Decreased platelet responsiveness to clopidogrel correlates with CYP2C19 and PON1 polymorphisms in atherosclerotic patients

Clopidogrel and aspirin are the most commonly used medications worldwide for dual antiplatelet therapy after percutaneous coronary intervention. However, clopidogrel hyporesponsiveness related to gene polymorphisms is a concern. Populations with higher degrees of genetic admixture may have increased prevalence of clopidogrel hyporesponsiveness. To assess this, we genotyped CYP2C19, ABCB1, and PON1 in 187 patients who underwent percutaneous coronary intervention. Race was self-defined by patients. We also performed light transmission aggregometry with adenosine diphosphate (ADP) and arachidonic acid during dual antiplatelet therapy. We found a significant difference for presence of the CYP2C19*2 polymorphism between white and non-white patients. Although 7% of patients had platelet resistance to clopidogrel, this did not correlate with any of the tested genetic polymorphisms. We did not find platelet resistance to aspirin in this cohort. Multivariate analysis showed that patients with PON1 and CYP2C19 polymorphisms had higher light transmission after ADP aggregometry than patients with native alleles. There was no preponderance of any race in patients with higher light transmission aggregometry. In brief, PON1 and CYP2C19 polymorphisms were associated with lower clopidogrel responsiveness in this sample. Despite differences in CYP2C19 polymorphisms across white and non-white patients, genetic admixture by itself was not able to identify clopidogrel hyporesponsiveness.

Resistência ao clopidogrel: prevalência e variáveis associadas / Resistance to clopidogrel: prevalence and associate variables

FUNDAMENTO: A dupla terapia antiagregante plaquetária com ácido acetilsalicílico e clopidogrel é pedra angular do tratamento de pacientes submetidos a angioplastia com implante de stents coronarianos. Todavia, parte desses pacientes, a despeito do uso de aspirina e clopidogrel, não se encontram eficazmente antiagregados, fenômeno conhecido como resistência aos antiagregantes plaquetários. A sua prevalência, assim como as condições a ela relacionadas são desconhecidas em nosso meio. OBJETIVO: Determinar a prevalência de resistência ao clopidogrel, assim como as variáveis a ela relacionadas. MÉTODOS: Pacientes admitidos para angioplastia eletiva em uso crônico de aspirina e clopidogrel entre janeiro de 2007 e janeiro de 2010. Uma hora após o procedimento, foi medida a agregação plaquetária utilizando a agregometria óptica com difosfato de adenosina 5 µmoles/l como agonista. Nesse momento, em um coorte transversal, determinou-se a prevalência de resistência ao clopidogrel, definida com um valor de agregação plaquetária > 43% e um modelo de regressão logística às variáveis a ela relacionadas. RESULTADOS: Foram analisados 205 pacientes (66,4 ± 11anos, 61,5% masculino). A prevalência de resistência ao clopidogrel foi 38,5% (IC95% 31,9 - 45,2%). O valor da glicemia (OR = 1,014 IC95% 1,004 - 1,023), infarto do miocárdio prévio (OR = 2,320 IC95% 1,1103 - 4,892) e a resposta terapêutica à aspirina (OR = 1,057 IC95% 1,017 - 1,099) foram as variavéis de associação independente à resistência ao clopidogrel. CONCLUSÃO: A prevalência de resistência ao clopidogrel foi alta. Glicemia, infarto agudo do miocárdio prévio e a resposta ao ácido acetilsalicílico foram variáveis a ela relacionadas. A melhor compreensão desse fenômeno se faz necessária frente às novas propostas de antiagregantes plaquetários.

BACKGROUND: The dual antiplatelet therapy with acetylsalicylic acid (ASA) and clopidogrel is the cornerstone of treatment for patients undergoing angioplasty with coronary stent implantation. However, some of these patients, despite the use of aspirin and clopidogrel, are not effectively anti-aggregated, a phenomenon known as resistance to antiplatelet agents. Its prevalence, as well as the conditions associated with it, is unknown in our country. OBJECTIVE: To determine the prevalence of clopidogrel resistance, as well as variables associated with it. METHODS: Patients admitted for elective angioplasty in chronic use of ASA and clopidogrel between January 2007 and January 2010 were studied. One hour after the procedure, platelet aggregation was measured using optical aggregometry with adenosine diphosphate 5 mmoles / l as agonist. At that moment, in a cross-sectional cohort, we determined the prevalence of clopidogrel resistance, defined as the value of platelet aggregation > 43% and a logistic regression model to the variables associated with it. RESULTS: A total of 205 patients were analyzed (66.4 ± 11 years, 61.5% males). The prevalence of clopidogrel resistance was 38.5% (95% CI: 31.9 - 45.2%). Blood glucose (OR = 1.014; 95%CI: 1.004 - 1.023), previous myocardial infarction (OR = 2.320; 95%CI: 1.1103 - 4.892) and therapeutic response to ASA (OR = 1.057; 95%CI: 1.017 - 1.099) were the variables independently associated with clopidogrel resistance. CONCLUSION: The prevalence of clopidogrel resistance was high. Glycemia, acute myocardial infarction and response to ASA were variables associated with it. A better understanding of this phenomenon is necessary considering the new antiplatelet aggregant agents.

Ausência de interação clopidogrel-estatina em pacientes submetidos a implante de "stent" coronário / Lack of clopidogrel-statin interaction in patients undergoing coronary stent implantation / Ausencia de interacción clopidogrel-estatina en pacientes sometidos a implante de "Stent" coronario

FUNDAMENTO: Alguns estudos têm sugerido redução da atividade do clopidogrel sobre a ativação e adesão plaquetárias em pacientes em uso de estatinas. OBJETIVO: Avaliar se a ativação e agregação plaquetárias diminuem com clopidogrel, e se ocorre redução da ação do clopidogrel quando associado à atorvastatina ou à sinvastatina. MÉTODOS: Estudo prospectivo que incluiu 68 pacientes com angina estável em uso prévio de sinvastatina, atorvastatina, ou nenhuma estatina (grupo controle), com indicação prévia eletiva de realização de intervenção coronária percutânea. Foi analisada a ativação plaquetária através do número de plaquetas, níveis de P-selectina e glucoproteína IIb/IIIa (com e sem estímulo de ADP) através de citometria de fluxo. Os resultados foram analisados antes e após a intervenção coronária percutânea e da administração de clopidogrel. RESULTADOS: Observamos redução da atividade plaquetária com uso de clopidogrel. Além disso, não houve diferenças entre as variáveis analisadas que comprovassem redução da atividade do clopidogrel quando associado à estatinas. Observou-se níveis de p-selectina (pré-angioplastia: 14,23±7,52 x 11,45±8,83 x 7,65±7,09; pós angioplastia: 21,49±23,82 x 4,37±2,71 x 4,82±4,47, ρ<0,01) e glicoproteína IIb/IIIa (pré-angioplastia: 98,97±0,43 x 98,79±1,25 x 99,21±0,40; pós angioplastia: 99,37±0,29 x 98,50±1,47 x 98,92±0,88, ρ=0,52), respectivamente nos grupos controle, atorvastatina e sinvastatina. CONCLUSÃO: Concluímos que a ativação plaquetária diminui com a administração de clopidogrel, e que o clopidogrel não tem seu efeito antiplaquetário reduzido na presença de sinvastatina ou atorvastatina.

BACKGROUND: Some studies have suggested reduced activity of clopidogrel on platelet activation and adherence in patients using statins. OBJECTIVE: To assess whether platelet activation and aggregation decrease with clopidogrel, and whether there is a reduction of the action of clopidogrel when associated with atorvastatin or simvastatin. METHODS: This prospective study included 68 patients with stable angina with previous use of simvastatin, atorvastatin, or no statin (control group), with previous elective indication of percutaneous coronary intervention (PCI). Platelet activation was analyzed by means of platelet count, levels of P-selectin and glycoprotein IIb/IIIa (with and without ADP stimulation) by flow cytometry. The findings were analyzed before and after percutaneous coronary intervention and the administration of clopidogrel. RESULTS: We observed reduction in platelet activity with use of clopidogrel. Furthermore, no differences were found between the variables analyzed to prove reduced activity of clopidogrel when combined with statins. We observed levels of p-selectin (pre-angioplasty: 14.23 ± 7.52 x 8.83 x 11.45 ± 7.65 ± 7.09; after angioplasty: 21.49 ± 23.82 x 4 37 ± 2.71 x 4.82 ± 4.47, ρ < 0.01) and glycoprotein IIb/IIIa (pre-angioplasty: 98.97 ± 0.43 ± 1.25 x 98.79 x 99.21 ± 0.40 after angioplasty: 99.37 ± 0.29 ± 1.47 x 98.50 x 98.92 ± 0.88, ρ = 0.52), respectively, in the control, atorvastatin and simvastatin groups. CONCLUSION: We concluded that platelet activation decreases with administration of clopidogrel, and clopidogrel has no antiplatelet effect reduced in the presence of simvastatin or atorvastatin.

FUNDAMENTO: Algunos estudios han sugerido reducción de la actividad del clopidogrel sobre la activación y adhesión plaquetarias en pacientes en uso de estatinas. OBJETIVO: Evaluar si la activación y agregación plaquetarias disminuyen con clopidogrel, y si ocurre reducción de la acción del clopidogrel cuando está asociado a la atorvastatina o a la sinvastatina. MÉTODOS: Estudio prospectivo que incluyó 68 pacientes con angina estable en uso previo de sinvastatina, atorvastatina, o ninguna estatina (grupo control), con indicación previa electiva de realización de intervención coronaria percutánea. Fue analizada la activación plaquetaria a través del número de plaquetas, niveles de P-selectina y glucoproteína IIb/IIIa (con y sin estímulo de ADP) a través de citometría de flujo. Los resultados fueron analizados antes y después de la intervención coronaria percutánea y de la administración de clopidogrel. RESULTADOS: Observamos reducción de la actividad plaquetaria con uso de clopidogrel. Además de eso, no hubo diferencias entre las variables analizadas que comprobasen reducción de la actividad del clopidogrel cuando está asociado a las estatinas. Se observaron niveles de p-selectina (pre-angioplastia: 14,23±7,52 x 11,45±8,83 x 7,65±7,09; post angioplastia: 21,49±23,82 x 4,37±2,71 x 4,82±4,47, ρ<0,01) y glicoproteína IIb/IIIa (pre-angioplastia: 98,97±0,43 x 98,79±1,25 x 99,21±0,40; post angioplastia: 99,37±0,29 x 98,50±1,47 x 98,92±0,88, ρ=0,52), respectivamente en los grupos control, atorvastatina y sinvastatina. CONCLUSIÓN: Concluimos que la activación plaquetaria disminuye con la administración de clopidogrel, y que el clopidogrel no tiene su efecto antiplaquetario reducido en la presencia de sinvastatina o atorvastatina.

Ticlopidina en el tratamiento experimental de la fase temprana de la peritonitis séptica / Ticlopidine in the experimental treatment of the early phase of the septic peritonitis

Evaluar el efecto en la mortalidad y repercusiones hematológicas hemostáticas y ácido básicas, de la ticlopidina administrada posterior a la ligadura y punción del ciego (CLP) en ratas. Utilizando el modelo experimental de ligadura y punción del ciego (CLP), fueron operadas 100 ratas Sprague-Dawley, distribuidas en dos grupos, el primero de 31 ratas con la administración de ticlopidina a la hora del procedimiento y el segundo con 69 animales sin aplicación de medicamento alguno (Grupo CLP). A las 18 horas se evaluó la mortalidad y se tomaron muestras para determinación de hematología, pruebas de coagulación y gases arteriales. Un tercer grupo denominado (control), con 31 ratas, sirvió para determinaciones en condiciones basales. Para el análisis estadístico se empleó la "t" de student. El grupo ticlodipina presentó menor mortalidad, normalización del número de plaquetas, monocitos, PTT y pH sanguíneo, siendo estadísticamente significativas las diferencias con respecto al grupo CLP (p<0.05), sin evidenciar significancia entre estas variables y las del grupo basal. La administración de ticlopidina, posterior a CLP, mejora la sobrevida por sepsis en animales, además de atenuar ciertos cambios en el estado hemátológico, ácido-base y de coagulación, pudiendo ejercer acciones en el tratamiento de la sepsis, función distinta para lo cual fue inicialmente empleada.

Polimorfismo del receptor P2Y12 de ADP plaquetario en pacientes con enfermedad coronaria y variabilidad en agregación plaquetaria: resultados preliminares / Platelet P2Y12 ADP receptor polymorphism in patients with coronary artery disease and varying degrees of platelet

Introducción: Uno de los mecanismos que explicaría la variabilidad en la agregación plaquetaria observada en la respuesta inhibitoria a clopidogrel es el polimorfismo del receptor P2Y12 de ADP plaquetario, específicamente, el haplotipo H2 y H1/H2. No se ha descrito la prevalencia del haplotipo H1/H2 del receptor plaquetario en pacientes con enfermedad coronaria. Objetivo: Evaluar la presencia del haplotipo H1/H2 del receptor P2Y12 en un grupo de pacientes con enfermedad coronaria Métodos: Estudio prospectivo en pacientes sometidos en forma electiva a angioplastía coronaria con stent. Todos recibieron aspirina y una dosis de carga de clopidogrel de 600 mg, seguido de dosis de mantención de 75 mg/día. En todos se midió agregación plaquetaria previo a la dosis de carga de clopidogrel (día 0) y luego entre 6º y 8º día det ratamiento. La agregación plaquetaria se expresó de acuerdo al porcentaje de cambio respecto del valor basal. Se utilizó test t student pareado para evaluar el porcentaje de cambio. Se amplificó el segmento de interés del ADN de los pacientes mediante PCR y se determinó la presencia del haplotipo H1/H2 usando enzimas de restricción. Resultados: Se enrolaron 40 pacientes, 34 (85 por ciento) hombres, edad promedio 61 +/-12 años. El promedio de agregación plaquetaria, previo y durante terapia con clopidogrel fue de 64 +/-10 por ciento y 41 +/-14 por ciento, respectivamente (p<0.0001) frente a ADP 8 µM. La respuesta de agregación a clopidogrel presentó una distribución normal según el test de Kolmogorov-Smirnov (p=0.58). Los pacientes se estratificaron de acuerdo al porcentaje de cambio en cuartiles y el cuartil de menor cambio representó una diferencia menor a 10 por ciento. De estos pacientes, 30 por ciento (3 pacientes) tenían el haplotipo H1/H2. En total, se demostró la presencia del haplotipo H1/H2 en 4 (10 por ciento) pacientes...

Background: One factor influencing the variability in the anti aggregation effect of clopidogrel is the polymorphism of the platelet P2Y12 ADP receptor, specifically the H2 and H1/H2 haplotypes. The prevalence of the H1/H2 haplotype has not been described in patients with coronary artery disease. Aim: To evaluate the presence of H1/H2 haplotype of P2Y12 receptor in patients with coronary artery disease. Methods: A prospective study was conducted in patients undergoing elective PTCA with stenting. All received aspirin followed by a loading dose of clopidogrel 600 mg and a maintenance dose of 75 mg daily. Platelet aggregation was measured prior to the loading clopidogrel dose and at 6 and 8 days post treatment. Platelet aggregation was indicated as the percent change over the basal value. The Student’s t test was used to evaluate the response. The DNA segment involved was amplified by PCR and the H1/H2 haplotype was determined using restriction enzymes. Results: Fourty patients (85 percent males) with mean age 61 years (SD 12) were studied. Mean platelet aggregation changed from a basal value of 64+/-10 to a post clopidogrel value of 41 +/-14 percent (p<0.0001) with an ADP level of 8 µM. The platelet aggregation response was normal according to Kolmogorov-Smirnov. The lowest quartile of platelet aggregation showed a <10 percent change. Three patients in this group (30 percent) had the H1/H2 haplotype. The overall incidence of this haplotype was 10 percent (4 patients). Conclusion: Clopidogrel does not induce a significant decreased platelet aggregation in 25 percent of patients subjected to coronary angioplasty. A third of this patients exhibited the H1/H2 haplotype for the P2Y12 receptor. This group of patients might be at increased risk from subsequent cardiovascular events.

Oral anti platelet drugs in dermatology

An up-to-date overview of antithrombotic drugs, with their currently reported beneficial cutaneous effects and skin side effect, is presented. Attempts to balance traditional pharmacodynamic concepts with the newly described empiric benefits are made. A concise, current and useful reference for dermatologists with an interest in dermatopharmacology and the practicing physician in the field of wound care, vasculitides and skin involvement of internal diseases is tried to be achieved

Newer orally active antiplatelet agents: Do they have an edge over aspirin?

An extensive body of research conducted in the past 25 years has helped foster understanding of the mechanisms and pathogenesis of the acute coronary syndromes and occlusive disease. The role of platelet and the endothelium in the pathogenesis of atherosclerosis and subsequent ischemic events is well established. The filed of antiplatelet therapy is rapidly expanding with the availability of newer antiplatelet agents. However, at the present time, there is no convincing data available that other antiplatelet drugs are superior to aspirin. Aspirin remains the cornrstone of therapy for various ischemic disorders and the foundation on which other therapies are added, both in the short and long term

Efeito da ticlopidina e do dipiridamol sobre a agregaçäo e contagem das plaquetas de pacientes com agina crônica estável / The effect of ticlopidine and dipyridamole on platelet aggregation and count in patients with chronic stable angina pectoris

Objetivo - Comparar o efeito da ticlopidina e do dipiridamol sobre a agregaçäo e a contagem plaquetárias nos pacientes com insuficiência coronariana crônica estável. Casuística e Métodos - Foram estudados 80 pacientes com idade média de 58,3 ñ 5,8 anos, portadores de insuficiência coronariana crônica estável, divididos em dois grupos de 40 pacientes e cada grupo tratado com ticlopidina ou dipiridamol. A agreagaçäo e contagem de plaquetas foram realizadas antes do início das drogas, e na primeira e quarta semanas de tratamento. Resultados - Ao final da quarta semana de tratamento observou-se hipogregabilidades espontânea, induzida pelo aDP e pela adrenalina em, respectivamente, 82,5%, 72,5% e 67,5% dos pacientes do grupo dipiridamol, a hipoagregabilidade espontânea, induzida pelo aDO e pela adrenalina foi, respectivamene, de 40%, 30% e 27,5% (p < 0,001). A contagem das plaquetas permaneceu inalterada para ambos os grupos. Conclusäo - O efeito antiagregante plaquetário da ticlopidina é significantemente maior que o do dipiridamol, e pode ser droga alternativa na prevençäo de complicaçöes cardiovasculares