Optimizing clopidogrel dose response: a new clinical algorithm comprising CYP2C19 pharmacogenetics and drug interactions

Precision dosing for patients on tricyclic antidepressants

OBJECTIVE

We aim to develop a personalized dosing tool for tricyclic antidepressants (TCAs) that integrates CYP2D6 and CYP2C19 gene variants and their effects while also considering the polypharmacy effect.

METHODS

The study first adopted a scoring system that assigns weights to each genetic variant. A formula was then developed to compute the effect of both genes' variants on drug dosing. The output of the formula was assessed by a comparison with the clinical pharmacogenetics implementation consortium recommendation. The study also accounts for the effect of the co-administration of inhibitors and inducers on drug metabolism. Accordingly, a user-friendly tool, Clinical Dosing Tool ver.2, was created to assist clinicians in dosing patients on TCAs.

RESULTS

The study provides a comprehensive list of all alleles with corresponding activity values and phenotypes for both enzymes. The tool calculated an updated area under the curve ratio that utilizes the effects of both enzymes' variants for dose adjustment. The tool provided a more accurate individualized dosing that also integrates the polypharmacy effect.

CONCLUSION

To the best of our knowledge, the literature misses such a tool that provides a numerical adjusted dose based on continuous numerical activity scores for the considered patients' alleles and phenoconversion.

Pharmacogenomics in Lebanon: current status, challenges and opportunities

Pharmacogenomics (PGx) research and applications are of utmost relevance in Lebanon considering its population genetic diversity. Moreover, as a country with regional leadership in medicine and higher education, Lebanon holds a strong potential in contributing to PGx research and clinical implementation. In this manuscript, we first review and evaluate the available PGx research conducted in Lebanon, then describe the current status of PGx practice in Lebanon while reflecting on the local and regional challenges, and highlighting areas for action, and opportunities to move forward. We specifically expand on the status of PGx at the American University of Beirut Faculty of Medicine and Medical Center as a case study and guide for the further development of local and regional comprehensive PGx research, teaching, and clinical implementation programs. We also delve into the status of PGx knowledge and education, and prospects for further advancement such as with online courses and certificates.

A software tool to adjust codeine dose based on CYP2D6 gene-pair polymorphisms and drug-drug interactions

Codeine is metabolized by the CYP2D6 enzyme, and individuals with certain genetic variations of the CYP2D6 gene may metabolize codeine differently, leading to variable efficacy and toxicity. Drug-drug interactions can also affect the metabolism of codeine. A tool to adjust codeine dose based on these factors does not currently exist. Healthcare providers should use their clinical judgment and reference different established dosing guidelines to determine the appropriate dose of codeine for individual patients. The study provides a tool that assists prescribers in adjusting codeine dose based on CYP2D6 gene-pair polymorphisms and drug-drug interactions. Highlighted is the need to consider pharmacogenetics and drug-drug interactions when determining the appropriate dosing of codeine and provide a framework for implementing individualized dosing based on these factors.

Acute Multiple In-Stent Thromboses in a Patient With Clopidogrel-Fluconazole Interaction

Clopidogrel is an anti-platelet that exerts its function by selectively inhibiting the binding of adenosine di-phosphate (ADP) to the P2Y12 receptor. Fluconazole is a fungistatic agent that alters fungal cell membranes. Both of these drugs act on the cytochrome P450 2C19. We report the case of an 83-year-old male that presented two days following coronary angioplasty with stent thrombosis, following the concomitant use of clopidogrel and fluconazole. We aim to study the interaction between clopidogrel and fluconazole. We hypothesize that fluconazole decreases the therapeutic level of clopidogrel, requiring an increase in dosage to achieve the same anti-thrombotic effect.

Blocker displacement amplification mediated PCR based screen-printed carbon electrode biosensor and lateral flow strip strategy for CYP2C19*2 genotyping

Single nucleotide variants in CYP2C19*2 are associated with clopidogrel resistance in coronary heart disease. In order the guidance the dosage of drug and personalized medicine, blocker displacement amplification was first used to specific amplify G site and A site alleles. For electrochemical strategy, forward primers were labeled electrochemical active methyl blue and ferrocene, generates signals on -0.26 for G site and 0.22 V for A site. For lateral flow strip assay, primers with specific modification were used to generates unique color in test line 1 for G site and test line 2 for A site. In conclusion, we developed a sensitive screen-printed carbon electrodes based electrochemical sensor and gold nano particle based lateral flow strip assay strategy to successfully genotyping CYP2C19*2 GG, GA and AA genotype. The proposed method can realize CYP2C19*2 analysis from multiple biological samples including whole blood, buccal swab, saliva and hair root, and showed good consistency with Sequencing. Due to the fact our proposed strategy merely relies on thermal cycler instrument and visual strip detection, this platform shows great potential in source-limited regions genotyping.

Clinical application and importance of one-step human CYP2C19 genotype detection

BACKGROUND

To directly achieve cytochrome P450 2C19 gene ( CYP2C19) classification using one-step real-time fluorescent PCR detection and to verify the capabilities of this method with nucleic acid extracted from whole blood samples.

METHODS

A human CYP2C19 genotyping kit based on one-step real-time fluorescent PCR detection was used to analyze whole blood or genomic DNA samples. This method was compared with pyrosequencing and another quantitative (q)PCR kit for its accuracy, repeatability, detection range analysis, sensitivity, specificity, and anti-interference analysis.

RESULTS

The one-step real-time PCR method achieved a 100% accuracy rate compared with pyrosequencing and the other qPCR kit. When detecting different concentrations of known genes, concentrations of each sample ranging from 0.2 to 125 ng/µL could be correctly detected. The genotypes of samples treated with anticoagulants, including EDTA and sodium citrate, and chyle blood samples could be correctly detected.

CONCLUSION

The one-step detection method demonstrated high accuracy and a wide detection range. It also had high levels of repeatability, sensitivity, and specificity for the assessment of genomic DNA test samples.

Influence of CYP2C19 Phenotype on the Effect of Clopidogrel in Patients Undergoing a Percutaneous Neurointervention Procedure

This observational retrospective study assessed the antiplatelet response and clinical events after clopidogrel treatment in patients who underwent percutaneous neurointervention, related to CYP2C19 metabolizer status (normal (NM), intermediate/poor (IM-PM), and ultrarapid (UM); inferred from *2, *3, and *17 allele determination). From 123 patients, IM-PM had a higher aggregation value (201.1 vs. 137.6 NM, 149.4 UM, P < 0.05) and lower response rate (37.5% vs. 69.8% NM, 61.1% UM), along with higher treatment change rate (25% vs. 5.7% NM, 10.5% UM). The highest ischemic events incidence occurred in NM (11.3% vs. 6.3% IM, 10.5% UM) and hemorrhagic events in UM (13.2% vs. 0% IM and 3.8% NM). No differences were found regarding ischemic event onset time, while hemorrhagic event frequency in UM was higher with shorter onset time (P = 0.047). CYP2C19 no-function and increased function alleles defined the clopidogrel response. UM patients had increased bleeding risk. Therapeutic recommendations should include dose reduction or treatment change in UM.

Pharmacogenomic Impact of CYP2C19 Variation on Clopidogrel Therapy in Precision Cardiovascular Medicine

Variability in response to antiplatelet therapy can be explained in part by pharmacogenomics, particularly of the CYP450 enzyme encoded by CYP2C19. Loss-of-function and gain-of-function variants help explain these interindividual differences. Individuals may carry multiple variants, with linkage disequilibrium noted among some alleles. In the current pharmacogenomics era, genomic variation in CYP2C19 has led to the definition of pharmacokinetic phenotypes for response to antiplatelet therapy, in particular, clopidogrel. Individuals may be classified as poor, intermediate, extensive, or ultrarapid metabolizers, based on whether they carry wild type or polymorphic CYP2C19 alleles. Variant alleles differentially impact platelet reactivity, concentration of plasma clopidogrel metabolites, and clinical outcomes. Interestingly, response to clopidogrel appears to be modulated by additional factors, such as sociodemographic characteristics, risk factors for ischemic heart disease, and drug-drug interactions. Furthermore, systems medicine studies suggest that a broader approach may be required to adequately assess, predict, preempt, and manage variation in antiplatelet response. Transcriptomics, epigenomics, exposomics, miRNAomics, proteomics, metabolomics, microbiomics, and mathematical, computational, and molecular modeling should be integrated with pharmacogenomics for enhanced prediction and individualized care. In this review of pharmacogenomic variation of CYP450, a systems medicine approach is described for tailoring antiplatelet therapy in clinical practice of precision cardiovascular medicine.

Thieno[2,3-b]pyridine derivatives are potent anti-platelet drugs, inhibiting platelet activation, aggregation and showing synergy with aspirin

Drugs which inhibit platelet function are commonly used to prevent blood clot formation in patients with Acute Coronary Syndromes (ACS) or those at risk of stroke. The thieno[3,2-c]pyridine class of therapeutic agents, of which clopidogrel is the most commonly used, target the P2Y₁₂ receptor, and are often used in combination with acetylsalicylic acid (ASA). Six thieno[2,3-b]pyridine were assessed for in vitro anti-platelet activity; all derivatives showed effects on both platelet activation and aggregation, and showed synergy with ASA. Some compounds demonstrated greater activity when compared to clopidogrel. These compounds, therefore, represent potential novel P2Y₁₂ inhibitors for improved treatment for patients.

The Personalization of Clopidogrel Antiplatelet Therapy: The Role of Integrative Pharmacogenetics and Pharmacometabolomics

Dual antiplatelet therapy of aspirin and clopidogrel is pivotal for patients undergoing percutaneous coronary intervention. However, the variable platelets reactivity response to clopidogrel may lead to outcome failure and recurrence of cardiovascular events. Although many genetic and nongenetic factors are known, great portion of clopidogrel variable platelets reactivity remain unexplained which challenges the personalization of clopidogrel therapy. Current methods for clopidogrel personalization include CYP2C19 genotyping, pharmacokinetics, and platelets function testing. However, these methods lack precise prediction of clopidogrel outcome, often leading to insufficient prediction. Pharmacometabolomics which is an approach to identify novel biomarkers of drug response or toxicity in biofluids has been investigated to predict drug response. The advantage of pharmacometabolomics is that it does not only predict the response but also provide extensive information on the metabolic pathways implicated with the response. Integrating pharmacogenetics with pharmacometabolomics can give insight on unknown genetic and nongenetic factors associated with the response. This review aimed to review the literature on factors associated with the variable platelets reactivity response to clopidogrel, as well as appraising current methods for the personalization of clopidogrel therapy. We also aimed to review the literature on using pharmacometabolomics approach to predict drug response, as well as discussing the plausibility of using it to predict clopidogrel outcome.