Clopidogrel

Impact of selected genetic factors on clopidogrel inactive metabolite level and antiplatelet response in patients after percutaneous coronary intervention

BACKGROUND AND OBJECTIVE

Clopidogrel is frequently used as part of optimal dual antiplatelet therapy in high-bleeding risk patients with the acute coronary syndrome. The concentration of the inactive carboxylic acid metabolite of clopidogrel might be useful to evaluate the response to clopidogrel therapy. Therefore, we sought to correlate the inhibition of platelet aggregation with the plasma level of the inactive metabolite of clopidogrel in patients after percutaneous coronary interventions (PCI) and their associations with the most frequently studied genetic polymorphisms. For this purpose, the fast and simple HPLC method for determining the concentration of the inactive metabolite was developed.

METHODS

The effect of CYP2C19, CYP3A4/5, ABCB1 and PON1 genes on the plasma inactive metabolite concentration of clopidogrel and the platelet aggregation was investigated in 155 patients before and after PCI.

RESULTS

The concentration of the inactive metabolite of clopidogrel was not significantly different in the intermediate metabolizers (IM) of CYP2C19 compared with extensive metabolizers (EM) both before and after PCI, while inhibition of platelet aggregation was found to be significantly better in EM than in IM. The presence of the A allele at position 2677 in the ABCB1 gene was associated with a significantly lower concentration of inactive metabolite of clopidogrel before PCI.

CONCLUSION

The CYP2C19*2 allele was associated with decreased platelet reactivity during clopidogrel therapy before and after PCI. Simultaneous determination of platelet aggregation and concentration of the inactive clopidogrel metabolite may be useful in clinical practice to find the cause of adverse effects or insufficient treatment effect in patients chronically treated with clopidogrel.

The influence of clopidogrel on ischemia diagnosed by myocardial perfusion stress testing

BACKGROUND

Clopidogrel is a platelet adenosine receptor antagonist which can influence coronary vascular tone and thus can potentially interfere with myocardial perfusion imaging. We investigated whether clopidogrel can hamper the diagnosis of ischemia in patients undergoing myocardial perfusion testing.

METHODS

Data from a database of 6349 myocardial perfusion stress tests were analyzed. Using a propensity analysis, patients who were taking clopidogrel were compared with patients not taking clopidogrel for the presence of reversible perfusion defects on myocardial single-photon emission computed tomography scans.

RESULTS

Of the 6349 tests, the stress technique was adenosine in 2713 patients and exercise in 3636. At the time of the stress test, 277 (4.3%) of the patients were taking clopidogrel. The odds ratio (OR) for patients taking clopidogrel to have a reversible perfusion defect was 2.75 (95% confidence interval [CI] 2.09-3.62; P < .01). After adjusting for the propensity to take clopidogrel, the OR was 1.06 (CI 0.76-1.49; P = .73) for patients undergoing adenosine stress tests and 1.60 (CI 0.85-3.00; P = .14) for patients undergoing exercise stress tests.

CONCLUSIONS

We found no evidence that the use of clopidogrel decreases the likelihood of ischemia on adenosine or exercise stress myocardial perfusion scans.

Ticagrelor: a review of its use in adults with acute coronary syndromes

Ticagrelor (Brilique™, Brilinta®), a cyclopentyl-triazolopyrimidine, is an orally active, reversible, and selective adenosine diphosphate (ADP) receptor antagonist indicated for use in patients with acute coronary syndromes (ACS). Ticagrelor has a faster onset of action and provides greater inhibition of platelet aggregation than clopidogrel. In the large well-designed, PLATO study in adult patients with ACS, 12 months' treatment with ticagrelor was more effective than clopidogrel in reducing the incidence of the primary composite endpoint of myocardial infarction, stroke, or cardiovascular (CV) death. Ticagrelor also reduced all-cause mortality relative to clopidogrel, although statistical significance of this was not confirmed in hierarchical testing. Benefit with ticagrelor was seen both in invasively and noninvasively managed patients. Ticagrelor was generally well tolerated and was not associated with an increased risk of major bleeding relative to clopidogrel. However, the incidences of non-coronary artery bypass grafting (CABG)-related bleeding, and major or minor bleeding, as well as some non-hemorrhagic adverse events, including dyspnea (usually of mild or moderate severity) and ventricular pauses (largely asymptomatic) were higher with ticagrelor. In addition, the ATLANTIC study showed that although pre-hospital administration of ticagrelor did not improve pre-percutaneous coronary intervention (PCI) coronary reperfusion in ACS patients relative to in-hospital administration, ticagrelor was safe in both instances, with no significant between-group differences in non-CABG-related major and minor bleeding events. Although further comparative studies with other antiplatelet agents, including prasugrel, are required to position it more definitively, current evidence indicates that ticagrelor is a useful option for the prevention of thrombotic CV events in ACS patients managed invasively or noninvasively.

A randomized, double-blind, placebo-controlled study of rebamipide for gastric mucosal injury taking aspirin with or without clopidogrel

INTRODUCTION

Antithrombotic drugs, such as low-dose aspirin (LDA) and clopidogrel, can cause upper gastrointestinal complications.

AIM

The goal of the present study was to investigate whether a mucosal-protective agent, rebamipide, could prevent gastric mucosal injuries induced by LDA with or without clopidogrel in healthy subjects.

MATERIALS AND METHODS

A randomized, double-blind, placebo-controlled trial was performed with 32 healthy male volunteers. Subjects were randomly assigned to a 14-day course of one of the following regimens: group A, placebo (tid) + LDA; group B, rebamipide (100 mg tid) + LDA (100 mg once-daily); group C, placebo + LDA + clopidogrel (75 mg once-daily); or group D, rebamipide + LDA + clopidogrel. The grade of gastric mucosal injuries was evaluated by esophagogastroduodenoscopy before and after dosing (on day 0 and day 14), and the grade of gastric mucosal injury was assessed according to the modified Lanza score. Subjective symptoms were assessed using the Gastrointestinal Symptom Rating Scale (GSRS). A rapid urease test was performed on day 0, and blood tests were performed on day 0 and day 14.

RESULTS

Rebamipide significantly inhibited gastric mucosal injury induced by LDA alone or by LDA plus clopidogrel when compared with placebo in healthy subjects. GSRS score and hemoglobin level were not significantly different among the four groups.

CONCLUSIONS

Rebamipide is useful for the primary prevention of gastric mucosal injury induced by LDA alone or by LDA plus clopidogrel in healthy subjects.

Influence of genetic variations on levels of inflammatory markers of healthy subjects at baseline and one week after clopidogrel therapy; results of a preliminary study

We aimed to assess the association between the most common polymorphisms of cytochrome P450 (CYP) epoxygenases on the plasma levels of inflammatory markers in a population of healthy subjects. We also sought to determine whether CYP2C19*2 polymorphism is associated with the anti-inflammatory response to clopidogrel. In a population of 49 healthy young males, the baseline plasma levels of inflammatory markers including C-reactive protein, haptoglobin, orosomucoid acid, CD-40 were compared in carriers vs. non-carriers of the most frequent CYP epoxygenase polymorphisms: CYP2C9*2, CYP2C9*3, CYP2C19*2, CYP2C8*2 and CYP2J2*7. Also, the variation of inflammatory markers from baseline to 7 days after administration of 75 mg per day of clopidogrel were compared in carriers vs. non-carriers of CYP2C19* allele and also in responders vs. hypo-responders to clopidogrel, determined by platelet reactivity tests. There was no significant association between epoxygenase polymorphisms and the baseline levels of inflammatory markers. Likewise, CYP2C19* allele was not associated with anti-inflammatory response to clopidogrel. Our findings did not support the notion that the genetic variations of CYP epoxygenases are associated with the level of inflammatory markers. Moreover, our results did not support the hypothesis that CYP2C19*2 polymorphism is associated with the variability in response to the anti-inflammatory properties of clopidogrel.