Inhibitory Influence of Panax notoginseng Saponins on Aspirin Hydrolysis in Human Intestinal Caco-2 Cells.

Herb-drug interactions are important safety concerns in clinical practice. The interactions occur firstly in the intestinal absorption for orally administered drugs. Aspirin and Panax notoginseng saponins (PNS)-based drugs are often combined in China to prevent larger-artery atherosclerosis. Here, we aimed to characterize the aspirin transport across Caco-2 cell monolayers, a model of the intestinal absorption, and further to evaluate the influence of PNS on aspirin hydrolysis and the relating mechanisms. Transcellular transport of aspirin and the influence of PNS were explored using Caco-2 cell monolayers. The protein expression of human carboxylesterase 1 (hCE1) and hCE2 in Caco-2 cells after PNS treatment was analyzed by ELISA, and the mRNA level were determined by qRT-PCR. In the study, Caco-2 cells showed high level of hydrolase activity, and most aspirin was hydrolyzed inside the cells during the transport process. Interestingly, PNS were demonstrated to inhibit the esterase activities responsible for aspirin hydrolysis in Caco-2 cells. PNS could also decrease the protein expression of hCE1 and hCE2, whereas exhibited minor effect on the mRNA expression. These results indicated that oral administration of PNS-based drugs might inhibit the hydrolysis of aspirin during intestinal absorption thus promoting its bioavailability.

Influence of omeprazole and famotidine on the antiplatelet effects of clopidogrel in addition to aspirin in patients with acute coronary syndromes: a prospective, randomized, multicenter study.

BACKGROUND: It remains unclear whether concomitant use of omeprazole attenuates platelet function as compared with that of famotidine in patients with acute coronary syndromes (ACS) who receive clopidogrel. METHODS AND RESULTS: In this prospective study, 130 ACS patients treated with aspirin and clopidogrel who underwent stent implantation were randomly assigned to receive a Japanese standard dose of omeprazole 10mg daily or famotidine 20mg daily for at least 4 weeks. Between 14 and 28 days after enrollment, there was no significant difference in the platelet reactivity index (PRI) measured with vasodilator-stimulated phosphoprotein phosphorylation assay between the omeprazole group (n=65) and famotidine group (n=65) (55±17% vs. 51±19%; P=0.26). The cumulative rate of adverse cardiovascular events at 12 months was similar in the groups (13% vs. 17%; P=0.81). The PRI was similar (54.9±17.9% vs. 54.0±17.8%; P=0.83) in the omeprazole group (n=33) and the famotidine group (n=39) among patients with ST-elevation myocardial infarction (STEMI). However, there was a trend toward a higher PRI (55.2±15.9% vs. 46.4±19.4%; P=0.06) in the omeprazole group (n=32) as compared with the famotidine group (n=26) among patients without persistent ST-segment elevation ACS. CONCLUSIONS: As compared with famotidine, concomitant use of low-dose omeprazole does not significantly attenuate the antiplatelet effects of clopidogrel in patients with ACS, especially in those with STEMI.

Emergency reversal of clopidogrel in the setting of spontaneous intracerebral hemorrhage.

OBJECTIVE: To compare outcomes in the setting of spontaneous intracerebral hemorrhage (ICH) in patients taking aspirin (acetylsalicylic acid [ASA]) versus patients taking clopidogrel before hospitalization. METHODS: Patients admitted to the neurosurgical service with a spontaneous ICH while taking an antiplatelet agent were prospectively identified and retrospectively reviewed. Two groups of 28 consecutive patients taking ASA or clopidogrel on admission were ultimately evaluated. RESULTS: Patients in the clopidogrel group had a mean age of 72.6 years, and patients in the ASA group had a mean age of 65.8 years (P=0.04). Patients taking clopidogrel before hospitalization were significantly more likely than patients taking ASA to experience an increase in hematoma volume (P=0.05). Patients in the ASA group trended toward being discharged to home more frequently than other destinations (P=0.07). The in-hospital mortality rates in this series were 14.3% for the ASA group and 28.6% for the clopidogrel group. However, this association did not reach statistical significance (P=0.19). CONCLUSIONS: In this study, patients taking clopidogrel showed more hematoma expansion, higher in-hospital mortality rates, and a decreased likelihood of a home discharge compared with patients taking ASA alone.

Antagonism of the antithrombotic and anti-atherosclerotic actions of aspirin by rofecoxib in the cholesterol-fed rabbit.

BACKGROUND AND PURPOSE: Most patients at elevated cardiovascular risk receive long-term aspirin (ASA) anti-platelet treatment. The present study specifically addresses the pharmacological interactions between selective COX-2 inhibitors and ASA and the possible consequences for the thrombotic risk during long-term treatment. EXPERIMENTAL APPROACH: New Zealand white rabbits were fed a standard laboratory diet supplemented with 1% cholesterol (CON) for 12 weeks. Age-matched control rabbits were fed the same standard diet without addition of cholesterol (SD). Rabbits were randomly assigned to one of the following groups: rofecoxib (ROFE, 25 mg·kg⁻¹, bid), acetylsalicylic acid (ASA, 5 mg·kg⁻¹, bid) or a combination of both (ASA + ROFE). At the end of the feeding period, the severity of atherosclerotic plaque formation was assessed in the aorta. Thrombus formation was assessed in the left carotid artery using a modified Folts procedure. KEY RESULTS: Treatment of cholesterol-fed rabbits with ASA significantly reduced plaque formation. This reduction in lesion size was not observed in animals treated with the combination of rofecoxib and ASA. In the modified Folts model, treatment with either rofecoxib or ASA increased the total blood flow above that of untreated animals. This increase was statistically significant in the case of ASA, while cotreatment with rofecoxib abolished this ASA effect completely and reduced the total flow rate to the levels seen in untreated hypercholesterolaemic controls. CONCLUSIONS: COX-2 inhibition by rofecoxib attenuates the antithrombotic and anti-atherosclerotic effects of ASA during long-term treatment in cholesterol-fed rabbits.

Investigating the antagonistic action between aspirin and tamoxifen with HSA: identification of binding sites in binary and ternary drug-protein systems by spectroscopic and molecular modeling approaches.

The combination of several drugs is often necessary, especially during long-term therapy. A competitive binding of the drugs can cause a decrease of the amount of drugs actually bound to the protein and increase the biologically active fraction of the drug. The aim of this study has been to analyze the interactions of tamoxifen (TMX) and aspirin (ASA) with human serum albumin (HSA) and to evaluate the mechanism of a simultaneous binding of TMX and ASA to the protein. Fluorescence analysis was used to estimate the effect of the drugs on the protein fluorescence and to define the binding and quenching properties of drug-HSA complexes. The binding sites for TMX and ASA were identified in ternary structures of HSA by means of spectrofluroscence. The analysis of the fluorescence quenching of HSA in binary and ternary systems pointed at TMX and ASA having an effect on the HSA-ASA and HSA-TMX complexes. Furthermore, the results of synchronous fluorescence, resonance light scattering and circular dichroism of the binary and ternary systems showed that the binding of TMX and ASA to HSA could induce conformational changes in HSA. Moreover, the simultaneous presence of TMX and ASA during binding to HSA should be taken into account in multi-drug therapy, as it induces the necessity of a monitoring therapy owing to the possible increase of uncontrolled toxic effects. Competitive site marker experiments demonstrated that the binding site of ASA and TMX to HSA differed in the binary system as opposed to in its ternary counterpart. Finally, molecular modeling of the possible binding sites of TMX and ASA in binary and ternary systems to HSA confirmed the experimental results.

Parameters of microcirculation in paired formations after single aspirin administration: laser Doppler flowmetry data.

Laser Doppler flowmetry showed that aspirin can induce blood flow reduction and transitory manifold increase or decrease in vascular tone in rat skin and kidneys. The dynamics is more illustrative when parameters of individual animals are evaluated and depends on the areas of blood flow recording. Deaths and reduction of narcotic sleep duration were noted in concomitant use of nembutal and aspirin.

In vitro effects of ethanol with aspirin on rat brain synaptosomes: the potential protective role of betaine.

Physicians recommend aspirin for prevention of heart attacks and stroke in people above the age of 40 years. In some cases, alcohol consumption accompanies aspirin intake. In this study, the in vitro effects of different doses of ethanol (50, 100, and 200 mM) and 100 microg/mL of aspirin and the possible protective role of betaine (0.5 and 1 mM) were investigated on rat cerebral synaptosomes. Synaptosomally enriched fractions, derived from Sprague Dawley rat brains, were incubated with ethanol and aspirin so as to measure sialic acid (SA), nitric oxide levels, and adenosine deaminase (ADA) activities, which are known to be the markers of alcohol damage. When combined with aspirin, ethanol increased SA levels compared with the control group at all doses, resulting in loss of SA residue from synaptosomal membrane. Betaine (0.5 mM) decreased SA levels with respect to the ethanol (200 mM) plus aspirin group (p < .05), thereby preventing SA loss. Moreover, betaine reversed the destructive effects of ethanol by elevating reduced nitric oxide levels. Aspirin, when combined with all doses of ethanol, increased ADA activity, which is crucial for purine metabolism. ADA activities were also elevated in betaine-administered groups. We propose that betaine is an effective compound in protecting the rat brain synaptosomes against ethanol and aspirin together.

Controversies and future perspectives of antiplatelet therapy in secondary stroke prevention.

Antiplatelet agents are a cornerstone in the treatment of acute arterial thrombotic events and in the prevention of thrombus formation. However, existing antiplatelet agents (mainly aspirin, the combination of aspirin and dipyridamole and clopidogrel) reduce the risk of vascular events only by about one quarter compared with placebo. As a consequence, more efficacious antiplatelet therapies with a reduced bleeding risk are needed. We give an overview of several new antiplatelet agents that are currently investigated in secondary stroke prevention: adenosine 5'-diphosphonate receptor antagonists, cilostazol, sarpogrelate, terutroban and SCH 530348. There are unique features in secondary stroke prevention that have to be taken into account: ischaemic stroke is a heterogeneous disease caused by multiple aetiologies and the blood-brain barrier is disturbed after stroke which may result in a higher intracerebral bleeding risk. Several small randomized trials indicated that the combination of aspirin and clopidogrel might be superior to antiplatelet monotherapy in the acute and early post-ischaemic phase. There is an ongoing debate about antiplatelet resistance. Decreasing response to aspirin is correlated independently with an increased risk of cardiovascular events. However, there is still no evidence from randomized trials linking aspirin resistance and recurrent ischaemic events. Similarly, randomized trials have not demonstrated a clinical significantly decreased antiplatelet effect by the concomitant use of clopidogrel and proton pump inhibitors. Nevertheless, a routine use of this drug combination is not recommended.

Identifying and assessing benefit-risk in primary care--a family physician's perspective.

For the family physician, NSAIDs, both traditional and cyclo-oxygenase-2 inhibitors, are a valuable contribution to managing arthritis and other rheumatological conditions in primary care. Yet, many of the patients seen by the family doctor have complex comorbidities and polypharmacy issues. This review looks at the main considerations for primary-care physicians while choosing an anti-inflammatory treatment for a hypothetical patient case study. In addition to looking at the evidence for gastrointestinal and cardiovascular risk, the concomitant use of aspirin with an NSAID is also examined. New evidence for interaction between selective serotonin re-uptake inhibitors is reviewed and the interaction between angiotensin-converting enzyme inhibitors and NSAIDs is considered. Making careful judgements based on individual needs, medical history and comorbidities is recommended based on the evidence reviewed.

The antiplatelet effect of aspirin is reduced by proton pump inhibitors in patients with coronary artery disease.

OBJECTIVE: To evaluate the effect of proton pump inhibitors (PPIs) on the platelet response to aspirin in patients with coronary artery disease (CAD). DESIGN: Case-control study. PATIENTS: 418 stable patients with CAD, 54 of whom were treated with PPIs. All patients were treated with non-enteric coated aspirin 75 mg/day and received no other antithrombotic drugs. MAIN OUTCOME MEASURES: Platelet aggregation was measured by Multiplate (Dynabyte, Munich, Germany) whole blood aggregometry induced by arachidonic acid 1.0 mmol/l and expressed as area under the aggregation curve (aggregation units*min). Platelet activation was assessed by soluble serum P-selectin. Compliance was confirmed by serum thromboxane B(2) levels. RESULTS: The distribution of age, sex, body mass index, blood pressure, family history of ischaemic heart disease, smoking, diabetes and the number of previous ischaemic events did not differ between groups. All patients were compliant with aspirin treatment according to serum thromboxane B(2) levels. Platelet aggregation (median 180 (interquartile range 119-312) vs 152 (84-226) aggregation units*min, p=0.003) and soluble serum P-selectin levels (88.5 (65.2-105.8) vs 75.4 (60.0-91.5) ng/ml, p=0.005) were significantly higher in patients treated with PPIs. Furthermore, these patients had significantly higher serum thromboxane B(2) levels (geometric mean 1.29 (95% CI 0.96 to 1.72) vs 0.92 (0.84 to 1.01) ng/ml, p=0.01). CONCLUSIONS: Patients with CAD treated with PPIs had a reduced platelet response to aspirin, as shown by increased residual platelet aggregation and platelet activation, compared with patients with CAD not taking PPIs. Concomitant use of aspirin and PPIs might reduce the cardiovascular protection by aspirin.

Emergency reversal of antiplatelet agents in patients presenting with an intracranial hemorrhage: a clinical review.

OBJECTIVE: Prehospital use of antiplatelet agents has been associated with an increased risk for intracranial hemorrhage (ICH) as well as a secondary increase in ICH volume after the initial hemorrhage. Strategies to reestablish platelet aggregation are used in clinical practice, but without any established guidelines or recommendations. This article serves to evaluate the literature regarding "reversal" of antiplatelet agents in neurosurgical populations. METHODS: PubMed and MEDLINE databases were searched for publications from 1966 to 2009 relating to intracranial hemorrhage and antiplatelet agents. The reference sections of recent articles, guidelines, and reviews were reviewed and pertinent articles identified. Studies were classified by two broad subsets: those describing intracranial hemorrhage relatable to a traumatic mechanism and those with a spontaneous intracranial hemorrhage. Two independent auditors recorded and analyzed study design and the reported outcome measures. RESULTS: For the spontaneous intracranial hemorrhage group, nine reports assessing antiplatelet effects on various outcome measures were identified. Eleven studies evaluating the use of prehospital antiplatelets before a traumatic intracranial hemorrhage were examined. CONCLUSION: The data assessing the relationship between outcome and prehospital antiplatelet agents in the setting of ICH is conflicting in both the trauma and the stroke literature. Only one retrospective review specifically addressed outcomes after attempted reversal with platelet transfusion. Further study is needed to determine whether platelet transfusion ameliorates hematoma enlargement and/or improves outcome in the setting of acute ICH.

Aspirin induces apoptosis through the blockade of IL-6-STAT3 signaling pathway in human glioblastoma A172 cells.

Aspirin has been reported to induce apoptosis in various cancer cell lines. However, the apoptotic effects of aspirin on human brain tumor cells are not well understood. Here, we have assessed the effect of aspirin on human gliobalstoma cell line A172 and found that aspirin induced the apoptosis of A172 cells, as determined by TUNEL assay, FACS analysis, and Hoechst staining. The underlying mechanism of this effect consists of reduction in the level of phosphorylated STAT3 (Tyr705), a transcription factor required for survival of A172 cells. Moreover, the expression of STAT3 target genes such as Cyclin D1, XIAP, and Bcl-2 that are essential for cell growth and survival was apparently attenuated after aspirin treatment. We also showed that the expression and secretion of interleukin-6 (IL-6), leading to STAT3 phosphorylation, was inhibited by aspirin. When administered exogenous IL-6 to aspirin-treated A172 cells, the phosphorylation of STAT3 and cellular apoptosis were restrained compared to aspirin only-treated cells. Taken together, our results indicate that aspirin causes apoptosis via down-regulation of IL-6-dependent STAT3 signaling, suggesting that aspirin could be therapeutically useful for a potential anti-glioblastoma therapeutic approach.

The interaction of ibuprofen and diclofenac with aspirin in healthy volunteers.

BACKGROUND AND PURPOSE: Aspirin reduces the risk of myocardial infarction and stroke by inhibiting thromboxane production in platelets. This inhibition can be competitively antagonized by some non-steroidal anti-inflammatory drugs (NSAIDs). EXPERIMENTAL APPROACH: By measuring thromboxane B(2) production in healthy volunteers, we investigated whether ibuprofen (800 mg three times daily for 7 days) or diclofenac (50 mg three times daily for 7 days) taken concurrently with aspirin 80 mg (once daily for 7 days) influenced the inhibitory effect of aspirin. The effects were compared with aspirin 30 mg (once daily for 7 days), which is the lowest dose of aspirin with a proven thromboprophylactic effect. KEY RESULTS: The median percentage inhibition of thromboxane B(2) levels by 30 mg or 80 mg aspirin was 90.3% (range 83.1-96.0%) and 98.0% (range 96.8-99.2%) respectively. The inhibition by concurrent administration of slow release diclofenac and 80 mg aspirin was 98.1% (range 97.2-98.9%), indicating no interference between aspirin and diclofenac. The inhibition decreased significantly by concurrent administration of immediate release ibuprofen and 80 mg aspirin (86.6%; range 77.6-95.1%) to a level less than 30 mg aspirin. CONCLUSIONS AND IMPLICATIONS: As alternatives are easily available, NSAIDs such as diclofenac should be preferred to ibuprofen for combined use with aspirin.

The ATP-gated P2X1 receptor plays a pivotal role in activation of aspirin-treated platelets by thrombin and epinephrine.

Human platelets express protease-activated receptor 1 (PAR1) and PAR4 but limited data indicate for differences in signal transduction. We studied the involvement of PAR1 and PAR4 in the cross-talk between thrombin and epinephrine. The results show that epinephrine acted via alpha(2A)-adrenergic receptors to provoke aggregation, secretion, and Ca(2+) mobilization in aspirin-treated platelets pre-stimulated with subthreshold concentrations of thrombin. Incubating platelets with antibodies against PAR4 or the PAR4-specific inhibitor pepducin P4pal-i1 abolished the aggregation. Furthermore, platelets pre-exposed to the PAR4-activating peptide AYPGKF, but not to the PAR1-activating peptide SFLLRN, were aggregated by epinephrine, whereas both AYPGKF and SFLLRN synergized with epinephrine in the absence of aspirin. The roles of released ATP and ADP were elucidated by using antagonists of the purinergic receptors P2X(1), P2Y(1), and P2Y(12) (i.e. NF449, MRS2159, MRS2179, and cangrelor). Intriguingly, ATP, but not ADP, was required for the epinephrine/thrombin-induced aggregation. In Western blot analysis, a low concentration of AYPGKF, but not SFLLRN, stimulated phosphorylation of Akt on serine 473. Moreover, the phosphatidyl inositide 3-kinase inhibitor LY294002 antagonized the effect of epinephrine combined with thrombin or AYPGKF. Thus, in aspirin-treated platelets, PAR4, but not PAR1, interacts synergistically with alpha(2A)-adrenergic receptors, and the PI3-kinase/Akt pathway is involved in this cross-talk. Furthermore, in PAR4-pretreated platelets, epinephrine caused dense granule secretion, and subsequent signaling from the ATP-gated P2X(1)-receptor and the alpha(2A)-adrenergic receptor induced aggregation. These results suggest a new mechanism that has ATP as a key element and circumvents the action of aspirin on epinephrine-facilitated PAR4-mediated platelet activation.

Pyrazolinone analgesics prevent the antiplatelet effect of aspirin and preserve human platelet thromboxane synthesis.

BACKGROUND: Anti-inflammatory analgesics, including ibuprofen and naproxen, are known to interfere with the antiplatelet effect of aspirin, presumably as a result of a drug-drug interaction at the level of platelet cyclooxygenase-1 (COX-1). OBJECTIVE: We studied whether dipyrone, which has recently been reported to inhibit COX isoforms by a mechanism different from conventional non-steroidal anti-inflammatory drugs (NSAIDs), also interferes with the antiplatelet effect of aspirin. METHODS: Arachidonic acid- and collagen-induced aggregation, as well as thromboxane formation, were measured in human platelet-rich plasma. Platelet P-selectin expression was determined by flow cytometry and cell-free COX enzyme activity was quantified by luminol-enhanced luminescence of human platelet microsomes. In addition, computerized docking was performed based on the crystal structure of COX-1. RESULTS: 4-Methylaminoantipyrine (MAA), the active metabolite of dipyrone, largely attenuated or even completely abolished the inhibition of arachidonic acid-induced platelet aggregation, thromboxane formation and P-selectin expression by aspirin. Similar results were obtained for other pyrazolinones, as well as for the conventional NSAIDs ibuprofen and naproxen. Moreover, MAA attenuated the effect of aspirin on COX activity of platelet microsomes, suggesting a competition with aspirin at the COX-1 enzyme. This was confirmed by docking studies, which revealed that MAA forms a strong hydrogen bond with serine 530 within the COX-1, thereby preventing enzyme acetylation by aspirin. CONCLUSION: This study demonstrates for the first time that dipyrone and other pyrazolinones have a high potential to attenuate or prevent the antiplatelet effect of aspirin. This should be considered if pyrazolinone analgesics are administered to patients with cardiovascular disease requiring antiplatelet aspirin therapy.

Accelerated thrombotic occlusion of a medium-sized coronary aneurysm in Kawasaki disease by the inhibitory effect of ibuprofen on aspirin.

The fate of coronary artery aneurysms (CAAs) caused by Kawasaki disease depends mainly on their initial size and shape. Small to medium-sized CAAs are known to regress to normal size or decrease in size, with a good outcome. A patient with Kawasaki disease is reported who had a medium-sized CAA prematurely occluded with thrombi during regression, resulting in myocardial ischemia. This event was probably due to simultaneous use of aspirin and ibuprofen. Thus, the concomitant use of ibuprofen should be avoided when aspirin is given as an antiplatelet agent because ibuprofen blocks the platelet inhibition induced by aspirin.