radiolabel with a half-life of 11 days. Effect of Food: Administration of PLAVIX (clopidogrel bisulfate) with meals did not significantly modify the bioavailability of clopidogrel as assessed by the pharmacokinetics of the main circulating metabolite. Absorption and
Distribution: Clopidogrel is rapidly absorbed after oral administration
of repeated doses of 75 mg clopidogrel (base), with peak plasma levels
( Clopidogrel and the main circulating metabolite bind reversibly in vitro to human plasma proteins (98% and 94%, respectively). The binding is nonsaturable in vitro up to a concentration of 100 µg/mL. Metabolism and Elimination: in vitro and in vivo, clopidogrel undergoes rapid hydrolysis into its carboxylic acid derivative. In plasma and urine, the glucuronide of the carboxylic acid derivative is also observed. Special Populations Geriatric Patients: Plasma concentrations of the main circulating metabolite are significantly higher in elderly (>75 years) compared to young healthy volunteers but these higher plasma levels were not associated with differences in platelet aggregation and bleeding time. No dosage adjustment is needed for the elderly. Renally Impaired Patients: After repeated doses of 75 mg PLAVIX per day, plasma levels of the main circulating metabolite were lower in patients with severe renal impairment (creatinine clearance from 5 to 15 mL/min) compared to subjects with moderate renal impairment (creatinine clearance 30 to 60 mL/min) or healthy subjects. Although inhibition of ADP-induced platelet aggregation was lower (25%) than that observed in healthy volunteers, the prolongation of bleeding time was similar to healthy volunteers receiving 75 mg of PLAVIX per day. Gender: No significant difference was observed in the plasma levels of the main circulating metabolite between males and females. In a small study comparing men and women, less inhibition of ADP-induced platelet aggregation was observed in women, but there was no difference in prolongation of bleeding time. In the large, controlled clinical study (Clopidogrel vs. Aspirin in Patients at Risk of Ischemic Events; CAPRIE), the incidence of clinical outcome events, other adverse clinical events, and abnormal clinical laboratory parameters was similar in men and women. Race: Pharmacokinetic differences due to race have not been studied. The clinical evidence
for the efficacy of PLAVIX is derived from two double-blind trials: the
CAPRIE study (Clopidogrel vs. Aspirin in Patients at Risk of Ischemic
Events), a comparison of PLAVIX to aspirin, and the CURE study (Clopidogrel
in Unstable Angina to Prevent Recurrent Ischemic Events), a comparison
of PLAVIX to placebo, both given in combination with aspirin and other
standard therapy.
As shown in the table, PLAVIX (clopidogrel bisulfate) was associated with a lower incidence of outcome events of every kind. The overall risk reduction (9.8% vs. 10.64%) was 8.7%, P=0.045. Similar results were obtained when all-cause mortality and all-cause strokes were counted instead of vascular mortality and ischemic strokes (risk reduction 6.9%). In patients who survived an on-study stroke or myocardial infarction, the incidence of subsequent events was again lower in the PLAVIX group. The curves showing the overall event rate are shown in Figure 1. The event curves separated early and continued to diverge over the 3-year follow-up period. Figure 1: Fatal or Non-Fatal Vascular Events in the CAPRIE Study
Although the statistical significance favoring PLAVIX over aspirin was marginal (P=0.045), and represents the result of a single trial that has not been replicated, the comparator drug, aspirin, is itself effective (vs. placebo) in reducing cardiovascular events in patients with recent myocardial infarction or stroke. Thus, the difference between PLAVIX and placebo, although not measured directly, is substantial. The CAPRIE trial included a population that was randomized on the basis of 3 entry criteria. The efficacy of PLAVIX relative to aspirin was heterogeneous across these randomized subgroups (P=0.043). It is not clear whether this difference is real or a chance occurrence. Although the CAPRIE trial was not designed to evaluate the relative benefit of PLAVIX over aspirin in the individual patient subgroups, the benefit appeared to be strongest in patients who were enrolled because of peripheral vascular disease (especially those who also had a history of myocardial infarction) and weaker in stroke patients. In patients who were enrolled in the trial on the sole basis of a recent myocardial infarction, PLAVIX was not numerically superior to aspirin. In the meta-analyses of studies of aspirin vs. placebo in patients similar to those in CAPRIE, aspirin was associated with a reduced incidence of atherothrombotic events. There was a suggestion of heterogeneity in these studies too, with the effect strongest in patients with a history of myocardial infarction, weaker in patients with a history of stroke, and not discernible in patients with a history of peripheral vascular disease. With respect to the inferred comparison of PLAVIX to placebo, there is no indication of heterogeneity. The CURE study included
12,562 patients with acute coronary syndrome without ST segment elevation
(unstable angina or non-Q-wave myocardial infarction) and presenting within
24 hours of onset of the most recent episode of chest pain or symptoms
consistent with ischemia. Patients were required to have either ECG changes
compatible with new ischemia (without ST segment elevation) or elevated
cardiac enzymes or troponin I or T to at least twice the upper limit of
normal. The patient population was largely Caucasian (82%) and included
38% women, and 52% patients >65 years of age.
The benefits of PLAVIX were maintained throughout the course of the trial (up to 12 months). Figure 2: Cardiovascular Death, Myocardial Infarction, and Stroke in the CURE Study
In CURE, the use of PLAVIX was associated with a lower incidence of CV death, MI or stroke in patient populations with different characteristics, as shown in Figure 3. The benefits associated with PLAVIX were independent of the use of other acute and long-term cardiovascular therapies, including heparin/LMWH (low molecular weight heparin), IV glycoprotein IIb/IIIa (GPIIb/IIIa) inhibitors, lipid-lowering drugs, beta-blockers, and ACE-inhibitors. The efficacy of PLAVIX was observed independently of the dose of aspirin (75-325 mg once daily). The use of oral anticoagulants, non-study anti-platelet drugs and chronic NSAIDs was not allowed in CURE. Figure 3: Hazard Ratio for Patient Baseline Characteristics and On-Study Concomitant Medications/Interventions for the CURE Study
The use of PLAVIX in CURE was associated with a decrease in the use of thrombolytic therapy (71 patients [1.1%] in the PLAVIX group, 126 patients [2.0%] in the placebo group; relative risk reduction of 43%, P=0.0001), and GPIIb/IIIa inhibitors (369 patients [5.9%] in the PLAVIX group, 454 patients [7.2%] in the placebo group; relative risk reduction of 18%, P=0.003). The use of PLAVIX in CURE did not impact the number of patients treated with CABG or PCI (with or without stenting), (2253 patients [36.0%] in the PLAVIX group, 2324 patients [36.9%] in the placebo group; relative risk reduction of 4.0%, P=0.1658). PLAVIX (clopidogrel bisulfate) is indicated for the reduction of atherothrombotic events as follows:
The use of PLAVIX is contraindicated in the following conditions:
Thrombotic thrombocytopenic purpura (TTP): TTP has been reported rarely following use of PLAVIX, sometimes after a short exposure (<2 weeks). TTP is a serious condition requiring prompt treatment. It is characterized by thrombocytopenia, microangiopathic hemolytic anemia (schistocytes [fragmented RBCs] seen on peripheral smear), neurological findings, renal dysfunction, and fever. TTP was not seen during clopidogrel's clinical trials, which included over 17,500 clopidogrel-treated patients. In world-wide postmarketing experience, however, TTP has been reported at a rate of about four cases per million patients exposed, or about 11 cases per million patient-years. The background rate is thought to be about four cases per million person-years. General As with other antiplatelet agents, PLAVIX prolongs the bleeding time and therefore should be used with caution in patients who may be at risk of increased bleeding from trauma, surgery, or other pathological conditions (particularly gastrointestinal and intraocular). If a patient is to undergo elective surgery and an antiplatelet effect is not desired, PLAVIX should be discontinued 5 days prior to surgery. Due to the risk of bleeding and undesirable hematological effects, blood cell count determination and/or other appropriate testing should be promptly considered, whenever such suspected clinical symptoms arise during the course of treatment (see ADVERSE REACTIONS). GI Bleeding: In CAPRIE, PLAVIX was associated with a rate of gastrointestinal bleeding of 2.0%, vs. 2.7% on aspirin. In CURE, the incidence of major gastrointestinal bleeding was 1.3% vs 0.7% (PLAVIX + aspirin vs placebo + aspirin, respectively.) PLAVIX should be used with caution in patients who have lesions with a propensity to bleed (such as ulcers). Drugs that might induce such lesions should be used with caution in patients taking PLAVIX. Use in Hepatically Impaired Patients: Experience is limited in patients with severe hepatic disease, who may have bleeding diatheses. PLAVIX should be used with caution in this population. Use in Renally Impaired Patients: Experience is limited in patients with severe renal impairment. PLAVIX should be used with caution in this population. Information for Patients Patients should be told that it may take them longer than usual to stop bleeding when they take PLAVIX, and that they should report any unusual bleeding to their physician. Patients should inform physicians and dentists that they are taking PLAVIX before any surgery is scheduled and before any new drug is taken.Drug Interactions Study of specific drug interactions yielded the following results: Aspirin: Aspirin did not modify the clopidogrel-mediated inhibition of ADP-induced platelet aggregation. Concomitant administration of 500 mg of aspirin twice a day for 1 day did not significantly increase the prolongation of bleeding time induced by PLAVIX. PLAVIX potentiated the effect of aspirin on collagen-induced platelet aggregation. PLAVIX and aspirin have been administered together for up to one year. Heparin: In a study in healthy volunteers, PLAVIX did not necessitate modification of the heparin dose or alter the effect of heparin on coagulation. Coadministration of heparin had no effect on inhibition of platelet aggregation induced by PLAVIX. Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): In healthy volunteers receiving naproxen, concomitant administration of PLAVIX was associated with increased occult gastrointestinal blood loss. NSAIDs and PLAVIX should be coadministered with caution. Warfarin: Because of the increased risk of bleeding, the concomitant administration of warfarin with PLAVIX should be undertaken with caution. (See Precautions-General). Other Concomitant Therapy: No clinically significant pharmacodynamic interactions were observed when PLAVIX was coadministered with atenolol, nifedipine, or both atenolol and nifedipine. The pharmacodynamic activity of PLAVIX was also not significantly influenced by the coadministration of phenobarbital, cimetidine or estrogen. The pharmacokinetics of digoxin or theophylline were not modified by the coadministration of PLAVIX (clopidogrel bisulfate). At high concentrations in vitro, clopidogrel inhibits P450 (2C9). Accordingly, PLAVIX may interfere with the metabolism of phenytoin, tamoxifen, tolbutamide, warfarin, torsemide, fluvastatin, and many non-steroidal anti-inflammatory agents, but there are no data with which to predict the magnitude of these interactions. Caution should be used when any of these drugs is coadministered with PLAVIX. In addition to the above specific interaction studies, patients entered into clinical trials with PLAVIX received a variety of concomitant medications including diuretics, beta-blocking agents, angiotensin converting enzyme inhibitors, calcium antagonists, cholesterol lowering agents, coronary vasodilators, antidiabetic agents (including insulin), antiepileptic agents, hormone replacement therapy, heparins (unfractionated and LMWH) and GPIIb/IIIa antagonists without evidence of clinically significant adverse interactions. The use of oral anticoagulants, non-study anti-platelet drug and chronic NSAIDs was not allowed in CURE and there are no data on their concomitant use with clopidogrel. Drug/Laboratory
Test Interactions Carcinogenesis,
Mutagenesis, Impairment of Fertility Clopidogrel was not genotoxic in four in vitro tests (Ames test, DNA-repair test in rat hepatocytes, gene mutation assay in Chinese hamster fibroblasts, and metaphase chromosome analysis of human lymphocytes) and in one in vivo test (micronucleus test by oral route in mice). Clopidogrel was found to have no effect on fertility of male and female rats at oral doses up to 400 mg/kg per day (52 times the recommended human dose on a mg/m2 basis). Pregnancy Nursing
Mothers Pediatric
Use PLAVIX has been evaluated
for safety in more than 17,500 patients, including over 9,000 patients
treated for 1 year or more. The overall tolerability of PLAVIX in CAPRIE
was similar to that of aspirin regardless of age, gender and race, with
an approximately equal incidence (13%) of patients withdrawing from treatment
because of adverse reactions. The clinically important adverse events
observed in CAPRIE and CURE are discussed below. Table 3: CURE
Incidence of bleeding complications
Ninety-two percent
(92%) of the patients in the CURE study received heparin/LMWH, and the
rate of bleeding in these patients was similar to the overall results. Neutropenia/agranulocytosis:
Ticlopidine, a drug chemically similar to PLAVIX, is associated with a
0.8% rate of severe neutropenia (less than 450 neutrophils/µL). In
CAPRIE severe neutropenia was observed in six patients, four on PLAVIX
and two on aspirin. Two of the 9599 patients who received PLAVIX and none
of the 9586 patients who received aspirin had neutrophil counts of zero.
One of the four PLAVIX patients in CAPRIE was receiving cytotoxic chemotherapy,
and another recovered and returned to the trial after only temporarily
interrupting treatment with PLAVIX (clopidogrel bisulfate). In CURE, the
numbers of patients with thrombocytopenia (19 PLAVIX + aspirin vs 24 placebo
+ aspirin) or neutropenia (3 vs 3) were similar. Gastrointestinal:
Overall, the incidence of gastrointestinal events (e.g. abdominal pain,
dyspepsia, gastritis and constipation) in patients receiving PLAVIX (clopidogrel
bisulfate) was 27.1%, compared to 29.8% in those receiving aspirin in
the CAPRIE trial. In the CURE trial the incidence of these gastrointestinal
events for patients receiving PLAVIX + aspirin was 11.7% compared to 12.5%
for those receiving placebo + aspirin. Rash and Other
Skin Disorders: In the CAPRIE trial, the incidence of skin and appendage
disorders in patients receiving PLAVIX was 15.8% (0.7% serious); the corresponding
rate in aspirin patients was 13.1% (0.5% serious). In the CURE trial the
incidence of rash or other skin disorders in patients receiving PLAVIX
+ aspirin was 4.0% compared to 3.5% for those receiving placebo + aspirin.
Adverse events occurring in >2.0% of patients on PLAVIX in the CURE controlled clinical trial are shown below regardless of relationship to PLAVIX. Table 5: Adverse Events Occurring in >2.0% of PLAVIX Patients in CURE
Other adverse experiences of potential importance occurring in 1% to 2.5% of patients receiving PLAVIX (clopidogrel bisulfate) in the CAPRIE or CURE controlled clinical trials are listed below regardless of relationship to PLAVIX. In general, the incidence of these events was similar to that in patients receiving aspirin (in CAPRIE) or placebo + aspirin (in CURE). Autonomic Nervous
System Disorders: Syncope, Palpitation. Body as a Whole-general
disorders: Asthenia, Fever, Hernia. Cardiovascular disorders:
Cardiac failure. Central and peripheral nervous system disorders:
Cramps legs, Hypoaesthesia, Neuralgia, Paraesthesia, Vertigo. Gastrointestinal
system disorders: Constipation, Vomiting. Heart rate and rhythm
disorders: Fibrillation atrial. Liver and biliary system disorders:
Hepatic enzymes increased. Metabolic and nutritional disorders:
Gout, hyperuricemia, non-protein nitrogen (NPN) increased. Musculo-skeletal
system disorders: Arthritis, Arthrosis. Platelet, bleeding &
clotting disorders: GI hemorrhage, hematoma, platelets decreased.
Psychiatric disorders: Anxiety, Insomnia. Red blood cell
disorders: Anemia. Respiratory system disorders: Pneumonia,
Sinusitis. Skin and appendage disorders: Eczema, Skin ulceration.
Urinary system disorders: Cystitis. Vision disorders:
Cataract, Conjunctivitis. Postmarketing
Experience
One case of deliberate overdosage with PLAVIX was reported in the large, CAPRIE controlled clinical study. A 34-year-old woman took a single 1,050-mg dose of PLAVIX (equivalent to 14 standard 75-mg tablets). There were no associated adverse events. No special therapy was instituted, and she recovered without sequelae. No adverse events were reported after single oral administration of 600 mg (equivalent to 8 standard 75-mg tablets) of PLAVIX in healthy volunteers. The bleeding time was prolonged by a factor of 1.7, which is similar to that typically observed with the therapeutic dose of 75 mg of PLAVIX per day. A single oral dose of clopidogrel at 1500 or 2000 mg/kg was lethal to mice and to rats and at 3000 mg/kg to baboons. Symptoms of acute toxicity were vomiting (in baboons), prostration, difficult breathing, and gastrointestinal hemorrhage in all species. Recommendations
About Specific Treatment: Recent MI,
Recent Stroke, or Established Peripheral Arterial Disease Acute Coronary
Syndrome No dosage adjustment is necessary for elderly patients or patients with renal disease. (See CLINICAL PHARMACOLOGY: Special Populations.) PLAVIX (clopidogrel bisulfate) is available as a pink, round, biconvex, film-coated tablet debossed with 75 on one side and 1171 on the other. Tablets are provided as follows: NDC 63653-1171-6 bottles of 30 Storage Distributed by:
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