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Inhibition of platelet aggregation by prostaglandin E1 (PGE1) in diabetic patients during therapy with clopidogrel and aspirin.

ABSTRACT: Diabetes mellitus (DM) is associated with increased platelet activation and reduced platelet inhibition by clopidogrel. Prostaglandin E1 (PGE1) stimulates adenyl cyclase activity in platelets and increases cyclic AMP concentrations, which inhibit Ca(2+)release and platelet aggregation induced by P2Y1 receptor activation. PGE1 is included in the VerifyNow P2Y12 assay to suppress P2Y1 induced platelet aggregation. We hypothesized that diabetes mellitus may be associated with altered response to PGE1 in subjects treated with clopidogrel. Subjects with established coronary artery disease who were taking clopidogrel 75?mg daily and aspirin for >14 days were enrolled (n?=?96). Diabetic (n?=?34) were compared with non-diabetic subjects (n?=?62). VerifyNow P2Y12 assay and light transmittance aggregometry (LTA) were performed using ADP as agonist with and without addition of PGE1. Genomic DNA was genotyped for common cytochrome P450 (CYP) 2C19 variants using Taqman assays. Residual on-treatment platelet aggregation induced by 20?µM ADP was not significantly different between subjects with and without DM. Addition of 22?nM and 88?nM PGE1 to 20?µM ADP resulted in a significant reduction of maximal platelet aggregation (MPA). Residual LTA platelet aggregation with PGE1 and VerifyNow P2Y12 platelet reactivity were significantly higher in subjects with DM than those without DM and in carriers of CYP 2C19*2 polymorphism. We conclude that an impaired inhibitory response to PGE1 may contribute to the high platelet reactivity phenotype in subjects with DM treated with clopidogrel. Addition of PGE1 to ADP agonist platelet assays may identify subjects with blunted inhibitory response to prostaglandins and result in a higher proportion of subjects with DM being classified as non-responders.

SUBMITTER: Kreutz RP

PROVIDER: S-EPMC4028123 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Inhibition of platelet aggregation by prostaglandin E1 (PGE1) in diabetic patients during therapy with clopidogrel and aspirin.

Kreutz Rolf P RP Nystrom Perry P Kreutz Yvonne Y Miao Jia J Kovacs Richard R Desta Zeruesenay Z Flockhart David A DA Jin Yan Y

Platelets 20120302 2

Diabetes mellitus (DM) is associated with increased platelet activation and reduced platelet inhibition by clopidogrel. Prostaglandin E1 (PGE1) stimulates adenyl cyclase activity in platelets and increases cyclic AMP concentrations, which inhibit Ca(2+)release and platelet aggregation induced by P2Y1 receptor activation. PGE1 is included in the VerifyNow P2Y12 assay to suppress P2Y1 induced platelet aggregation. We hypothesized that diabetes mellitus may be associated with altered response to PG ...[more]

PMID: 22385219

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Project description:1. Human platelet nucleotides were labelled by incubating platelet-rich plasma with [U-(14)C]adenine. With such platelets, the effects of prostaglandin E1, theophylline and aspirin were determined on collagen-induced platelet aggregation and release of platelet ATP and ADP. Intracellular changes of platelet radioactive nucleotides, particularly 3':5'-cyclic AMP, were also determined both with and without collagen treatment. 2. Prostaglandin E1, theophylline and aspirin inhibited collagen-induced aggregation of platelets in a dose-dependent manner. Collagen-induced release of ATP and ADP and breakdown of radioactive ATP were also inhibited in a dose-dependent manner. 3. Prostaglandin E1 stimulated the formation of platelet radioactive 3':5'-cyclic AMP in a dose-dependent manner. With a given dose of prostaglandin E1, maximum formation of radioactive 3':5'-cyclic AMP occurred by 10-30s and thereafter the concentrations declined. The degree of inhibition of aggregation produced by prostaglandin E1, however, increased with its time of incubation in platelet-rich plasma before addition of collagen, so that there was an inverse relationship between the radioactive 3':5'-cyclic AMP concentration measured at the time of collagen addition and the subsequent degree of inhibition of aggregation obtained. 4. Neither theophylline nor aspirin at a concentration in platelet-rich plasma of 1.7mm altered platelet radioactive 3':5'-cyclic AMP contents. In the presence of prostaglandin E1, theophylline increased the concentration of radioactive 3':5'-cyclic AMP over that noted with prostaglandin E1 alone, but aspirin did not. 5. Mixtures of prostaglandin E1 and theophylline had a synergistic effect on inhibition of platelet aggregation. The same was true to a lesser extent with mixtures of prostaglandin E1 and aspirin. Such mixtures also inhibited collagen-induced release of platelet ATP and ADP and breakdown of platelet radioactive ATP. 6. Certain concentrations of either theophylline or aspirin and mixtures of small concentrations of prostaglandin E1 with either theophylline or aspirin caused little or no increase of radioactive 3':5'-cyclic AMP at the time of collagen addition, but inhibited aggregation to a marked degree, whereas higher concentrations of prostaglandin E1 alone caused a much greater increase of radioactive 3':5'-cyclic AMP at the time of collagen addition but inhibited aggregation to a lesser extent. With these compounds there does not appear to be a correlation between these parameters.

Project description:BackgroundDual antiplatelet therapy using acetylsalicylic acid (ASA, aspirin) and clopidogrel is of great importance following coronary stenting. However, the variable platelet inhibitory effectiveness compromises the antithrombotic advantages provided by dual antiplatelet therapy. The aim of this single-center prospective study was to reduce the low response incidence of dual antiplatelet therapy with ASA and clopidogrel according to a prespecified therapy algorithm.MethodsPlatelet function testing using whole blood aggregometry (Chronolog 590) was performed 48 hours following coronary stenting (for either acute coronary syndromes or stable coronary artery disease) on 504 patients. The antiplatelet therapy included a loading dose of 600 mg clopidogrel and 500 mg ASA, followed by 75 mg clopidogrel and 100 mg ASA once daily. Clopidogrel low responders (CLR: >5 ohm; adenosine diphosphate (ADP) 5 μM) and/or ASA low responders (ALR: >0 ohm; arachidonic acid 10 μM) were treated according to a structured therapy plan: in the case of CLR, the maintenance + dose was doubled (repeated loading dose followed by 150 mg daily), and when still ineffective ticlopidine or prasugrel, if available and not contraindicated, were used. ALR was treated by increasing the dose to 300 mg in a first step or to 500 mg ASA when the first modification did not take effect sufficiently. In addition, ADP receptor antagonist 2-methylthioadenosine 5'-monophosphate triethylammonium salt (MeSAMP) testing and ASA incubation were performed to rule out either a platelet ADP-receptor defect or an ASA pharmacokinetic resistance.ResultsOf the total cohort of 504 patients, we detected 30.8% clopidogrel low-responders and 19.4% aspirin low-responders. For ALR, with a dose adjustment of 300 mg ASA daily, 94.6% of ALR were effectively treated and the residual 5.4% by administration of daily dosages of 500 mg ASA. This means that after modification of the ASA maintenance dose, all initial ALRs had an adequate antiplatelet response. The results for clopidogrel revealed that 69% of the CLR were treated effectively by increasing the clopidogrel dose to 150 mg daily. When prasugrel was not available or contraindicated, 12.7% of the remaining low responders showed an adequate result after being switched to ticlopidine. Consequently, by applying the therapy algorithm, we were able to reduce the CLR prevalence by 86.6%. On including prasugrel in the therapy plan, we were finally able to eliminate thienopyridine low response. In addition, no ADP receptor defect was found in this study as a potential reason for CLR. We identified the following factors associated with both CLR and ALR status: acute coronary syndromes, positive troponin values as well as diabetes mellitus and elevated HbA1C values and a higher platelet count. Furthermore, our data revealed for CLR elevated C-reactive protein values and a high PREDICT-score (including an age >65 years, acute coronary syndrome, diabetes mellitus, renal failure, and reduced left ventricular function) as risk factors. The following factors correlated with the risk of ASA low response: patients with elevated hemoglobin, serum creatinine and C-reactive protein values. In addition, medication with nitrates reduced the risk of being CLR. As also holds true for CLR, we found the PREDICT-score to be correlated to the risk of being ALR. However, by far the strongest risk factor for CLR or ALR was the fact of dual resistance.ConclusionFollowing a structured therapy plan based on a "test and treat" strategy, the prevalence of clopidogrel or aspirin low response can be significantly reduced and the risk of inadequate dual antiplatelet therapy minimized.

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Inhibition of platelet aggregation by prostaglandin E1 (PGE1) in diabetic patients during therapy with clopidogrel and aspirin.

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Inhibition of platelet aggregation by prostaglandin E1 (PGE1) in diabetic patients during therapy with clopidogrel and aspirin.

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