Comparison of the antiplatelet effect of two clopidogrel bisulfate formulations: Plavix and generic-Egitromb

Are Generic Drugs Used in Cardiology as Effective and Safe as their Brand-name Counterparts? A Systematic Review and Meta-analysis

BACKGROUND

Previous systematic reviews (2008; 2016) concluded similarity in outcomes between brand-name and generic drugs in cardiology, but they included ≥ 50% comparative bioavailability studies, not designed or powered to detect a difference in efficacy or safety between drug types. We aimed to summarise best-evidence regarding the effectiveness and safety of generic versus brand-name drugs used in cardiology.

METHODS

For this systematic review of the literature, scientific databases (MEDLINE and EMBASE) were searched from January 1984 to October 2018. Original research reports comparing the clinical impact of brand-name versus generic cardiovascular drugs on humans treated in a real-life setting, were selected. Meta-analyses and subgroup analyses were performed. Heterogeneity (I²) and risk of bias were tested.

RESULTS

Among the 3148 screened abstracts, 72 met the inclusion criteria (n ≥ 1,000,000 patients, mean age 65 ± 10 years; 42% women). A total of 60% of studies showed no difference between drug types, while 26% concluded that the brand-name drug was more effective or safe, 13% were inconclusive and only 1% concluded that generics did better. The overall crude risk ratio of all-cause hospital visits for generic versus brand-name drug was 1.14 (95% confidence interval: 1.06-1.23; I²: 98%), while it was 1.05 (0.98-1.14; I²: 68%) for cardiovascular hospital visits. The crude risk ratio was not statistically significant for randomised controlled trials only (n = 4; 0.92 [0.63-1.34], I²: 35%).

CONCLUSION

The crude risk of hospital visits was higher for patients exposed to generic compared to brand-name cardiovascular drugs. However, the evidence is insufficient and too heterogeneous to draw any firm conclusion regarding the effectiveness and safety of generic drugs in cardiology.

Platelet reactivity patterns in patients treated with dual antiplatelet therapy

AIM

The aim of the present study was to investigate the patterns of platelet reactivity and discriminators of therapeutic response to dual antiplatelet therapy (DAPT) with aspirin and ticagrelor or prasugrel in patients with acute coronary syndrome (ACS).

DESIGN

In this multicentre prospective observational study, 492 patients with ACS were enrolled. Platelet aggregation was determined by multiple electrode aggregometry after stimulation with adenosine diphosphate (ADP) or arachidonic acid (AA) as agonists in the maintenance phase of treatment with prasugrel or ticagrelor.

RESULTS

Age emerged as the strongest variable influencing aspirin response status: The mean AA-induced platelet aggregation in patients <49 years of age was 49% higher than in those >49 years (13.1 U vs 8.8 U; P = 0.011). The second strongest discriminator of aspirin response was sex: Male patients had a 40% higher AA-induced platelet aggregation values than female patients (9.5 U vs 6.8 U; P = 0.026). Platelet count emerged as the only variable influencing ADP antagonists response status showing that patients with platelet count >320 g/L displayed higher ADP-induced platelet aggregation. About 12% of patients had high on-treatment platelet reactivity (HTPR) to aspirin, 3% and 4% a HTPR to prasugrel and ticagrelor, respectively, and only 2% displayed HTPR to dual antiplatelet therapy.

CONCLUSION

When potent platelet inhibitors as prasugrel and ticagrelor are administered with aspirin, HTPR to DAPT plays only a marginal role.

Did Generic Clopidogrel Commercialization Affect Trends of ER Consultations and Hospitalizations in the Population Treated with Clopidogrel?

BACKGROUND

Clopidogrel has been widely used to prevent atherothrombotic events. Since 2011, pharmacists have offered their patients the opportunity to switch to generic clopidogrel, an economic alternative. Whether bioequivalence of generic cardiovascular drugs translates into clinical equivalence at a population level remains unclear and needs to be further documented.

OBJECTIVE

We aimed to evaluate the impact of generic clopidogrel commercialization on adverse events (AEs): hospitalizations or emergency room (ER) consultations.

METHODS

This is an interrupted time series analysis using the Quebec Integrated Chronic Disease Surveillance System. We included all patients ≥ 66 years old who were users of the brand-name clopidogrel or a generic version (n = 6) 24 months before and up to 12 months after generics commercialization. Rates of AEs were computed, and periods before and after generics commercialization were analyzed by segmented regression models along with exploratory analyses (generic vs. brand name). Sensitivity analyses were also performed using stratification of the time series by (1) sex, (2) the number of prevalent cardiovascular comorbidities, and (3) socioeconomic status.

RESULTS

Time series were constituted of 89,525 clopidogrel users (mean age 78 years, 45% women, 71% ischemic heart disease, 34% stroke). For all users, there was a mean rate of 157 AEs per 1000 user-months, stable trend before (-0.1% [95% confidence interval -0.3 to 0.1] and after (0.0% [- 0.5 to 0.6]) generics commercialization. In exploratory analyses, once generic clopidogrel versions were commercialized, rates of AEs were 19.2% (95% CI 11.7-26.7) higher for generic versus brand-name users. This difference persisted up to 1 year. Sensitivity analyses yielded similar results.

CONCLUSIONS

The population treated with clopidogrel had similar rates of hospitalizations or ER consultations before and after generics commercialization. However, differences in rates of hospitalizations or ER consultations between generic and brand-name clopidogrel users may represent a drug safety signal which remains to be validated. Using a different study design, permitting adjustment for potential confounders, could be useful in this regard.

Mortality and adverse events with brand and generic clopidogrel in the US Food and Drug Administration Adverse Event Reporting System

Aims

Clopidogrel is commonly used even after expiring patents. The brand clopidogrel (BC) was dealt by single company, while numerous manufacturers produce generic clopidogrel (GC). There are no convincing data to compare the safety of different formulations. Therefore, the data yielded from international, uniform, government-mandated registries may be useful.

Methods and results

We assessed primary causative adverse events (PCAE) after BC and GC in the US Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS). The outcomes were divided into death, cardiac, thrombotic/embolic, haemorrhagic, and rash/dermal complications. These primary endpoints were then examined by proportional reporting ratios (PRR) and chi-square (χ2). Among total FAERS (n = 9 466 679) reports, overall BC (n = 88 863) cases were more common than after GC (n = 36 559). When triaged by PCAE role, BC (n = 18 328) was also more abundant than GC (n = 3987). The reported death rates were more than doubled after BC [18.4% vs. 7.0%; PRR = 0.38; 95% confidence interval (95% CI) 0.32–0.43; χ2=369.7; P<0.0001] for total FAERS, and consistent for late 2010–2017 (17.6% vs. 7.0% PRR = 0.40; 95% CI 0.37–0.45; χ2=286.2; P<0.004) PCAE cases. In contrast, GC trended to co-report more cardiac (14.6% vs. 13.3%; PRR = 1.12; 95% CI 1.0–1.25; χ2=3.5; P<0.06). The haemorrhagic (40.9% vs. 32.3%; PRR = 1.45; 95% CI 1.33–1.57; χ2=75.8; P<0.0001), and rash/dermal (5.4% vs. 4.6%; PRR = 1.20; 95% CI 1.0–1.44; χ2=3.75; P<0.05) events were also more common for GC. Thrombotic/embolic events were reported equally (at 7.0%) after each formulation.

Conclusion

The PCAE profiles differ with BC and GC in FAERS. While deaths reports were higher, the rates of cardiac, haemorrhagic, and skin complications were less common for BC. Despite expected reporting bias, this may indicate that the manufacturers of GC are reluctant to report deaths to the FDA. However, the overall adverse event profile suggests potentially better safety of BC over GC formulations.

How to improve the concept of individualised antiplatelet therapy with P2Y12 receptor inhibitors – is an algorithm the answer?

Within the past decade, high on-treatment platelet reactivity (HTPR) on clopidogrel and its clinical implications have been frequently discussed. Although it has been previously assumed that HTPR is a phenomenon occurring only in patients treated with clopidogrel, recent data show that HTPR might also occur during treatment with prasugrel or ticagrelor in the acute phase of ST-elevation myocardial infarction. Moreover, it has been postulated that there is a therapeutic window for P2Y12 receptor blockers, thus indicating that HTPR is associated with thrombotic events whereas low on-treatment platelet reactivity (LTPR) is associated with bleeding events. The current paper focuses on tools to identify risk factors for HTPR (pharmacogenomic testing, clinical scoring and drug-drug interactions) and on the use of platelet function testing in order to identify patients who might not respond adequately to clopidogrel. The majority of recent clinical randomised trials have not supported the hypothesis that platelet function testing and tailored antiplatelet therapy are providing a favourable clinical outcome. These trials, mainly performed in low-to-moderate risk patients, will be reviewed and discussed. Finally, an algorithm based on current knowledge is suggested, which might be of use for design of clinical trials.

Cell-derived microvesicles in cardiovascular diseases and antiplatelet therapy monitoring - A lesson for future trials? Current evidence, recent progresses and perspectives of clinical application

Circulating cell-derived microvesicles (MV) represent a subject of increasing interest in recent years as potential effectors in thrombosis, inflammation and vascular injury. Although several studies demonstrated an association between MV plasma concentrations and clinical manifestations of atherosclerosis as well as a clear effect of cardiovascular pharmacotherapy on MV formation pattern, the application of this promising biomarkers in clinical cardiology has been hindered so far due to heterogeneity of the hitherto studies employing non-standardized methodologies. Recently great progresses have been done and international initiatives were started to unify the pre-analytical and analytical procedures, improve the comparison of measurements between the laboratories and increase detector sensitivity of flow cytometry - a golden standard for MV assessment. Likewise, the concept of a "therapeutic window" of P2Y12 inhibitor therapy was introduced, as the prognostic significance of bleeding consequences is equally important with that of ischemic events, particularly with the expanding use of more potent P2Y12 inhibitors. In this review we summarize currently available studies on circulating MV in terms of cardiovascular diagnosis, risk stratification and influence of antiplatelet agents on the MV release to postulate possible future role of MV as supplementary biomarker in monitoring of individual response to antiplatelet therapy. Methodological pitfalls faced in the previous studies and obstacles that need to be addressed before further trials and translation of MV-based assays into clinical practice were defined.

Abciximab as a bridging strategy to overcome morphine-prasugrel interaction in STEMI patients

OBJECTIVE

The present study investigated whether the glycoprotein (GP)IIb/IIIa receptor blocker abciximab might be a successful bridging strategy to achieve adequate levels of platelet inhibition rapidly in cases where prasugrel is used in morphine-pretreated ST-elevation myocardial infarction (STEMI) patients.

METHODS

In a prospective observational cohort study, 32 patients presenting with STEMI were given prasugrel at a loading dose of 60 mg. Patients were stratified into four groups, according to morphine and/or abciximab use. Adenosine diphosphate (ADP)-induced platelet aggregation was measured at four time points: at baseline, and at 2 h, 1 day and 2 days after prasugrel loading.

RESULTS

Morphine use was associated with a three-fold higher level of ADP-induced platelet aggregation 2 h after prasugrel loading compared with no morphine/no abciximab (P = 0.019). However, when abciximab was infused in the catheterization laboratory, the effect of morphine on ADP-induced platelet aggregation disappeared (P = 0.884). This interaction was also seen in the presence of high on-treatment platelet reactivity (HTPR) at 2 h; while HTPR was seen in 88% of morphine users/no abciximab users, it was found in only 17-20% in the three other groups (P = 0.003). The effect of morphine disappeared by day 1 - 2.

CONCLUSION

The infusion of the GPIIb/IIIa receptor blocker abciximab allows immediate and efficient platelet inhibition in STEMI patients concomitantly receiving the oral ADP receptor blocker prasugrel and morphine.

Generic versus brand-name drugs used in cardiovascular diseases

This meta-analysis aimed to compare the efficacy and adverse events, either serious or mild/moderate, of all generic versus brand-name cardiovascular medicines. We searched randomized trials in MEDLINE, Scopus, EMBASE, Cochrane Controlled Clinical Trial Register, and ClinicalTrials.gov (last update December 1, 2014). Attempts were made to contact the investigators of all potentially eligible trials. Two investigators independently extracted and analyzed soft (including systolic blood pressure, LDL cholesterol, and others) and hard efficacy outcomes (including major cardiovascular adverse events and death), minor/moderate and serious adverse events. We included 74 randomized trials; 53 reported ≥1 efficacy outcome (overall sample 3051), 32 measured mild/moderate adverse events (n = 2407), and 51 evaluated serious adverse events (n = 2892). We included trials assessing ACE inhibitors (n = 12), anticoagulants (n = 5), antiplatelet agents (n = 17), beta-blockers (n = 11), calcium channel blockers (n = 7); diuretics (n = 13); statins (n = 6); and others (n = 3). For both soft and hard efficacy outcomes, 100 % of the trials showed non-significant differences between generic and brand-name drugs. The aggregate effect size was 0.01 (95 % CI -0.05; 0.08) for soft outcomes; -0.06 (-0.71; 0.59) for hard outcomes. All but two trials showed non-significant differences in mild/moderate adverse events, and aggregate effect size was 0.07 (-0.06; 0.20). Comparable results were observed for each drug class and in each stratified meta-analysis. Overall, 8 serious possibly drug-related adverse events were reported: 5/2074 subjects on generics; 3/2076 subjects on brand-name drugs (OR 1.69; 95 % CI 0.40-7.20). This meta-analysis strengthens the evidence for clinical equivalence between brand-name and generic cardiovascular drugs. Physicians could be reassured about prescribing generic cardiovascular drugs, and health care organization about endorsing their wider use.

Personalized antiplatelet therapy with P2Y12 receptor inhibitors: benefits and pitfalls

Antiplatelet therapy with P2Y₁₂ receptor inhibitors has become the cornerstone of medical treatment in patients with acute coronary syndrome, after percutaneous coronary intervention and in secondary prevention of atherothrombotic events. Clopidogrel used to be the most broadly prescribed P2Y₁₂ receptor inhibitor with undisputable benefits especially in combination with aspirin, but a considerable number of clopidogrel-treated patients experience adverse thrombotic events in whom insufficient P2Y₁₂-inhibition and a consequential high on-treatment platelet reactivity is a common finding. This clinically relevant limitation of clopidogrel has driven the increased use of new antiplatelet agents. Prasugrel (a third generation thienopyridine) and ticagrelor (a cyclopentyl-triazolo-pyrimidine) feature more potent and predictable P2Y₁₂-inhibition compared to clopidogrel, which translates into improved ischemic outcomes. However, excessive platelet inhibition and consequential low on-treatment platelet reactivity comes at the price of increased risk of major bleeding. The majority of randomized clinical trials failed to demonstrate improved clinical outcomes with platelet function testing and tailored antiplatelet therapy, but results of all recent trials of potent antiplatelets and prolonged antiplatelet durations point towards a need for individualized antiplatelet approach in order to decrease thrombotic events without increasing bleeding. This review focuses on potential strategies for personalizing antiplatelet treatment.

Switching from generic to brand clopidogrel in male patients after ST-elevated myocardial infarction

OBJECTIVE

To detect residual platelet aggregation following the switch from generic (GC) to brand clopidogrel (BC) in male patients after ST-elevated myocardial infarction (STEMI).

METHODS

The study was designed as an open-label, prospective cohort trial. Thirty-three male STEMI patients were enrolled. All patients received dual antiplatelet therapy with aspirin (100 mg/daily) and one of six GC at a daily dose of 75 mg. After 2 weeks, all patients were switched to BC. Adrenaline- and adenosine diphosphate (ADP)-induced platelet aggregation was assessed twice: on day 14 (before the switch) and on day 21 (after 1 week of BC therapy).

RESULTS

Adrenaline-induced platelet aggregation did not differ among clopidogrel formulations. In contrast, residual 5 µM ADP-induced platelet aggregation after BC differs from GC by 14% (28.0 ± 2.5 vs. 23.9 ± 2.1%; p = 0.03). When 20 µM ADP was used as agonist, the difference was smaller (36.2 ± 2.9 vs. 34.6 ± 2.8%) but still significant (p = 0.04) favoring BC.

CONCLUSIONS

After 2 weeks of therapy, switching from GC to BC was associated with a mild but significant reduction in ADP-induced platelet aggregation in male post-STEMI patients. The observed differences between GC and BC should be confirmed in a larger randomized study, but may represent a risk in underdeveloped countries, where GC therapy is mandatory for post-MI inpatients.