Effects of ilaprazole on the steady-state pharmacodynamics of clopidogrel in healthy volunteers: An open-label randomized crossover study.

Background: Previous studies have suggested that proton pump inhibitors could impair the antiplatelet effect of clopidogrel. It is uncertain whether ilaprazole affects the antiplatelet effect of clopidogrel. This study aimed to determine the drug-drug interaction between ilaprazole and clopidogrel. Methods: A randomized crossover trial of 40 healthy subjects was performed. Clopidogrel was administered alone or in combination with ilaprazole for 7 days. The maximal platelet aggregation (MPA) to 5 µmol/L adenosine diphosphate was measured by light transmission aggregometry and the platelet reactivity index (PRI) was determined by vasodilator-stimulated phosphoprotein P2Y12 assay. High on-treatment platelet reactivity (HOPR) was defined as a MPA of >40%. The inhibition of platelet aggregation (IPA) and PRI in the two phases were compared between two regimens after the last dosing. Results: IPA was comparable between the two regimens at 0, 10 and 24 h (p > 0.05), but higher at 4 h in the clopidogrel alone regimen compared with that in the combined treatment regimen (75.66 ± 18.44% vs. 70.18 ± 17.67%, p = 0.031). The inhibition of PRI was comparable between the two regimens at 0 and 24 h. There were no significant differences in the area under the time-IPA% curve (AUC) or the incidence of HOPR at all time-points between the two regimens. Conclusion: In healthy subjects, ilaprazole has limited effect on the pharmacodynamics of clopidogrel and it may not be clinically relevant. Clinical Trial Registration: [www.chictr.org.cn], identifier [ChiCTR2000031482].

Simultaneous determination of clopidogrel, 2-oxo-clopidogrel, and the thiol metabolite of clopidogrel in human plasma by LC-MS/MS.

Clopidogrel is a pro-drug which needs two-step metabolism to produce the active thiol metabolite. This study aimed to explore an efficient method to simultaneously determine the plasma clopidogrel, 2-oxo-clopidogrel (2-Oxo-CLP), and the clopidogrel active metabolite (CAM). A high-throughput liquid chromatography tandem mass spectrometry (LC-MS/MS) was therefore developed. The analytes were extracted from plasma by using methyl tert-butyl ether (MTBE). Chromatographic separation was performed on a C18 column under an isocratic elution, accompanied with acetonitrile and deionized water containing 0.1% formic acid. After optimizing the condition of LC-MS/MS, a stable linearity was observed in the standard curves over the concentration ranges of 0.05 to 50.0 ng/mL for clopidogrel, 0.5 to 50.0 ng/mL for 2-Oxo-CLP, and 0.5 to 100 ng/mL for clopidogrel active metabolite derivative (CAMD). The retention time was 4.78 minutes, 3.79 minutes, 3.59 minutes, and 4.82 minutes for clopidogrel, 2-Oxo-CLP, CAMD, and internal standard, respectively. Both the relative standard deviation and the relative error were within the requirement of operating criteria. No significant degradation of clopidogrel, 2-Oxo-CLP, and CAMD occurred under different storage conditions. This method was successfully validated in 3 patients with coronary artery disease. The results showed that the current LC-MS/MS method was efficient for simultaneously detecting clopidogrel, 2-Oxo-CLP, and CAM with fine linearity, accuracy, precision, and stability.

An optimal window of platelet reactivity by LTA assay for patients undergoing percutaneous coronary intervention.

OBJECTIVE: This study was aimed to determine how platelet reactivity (PR) on dual antiplatelet therapy predicts ischemic and bleeding events in patients underwent percutaneous coronary intervention (PCI). DESIGN: A total of 2768 patients who had received coronary stent implantation and had taken aspirin 100 mg in combination with clopidogrel 75 mg daily for > 5 days were consecutively screened and 1885 were enrolled. The recruited patients were followed-up for 12 months. The primary end-point was the net adverse clinical events (NACE) of cardiovascular death, nonfatal myocardial infarction (MI), target vessel revascularization (TVR), stent thrombosis (ST) and any bleeding. RESULT: 1709 patients completed the clinical follow-up. By using the receiver operating characteristic (ROC) curve analysis, the optimal cut-off values were found to be 37.5 and 25.5% respectively in predicting ischemic and bleeding events. Patients were classified into 2 groups according to PR: inside the window group (IW) [adenosine diphosphate (ADP) induced platelet aggregation (PLADP) 25.5-37.4%)] and outside the window group (OW) (PLADP < 25.5% or ≥ 37.5%). The incidence of NACE was 16.8 and 23.1% respectively in the IW and OW group. The hazard ratio of NACE in IW group was significantly lower [0.69 (95% CI, 0.54-0.89, P = 0.004)] than that in the OW group during 12-month follow-up. CONCLUSION: An optimal therapeutic window of 25.5-37.4% for PLADP predicts the lowest risk of NACE, which could be referred for tailored antiplatelet treatment while using LTA assay. TRIAL REGISTRATION: Trial registration number: ClinicalTrials.gov NCT01968499 . Registered 18 October 2013 - Retrospectively registered.

Pharmacodynamic effects of indobufen compared with aspirin in patients with coronary atherosclerosis.

PURPOSE: This study aimed to investigate the pharmacodynamic effects of indobufen and low-dose aspirin in patients with coronary atherosclerosis. METHODS: In the first phase, 218 patients with coronary atherosclerosis were randomly assigned to receive aspirin 100 mg once daily (standard dose); 100 mg once every 2 days; 100 mg once every 3 days; 50 mg twice daily; 75 mg once daily; 50 mg once daily; or indobufen 100 mg twice daily for 1 month. In the second phase, 20 healthy subjects were treated with indobufen 100 mg twice daily for 1 week followed after a 2-week washout by aspirin 100 mg once daily for 1 week. The primary outcome was arachidonic acid-induced platelet aggregation (PLAA), and the secondary outcomes included plasma thromboxane B2 (TXB2) and urinary 11-dehydro-TXB2 (11-dh-TXB2) levels at the end of each treatment.  RESULTS: In the first phase, compared with aspirin 100 mg once daily: all aspirin groups had similar suppression of PLAA whereas indobufen group had significantly less suppressed PLAA. Aspirin given every second or third day, and indobufen produced less suppression of plasma TXB2. All treatment regimens produced similar inhibition of 11-dh-TXB2. In the second phase, compared with aspirin, indobufen produced less suppression of plasma TXB2 at 8 h and 12 h after the last dose. CONCLUSIONS: Aspirin 50 mg twice daily, 75 mg once daily, and aspirin 50 mg once daily produce antiplatelet effects that are similar to aspirin 100 mg once daily. Aspirin given less often than once daily and indobufen 100 mg twice daily do not suppress platelets as effectively as aspirin 100 mg once daily.

Serum uric acid level negatively correlated with the prevalence of clopidogrel low response in patients undergoing antiplatelet treatment with aspirin and clopidogrel.

BACKGROUND AND AIMS: It has been reported that elevated serum uric acid (SUA) is related to inflammation and potentially to platelet hyper-reactivity. However, the relationship between elevated SUA and residual platelet reactivity is uncertain in patients on dual antiplatelet treatment (DAPT) with aspirin and clopidogrel. METHODS AND RESULTS: A cross-sectional cohort study was conducted on 2569 patients undergoing DAPT with aspirin and clopidogrel. Patients' SUA levels, residual platelet aggregation, routine blood tests and clinical characteristics were recorded. The relationship between SUA level and residual platelet aggregation was assessed by correlation analysis, and the relationship between SUA level and the prevalence of clopidogrel low response (CLR) was assessed by multivariate logistic regression analysis. Adenosine diphosphate (ADP) induced platelet aggregation (PLADP) was higher in normal-SUA group than that in hyperuricemia group [30(21, 40) % vs. 27(19, 39) %, p = 0.032]. No significant difference was found for arachidonic acid (AA) induced platelet aggregation (PLAA) between the two groups [4(2, 5) % vs. 3(2, 5) %, p = 0.557]. The correlation between SUA and PLADP was statistically significant(r = -0.115, p < 0.001), while that between SUA and PLAA was non-significant (r = -0.012, p = 0.643). Using the multivariate logistic regression analysis, higher SUA concentration was associated with a decreased risk of clopidogrel low response (CLR) (OR [95%CI] = 0.997 [0.995-0.999], p = 0.001). CONCLUSION: This is the largest study to date showing that in patients receiving DAPT with aspirin and clopidogrel, SUA is independently and negatively associated with the prevalence of clopidogrel low response. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov Unique Identifier: NCT01955200.