Determination of acetylsalicylic acid and its major metabolite, salicylic acid, in human plasma using liquid chromatography-tandem mass spectrometry: application to pharmacokinetic study of Astrix in Korean healthy volunteers

Pharmacokinetic Profile and Comparative Bioavailability of an Oral Fixed-Dose Combination of Metformin and Acetylsalicylic Acid (Aspirin)

Patients with diabetes face a 2-4-fold greater cardiovascular risk compared to those without diabetes. Both metformin and acetylsalicylic acid (aspirin) treatment have demonstrated a significant reduction in this risk. This single-center, open-label, sequence randomized, 2 × 2 crossover, single-dose clinical trial evaluated the pharmacokinetics profile and comparative bioavailability of a novel oral fixed-dose combination (FDC) of metformin/acetylsalicylic acid (500/100 mg tablet) versus the reference mono-drugs administered concomitantly, metformin 500 mg tablet and acetylsalicylic acid 100 mg tablet, in 22 healthy Mexican adult volunteers under fasting conditions. Blood samples were collected predose and at specified intervals across a 24-hour period following administration and were analyzed for metformin and salicylic acid using high-performance liquid chromatography coupled with tandem mass spectrometry. Test products were considered to have comparative bioavailability if confidence intervals of natural log-transformed (maximum plasma drug concentration (Cmax), (area under the plasma drug concentration-time curve form 0 up to last sampling time (AUC0 -t), and (area under the plasma drug concentration-time cruve from 0 up to infinity (AUC0 ∞) data were within the range of 80%-125%. The results obtained from the present clinical study demonstrate the comparative bioavailability of the FDC when compared with the coadministration of reference mono-drugs. There were no adverse events or adverse reactions reported throughout the study.

Atmospheric solids analysis probe mass spectrometry: An easy bolt-on for the synthetic undergraduate teaching laboratory

RATIONALE

High costs and student numbers can often hinder implementation of mass spectrometry (MS) in the undergraduate teaching laboratory, often with technicians running samples on students' behalf, and the implementation of MS only in discrete or isolated experiments. This study explores the use of atmospheric solids analysis probe MS (ASAP-MS) as a relatively low-cost, benchtop instrument, and its potential for application as a 'bolt-on' to existing undergraduate organic chemistry experiments.

METHODS

Thirteen products synthesised in undergraduate laboratory experiments were analysed by ASAP-MS, along with their starting materials. Analysis was carried out with a Waters RADIAN ASAP mass spectrometer, at four different cone voltages simultaneously to provide fragmentation information.

RESULTS

Out of the 13 undergraduate experiments, ASAP-MS was shown to be complementary in 11 of these, either through simple analysis of the precursor ion or by a more complex analysis of the fragments.

CONCLUSIONS

ASAP-MS provided spectra that both complement and enhance intended learning outcomes in existing organic chemistry experiments, showing its versatility as a bolt-on technique. Moving forward, ASAP-MS will be integrated into the University of Surrey's undergraduate teaching laboratory.

Synchronous spectrofluorimetric determination of favipiravir and aspirin at the nano-gram scale in spiked human plasma; greenness evaluation

Favipiravir and aspirin are co-administered during COVID-19 treatment to prevent venous thromboembolism. For the first time, a spectrofluorometric method has been developed for the simultaneous analysis of favipiravir and aspirin in plasma matrix at nano-gram detection limits. The native fluorescence spectra of favipiravir and aspirin in ethanol showed overlapping emission spectra at 423 nm and 403 nm, respectively, after excitation at 368 nm and 298 nm, respectively. Direct simultaneous determination with normal fluorescence spectroscopy was difficult. The use of synchronous fluorescence spectroscopy for analyzing the studied drugs in ethanol at Δλ = 80 nm improved spectral resolution and enabled the determination of favipiravir and aspirin in the plasma matrix at 437 nm and 384 nm, respectively. The method described allowed sensitive determination of favipiravir and aspirin over a concentration range of 10-500 ng/mL and 35-1600 ng/mL, respectively. The described method was validated with respect to the ICH M10 guidelines and successfully applied for the simultaneous determination of the mentioned drugs in pure form and in the spiked plasma matrix. Moreover, the compliance of the method with the concepts of environmentally friendly analytical chemistry was evaluated using two metrics, the Green Analytical Procedure Index and the AGREE tool. The results showed that the described method was consistent with the accepted metrics for green analytical chemistry.

Spider diagram and sustainability evaluation of UV-methods strategy for quantification of aspirin and sildenafil citrate in the presence of salicylic acid in their bulk and formulation

The cutting-edge combination of aspirin (ASA) and sildenafil citrate (SIC) has been presented as a suggested dosage form for the treatment of thin endometrium and erectile dysfunction, particularly in patients with cardiovascular diseases. However, ASA is highly sensitive to degradation into its major deterioration product, known as salicylic acid (SA). Consequently, it is eminently essential to evolve approaches for the synchronous quantification of ASA and SIC in the presence of SA. The main objective of this work is to develop three approaches for the synchronous quantification of ASA and SIC in the presence of SA in their commixtures and suggested formulations without any prior separation. Three green UV-methods were employed for the synchronous quantification, namely: Dual Wavelength in Ratio Spectra (DW-RS), Advanced Amplitude Centering (AAC), and Double Divisor of Ratio Difference Derivative (DDRD-D₁). In DW-RS and AAC two-wavelength manipulation was used for resolution, while in DDRD-D₁ only an appropriate wavelength for the synchronous quantification of the triplex commixture was used. All approaches can be able to resolve the highly interfering spectrum of the three components presented in the triplex commixture. Good linearity was inspected in the range of 20.0-100.0, 5.0-50.0, and 4.0-60.0 μg/mL for the ASA, SIC, and SA, respectively. All developed approaches have been advocated in accordance with ICH guidelines. All results from these approaches are presented and statistically reconciled with the proclaimed HPLC method, with no considerable differences. Furthermore, the approaches' eco-friendliness was predestined by Analytical Greenness (AGREE), and the complex GAPI. Moreover, the sustainability of the used solvent was evaluated by Green Solvents Selecting Tool (GSST); in addition, the greenness of the solvent was evaluated by Greenness Index tool with a spider diagram. The suggested UV-methods may be employed for routine quality control studies of the suggested formulations ASA & SIC since they were considered sustainable, economical, and effective.

Spectrophotometric Quantitative Analysis of Aspirin and Vonoprazan Fumarate in Recently Approved Fixed-Dose Combination Tablets Using Ratio Spectra Manipulating Tools

BACKGROUND

Low-dose aspirin (ASP) is prescribed to millions of people around the world as a secondary preventative strategy for the majority of significant cardiovascular events; however, it carries a substantial risk of gastric ulcer and bleeding. Cabpirin® tablets, which include low-dose ASP and vonoprazan fumarate (VON), are approved in Japan for the treatment of acid-related diseases in patients who require a low dose of ASP but are at risk of ASP-associated gastric ulcers.

OBJECTIVE

This paper describes the first published quantitative analytical approaches for the determination of ASP and VON.

METHOD

The normal ultraviolet absorption spectra of ASP and vonoprazan overlap significantly. The ratio spectra of the studied drugs were created and manipulated by ratio difference (RD) and first derivative of ratio spectra approaches. In the RD approach, the differences in the amplitude values between 229 and 283 nm enabled the quantitative analysis of ASP, and the differences in the amplitude values between 255 and 212 nm enabled the quantitative analysis of vonoprazan. In the first derivative of the ratio spectra approach, the created ratio spectra of each drug were transformed to the first-order derivative. ASP could be determined selectively at 237.40 nm without interference from vonoprazan. Moreover, vonoprazan could be determined selectively at 244 nm without interference from ASP.

RESULTS

The applied approaches were validated according to the ICH guideline, with good results. Linear correlations were obtained for ASP and vonoprazan over concentration ranges of 2-25 and 1-10 µg/mL, respectively.

CONCLUSIONS

The described methods were optimized, validated, and applied for determination of the studied drugs in the synthetic mixtures and in pharmaceutical tablets without interferences.

HIGHLIGHTS

Two spectrophotometric ratio spectra manipulating approaches were developed for the determination of the ASP and vonoprazan in their pharmaceutical combination tablets.

Aspirin Protects against UVB-Induced DNA Damage through Activation of AMP Kinase

The anti-inflammatory and chemopreventive activities of aspirin (ASA) may be mediated through its cyclooxygenase inhibitor function. We have previously shown that ASA can protect against UVR-induced skin inflammation and DNA damage; however, the role of inflammation in UV-induced DNA damage and the mechanism underlying ASA protection are poorly characterized. Using immunodeficient NOD scid gamma mice and immunocompetent C57BL/6 mice treated with immune cell‒depleting antibodies, we found that inflammation was not required for UVB-induced 8-oxoguanine and cyclobutane pyrimidine dimers in vivo. Unlike ASA, neither its immediate metabolite salicylate nor the cyclooxygenase inhibitor indomethacin reduced UVB-induced 8-oxoguanine or cyclobutane pyrimidine dimers in melanocyte Melan-a or keratinocyte HaCat cells in vitro. Moreover, addition of prostaglandin E₂ did not reverse the protective effect of ASA on UVB-treated cells. Phosphorylation of the 5' AMP protein kinase, observed in ASA-treated cells, could be blocked by the 5' AMP protein kinase inhibitor compound C. Compound C or 5' AMP protein kinase knockdown partially reduced ASA-mediated protection against UVB-induced DNA damage. Finally, injection of compound C partially reversed the protective effect of ASA on UVB-treated mouse skin in vivo. These studies suggest that ASA confers protection against UVB-induced DNA damage through the activation of 5' AMP protein kinase rather than through cyclooxygenase inhibition.

ASA Suppresses PGE2 in Plasma and Melanocytic Nevi of Human Subjects at Increased Risk for Melanoma

Potential anti-inflammatory and anticarcinogenic effects of aspirin (ASA) may be suitable for melanoma chemoprevention, but defining biomarkers in relevant target tissues is prerequisite to performing randomized controlled chemoprevention trials. We conducted open-label studies with ASA in 53 human subjects with melanocytic nevi at increased risk for melanoma. In a pilot study, 12 subjects received a single dose (325 mg) of ASA; metabolites salicylate, salicylurate, and gentisic acid were detected in plasma after 4-8 h, and prostaglandin E2 (PGE2) was suppressed in both plasma and nevi for up to 24 h. Subsequently, 41 subjects received either 325 or 81 mg ASA (nonrandomized) daily for one week. ASA metabolites were consistently detected in plasma and nevi, and PGE2 levels were significantly reduced in both plasma and nevi. Subchronic ASA dosing did not affect 5" adenosine monophosphate-activated protein kinase (AMPK) activation in nevi or leukocyte subsets in peripheral blood, although metabolomic and cytokine profiling of plasma revealed significant decreases in various (non-ASA-derived) metabolites and inflammatory cytokines. In summary, short courses of daily ASA reduce plasma and nevus PGE2 and some metabolites and cytokines in plasma of human subjects at increased risk for melanoma. PGE2 may be a useful biomarker in blood and nevi for prospective melanoma chemoprevention studies with ASA.

Gut Microbiota-Mediated Drug-Drug Interaction between Amoxicillin and Aspirin

The effects of antibiotics on the intestinal flora can create potential drug-drug interactions. The combination of amoxicillin and aspirin is high and there is a high probability of interaction. We used 16S rRNA, incubation experiments and liquid chromatography-tandem mass spectrometry to analyze rat biological samples to characterize the effect of amoxicillin on the pharmacokinetics of aspirin metabolites. We first discovered that amoxicillin reduced the species and number of intestinal flora in rats, such as reducing the abundance of Helicobacter pylori and Prevotella_copri. After 12, 24, and 36 hours of incubation, the remaining amount of aspirin in the aspirin and amoxicillin treatment groups decreased, and salicylic acid production increased, suggesting that aspirin is metabolized by the intestinal flora, and the main metabolite is salicylic acid. As the incubation time prolonged, the reduction of aspirin and the production of salicylic acid in the amoxicillin treatment group were slower. It is indicated that the metabolic activity of aspirin through the intestinal flora is slowed down after administration of amoxicillin. The pharmacokinetic experiments showed that after administration of amoxicillin, the area under the salicylic acid curve increased by 91.38%, the peak concentration increased by 60.43%, and the clearance rate decreased by 43.55%.The results demonstrated that amoxicillin affected the pharmacokinetics of aspirin active metabolite salicylic acid by slowing down the metabolic activity of intestinal flora on aspirin. The interaction between amoxicillin and aspirin mediated by the intestinal flora may affect the efficacy of aspirin and cause more significant adverse effects.

Evaluation of stability using one versus three tubes for each quality control concentration in matrix-based bioanalysis

Aim: Contract research organizations and pharmaceutical firms have performed stability testing using one of two methods: storing in the freezer a single tube of matrix for each quality control concentration (Method 1), followed by aliquoting and analysis; and storing three tubes for each quality control concentration, followed by analysis (Method 2). This research project was conducted to determine if there were detectable differences between Method 1 and Method 2. Methodology: Five model drugs were selected: teriflunomide (stable compound) and acetyl salicylic acid, simvastatin, tenofovir alafenamide and valganciclovir (stability concerns). Samples were stored at -80°C for 1, 3 and 12 months and then analyzed. Samples were also placed at different locations within the freezer. Results: For the drugs tested, the results suggest that there is no significant difference in the outcome of stability testing, regardless whether Method 1 or Method 2 was followed.

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.

Quantitative analysis of acetylsalicylic acid in human blood using volumetric absorptive microsampling

Volumetric absorptive microsampling (VAMS) is a novel sampling technique that allows for the collection of an accurate volume of blood by dipping a microsampler tip. The purpose of this study is to compare the requirement of a stabilizing reagent for the conventional venous blood sampling method versus VAMS in the analytical measurement of the concentration of acetylsalicylic acid. A high-performance liquid chromatography with mass spectrometry (LC-MS/MS) method was developed and validated for the accurate determination of acetylsalicylic acid in human blood. The blood samples spiked with acetylsalicylic acid with and without stabilizing reagent were absorbed into VAMS tips. In the whole blood sample, the same concentration was shown regardless of the addition of the stabilizing reagent, but the concentration decreased when the stabilizing reagent was not added to the VAMS sample. To apply the VAMS technology as a new blood sampling method, stabilizing reagents should be added before the analysis of acetylsalicylic acid concentration.

Acetylsalicylic acid in critically ill patients: a cross-sectional and a randomized trial

BACKGROUND

Despite decades of clinical use, the pharmacokinetics and the effects of acetylsalicylic acid (ASA) in critically ill patients remain ill-defined. We aimed to investigate the pharmacokinetics and the effects of different ASA formulations during critical illness.

DESIGN

A cross-sectional study and a randomized, parallel-group trial were performed. Critically ill patients under chronic oral ASA treatment (100 mg enteric-coated) were screened for high 'on-treatment' platelet reactivity (HTPR) according to arachidonic acid-induced whole-blood aggregometry. Thirty patients with HTPR were randomized to receive 100 mg ASA intravenously, 100 mg enteric-coated ASA bid (bis in die) or 81 mg chewable ASA (n = 10 per group). Serum thromboxane B2 (TXB2) levels, ASA and salicylic acid levels were quantified.

RESULTS

Of 66 patients, 85% (95% confidence intervals 74-93%) had HTPR. Compared to baseline infusion of 100 mg, ASA significantly reduced platelet aggregation after 24 h to median 80% (Quartiles: 66-84%). Intake of 81 mg chewable ASA significantly reduced platelet aggregation to 75% (54-86%) after four hours, but increased it to 117% after 24 h (81-163%). Treatment with 100 mg enteric-coated ASA bid decreased platelet aggregation after 24 h to median 56% (52-113%). Baseline TXB2 levels were median 0·35 ng/mL (0·07-0·94). Infusion of ASA or intake of 100 mg ASA bid reduced TXB2 levels to 0·07-0·18 ng/mL after 24 h, respectively. Chewable ASA reduced TXB2 levels only transiently. Pharmacokinetic analysis revealed highly variable absorption patterns of oral ASA formulations.

CONCLUSION

There is a very high prevalence of HTPR in critically ill patients on peroral ASA therapy, caused by an incomplete suppression of TXB2 and/or by impaired absorption of ASA.

ABCC3 Polymorphisms and mRNA Expression Influence the Concentration of a Carboxylic Acid Metabolite in Patients on Clopidogrel and Aspirin Therapy

Acetylsalicylic acid (ASA) and clopidogrel combined therapy has been reported to be beneficial in patients with acute coronary syndrome (ACS). Antiplatelet drug resistance, especially to clopidogrel, is a multifactorial phenomenon that affects a large number of ACS patients. The genetic contribution to this drug response is not fully elucidated. We investigated the relationship of ABC-type efflux subfamily C member 3 (ABCC3) polymorphisms and mRNA expression with plasma concentrations of clopidogrel, salicylic acid (SA) and a carboxylic acid metabolite (CAM). Clopidogrel, CAM and SA plasma concentrations were measured simultaneously by liquid chromatography-tandem mass spectrometry (LCMS/MS) from 83 ACS patients undergoing percutaneous coronary intervention. ABCC3 (rs757421, rs733392 and rs739923) and CYP2C19*2 (rs4244285) polymorphisms as well as mRNA expression were evaluated. A positive correlation was found between CAM concentrations and ABCC3 mRNA expression (r = 0.494, p < 0.0001). Patients carrying genotype AA (rs757421 variant) had higher CAM concentrations and ABCC3 mRNA expression as compared to those of GG + GA carriers (p = 0.017). A multiple linear regression analysis revealed that ABCC3 mRNA expression (p = 0.017), rs757421 AA genotype (p = 0.001), blood collection time (p = 0.018) and clopidogrel dose (p = 0.001) contributed to the concentration of CAM. No associations were observed for the CYP2C19*2 polymorphism. These results suggest that up-regulation of ABCC3 mRNA expression leads to increased plasma CAM levels through MRP3-mediated cell efflux. The ABCC3 rs757421 polymorphism may contribute to gene expression. Therefore, ABCC3 may be a potential biomarker for the response to clopidogrel.

Pharmacokinetics and relative bioavailability of fixed-dose combination of clopidogrel and aspirin versus coadministration of individual formulations in healthy Korean men

Background

Simultaneous prescription of clopidogrel and low-dose aspirin is recommended for the treatment of acute coronary syndrome because of improvements in efficacy and patient compliance. In this study, the pharmacokinetics of a fixed-dose combination (FDC) of clopidogrel and aspirin was compared with coadministration of individual formulations to clarify the equivalence of the FDC.

Methods

This was a randomized, open-label, two-period, two-treatment, crossover study in healthy Korean men aged 20–55 years. Subjects received two FDC capsules of clopidogrel/aspirin 75/100 mg (test) or two tablets of clopidogrel 75 mg and two capsules of aspirin 100 mg (reference) with a 14-day washout period. Plasma concentrations of clopidogrel, aspirin, and salicylic acid were measured using validated ultraperformance liquid chromatography–tandem mass spectrometry. Bioequivalence was assessed by analysis of variance and calculation of the 90% confidence intervals (CIs) of the ratios of the geometric means (GMRs) for AUC_last and C_max for clopidogrel and aspirin.

Results

Sixty healthy subjects were enrolled, and 53 completed the study. Clopidogrel, aspirin, and salicylic acid showed similar absorption profiles and no significant differences in C_max, AUC_last, and T_max between FDC administration and coadministration of individual formulations. The GMRs (90% CI) for the C_max and AUC_last of clopidogrel were 1.08 (0.95, 1.23) and 0.93 (0.84, 1.03), respectively. The GMRs (90% CI) for the C_max and AUC_last of aspirin were 0.98 (0.84, 1.13) and 0.98 (0.93, 1.04), respectively. Both treatments were well tolerated in the study subjects.

Conclusion

The FDC of clopidogrel and aspirin was bioequivalent to coadministration of each individual formulation. The FDC capsule exhibited similar safety and tolerability profiles to the individual formulations. Therefore, clopidogrel/aspirin 75 mg/100 mg FDC capsules can be prescribed to improve patient compliance.

Acetyl salicylic acid attenuates cardiac hypertrophy through Wnt signaling

Ventricular hypertrophy is a powerful and independent predictor of cardiovascular morbid events. The vascular properties of low-dose acetyl salicylic acid (aspirin) provide cardiovascular benefits through the irreversible inhibition of platelet cyclooxygenase 1; however, the possible anti-hypertrophic properties and potential mechanism of aspirin have not been investigated in detail. In this study, healthy wild-type male mice were randomly divided into three groups and subjected to transverse aortic constriction (TAC) or sham operation. The TAC-operated mice were treated with the human equivalent of low-dose aspirin (10 mg·kg(-1)·d(-1)); the remaining mice received an equal amount of phosphate buffered saline with 0.65% ethanol, which was used as a vehicle. A cardiomyocyte hypertrophy model induced by angiotensin II (10 nmol·L(-1)) was treated with the human equivalent of low (10 or 100 μmol·L(-1)) and high (1000 μmol·L(-1)) aspirin concentrations in plasma. Changes in the cardiac structure and function were assessed through echocardiography and transmission electron microscopy. Gene expression was determined through RT-PCR and western blot analysis. Results indicated that aspirin treatment abrogated the increased thickness of the left ventricular anterior and posterior walls, the swelling of mitochondria, and the increased surface area in in vivo and in vitro hypertrophy models. Aspirin also normalized the upregulated hypertrophic biomarkers, β-myosin heavy chain (β-MHC), atrial natriuretic peptide (ANP), and b-type natriuretic peptide (BNP). Aspirin efficiently reversed the upregulation of β-catenin and P-Akt expression and the TAC- or ANG II-induced downregulation of GSK-3β. Therefore, low-dose aspirin possesses significant anti-hypertrophic properties at clinically relevant concentrations for anti-thrombotic therapy. The downregulation of β-catenin and Akt may be the underlying signaling mechanism of the effects of aspirin.

Simultaneous quantitation of acetylsalicylic acid and clopidogrel along with their metabolites in human plasma using liquid chromatography tandem mass spectrometry

The interest in therapeutic drug monitoring has increased over the last few years. Inter- and intra-patient variability in pharmacokinetics, plasma concentration related toxicity and success of therapy have stressed the need of frequent therapeutic drug monitoring of the drugs. A sensitive, selective and rapid liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous quantification of acetylsalicylic acid (aspirin), salicylic acid, clopidogrel and carboxylic acid metabolite of clopidogrel in human plasma. The chromatographic separations were achieved on Waters Symmetry Shield(TM) C18 column (150 × 4.6 mm, 5 µm) using 3.5 mm ammonium acetate (pH 3.5)-acetonitrile (10:90, v/v) as mobile phase at a flow rate of 0.75 mL/min. The present method was successfully applied for therapeutic drug monitoring of aspirin and clopidogrel in 67 patients with coronary artery disease.

Aspirin and salicylic acid decrease c-Myc expression in cancer cells: a potential role in chemoprevention

Epidemiological studies have demonstrated a significant correlation between regular aspirin use and reduced colon cancer incidence and mortality; however, the pathways by which it exerts its anti-cancer effects are still not fully explored. We hypothesized that aspirin's anti-cancer effect may occur through downregulation of c-Myc gene expression. Here, we demonstrate that aspirin and its primary metabolite, salicylic acid, decrease the c-Myc protein levels in human HCT-116 colon and in few other cancer cell lines. In total cell lysates, both drugs decreased the levels of c-Myc in a concentration-dependent fashion. Greater inhibition was observed in the nucleus than the cytoplasm, and immunofluorescence studies confirmed these observations. Pretreatment of cells with lactacystin, a proteasome inhibitor, partially prevented the downregulatory effect of both aspirin and salicylic acid, suggesting that 26S proteasomal pathway is involved. Both drugs failed to decrease exogenously expressed DDK-tagged c-Myc protein levels; however, under the same conditions, the endogenous c-Myc protein levels were downregulated. Northern blot analysis showed that both drugs caused a decrease in c-Myc mRNA levels in a concentration-dependent fashion. High-performance liquid chromatography (HPLC) analysis showed that aspirin taken up by cells was rapidly metabolized to salicylic acid, suggesting that aspirin's inhibitory effect on c-Myc may occur through formation of salicylic acid. Our result suggests that salicylic acid regulates c-Myc level at both transcriptional and post-transcription levels. Inhibition of c-Myc may represent an important pathway by which aspirin exerts its anti-cancer effect and decrease the occurrence of cancer in epithelial tissues.

The simultaneous detection and quantification of p-aminobenzoic acid and its phase 2 biotransformation metabolites in human urine using LC–MS/MS

Background: p-Aminobenzoic acid (PABA) can be used as a probe substance to investigate glycine conjugation, a reaction of phase 2 biotransformation. Methodology/Results: An LC–MS/MS method for simultaneous quantification of PABA and its metabolites from human urine was developed and validated. The metabolites can be quantified with acceptable precision and accuracy directly from human urine samples after ingestion of 550 mg PABA. Conclusion: The developed LC–MS/MS assay is to our knowledge the first method available for the simultaneous quantification of PABA and its glycine conjugation metabolites in human urine and provides important quantitative data for studies of this phase 2 biotransformation pathway.

Determination of acetylsalicylic acid and its major metabolites in bovine urine using ultra performance liquid chromatography

A new method based on ultra high performance liquid chromatography (UPLC) with photometric and fluorometric detection for the determination of acetylsalicylic acid and its main metabolites, namely gentisic, salicylic and salicyluric acids, in bovine urine samples is reported. Photometric detection was used for acetylsalicylic acid determination, whereas the native fluorescence of the metabolites was monitored using fluorometric detection. The separation was performed under isocratic conditions, using acetonitrile-phosphate solution (3.5mM, pH 3.5) (26:74, v/v) as the mobile phase. The retention times of the four compounds were lower than 2min, which are shorter than those achieved using conventional HPLC. Under the optimum separation conditions, the dynamic ranges and detection limits (ngmL(-1)) were: 0.2-2500, 0.09 for gentisic acid; 0.2-2500, 0.08 for salicylic acid and 2.5-15,000, 1.1 for salicyluric acid, using fluorescence detection, and 10-25,000, 2.2 for acetylsalicylic acid, using UV detection. Intra-day and inter-day precision data were assessed at two levels of concentration of each analyte using both detection systems. The selectivity of the method was checked by assaying different drugs of veterinary use showing that most of them did not interfere with the determination of the analytes. The method has been applied to the analysis of bovine urine samples, which only required a simple clean up step of the samples prior to injection in the UPLC system. A recovery study was performed, which provided values in the range of 80-100%. This fact proves the practical usefulness of this method as an ultrafast analytical tool for the therapeutic control of acetylsalicylic acid administration in bovine animals intended for food production.

Aspirin decreases systemic exposure to clopidogrel through modulation of P-glycoprotein but does not alter its antithrombotic activity

Decreased oral clopidogrel absorption caused by induction of intestinal permeability glycoprotein (P-gp) expression after aspirin administration was observed in rats. This study evaluated the effect of aspirin coadministration on the pharmacokinetics/pharmacodynamics of clopidogrel in humans. A single 75-mg dose of clopidogrel was orally administered before and after 2 and 4 weeks of once-daily 100-mg aspirin administration in 18 healthy volunteers who were recruited based on CYP2C19 and PON1 genotypes. Plasma concentrations of clopidogrel and its active metabolite, H4, and relative platelet inhibition (RPI) were determined. The P-gp microRNA miR-27a increased by up to 7.67-fold (P = 0.004) and the clopidogrel area under the concentration-time curve (AUC) decreased by 14% (P > 0.05), but the AUC of H4 remained unchanged and RPI increased by up to 15% (P = 0.002) after aspirin administration. These findings indicate low-dose aspirin coadministration may decrease clopidogrel bioavailability but does not decrease its efficacy.

Controlled electrochemical synthesis of new rare earth metal lutetium hexacyanoferrate on reduced graphene oxide and its application as a salicylic acid sensor

A controlled electrochemical synthesis of new rare earth metal lutetium hexacyanoferrate on reduced graphene oxide and its application as a salicylic acid sensor.

Simultaneous Determination of Atorvastatin and Aspirin in Human Plasma by LC-MS/MS: Its Pharmacokinetic Application

A simple, rapid, and sensitive liquid chromatography tandem mass spectro-metric (LC-MS/MS) assay method has been developed and fully validated for the simultaneous quantification of atorvastatin and aspirin in human plasma using a polarity switch. Proguanil and furosemide were used as the internal standards for the quantification of atorvastatin and aspirin, respectively. The analytes were extracted from human plasma by the liquid-liquid extraction technique using methyl tert-butyl ether. The reconstituted samples were chromatographed on a Zorbax XDB Phenyl column by using a mixture of 0.2% acetic acid buffer, methanol, and acetonitrile (20:16:64, v/v) as the mobile phase at a flow rate of 0.8 mL/min. Prior to detection, atorvastatin and aspirin were ionized using an ESI source in the multiple reaction monitoring (MRM) mode. The ions were monitored at the positive m/z 559.2→440.0 transition for atorvastatin and the negative m/z 179.0→136.6 transition for aspirin. The calibration curve obtained was linear (r(2) ≥ 0.99) over the concentration range of 0.20-151 ng/mL for atorvastatin and 15.0-3000 ng/mL for aspirin. The method validation was performed as per FDA guidelines and the results met the acceptance criteria. A run time of 3.0 min for each sample made it possible to analyze more than 300 human plasma samples per day. The proposed method was found to be applicable to clinical studies.

Simultaneous determination of carisoprodol and aspirin in human plasma using liquid chromatography-tandem mass spectrometry in polarity switch mode: application to a human pharmacokinetic study

A simple, sensitive and rapid LC-MS/MS-ESI method has been developed and validated for simultaneous quantification of the carisoprodol and aspirin in human plasma. Carisoprodol was detected in positive ion mode, whereas aspirin was detected in negative ion mode. Carbamazepine and furosemide were used as internal standards (IS) for quantification of carisoprodol and aspirin, respectively. The extraction procedure involves a liquid-liquid extraction method with ter-butyl methyl ether. Chromatographic separation was achieved on a Zorbax XDB-Phenyl (4.6 × 75 mm, 3.5 µm) column using an isocratic mobile phase (5 mm ammonium acetate:methanol, 20:80, v/v) at a flow rate of 0.8 mL/min with a total run time of 2.2 min. A detailed method validation was performed as per the FDA guidelines. The standard curves found to be linear in the range of 25.5-4900 and 15.3-3000 ng/mL for carisoprodol and aspirin, respectively. The results met the acceptance criteria. Carisoprodol and aspirin were found to be stable in various stability studies. The validated method was successfully applied to a pharmacokinetic study following co-administration of carisoprodol (250 mg) and aspirin (75 mg) tablets by oral route to human volunteers.

Review of HPLC methods and HPLC methods with mass spectrometric detection for direct determination of aspirin with its metabolite(s) in various biological matrices

Aspirin, the most widely used drug in the world, has been known to mankind for over a century. It is not only the pharmacologically active entity, but is also biotransformed into a major metabolite, i.e. salicylic acid, which also exhibits similar pharmacologic/pharmacodynamic properties. Hence it is necessary to quantitate aspirin along with its metabolite(s) in various biological matrices accurately and precisely to correlate with pharmacological/pharmacodynamic activity. This paper provides a comprehensive overview of various bioanalytical methods (HPLC and LC-MS/MS) that have been reported for direct quantitation of aspirin along with its metabolite(s). The review also provides general information on sample collection, sample processing, internal standard selection, conditions for chromatographic separation, succinct validation data and applicable conclusions for reported assays in a structured manner.

Differential presence of anthropogenic compounds dissolved in the marine waters of Puget Sound, WA and Barkley Sound, BC

Organic compounds were evaluated in March 2010 at 22 stations in Barkley Sound, Vancouver Island Canada and at 66 locations in Puget Sound. Of 37 compounds, 15 were xenobiotics, 8 were determined to have an anthropogenic imprint over natural sources, and 13 were presumed to be of natural or mixed origin. The three most frequently detected compounds were salicyclic acid, vanillin and thymol. The three most abundant compounds were diethylhexyl phthalate (DEHP), ethyl vanillin and benzaldehyde (∼600 n g L(-1) on average). Concentrations of xenobiotics were 10-100 times higher in Puget Sound relative to Barkley Sound. Three compound couplets are used to illustrate the influence of human activity on marine waters; vanillin and ethyl vanillin, salicylic acid and acetylsalicylic acid, and cinnamaldehyde and cinnamic acid. Ratios indicate that anthropogenic activities are the predominant source of these chemicals in Puget Sound.

Simultaneous determination of salicylic acid and salicylamide in biological fluids

A new methodology for the simultaneous determination of salicylic acid and salicylamide in biological fluids is proposed. The strong overlapping of the fluorescence spectra of both analytes makes impossible the conventional fluorimetric determination. For that reason, the use of fluorescence decay curves to resolve mixtures of analytes is proposed; this is a novel technique that provides the benefits in selectivity and sensitivity of the fluorescence decay curves. In order to assess the goodness of the proposed method, a prediction set of synthetic samples were analyzed obtaining recuperation percentages between 98.2 and 104.6%. Finally, a study of the detection limits was done using a new criterion resulting in values for the detection limits of 8.2 and 11.6 μg L(-1) for salicylic acid and salicylamide respectively. The validity of the method was tested in human serum and human urine spiked with aliquots of the analytes. Recoveries obtained were 96.2 and 94.5% for salicylic acid and salicylamide respectively.

Intra-Laboratory Pre-Validation of a Human Cell Based in vitro Angiogenesis Assay for Testing Angiogenesis Modulators

The developed standardized human cell based in vitro angiogenesis assay was intra-laboratory pre-validated to verify that the method is reliable and relevant for routine testing of modulators of angiogenesis, e.g., pharmaceuticals and industrial chemicals. This assay is based on the earlier published method but it was improved and shown to be more sensitive and rapid than the previous assay. The performance of the assay was assessed by using six reference chemicals, which are widely used pharmaceuticals that inhibit angiogenesis: acetyl salicylic acid, erlotinib, 2-methoxyestradiol, levamisole, thalidomide, and anti-vascular endothelial growth factor. In the intra-laboratory pre-validation, the sensitivity of the assay (upper and lower limits of detection and linearity of response in tubule formation), batch to batch variation in tubule formation between different Master cell bank batches, and precision as well as the reliability of the assay (reproducibility and repeatability) were tested. The pre-set acceptance criteria for the intra-laboratory pre-validation study were met. The relevance of the assay in man was investigated by comparing the effects of reference chemicals and their concentrations to the published human data. The comparison showed a good concordance, which indicates that this human cell based angiogenesis model predicts well the effects in man and has the potential to be used to supplement and/or replace of animal tests.

Immunomodulatory drugs increase endothelial tissue factor expression in vitro

INTRODUCTION

Immunomodulatory compounds such as thalidomide (THL) and lenalidomide (LEN) represent treatment options for multiple myeloma. Venous thromboembolism is a potential complication of immunomodulatory treatment in myeloma patients. The optimal thromboprophylactic strategy to prevent this drug-induced hypercoagulable state is debated. It is the aim of this study to investigate i) the effect of immunomodulatory treatment on endothelial cell tissue factor (TF) expression and function, ii) the regulation of the observed TF activity, and iii) the modulating effect of low molecular weight heparin and aspirin on TF activity in vitro.

MATERIALS AND METHODS

These aims were addressed in an in vitro culture model, human umbilical vein endothelial cells, using TF activity and antigen assays as well flow cytometry, real time PCR and electron microscopy.

RESULTS

At THL and LEN concentrations resembling those observed in myeloma patients in vivo and in the presence of tumor necrosis factor-α (TNFα) we observed significantly increased TF activity in human umbilical vein endothelial cells in vitro. Concordant changes were detected for tissue factor mRNA and TF whole cell antigen. Dalteparin and a mixture of monoclonal anti-TF antibodies inhibited TF activity by 100% and more than 80% respectively, while aspirin's inhibitory effect was only approximately 30%. In the presence of TNFα we detected the generation of endothelial cell-derived microparticles which expressed TF activity.

CONCLUSIONS

Our in vitro data support the hypothesis that THL and LEN induce a hypercoagulable state through increased endothelial TF expression.

Rapid and sensitive determination of acetylsalicylic acid and salicylic acid in plasma using liquid chromatography-tandem mass spectrometry: application to pharmacokinetic study

A simple and sensitive analytical method using liquid chromatography-tandem mass spectrometry (LC/MS/MS) for determination of acetylsalicylic acid (aspirin, ASA) and its major metabolite, salicylic acid (SA), in animal plasma has been developed and validated. Both ASA and SA in plasma samples containing potassium fluoride were extracted using acetonitrile (protein precipitation) with 0.1% formic acid in it. 6-Methoxysalicylic acid was used as the internal standard (IS). The compounds were separated on a reversed-phase column. The multiple reaction monitoring mode was used with ion transitions of m/z 178.9 --> 136.8, 137.0 --> 93.0 and 167.0 --> 123.0 for ASA, SA and IS, respectively. The lower limits of quantification for ASA and SA were 3 and 30 ng/mL, respectively. The developed method was successfully applied for the evaluation of pharmacokinetics of ASA and SA after p.o. and i.v. administration of 1 mg/kg to rats.

Coxibs interfere with the action of aspirin by binding tightly to one monomer of cyclooxygenase-1

Pain associated with inflammation involves prostaglandins synthesized from arachidonic acid (AA) through cyclooxygenase-2 (COX-2) pathways while thromboxane A(2) formed by platelets from AA via cyclooxygenase-1 (COX-1) mediates thrombosis. COX-1 and COX-2 are both targets of nonselective nonsteroidal antiinflammatory drugs (nsNSAIDs) including aspirin whereas COX-2 activity is preferentially blocked by COX-2 inhibitors called coxibs. COXs are homodimers composed of identical subunits, but we have shown that only one subunit is active at a time during catalysis; moreover, many nsNSAIDS bind to a single subunit of a COX dimer to inhibit the COX activity of the entire dimer. Here, we report the surprising observation that celecoxib and other coxibs bind tightly to a subunit of COX-1. Although celecoxib binding to one monomer of COX-1 does not affect the normal catalytic processing of AA by the second, partner subunit, celecoxib does interfere with the inhibition of COX-1 by aspirin in vitro. X-ray crystallographic results obtained with a celecoxib/COX-1 complex show how celecoxib can bind to one of the two available COX sites of the COX-1 dimer. Finally, we find that administration of celecoxib to dogs interferes with the ability of a low dose of aspirin to inhibit AA-induced ex vivo platelet aggregation. COX-2 inhibitors such as celecoxib are widely used for pain relief. Because coxibs exhibit cardiovascular side effects, they are often prescribed in combination with low-dose aspirin to prevent thrombosis. Our studies predict that the cardioprotective effect of low-dose aspirin on COX-1 may be blunted when taken with coxibs.