Continuous stationary phase gradient preparation on planar chromatographic media using vapor phase deposition of silane.

A new, versatile, and straightforward vapor phase deposition (VPD) approach was used to prepare continuous stationary phase gradients (cSPGs) on silica thin-layer chromatography (TLC) plates using phenyldimethylchlorosilane (PDCS) as a precursor. A mixture of paraffin oil and PDCS was placed at the bottom of an open-ended rectangular chamber, allowing the reactive silanes to evaporate and freely diffuse under a controlled atmosphere. As the volatile silane diffused across the length of the TLC plate, it reacted with the surface silanol groups thus functionalizing the surface in a gradient fashion. Characterization of the gradient TLC plates was done through UV visualization and diffuse reflectance spectroscopy (DRS). Visualizing the fluorescent gradient plates under UV radiation shows the clear presence of a gradient with the side closest to the vapor source undergoing the most modification. More quantitative characterization of the shape of the gradient was provided by DRS. The DRS showed that the degree of modification and shape of the gradient was dependent on the concentration of silane, VPD time, and relative humidity. To evaluate the chromatographic performance, a mixture of three aromatic compounds (acetaminophen (A), aspirin (As), and 3-hydroxy-2-naphthoic acid (3H)) was spotted on the high (GHP) and low phenyl (GLP) ends of the gradient TLC plates and the results compared to the separations carried out on unmodified and uniformly modified plates. The GHP TLC plates showed retention factors (Rf) of 0.060 ± 0.006, 0.391 ± 0.006, and 0.544 ± 0.006, whereas the unmodified plate displayed Rf values of 0.059 ± 0.006, 0.092 ± 0.003, and 0.037 ± 0.002 for the analytes A, As, and 3H, respectively. From the Rf values, it was observed that each modified plate exhibited different selectivity for the analytes. The GHP TLC plates exhibited better separation performance, and improved resolution compared to the GLP, unmodified, and uniformly modified plates. Overall, VPD is a new, cost-effective method for creating a gradient on the stationary phase which has the potential to advance chromatographic separation capabilities.

Evaluating the Improvement of Blend Potency Measurements in the Feed Frame of a Rotary Tablet Press Using Combined NIR and Raman Spectroscopy.

This study investigated the added value of combining both near-infrared (NIR) and Raman spectroscopy into a single NIRaman Combi Fiber Probe for in-line blend potency determination in the feed frame of a rotary tablet press. A five-component platform formulation was used, containing acetylsalicylic acid as the Active Pharmaceutical Ingredient (API). Calibration models for the determination of 1 and 5%w/w label claim tablets were developed using NIR and Raman spectra of powder blends ranging from 0.75 to 1.25%w/w and 3.75 to 6.25%w/w API, respectively. Step-change experiments with deliberate 10% deviation steps from the label claims were performed, from which the collected spectra were used for model validation. For model development and validation, low-level data fusion was explored through concatenation of preprocessed NIR and Raman spectra. Mid-level data fusion was also evaluated, based on extracted features of the preprocessed data. Herewith, score vectors were extracted by transforming preprocessed spectra through Principal Component Analysis, followed by critical feature selection through Elastic Net Regression. Partial Least Squares regression was applied to regress singular, low-level or mid-level fused data versus blend potency. It could be concluded that irrespective of the data fusion technique, an increase in Step-Change Sensitivity (SCS) and decrease in Root Mean Squared Error (RMSE) was observed when predicting the 5%w/w step-change experiment. For the prediction of the 1%w/w step-change experiment, no added benefit with regard to SCS and RMSE was observed due to the addition of the noisy NIR spectra.

A Novel Low-Frequency Electromagnetic Active Inertial Sensor for Drug Detection.

The purpose of this paper is to demonstrate a new discovery regarding the interaction between materials and very low radio frequencies. Specifically, we observed a feedback response on an inertia active sensor when specific frequencies (around 2-4 kHz) are used to irradiate targeted pharmaceutical samples like aspirin or paracetamol drugs. The characteristics of this phenomenon, such as excitation and relaxation time, the relation between deceleration and a material's quantity, and signal amplitude, are presented and analyzed. Although the underlying physics of this phenomenon is not yet known, we have shown that it has potential applications in remote identification of compounds, detection, and location sensing, as well as identifying substances that exist in plants without the need for any processing. This method is fast, accurate, low-cost, non-destructive, and non-invasive, making it a valuable area for further research that could yield spectacular results in the future.

Development and Validation of Chromatographic Methods for Simultaneous Estimation of Aspirin and Pantoprazole Sodium in Pure and Mixture Form.

This technique is employed for the simultaneous quantification of aspirin (ASP) and pantoprazole sodium in both pure powder form and formulations. The high performance liquid chromatography (HPLC) method uses a C-18 column (250 mm × 4.6 mm, 5 µm) with a mobile phase consisting of 0.05 M disodium hydrogen phosphate and methanol in a 40:60% v/v ratio. The flow rate is maintained at 1.0 mL/min. On a layer of silica gel 60F254 with an aluminum backing, the high performance thin layer chromatography (HPTLC) separation was carried out with ethyl acetate and methanol (8: 1.5 v/v) as the mobile phase. With a mean recovery of 100.54% and 99.55% for ASP and PNT, respectively, quantification was accomplished using the HPLC method with UV detection at 286 nm over the concentration range of 0.1-0.6 g/mL for PNT and 0.4-2.4 g/mL for ASP. With a mean recovery of 99.44% and 99.01% for ASP and PNT, respectively, quantification was achieved using the HPTLC method with UV detection at 298 nm over the concentration range of 400-2400 ng/spot for ASP and 100-600 ng/spot for PNT, respectively. The methods can be used for the simultaneous determination of ASP and PNT in pure powder form and formulations as they are simple, accurate and sensitive.

Remediation of water tainted with noxious aspirin and fluoride ion using UiO-66-NH2 loaded peanut shell.

One green adsorbent, UiO-66-NH2 modified peanut shell (c-PS-MOF), was prepared in a green synthetic route for improving the capture level of aspirin (ASP) and fluoride ion (F-). The adsorption properties of c-PS-MOF were evaluated by batch experiments and its physicochemical properties were explored by various characterization methods. The results showed that c-PS-MOF exhibited a wide range of pH applications (ASP: 2-10; F-: 3-12) and high salt resistance in the capturing processes of ASP and F-. The unit adsorption capacity of c-PS-MOF was as high as 84.7 mg·g-1 for ASP as pH = 3 and 11.2 mg·g-1 for F- under pH = 6 at 303 K from Langmuir model, respectively. When the solid-liquid ratio was 2 g·L-1, the content of ASP (C0 = 100 mg·L-1) and F- (C0 = 20 mg·L-1) in solution can be reduced to 0.48 mg·L-1 and 1.05 mg·L-1 separately. The recycling of c-PS-MOF can be realized with 5 mmol·L-1 NaOH as eluent. Analysis of simulated water samples showed that c-PS-MOF could be used to remove ASP and F- from actual water. The c-PS-MOF is promising to bind ASP and F- from rivers, lakes, etc.

Implementing Preeclampsia Screening in Switzerland (IPSISS): First Results from a Multicentre Registry.

INTRODUCTION: The Fetal Medicine Foundation (FMF) London developed a first trimester combined screening algorithm for preterm preeclampsia (pPE) that allows a significantly higher detection of pregnancies at risk compared to conventional screening by maternal risk factors only. The aim of this trial is to validate this screening model in the Swiss population in order to implement this screening into routine first trimester ultrasound and to prescribe low-dose aspirin 150 mg (LDA) in patients at risk for pPE. Therefore, a multicentre registry study collecting and screening pregnancy outcome data was initiated in 2020; these are the preliminary results. METHODS: Between June 1, 2020, and May 31, 2021, we included all singleton pregnancies with pPE screening at the hospitals of Basel, Lucerne, and Bern. Multiple of medians of uterine artery pulsatility index (UtA-PI), mean arterial pressure (MAP), placental growth factor (PlGF), and pregnancy-associated plasma protein A (PAPP-A) as well as risks were analysed as calculated by each centre's software and recalculated on the FMF online calculator for comparative reasons. Statistical analyses were performed by GraphPad Version 9.1. RESULTS: During the study period, 1,027 patients with singleton pregnancies were included. 174 (16.9%) had a risk >1:100 at first trimester combined screening. Combining the background risk, MAP, UtA-PI, and PlGF only, the cut-off to obtain a screen positive rate (SPR) of 11% is ≥1:75. Outcomes were available for 968/1,027 (94.3%) of all patients; 951 resulted in live birth. Fifteen (1.58%) developed classical preeclampsia (PE), 23 (2.42%) developed PE according to the International Society for the Study of Hypertension in Pregnancy (ISSHP) definition. CONCLUSION: First trimester combined screening for PE and prevention with LDA results in a low prevalence of PE. The screening algorithm performs according to expectations; however, the cut-off of >1:100 results in a SPR above the accepted range and a cut-off of ≥1:75 should be considered for screening. More data are needed to evaluate, if these results are representative for the general Swiss population.

Green surface functionalization of chitosan with spent tea waste extract for the development of an efficient adsorbent for aspirin removal.

This study investigates the feasibility of spent tea waste extract (STWE) as a green modifying agent for the modification of chitosan adsorbent towards aspirin removal. Response surface methodology based on Box-Behnken design was employed to find the optimal synthesis parameters (chitosan dosage, spent tea waste concentration, and impregnation time) for aspirin removal. The results revealed that the optimum conditions for preparing chitotea with 84.65% aspirin removal were 2.89 g of chitosan, 18.95 mg/mL of STWE, and 20.72 h of impregnation time. The surface chemistry and characteristics of chitosan were successfully altered and improved by STWE, as evidenced by FESEM, EDX, BET, and FTIR analysis. The adsorption data were best fitted to pseudo 2nd order, followed by chemisorption mechanisms. The maximum adsorption capacity of chitotea was 157.24 mg/g, as fitted by Langmuir, which is impressive for a green adsorbent with a simple synthesis method. Thermodynamic studies demonstrated the endothermic nature of aspirin adsorption onto chitotea.

An effective and stability-indicating method development and optimization utilizing the Box-Behnken design for the simultaneous determination of acetaminophen, caffeine, and aspirin in tablet formulation.

Analytical techniques must be sensitive, specific, and accurate to assess the active pharmaceutical ingredients in pharmaceutical dosage forms. The quality-by-design (QbD) application has proven to be a practical method for magnifying HPLC operations. This article discusses the successfully developed QbD-based stability-indicative LC method for evaluating acetaminophen, caffeine, and aspirin (ASP) in tablet dosage form. To achieve the necessary chromatographic separation, Milli-Q water, methanol, and glacial acetic acid were employed in the following ratios: 63:35:2 (v/v/v) for mobile phase A and 18:80:2 (v/v/v) for mobile phase B. The flow rate, column temperature, and detecting wavelength were 1.0 ml/min, 40°C, and 275 nm, respectively, and an InertSustain C18 analytical column (150 × 4.6 mm, 3 µm) was used. Linearity was between 10.0 and 150.0 µg/ml for ASP and acetaminophen and between 2.6 and 39.0 µg/ml for caffeine. The accuracy findings were more than 97%, and the correlation coefficient for all three components was found to be greater than 0.999. The validated HPLC method yielded reliable and accurate results. ASP was shown to be vulnerable to both acid and alkaline hydrolysis in the forced degradation study. The described method is capable of separating the degradants produced during stress testing and is regarded as stability indicating. The proposed method can be used for a wider range of other formulations with an appropriate diluent selection and sample preparation procedure optimization.

Monitoring of salicylic acid content in human saliva and its relationship with plasma concentrations.

Aspirin is a widely used anti-inflammatory drug. It is reported that a relationship may exist between salicylic acid content in plasma and saliva after taking aspirin. This study established a rapid, convenient, and safe method to assess salicylic acid concentration in human saliva. A novel HPLC-ultraviolet detector was used to measure salicylic acid concentrations in human saliva and plasma. A C18 reversed-phase column with an aqueous solution of 0.1% trifluoroacetic acid (TFA)-acetonitrile mobile phase was used, and drug peaks were recorded at 303 nm. Salicylic acid was completely separated in saliva and plasma. Excellent linearity and correlation (r2 ≥ 0.9999) was observed between 0.1 and 2.0 µg/mL. The detection limit (S/N = 3) was 33 ng/mL, and intra- and inter-day recoveries were 103.5-113.3% and 101.1-109.5%, respectively. Salicylic acid was measured within nine hours after administration of acetylsalicylic acid tablets. A positive correlation between salicylic acid content in saliva and plasma was found (r = 0.867, p < 0.001). The proposed method was used successfully to measure salicylic acid concentration in human saliva. Meanwhile, we explored the relationship between salicylic acid levels in plasma and saliva. Saliva might replace blood for monitoring aspirin treatment. In addition, the research provides a reference for application to saliva samples.

Micelle-Incorporated Liquid Chromatography in the Light of Green Chemistry: An Application for the Quality Control Analysis of Anti-Platelet Fixed-Dose Combinations.

BACKGROUND: Oral anti-platelet agents are the cornerstone of the treatment of multiple cardiovascular diseases and in the long-term prevention of their recurrence. OBJECTIVE: In the present work, we report a method based on micellar liquid chromatography coupled with ultraviolet detection (MLC/UV), for the simultaneous quantification of combined anti-platelet therapy namely, clopidogrel bisulfate (CPS), aspirin (ASP), together with salicylic acid (SA), in their pharmaceutical dosage form. METHODS: The incorporation of 0.1M polyoxyethylene 23 lauryl ether (Brij-35) as a surfactant into the mobile phase improved solute-mobile phase interaction allowing for minimal organic solvent utilization, enhanced resolution, and rapid analysis (7 min). Furthermore, we performed a comprehensive evaluation of the environmental impact caused by our procedures versus previously reported analytical procedures applied in the determination of CPS and ASP. The evaluation was made using the Eco-scale tool. RESULTS: The results of the developed method indicated the superiority of our procedures in terms of greenness without compromising the quality of performance characteristics. The method was linear in the range of 1-100 µg/mL with limits of detection of 0.28, 0.32, and 0.29 µg/mL for CPS, ASP, and SA, respectively. The developed method can also be utilized to test the purity and the stability of ASP in pharmaceutical formulations through monitoring SA as its main degradation product. CONCLUSION: The MLC/UV method was successfully applied to the quantitative analysis of CPS, ASP together with SA-as a main degradation product of ASP-in their pharmaceutical dosage form. HIGHLIGHTS: The developed method was successfully applied for the determination of clopidogrel bisulfate (CPS), aspirin (ASP), together with salicylic acid (SA), in their pharmaceutical dosage form.

Management of validation of HPLC method for determination of acetylsalicylic acid impurities in a new pharmaceutical product.

The work mainly focused on a validation of the method for determining the content of salicylic acid and individual unknown impurities in new pharmaceutical product-tablets containing: 75, 100 or 150 mg of acetylsalicylic acid and glycine in the amount of 40 mg for each dosage. The separation of the components was carried out by means of HPLC, using a Waters Symmetry C18 column (4.6 × 250 mm, 5 µm) as the stationary phase. The mobile phase consisted of a mixture of 85% orthophosphoric acid, acetonitrile and purified water (2:400:600 V/V/V). Detection was carried out at a wavelength of 237 nm, with a constant flow rate of 1.0 ml min-1. In order to verify the method, linearity, precision (repeatability and reproducibility), accuracy, specificity, range, robustness, system precision, stability of the test and standard solution, limit of quantification and forced degradation were determined. Validation tests were performed in accordance with ICH (International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use) guidelines. The method was validated successfully. It was confirmed that the method in a tested range of 0.005-0.40% salicylic acid with respect to acetylsalicylic acid content is linear, precise and accurate.

Utility of Platelet Endothelial Cell Adhesion Molecule 1 in the Platelet Activity Assessment in Mouse and Human Blood.

In our previous study, we introduced the platelet endothelial cell adhesion molecule 1 (PECAM-1)/thrombus ratio, which is a parameter indicating the proportion of PECAM-1 in laser-induced thrombi in mice. Because PECAM-1 is an antithrombotic molecule, the higher the PECAM-1/thrombus ratio, the less activated the platelets. In this study, we used an extracorporeal model of thrombosis (flow chamber model) to verify its usefulness in the assessment of the PECAM-1/thrombus ratio in animal and human studies. Using the lipopolysaccharide (LPS)-induced inflammation model, we also evaluated whether the PECAM-1/thrombus ratio determined in the flow chamber (without endothelium) differed from that calculated in laser-induced thrombosis (with endothelium). We observed that acetylsalicylic acid (ASA) decreased the area of the thrombus while increasing the PECAM-1/thrombus ratio in healthy mice and humans in a dose-dependent manner. In LPS-treated mice, the PECAM-1/thrombus ratio decreased as the dose of ASA increased in both thrombosis models, but the direction of change in the thrombus area was inconsistent. Our study demonstrates that the PECAM-1/thrombus ratio can more accurately describe the platelet activation status than commonly used parameters such as the thrombus area, and, hence, it can be used in both human and animal studies.

Core-shell MOF@COFs used as an adsorbent and matrix for the detection of nonsteroidal anti-inflammatory drugs by MALDI-TOF MS.

A core-shell material (UiO@TapbTp) has been developed as an adsorbent and matrix to detect nonsteroidal anti-inflammatory drugs (NSAIDS) by matrix laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in complex samples. The hybrid material is prepared by growing covalent organic framework (COF, TapbTp) layers in situ on an amino-modified metal-organic framework (MOF, UiO-66-NH2). The combination of the MOF and COF overcomes their individual shortcomings and integrates both of their advantages. Compared with the bare COF and MOF, the core-shell composite exhibits improved enrichment ability and matrix performance. With the help of pre-enrichment under optimized conditions, the limits of detection (LODs) for ketoprofen, naproxen, and aspirin are reduced by nearly 1000 times, with values of 0.001 mg L-1, 0.010 mg L-1, and 0.001 mg L-1, respectively, and the relative standard deviations (RSDs) are all below 12.35%. The good recoveries (84.8-118%) in (spiked) saliva and environmental water sample further verify the applicability of the method in complex samples.

Green analysis of newly approved binary omeprazole/aspirin mixture in presence of aspirin impurity using ultra-high-performance liquid chromatography and thin-layer chromatography methods.

Two green, simple, and accurate chromatographic methods were developed and validated for the simultaneous determination of omeprazole and aspirin mixture in the presence of salicylic acid, a major impurity of aspirin. Method A is a reversed-phase ultra-high-performance liquid chromatography; the separation was performed on a C18 column, with a mobile phase composed of ethanol:0.1% aqueous solution of triethylamine acidified with orthophosphoric acid (pH 3) (30:70, v/v) at 0.15 mL/min flow rate and 230 nm. Omeprazole, aspirin, and aspirin impurity retention times were 7.47, 4.40, and 5.13 min, respectively. Good linearity was achieved in the concentration ranges of 5-80, 5-85, and 3-50 µg/mL for the three mentioned components, respectively. Method B is thin-layer chromatography (TLC) where silica gel TLC F254 plates were utilized to achieve separation using ethanol:ethyl acetate (2:8, v/v) as a developing system at 240 nm. The resulted Rf values were 0.83, 0.65, and 0.23 for omeprazole, aspirin, and impurity, respectively. The concentration ranges of 0.1-3 µg/band for the three drugs showed good linearity. The proposed methods are eco-friendly and greener when compared to the already reported method (Microchemical Journal, 152, 104350). This is the first use of TLC method for the determination of the three drugs. International Council for Harmonization (ICH) guidelines were followed to ensure the validity of developed methods.

Impact of Magnesium Stearate Content: Modeling of Drug Degradation Using a Modified Arrhenius Equation.

To accelerate drug development, the pharmaceutical industry is working to shorten and improve studies on stability. The Accelerated Stability Assessment Program (ASAP) incorporating the humidity-corrected Arrhenius equation as an accelerated methodology has been proposed for both drug substances and drug products. In this study, the effect of magnesium stearate (MgSt) content on the chemical stability of acetylsalicylic acid was evaluated as a model system of drug-excipient compatibility studies using ASAP. In the acetylsalicylic acid powder blends, temperature and humidity showed a first-order linear response to the natural logarithm of the reaction rate constant, and MgSt content also showed a first-order linear response. A polynomial model was built in which temperature, humidity, and MgSt content were independent each other. The fitting index of the model, the coefficient of determination, was 0.9567, which was a good fit. In the long-term stability study (25 °C/60% relative humidity, 6 months), there was good agreement in total between measured values and model-predicted values. Using this model, we inferred that the degradation rates were depended on MgSt content at the fixed temperature and humidity because the micro-environmental pH of the excipient was catalytically affected. Applying this model equation can significantly reduce the duration of formulation design and stability studies and save time and costs in drug development.

Comparison of acetylsalicylic acid and clopidogrel non-responsiveness assessed by light transmittance aggregometry and PFA-100® in patients undergoing neuroendovascular procedures.

Objectives: Dual platelet inhibition is commonly used for prevention of cardiovascular events in patients undergoing neuroendovascular procedures. Non-responsiveness to platelet inhibitors may be associated with adverse outcomes. The aim of this study was to evaluate the reliability of the platelet function analyzer PFA-100® in comparison to light transmittance aggregometry (LTA) for monitoring clopidogrel and acetylsalicylic acid (ASA) non-responsiveness in a cohort of patients treated for intracranial aneurysm or cranial artery stenosis. Methods: Non-responsiveness to clopidogrel and ASA was assessed by LTA using adenosine diphosphate (ADP) and arachidonic acid and by PFA-100® with the ADP/prostaglandin E1 (PGE1) and collagen/epinephrine cartridges, respectively. Results: A total of 203 patients (145 females; median age, 57 years) were analyzed. Agreement between the two tests was poor for clopidogrel non-responsiveness (ƙ=0.19) and not better than chance for ASA non-responsiveness (ƙ=0.01). Clopidogrel non-responsiveness by LTA and PFA-100® was associated with higher von Willebrand factor antigen and activity levels. ADP-induced platelet disaggregation was lower in patients with clopidogrel non-responsiveness as assessed by PFA-100®. Clopidogrel non-responsiveness by LTA was associated with a higher prevalence of diabetes and a higher body mass index (BMI). Adverse outcomes (death, thromboembolism, or in-stent thrombosis) occurred in 13% (n=26) of all patients independently of ASA and clopidogrel non-responsiveness as assessed by both devices. Conclusions: Our results show that LTA and PFA-100® are not interchangeable in the assessment of ASA and clopidogrel non-responsiveness in patients undergoing neuroendovascular interventions.

Analysis of quinary therapy targeting multiple cardiovascular diseases using UV spectrophotometry and chemometric tools.

Herein, UV spectrophotometry assisted by multivariate chemometric analysis have been presented for quantitative determination of complex quinary therapy containing atenolol, ramipril, hydrochlorothiazide, simvastatin and aspirin without any prior separation. Such combination is very useful for treating various cardiovascular diseases (CVD) including high blood pressure, hypercholesterolemia in addition to its antiplatelet aggregating activity. Calibration (15 samples) and validation (10 samples) sets were prepared of different concentrations for these drugs via implementing partial factorial experimental design. The zero order UV spectra of these sets were recorded and then subjected for further chemometric analysis. Partial least square (PLS) with/without variable selection procedure i.e. genetic algorithm (GA) were employed to untangle the UV spectral overlapping of these mixtures. The performance of these chemometric techniques were compared in terms of accuracy and predictive abilities using cross-validation and external validation methods. It was found that PLS provides good recoveries with prompt predictive ability albeit GA-PLS exhibited better analytical performance owing to its capability to remove redundant variables i.e. the number of absorbance variables had been reduced to about 19-28%. The developed methods allowed reliable determination of such complex therapy in its laboratory prepared mixtures and pharmaceutical preparation within comparable results to those reported by HPLC method, posing these chemometric methods as valuable and indispensable analytical tools in in-process testing and quality control analysis of many pharmaceutical compounds targeting CVD.

End-to-end continuous manufacturing of conventional compressed tablets: From flow synthesis to tableting through integrated crystallization and filtration.

An end-to-end continuous pharmaceutical manufacturing process was developed for the production of conventional direct compressed tablets on a proof-of-concept level for the first time. The output reaction mixture of the flow synthesis of acetylsalicylic acid was crystallized continuously in a mixed suspension mixed product removal crystallizer. The crystallizer was directly connected to a continuous filtration carousel device, thus the crystallization, filtration and drying of acetylsalicylic acid (ASA) was carried out in an integrated 2-step process. Steady state was reached during longer operations and the interaction of process parameters was evaluated in a series of experiments. The filtered crystals were ready for further processing in a following continuous blending and tableting experiment due to the good flowability of the material. The ASA collected during the crystallization-filtration experiments was fed into a continuous twin-screw blender along with microcrystalline cellulose as tableting excipient. After continuous blending Near-Infrared spectroscopy was applied to in-line analyze the drug content of the powder mixture. A belt conveyor carried the mixture towards an eccentric lab-scale tablet press, which continuously produced 500 mg ASA-loaded compressed tablets of 100 mg dose strength. Thus, starting from raw materials, the final drug product was obtained by continuous manufacturing steps with appropriate quality.

An electrochemical sensor based on chitosan capped with gold nanoparticles combined with a voltammetric electronic tongue for quantitative aspirin detection in human physiological fluids and tablets.

Inflammatory diseases increase has recently sparked the research interest for drugs diagnostic tools development. At therapeutic doses, acetylsalicylic acid (ASA or aspirin) is widely used for these diseases' treatment. ASA overdoses can however give rise to adverse side effects including ulcers, gastric damage. Hence, development of simple, portable and sensitive methods for ASA detection is desirable. This paper reports aspirin analysis in urine, saliva and pharmaceutical tablet using an electrochemical sensor and a voltammetric electronic tongue (VE-Tongue). The electrochemical sensor was fabricated by self-assembling chitosan capped with gold nanoparticles (Cs + AuNPs) on a screen-printed carbon electrode (SPCE). It exhibits a logarithmic-linear relationship between its response and the ASA concentration in the range between 1 pg/mL and 1 µg/mL. A low detection limit (0.03 pg/mL), good selectivity against phenol and benzoic acid interference, and successful practical application were demonstrated. Qualitative analysis was performed using the VE-Tongue based unmodified metal electrodes combined with two chemometric approaches to classify urine samples spiked with different aspirin concentrations. Partial least squares (PLS) method provided prediction models obtained from the data of both devices with a regression correlation coefficient R2 = 0.99. Correspondingly, the SPCE/(Cs + AuNPs) electrochemical sensor and VE-Tongue could be viable tools for biological analysis of drugs.

Identifying aspirin polymorphs from combined DFT-based crystal structure prediction and solid-state NMR.

A combined experimental and computational approach was used to distinguish between different polymorphs of the pharmaceutical drug aspirin. This method involves the use of ab initio random structure searching (AIRSS), a density functional theory (DFT)-based crystal structure prediction method for the high-accuracy prediction of polymorphic structures, with DFT calculations of nuclear magnetic resonance (NMR) parameters and solid-state NMR experiments at natural abundance. AIRSS was used to predict the crystal structures of form-I and form-II of aspirin. The root-mean-square deviation between experimental and calculated 1 H chemical shifts was used to identify form-I as the polymorph present in the experimental sample, the selection being successful despite the large similarities between the molecular environments in the crystals of the two polymorphs.