In-vitro and in-vivo metabolism of different aspirin formulations studied by a validated liquid chromatography tandem mass spectrometry method.

Low-dose aspirin (ASA) is used to prevent cardiovascular events. The most commonly used formulation is enteric-coated ASA (EC-ASA) that may be absorbed more slowly and less efficiently in some patients. To uncover these "non-responders" patients, the availability of proper analytical methods is pivotal in order to study the pharmacodynamics, the pharmacokinetics and the metabolic fate of ASA. We validated a high-throughput, isocratic reversed-phase, negative MRM, LC-MS/MS method useful for measuring circulating ASA and salicylic acid (SA) in blood and plasma. ASA-d4 and SA-d4 were used as internal standards. The method was applied to evaluate: (a) the "in vitro" ASA degradation by esterases in whole blood and plasma, as a function of time and concentration; (b) the "in vivo" kinetics of ASA and SA after 7 days of oral administration of EC-ASA or plain-ASA (100 mg) in healthy volunteers (three men and three women, 37-63 years). Parameters of esterases activity were Vmax 6.5 ± 1.9 and Km 147.5 ± 64.4 in plasma, and Vmax 108.1 ± 20.8 and Km 803.2 ± 170.7 in whole blood. After oral administration of the two formulations, tmax varied between 3 and 6 h for EC-ASA and between 0.5 and 1.0 h for plain-ASA. Higher between-subjects variability was seen after EC-ASA, and one subject had a delayed absorption over eight hours. Plasma AUC was 725.5 (89.8-1222) for EC-ASA, and 823.1(624-1196) ng h/mL (median, 25-75% CI) for plain ASA. After the weekly treatment, serum levels of TxB2 were very low (< 10 ng/mL at 24 h from the drug intake) in all the studied subjects, regardless of the formulation or the tmax. This method proved to be suitable for studies on aspirin responsiveness.

Is it safe to take Radix Salvia Miltiorrhiza - Radix Pueraria Lobate product with warfarin and aspirin? A pilot study in healthy human subjects.

ETHNOPHARMACOLOGICAL RELEVANCE: Radix Salvia Miltiorrhiza (Danshen) and Radix Pueraria Lobate (Gegen) are officially listed in the Chinese Pharmacopoeia and have long been used together as a Compound Chinese Traditional Medicine (CCTM) for treatment of coronary heart diseases, which are often co-administered with aspirin or warfarin to patients suffering from cardiovascular diseases. AIM OF STUDY: Since significant pharmacokinetic and pharmacodynamic interactions between Danshen-Gegen (DG) formula and aspirin/warfarin have been observed in our previous rat studies, the current study was proposed aiming to further verify such pharmacokinetic and pharmacodynamic interactions in healthy human subjects and explore related mechanisms. MATERIALS AND METHODS: A 5-day, multiple dose, five-session clinical trial has been carried out (n = 14) with 2-week washout periods between sessions, during which the subjects would receive different combinations of the medications. Plasma samples were collected for pharmacokinetic evaluation, and whole blood samples were collected for pharmacodynamic evaluation. In addition, an in-vitro mechanistic study is conducted to investigate the role of danshensu on the anti-thrombotic and anti-platelet aggregation effects of warfarin and aspirin respectively. RESULTS: Significant pharmacokinetic and pharmacodynamic herb-drug interactions were observed in healthy human subjects. pharmacokinetically, co-administration of DG with aspirin or warfarin could lead to a moderately increased AUC0→t of aspirin and a decreased AUC0→t of 7-hydroxyl warfarin respectively. The systemic exposure of danshensu (DSS, the marker component of DG) would be significantly increased after co-administration with warfarin. Pharmacodynamically, a reduction in systemic thromboxane B2 concentration was noticed after administration of DG with aspirin, which could be associated with the increased systemic exposure of aspirin and the synergistic effect of danshensu, aspirin and salicylic acid on cyclooxygenase (COX) inhibition. An offset on the warfarin induced soluble thrombomodulin induction was observed after its co-administration with DG, which could be partially attributed to the COX-2 inhibition effect of danshensu. CONCLUSION: Our results indicated that co-administration of DG with aspirin/warfarin would lead to significant pharmacokinetic and pharmacodynamic herb-drug interactions in healthy human subjects.

Effect of low-dose aspirin on serum uric acid levels in Chinese individuals over 60: subanalysis of a multicentre randomized clinical trial.

OBJECTIVE: Uric acid is considered a biomarker for cardiovascular risk. Only a few studies have investigated the effect of aspirin on serum uric acid (SUA) levels with contradictory results. The present study evaluated the effect of aspirin on SUA levels in Chinese individuals over 60 years of age. PATIENTS AND METHODS: Subjects over 60 with coronary artery disease or multiple cardiovascular risk factors were enrolled in a multicentre randomized clinical trial. Eligible subjects were randomized to receive 50 mg or 100 mg aspirin daily. Levels of arachidonic acid-induced platelet aggregation performed by light transmission aggregometry (LTA-AA) and SUA were measured at randomization and two weeks thereafter. In this subanalysis, subjects without aspirin use prior to enrolment were chosen. RESULTS: A total of 446 subjects were analysed, of which 151 subjects took 50 mg aspirin, and 295 took 100 mg aspirin. Hyperuricaemia was present in 23.3% (104/446) of subjects at baseline. LTA-AA levels were significantly reduced in subjects after taking aspirin for two weeks (both 50 mg and 100 mg, p < 0.001). SUA levels were decreased after aspirin administration (311 µmol/L vs. 302 µmol/L, p < 0.001). Further analysis showed SUA levels were unchanged in normouricaemic subjects (284 µmol/L vs. 280 µmol/L, p > 0.05), while slightly decreased in hyperuricaemic subjects (429 µmol/L vs. 392 µmol/L, p < 0.001). CONCLUSIONS: Our study showed that both 50 mg and 100 mg aspirin significantly inhibited platelet aggregation. Aspirin treatment for two weeks showed no hyperuricaemic effect in people over 60. SUA levels were unchanged after taking aspirin in normouricaemic subjects but decreased in hyperuricaemic subjects. This trial was registered at www. chictr.org.cn as ChiCTR1800018517.

Safety and Pharmacokinetics of DS-1040 Drug-Drug Interactions With Aspirin, Clopidogrel, and Enoxaparin.

DS-1040, a novel low-molecular-weight inhibitor of activated thrombin-activatable fibrinolysis inhibitor, is under development for the treatment of thromboembolic diseases including venous thromboembolism and acute ischemic stroke. Here we describe the results of 3 studies that evaluated the safety and tolerability of DS-1040 along with the effect on DS-1040 pharmacokinetic (PK) parameters, when dosed alone or when coadministered with aspirin (NCT02071004), clopidogrel (NCT02560688), or enoxaparin in healthy subjects. Concomitant administration of single-dose DS-1040 with multiple-dose aspirin, multiple-dose clopidogrel, or single-dose enoxaparin, consistent with clinically relevant dose regimens, was safe and well tolerated with no serious treatment-emergent adverse events (TEAEs), TEAEs leading to discontinuation, bleeding-related TEAEs, and no significant changes in coagulation parameters. DS-1040 did not prolong bleeding time when administered concomitantly with aspirin or clopidogrel. In the aspirin study, DS-1040 PK was evaluated following the concomitant administration with multiple-dose aspirin, where the plasma DS-1040 exposure (peak plasma concentration [Cmax ] and area under the concentration-time curve [AUCinf ]) was to be similar to the data previously published in the first-in-human study of DS-1040 in healthy subjects. The PK parameters of DS-1040 coadministered with clopidogrel were similar to those of DS-1040 alone, with small increases in geometric means for Cmax (7%) and AUClast (9%). When coadministered with enoxaparin, the PK parameters of DS-1040 were not affected (1.1% and 1.5% decreases in geometric means for Cmax and AUClast , respectively). Therefore, concomitant administration of DS-1040 and clopidogrel or enoxaparin did not demonstrate PK drug-drug interactions.

Intake of aspirin prior to metamizole does not completely prevent high on treatment platelet reactivity.

PURPOSE: Metamizole can sterically inhibit aspirin (ASA) from binding to cyclooxygenase 1 (COX1). It is recommended that ASA should be taken 30 min prior to metamizole to maintain the irreversible inhibition of arachidonic acid (AA)-induced platelet aggregation. We aimed to analyse the inhibitory effect of ASA and metamizole on AA-induced platelet aggregation over the course of the day. METHODS: We analysed hospitalized patients who ingested ASA at least 30 min prior to metamizole (recommended dosing group, n = 15), metamizole prior or simultaneously with ASA (not recommended dosing group, n = 16) and patients with unknown or mixed intake (mixed dosing group, n = 5). AA-induced light transmission (LTA) and impedance aggregometry (IA) were measured before, 1-2 and 5-6 h after the intake of ASA ± metamizole. RESULTS: Maximum AA-induced LTA prior to the intake of ASA was significantly lower and the rate of high on treatment platelet reactivity (HTPR) higher in the recommended compared with the not recommended dosing group (19.6% vs. 46.9%, p = 0.011 and 4/15 vs. 12/16 patients, p = 0.017). There was no difference when IA was used. Maximum AA-induced LTA after the intake of ASA ± metamizole was lower in patients in the not recommended but not in the recommended dosing group. All patients with HTPR in the recommended dosing group had regular inhibition of AA-induced LTA after discontinuation of metamizole. CONCLUSION: Co-medication of ASA and metamizole significantly influences platelet inhibition with variations during the day and can cause HTPR in patients taking ASA prior to metamizole or simultaneously.

Hepatic dysfunction secondary to Kawasaki disease: characteristics, etiology and predictive role in coronary artery abnormalities.

Coronary artery abnormalities (CAAs) are prominent during the acute Kawasaki disease (KD) episode and represent the major contributors to the long-term prognosis. Several meta-analysis and published scoring systems have identified hepatic dysfunction as an independent predictor of CAA risks. The medical records of 210 KD children were reviewed. Blood samples were collected from all subjects at 24 h pre-therapy and 48 h post-therapy, respectively. Liver function test (LFT) and inflammatory mediators were detected. Multivariate logistic regression analysis was conducted to identify the reliable biomarkers predicting whether CAAs existed or not in KD patients. 90.95% of KD patients had at least 1 abnormal LFT. Hypoalbuminemia was the most prevalent type of hepatic dysfunction, followed by elevated aspartate aminotransferase, low TP, low A/G and hyperbilirubinemia, respectively. The elevated inflammatory mediators (procalcitonin and C-reactive protein) and moderate dose of aspirin played a synthetic role in hepatic dysfunction secondary to KD. However, LFT presented no significant differences between infectious and noninfectious conditions. By a multivariate analysis, a lower albumin/globulin ratio (A/G, OR 13.50, 95% CI 3.944-46.23) served as an independent predictor of CAAs and had a sensitivity of 56.25%, and a specificity of 61.11% at a cutoff value of < 1.48. In conclusion, hepatic dysfunction is a common complication during the acute KD episode, characterized by elevated serum liver enzymes, hypoalbuminemia and hyperbilirubinemia. Systemic inflammation and aspirin, rather than infectious agents, are both the major contributors of hepatic dysfunction secondary to KD. A lower A/G serves as an independent predictor of CAAs.

Role of aspirin-triggered lipoxin A4, aspirin, and salicylic acid in the modulation of the oxidative and inflammatory responses induced by plasma from women with pre-eclampsia.

PROBLEM: Oxidative stress and inflammation are key events leading to pre-eclampsia, involved in several maternal deaths. Low doses of acetylsalicylic acid (ASA) are used in the prevention and treatment of pre-eclampsia. The synthesis of aspirin-triggered lipoxin (ATL) by cyclooxygenase-2 acetylation is an alternative mechanism of ASA, which could explain the effectiveness of ASA treatments. The aim of this study was to evaluate the role of ASA, salicylates, and ATL in the modulation of the oxidative and inflammatory responses induced by plasma from women with pre-eclampsia. METHOD OF STUDY: Plasma from 14 women with pre-eclampsia and 17 normotensive pregnant women was probed for inducing oxidative and inflammatory responses on endothelial cells and U937 promonocytes. The role of ATL, ASA, and salicylic acid (SA) on these events was evaluated. RESULTS: Plasma from women with pre-eclampsia induced TBARS and nitrotyrosine production on endothelial and U937 cells. Pre-treatment with both ATL and ASA decreased the TBARS production, while ATL decreased the nitrotyrosine. Pre-eclamptic plasma augmented the translocation of NF-kB on U937 cells, which decreased by a high dose of ASA and SA. Finally, the pre-eclamptic plasma increased the adhesion of leukocytes-PMN and monocytes-to endothelium, and we were able to determine a state of resolution of inflammation, since ATL decreased the PMN adhesion, and conversely, it increased the monocytes adhesion to endothelium. CONCLUSION: Together, these results suggest that ATL could explain the beneficial actions of ASA and support further research on mechanisms, real efficacy, and rational use of ASA in pre-eclampsia.

Characterization of aspirin esterase activity in health and disease: In vitro and ex vivo studies.

Due to its ability to irreversibly inactivate platelet cyclooxygenase, low-dose aspirin (ASA) is the most widely used antithrombotic agent. Although, studies in specific types of patients with cardiovascular disease (CVD) have shown an incomplete inhibition of platelet's cyclooxygenase, which may increase the variability in drug response. Some aspects of ASA pharmacokinetics (PK) still need further investigation. In this study, we aimed to characterise the contribution of esterase enzymes to ASA hydrolysis in the peripheral blood and to assess their activity in 36 healthy subjects (Ctrl) and 77 CVD patients. To this aim, an in vitro assay testing esterase activity in parallel to a liquid chromatography-tandem mass spectrometry method simultaneously detecting ASA and its main metabolites salicylic (SA) and gentisic acids, have been developed. Michaelis-Menten constant (Km) calculation, ASA esterase isoforms characterisation, and ASA PK study were then achieved. The calculated Km identified plasma esterases as the enzymes with the higher affinity for the substrate compared to the RBC ones. Both rivastigmine and 4-bis-nitrophenyl phosphate inhibited plasma esterase activities, suggesting that acetylcholinesterase and carboxylesterase largely contribute to ASA hydrolysis. The feasibility of the method here developed has been explored in Ctrl and CVD patients. The effect of ASA treatment on enzyme activity was further evaluated on an age, sex and BMI matched subgroup of patients and Ctrl (n = 10 for each subgroup, on and off ASA). No overall variations were evidenced in both CVD and Ctrl groups, even when the effect of ASA treatment was tested. This result suggests the absence of any influence of disease state, drug treatments, and comorbidities on plasma esterase and the inability of ASA intake to induce esterase function. In conclusion, the method here developed allows a better characterisation of ASA esterase activity and could be helpful to define the PK-related determinants of ASA responsiveness in order to personalise regimen in specific pathological conditions.

Hemorrhagic Complications of External Ventriculostomy in the Aspirin and P2Y12 Response Assay Era.

OBJECTIVE: Hemorrhagic complications reported from external ventricular drain (EVD) placement range from 10% to 44%. There remains limited literature investigating the incidence, risk factors, and mechanisms to prevent its occurrence, especially in the setting of antiplatelet agent use. We investigated EVD-related hemorrhagic complications after the implementation of VerifyNow platelet inhibition assays at our institution. METHODS: Medical records from 445 patients requiring EVD placement during a 2-year period during which our institution used the assays were reviewed. In total 345 patients were included, and 208 of them underwent assay testing. Indications for EVD included complications of cerebrovascular disease (n = 215), traumatic brain injury (n = 74), primary hydrocephalus (n = 23), and tumor (n = 33). Hemorrhage was defined as any new area of hyperdensity adjacent to or immediately along the catheter trajectory on computed tomography. RESULTS: There was no significant decrease in catheter-induced hemorrhage (CIH) between patients who underwent the VerifyNow assay and those who did not. Platelet transfusion did not significantly decrease the risk of CIH. CIH occurred in 17.7% of patients, significantly decreased when compared with our previously published incidence of 33% before platelet inhibition assay use (P < 0.05). Patients with cerebrovascular disease complications exhibited a significant decrease in CIH, 20% versus 39%, before assay use (P < 0.01). CONCLUSIONS: The incidence of hemorrhage is lower in our new cohort when compared with that of our previously published cohort. Despite the overall decreased rate of hemorrhage, there was no significant difference in hemorrhage rates between patients who did or did not undergo the assay. Platelet transfusion did not decrease the incidence of hemorrhage in patients with inhibited platelet function.

Acetaminophen and Acetylsalicylic Acid Exposure in a Preterm Infant after Maternal Overdose.

Here, we review the case of a 26 1/7 weeks' gestation premature female infant born to a mother who intentionally ingested a large quantity of Tylenol, aspirin, quetiapine, and prenatal vitamins. The neonate subsequently had markedly elevated levels of both Tylenol and aspirin when checked on the first day of life. While overall clinically stable, the neonate did demonstrate coagulopathy as evidenced by abnormal coagulation studies. Both poison control and a pediatric gastroenterologist/hepatologist were consulted. She successfully tolerated a course of N-acetylcysteine; her subsequent Tylenol level was markedly decreased and the neonate exhibited no further effects of toxicity. The salicylate level decreased on its own accord. To our knowledge, this is the first report of a neonate at 26 weeks' gestation that has been successfully managed for supratherapeutic concentrations of acetaminophen and acetylsalicylic acid secondary to maternal ingestion. While rare, this case may serve as a reference for the effectiveness of N-acetylcysteine in premature infants in such instances.

Investigation into the causes of aspirin resistance in healthy dogs.

Antiplatelet effects of acetylsalicylic acid (ASA, aspirin) may be poor in some individuals. Additionally, no method exists for predicting poor ASA response (resistance) in individual dogs. This study's main objective was to determine whether poor ASA response results from pharmacodynamic or pharmacokinetic causes. ASA concentrations causing 50% inhibition of platelet aggregation (in vitro IC50) were determined using whole blood collected from 21 drug-free healthy dogs to evaluate intrinsic sensitivity of platelets to ASA. Dogs were then administered ASA at 4 mg/kg once orally. Percent decrease in platelet aggregation from baseline, and plasma ASA and salicylic acid (SA) concentrations (expressed as AUC values) were measured for up to 3 hr. By 3 hr, 13/21 (62%) dogs showed >50% aggregation inhibition, while 8/21 (38%) dogs showed <50% inhibition. Aggregation inhibition values were negatively correlated with in vitro IC50 values (Rs = -0.49; p = 0.028) and positively correlated with ASA concentrations (Rs = 0.48; p = 0.03). Furthermore, ASA concentrations were strongly negatively correlated (Rs = -0.88; p < 0.001) with SA/ASA concentration ratios, an index of ASA metabolism to SA by esterase enzymes. Multiple linear regression analysis indicated that 59% (p < 0.001) of interindividual variability in aggregation inhibition was explained by in vitro IC50 values (29% of variability) and ASA concentrations (29% of variability). Consequently, poor in vivo ASA response in these dogs resulted from both pharmacodynamic (decreased platelet sensitivity) and pharmacokinetic (lower ASA concentrations) causes. Lower ASA concentrations may be explained by reduced bioavailability associated with higher esterase activities.

Malondialdehyde Assay in the Evaluation of Aspirin Antiplatelet Effects.

Aspirin is essential in secondary prevention of patients after myocardial infarction and with coronary artery disease. However, impaired pharmacodynamic response to aspirin is frequent (high on-treatment platelet reactivity [HTPR]). This leads to an enhanced prevalence of cardiovascular events and to an impaired clinical outcome. The current specific assays to evaluate aspirin antiplatelet effects are complex, time-consuming and demand for a high laboratory expertise. Therefore, we developed a potentially bedside assay based on the determination of malondialdehyde (MDA). MDA is a by-product of the thromboxane (TX) formation, which is synthesized in equimolar concentrations. In this study, we compared this MDA assay to the conventional assays in determination of pharmacodynamic aspirin response. For this, aspirin antiplatelet effects were measured in 22 healthy individuals and 63 aspirin treated patients using TX B2 formation enzyme-linked antibody assay, arachidonic acid induced light transmission aggregometry (LTA) and the new fluorometric MDA assay. In patients, MDA levels correlated well with TX formation (R = 0.81; 95% CI 0.69-0.88; p < 0.001) and LTA (R = 0.84; CI 0.74-0.91; p < 0.001). Receiver operating characteristic analyses revealed that the MDA assay does detect HTPR to aspirin sufficiently (area under the curve: 0.965; p < 0.001). The optimal cut-off was > 128 nmol/L (sensitivity of 100%, specificity of 91%). The new MDA assay is reliable in detecting HTPR. It is highly specific in the evaluation of antiplatelet effects by aspirin. This promising and potential bedside assay needs to be evaluated in clinical practice.

Research on the mechanism of drug-drug interaction between salvianolate injection and aspirin based on the metabolic enzyme and PK-PD model: study protocol for a PK-PD trial.

BACKGROUND: Coronary heart disease (CHD) is a common cardiovascular disease accounting for 10-20% mortality by heart disease worldwide. The gold standard treatment to manage CHD is aspirin, which may prevent myocardial infarction and sudden death; however, long-term use of aspirin may increase its side effects. Currently, more and more clinicians are exploring different approaches to use the right combination of medicine to enhance the efficacy and reduce side effects. Salvianolate can significantly inhibit the aggregation and activation of platelets in patients with CHD; however, its optimum combination with western medicine is not established or supported by clinical trial results. METHODS/DESIGN: This trial is a prospectively planned, open-labeled, parallel-grouped, single-centered clinical trial with aggregated pharmacodynamics-pharmacokinetics (PK-PD) data. All treatment courses will last for 10 days and blood sample will be acquired before administration on days 8, 9, and 10, and after administration at 5 min, 15 min, 30 min, 45 min, 1 h, 2 h, 4 h, 8 h, 12 h, and 24 h on day 10. This trial uses PK-PD modeling to provide a description of the concentration-effect relationship and an estimate of pharmacological potency of the medicine. The primary outcome will be changes in aspirin esterase and catechol-o-methyltransferase (COMT) activity at different blood concentrations to determine the PK-PD characteristics of the combination of salvianolate and aspirin, followed by analysis of the correlation between exposure level and pharmacodynamic index of the medicines. DISCUSSION: This trial will aim to evaluate the relationship between changes in the pharmacokinetics and therapeutic effect index in the combined use of salvianolate and aspirin. It also discusses the possible mechanism of medicine combination in the treatment for CHD and provides an experimental basis for a clinically rational medicine combination. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03306550 . Registered on 9 October 2017. ClinicalTrials.gov https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S0007D8H&selectaction=Edit&uid=U0003QY8&ts=2&cx=oiuc9g.

Metal-Organic Frameworks as Efficient Oral Detoxifying Agents.

Poisoning and accidental oral intoxication are major health problems worldwide. Considering the insufficient efficacy of the currently available detoxification treatments, a pioneering oral detoxifying adsorbent agent based on a single biocompatible metal-organic framework (MOF) is here proposed for the efficient decontamination of drugs commonly implicated in accidental or voluntary poisoning. Furthermore, the in vivo toxicity and biodistribution of a MOF via oral administration have been investigated for the first time. Orally administered upon a salicylate overdose, this MOF is able to reduce the salicylate gastrointestinal absorption and toxicity more than 40-fold (avoiding histological damage) while exhibiting exceptional gastrointestinal stability (<9% degradation), poor intestinal permeation, and safety.

Effect of Red Ginseng Extract on the Pharmacokinetics of Aspirin Metabolite in Sprague Dawley Rats.

Objective To investigate whether red ginseng extract can affect the pharmacokinetics of aspirin in Sprague Dawley (SD) rats.Methods Totally, 12 male SD rats were randomly and uniformly divided into the aspirin group (aspirin 10.42 mg·kg -1) and the combined group (red ginseng extraction 0.5 mg·g -1 + aspirin 10.42 mg·kg -1). After intragastric administration of drugs, blood samples (0.5 ml once) were drawn from orbit at 0.083, 0.25, 0.5, 1, 2, 4, 6, 8, 10 and 12 hours after dosing. Plasma concentration of salicylic acid (metabolite of aspirin) was detected with ultraviolet-visible high performance liquid chromatography (HPLC). The reliability of the procedure was verified with respect to specificity, linearity, accuracy, precision, extraction recovery and matrix effect, and stability. Pharmacokinetics of salicylic acid was evaluated by using non-compartmental model. Results The method was proved to be validated. Compared with the aspirin group, area under the curve (AUC 0-t) and maximum concentration of salicylic acid in rats of the combined group increased obviously (P<0.01), while clearance rate (CLz/F) decreased clearly (P<0.05).Conclusion The in vivo study showed that red ginseng extract can help the internal absorption of aspirin, and delay the in vivo metabolism of aspirin.

Metamizole and Platelet Inhibition by Aspirin Following On-Pump Coronary Artery Bypass Grafting.

OBJECTIVE: The purpose of the study was to evaluate the impact of intravenous metamizole on platelet inhibition by aspirin in patients with coronary artery disease early after on-pump coronary artery bypass grafting (CABG). DESIGN: Prospective, single-blind, randomized trial. SETTING: Tertiary referal hospital. PARTICIPANTS: The study comprised 43 patients with multivessel coronary artery disease undergoing CABG. INTERVENTIONS: Patients were randomized to postoperative intravenous metamizole ± opioids (study group; n = 23) or opioids alone (control group; n = 20). Aspirin was withheld at least 7 days before the surgery and reinitiated (300 mg) immediately after the procedure prior to metamizole use, and continued daily thereafter (150 mg). Platelet function was evaluated using multielectrode impedance aggregometry (acid-induced platelet activation [ASPI] and collagen-induced platelet activation [COL] test), P-selectin expression and urinary 11-dehydro-thromboxane B2 (11-DTXB2) level at baseline, postoperative day (POD) 0, POD 1, POD 2, and POD 6. Residual platelet reactivity (RPR) was defined as ASPI test >400 AU*min. MEASUREMENTS AND MAIN RESULTS: In all study participants, postoperative ASPI test value moderately decreased (1058.2 v 966.6 AU*min, p = 0.047), urinary 11-DTXB2 level increased (923.4 v 4367.3 pg/mg, p < 0.001), and P-selectin expression and COL test value remained stable postprocedure. The decreases of ASPI (p = 0.146) and COL test (p = 0.642), and P-selectin expression (p = 0.318) did not differ between both groups. Patients in the control group had higher postoperative increase of urinary 11-DTXB2 level (p = 0.001). The prevalence of RPR was high and comparable between study and control groups (day 1, 95.6% v 100%, p = 0.535; day 6, 100% v 90%, p = 0.21). Multivariate analysis revealed that metamizole use did not predict the fluctuations of ASPI and COL test values and P-selectin expression, yet it independently predicted postoperative change of 11-DTXB2 level (b = -0.518, p = 0.001). CONCLUSIONS: Intravenous metamizole preceded by a loading dose of aspirin did not modify platelet response to aspirin in the postoperative period after CABG.

Impaired liver cytochrome P450 2C11 activity after dual antiplatelet therapy with aspirin and clopidogrel in rats.

1. Aspirin (ASA) and clopidogrel (CLP) are used in combination as dual antiplatelet therapy (DAPT) for acute coronary syndrome based on their complementary mechanisms for platelet aggregation inhibition. However, the pharmacokinetics of such drug combination usage has not been thoroughly investigated. 2. In the current study, an LC-MS/MS method was developed to simultaneously determine the plasma concentrations of ASA and its metabolite salicylic acid (SA) with CLP and its metabolites, clopidogrel carboxylic acid (CLPM) and clopidogrel active metabolite derivative (CAMD). The pharmacokinetics of ASA, SA, CLP, CLPM and CAMD in rats receiving two-week DAPT with ASA and CLP were then determined. 3. After two-week DAPT with ASA and CLP in rats, the activities of aspirin esterase and rCyp2c11, enzymes mediating rat metabolism of ASA and CLP, respectively, in prepared rat liver microsomes were measured followed by further determination of rCyp2c11 mRNA expressions. The results demonstrated that DAPT led to minimal impact on aspirin esterase activity but significant decrease in rCyp2c11 activity and mRNA expression. 4. In conclusion, our findings on impairment in rCyp2C11 activity and mRNA expression by DAPT in rats could provide guidance on its safe clinical use with other CYP 2C19 substrates.

Hansen solubility parameters for assay method optimization of simvastatin, ramipril, atenolol, hydrochlorothiazide and aspirin in human plasma using liquid chromatography with tandem mass spectrometry.

A simple, specific, sensitive, validated method was developed using liquid chromatography with tandem mass spectrometry with electrospray ionization of human plasma for the simultaneous estimation of drugs (simvastatin, ramipril, atenolol, hydrochlorothiazide, and aspirin) of PolycapTM capsule used in cardiovascular therapy. The interaction of these actives including internal standards between the stationary and mobile phase were investigated using Hansen solubility parameters. Chromatographic separation was performed on Phenomenex Synergi Polar-RP (30 × 2 mm, 4 µm) column with a gradient mobile phase composition of acetonitrile and 5 mM ammonium formate for positive mode and 0.1% formic acid in both water and acetonitrile for negative mode. The flow rate and runtime were 1.0 mL/min and 3.5 min, respectively. Sample extraction was done by protein precipitation using acetonitrile, enabling a fast analysis. The calibration ranges from 0.1 to 100, 0.1 to 100, and 1 to 1000 ng/mL for simvastatin, ramipril, and atenolol using internal standard carbamazepine in positive mode, respectively, whereas it was 0.3-300 and 2-2000 ng/mL for hydrochlorothiazide and aspirin using internal standard 7-hydroxy coumarin in negative mode, respectively. Hansen solubility parameters can be used as a high-throughput optimizing tool for column and mobile phase selection in bioanalysis. This validated bioanalytical method has the potential for future fixed dose combination based preclinical and clinical studies that can save analysis time.

Fisher Discrimination of Metabolic Changes in Rats Treated with Aspirin and Ibuprofen.

BACKGROUND: Aspirin and ibuprofen are the most frequently prescribed non-steroidal anti-inflammatory drugs in the world. However, both are associated with a variety of toxicities. We applied serum metabonomics and Fisher discrimination for the early diagnosis of its toxic reaction in order to help diagnose these toxicities. METHODS: A total of 45 rats were randomly divided into Control group, Aspirin group, and Ibuprofen groups. The experiment groups were given intragastric aspirin (15 mg/kg) or ibuprofen (15 mg/kg) for 3 weeks. Liver function tests were performed and blood metabonomics were analyzed by gas chromatography-mass spectrometry. RESULTS: The most important compounds altered were trihydroxybutyric acid and l-alanine in the aspirin group, and acetoacetic acid, l-alanine, and trihydroxybutyric acid in the ibuprofen group. With respect to metabolic profiles, all 3 groups were completely distinct from one another. Fisher discrimination showed that 91.1% of the original grouped cases were correctly classified by the third week. However, only 55.6% of liver function tests were able to classify grouped cases correctly. CONCLUSION: Trihydroxybutyric acid, l-alanine, and acetoacetic acid were the most significant indicators of altered serum metabolites following intragastric administration of aspirin and ibuprofen in rates. These metabolomic data may be used for classification of aspirin and ibuprofen toxicity.

Suspected aspirin resistance in individual healthy adult warmblood horses.

The reasons for this prospective experimental study were to determine a dosing scheme with loading and maintenance dose of aspirin inducing inhibition of platelet function measured by whole blood impedance aggregometry. Ten horses received aspirin orally in the morning with one loading dose of 4.7-5 mg/kg and maintenance doses of 1-1.3 mg/kg daily the following 4 days. Aggregometries (COLtest, ASPItest, ADPtest) and serum salicylic acid were measured. ASPItest showed significant difference in inhibition at 24 and 48 hr (p < .05) and 96 hr (p < .01). Significant change for ADPtest and COLtest couldn't be detected. Serum salicylic acid concentrations were significantly (p < .01) increased at 6 and 12 hr. Despite this, three horses failed any inhibitory effect of platelet function, suspecting an aspirin resistance. Regarding the other seven horses platelet aggregation induced by ASPItest was reduced between 37% and 100% from baseline at 6 and 12 hr and between 0 and 98% during the next 4 days. Correlations of serum concentration of salicylic acid and aggregometries couldn't be detected. It can be presumed that equine platelets are less susceptible to aspirin what may compromise eventually the anticoagulatory effects and efficacy in preventing and treating diseases with increased platelet activation as endotoxaemia or laminitis.