The role of clopidogrel in the management of acute coronary syndromes

Point-of-care measurements of platelet inhibition after clopidogrel loading in patients with acute coronary syndrome: comparison of generic and branded clopidogrel bisulfate

PURPOSE

Platelet-function suppression with antiplatelet therapy is effective in preventing and treating cardiovascular disease. Clopidogrel is a thienopyridine derivative that blocks platelet activation by adenosine diphosphate receptor binding. This study demonstrates the effects of generic clopidogrel bisulfate in comparison to branded clopidogrel bisulfate in patients with acute coronary syndromes.

METHODS

This prospective, 2-arm, single-center, open-label trial used 1:1 randomization to assign patients to receive generic or branded clopidogrel bisulfate. Patients with unstable angina or non-ST-segment elevation myocardial infarction and scheduled to undergo coronary angiography were enrolled. Platelet function was measured with a P2Y12 assay and reported in P2Y12 reaction units (PRU) and aspirin reaction units (ARU) after randomization. Platelet function was measured at 2, 4, 8, and 24 hours after 600-mg clopidogrel loading. The clinical outcome was checked at 1 month after coronary angiography.

FINDINGS

Ninety-five patients were enrolled and randomized to the generic or branded group. Ninety patients (62 men [69%], 28 women [31%]; mean age, 58 years) completed the study protocol. The clinical characteristics were similar between the 2 groups. The difference in the baseline PRU measurements between the generic and branded groups was not significant (274.8 [59.7] vs 285.4 [62.4], respectively; P = 0.414). There were significant differences in 2-hour PRU (231.1 [71.3] vs 266.9 [67.4]; P = 0.017) and 4-hour PRU (227.3 [80.4] vs 265.7 [71.0]; P = 0.020); however, 24-hour PRU (200.5 [82.1] vs 220.6 [75.8]; P = 0.253) was similar. No death, myocardial infarction, target lesion revascularization, stent thrombosis, or Thrombolysis in Myocardial Infarction-defined major bleeding complications were reported during in-hospital stay or 1-month follow-up.

IMPLICATION

In patients with ACS, loading of generic clopidogrel bisulfate was associated with an antiplatelet effect comparable to that of branded clopidogrel bisulfate. ClinicalTrials.gov identifier: NCT02060786.

Impact of antiplatelet treatment on colorectal cancer staging characteristics

AIM: To evaluate whether antiplatelet medication leads to an earlier stage colorectal cancer (CRC) diagnosis.

METHODS: From January 2002 until March 2010, patients that presented to our institution with the initial diagnosis of CRC and were submitted to an open curative CRC resection or a palliative procedure were retrospectively reviewed. Exclusion criteria were the use of antithrombotic medication, i.e., coumarins, and appendiceal malignancies. Data acquired from medical files included age, gender, past medical history, antithrombotic treatment received prior to endoscopic diagnosis, preoperative imaging staging, location of the tumor, surgical and final histopathological report. Patients that did not receive any antithrombotic medication prior to the endoscopic diagnosis comprised the control group of the study, while patients that were on antiplatelet medication comprised the antiplatelet group. Primary end point was a comparison of CRC stage in the two groups of the study. CRC presenting symptoms and the incidence of each cancer stage in the two groups were also evaluated.

RESULTS: A total of 387 patients with the diagnosis of CRC were submitted to our department for further surgical treatment. Ninety-eight patients (25.32%), with a median age of 71 years (range 52-91 years), were included in the antiplatelet group, while 289 (74.67%) patients, with a median age of 67 years (range 41-90 years), were not in any thrombosis prophylaxis medication (control group). Thirty-one patients were treated with some kind of palliative procedure, either endoscopic, such as endoscopic stent placement, or surgical, such as de-compressive colostomy or deviation. Coronary disease (77.55% - 76 patients), stroke recurrence prevention (14.28% - 14 patients) and peripheral arterial disease (8.16% - 8 patients) were the indications for the administration of antiplatelet treatment (aspirin, clopidogrel, ticlopidine or dipyridamole) in the antiplatelet group. All patients on aspirin treatment received a dosage of 100 mg/d, while the minimum prophylactic dosages were also used for the rest of the antiplatelet drugs. Investigation of an iron deficiency anemia (147 patients), per rectum blood loss (84 patients), bowel obstruction and/or perforation (81 patients), bowel habits alterations (32 patients), non-specific symptoms, such as weight loss, intermittent abdominal pain and fatigue, (22 patients) or population screening (21 patients) were the indications for the endoscopic investigation in both groups. Bleeding, either chronic presenting as anemia or acute was significantly higher (P = 0.002) for the antiplatelet arm of the study (71 patients - 72.4% of the antiplatelet group vs 160 patients - 55.3% of the control group). The mean tumor, node and metastasis stage was 2.57 ± 0.96 for the control group, 2.27 ± 0.93 for the antiplatelet group (P = 0.007) and 2.19 ± 0.92 for the subgroup of patients taking aspirin (P = 0.003). The incidence of advanced disease (stage IV) was lower for the antiplatelet group of the study (P = 0.033).

CONCLUSION: The adverse effect of bleeding that is justifiably attached to this drug category seems to have a favorable impact on the staging characteristics of CRC.

Antithrombotic Therapy in Atrial Fibrillation

Warfarin is highly effective at reducing the risk of stroke in atrial fibrillation. The benefit of oral anticoagulant therapy strongly outweighs the risk in most patients with atrial fibrillation. More data are needed to define better the overall risk-to-benefit ratio for patients age 80 years and greater. Because a significant proportion of elderly individuals may not be optimal candidates for anticoagulant therapy, alternative stroke prevention strategies must continue to be evaluated while redoubling efforts to understand the mechanisms underlying atrial fibrillation and thrombogenesis.

Quantification of clopidogrel in human plasma by sensitive liquid chromatography/tandem mass spectrometry

A simple, sensitive and rapid high-performance liquid chromatography/positive electrospray ionization tandem mass spectrometry method was developed and validated for the assay of clopidogrel in human plasma. Following liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase column and analyzed by mass spectrometry in the multiple reaction monitoring mode using the respective [M+H](+) ions, m/z 322/212 for clopidogrel and m/z 264/154 for the internal standard. The assay exhibited a linear dynamic range of 5-6000 pg/mL for clopidogrel in human plasma. The lower limit of quantification was 5 pg/mL with a relative standard deviation of less than 8%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.5 min for each sample made it possible to analyze more than 400 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies.