Role of genetic factors on the effect of additional loading doses and two maintenance doses used to overcome clopidogrel hyporesponsiveness

Dosage optimization of clopidogrel via a precision medicine approach: the way forward

Clopidogrel is a prodrug chiefly metabolized by the hepatic isoenzyme CYP2C19 to its active metabolite that inhibits the platelet aggregation. It has been proven in many populations that the genetic polymorphism of CYP2C19 has influence on the pharmacokinetic and or pharmacodynamics of this drug and resulting in high inter-individual variability in the treatment outcomes. As CYP2C19 genetic polymorphism is highly prevalent among the Asian population, the influence of the same on the pharmacokinetics and; thereby, the pharmacodynamics of clopidogrel needs more attention. Using the pharmacogenetic information for drug therapy could help overcome these issues and to optimize the dosage regimen of clopidogrel, this review advocates the precision medicine approach for reducing the clopidogrel resistance and adverse cardiovascular events.

Comparison of the effects of ticagrelor and clopidogrel on heart rate variability and heart rate turbulence in patients with percutaneous coronary interventions

Introduction

Clopidogrel and ticagrelor are commonly used, antiplatelet agents. Ticagrelor has an effect of enhancing the plasma level of adenosine that may alter the autonomic function. The aim of this study is to compare the effects of ticagrelor and clopidogrel on heart rate variability (HRV) and heart rate turbulence (HRT).

Methods

Thirty subjects who performed percutaneous coronary intervention (PCI) were included in the randomized, crossover study. These patients were divided into two groups. Clopidogrel or ticagrelor was administered in two different testing sessions (1-month treatment for each session). In group 1, clopidogrel and ticagrelor treatment were used while in group 2, ticagrelor and clopidogrel treatment were used respectively. Three times rhythm Holter recording (baseline, 1st and 2nd month) was performed. The HRV (time domain and frequency domain) and HRT (turbulence onset (TO) and turbulence slope (TS)) parameters were analyzed from the Holter recordings.

Results

According to baseline Holter recording, pNN50 (5.82 ± 5.83 vs 10.56 ± 8.28; p = 0.03) and HF(nu) (6.85 ± 9.33 vs 9.53 ± 7.41; p = 0.04) parameters were higher in group 2 than in group 1, while TO(0.004 ± 0.02 vs −0.01 ± 0.02; p = 0.01) parameter was positive and higher in group 1 than in group 2. In the second month, the LF/HF ratio (4.47 ± 2.43 vs 3.18 ± 2.45; p = 0.04) was higher in group 1 than in group 2. However, when the evaluation was done within the groups themselves, there were no statistically significant differences in HRV and HRT parameters obtained before and after clopidogrel and ticagrelor administration in group 1 and group 2.

Conclusion

Ticagrelor and clopidogrel treatments did not have a significant effect on HRV and HRT parameters.