Application of quality by design elements for the development and optimization of an analytical method for protamine sulfate

QbD-based co-loading of paclitaxel and imatinib mesylate by protamine-coated PLGA nanoparticles effective on breast cancer cells

Aim: Paclitaxel and imatinib mesylate are drugs used in the treatment of breast cancer. Conventional drug-delivery systems have limitations in the effective treatment of breast cancer using the drugs. Materials & methods: Combination index studies were used to identify the optimum ratio of both drugs showing maximum synergistic effect. Using a systematic quality-by-design approach, protamine-coated PLGA nanoparticles co-loaded with paclitaxel and imatinib mesylate were formulated. Further characterization and cell line evaluations were performed. Results: Encapsulation efficiency obtained was 92.54% for paclitaxel and 75.12% for imatinib mesylate. A sustained (24 h) and controlled zero-order drug release was obtained. Conclusion: Formulated nanoparticles had a low IC50 value and enhanced cellular uptake.

An innovative charge-based extracellular vesicle isolation method for highly efficient extraction of EV-miRNAs from liquid samples: miRQuick

Extracellular vesicle-derived microRNAs (EV-miRNAs) are promising biomarkers for early cancer diagnosis. However, existing EV-miRNA extraction technologies have a complex two-step process that results in low extraction efficiency and inconsistent results. This study aimed to develop and evaluate a new single-step extraction method, called miRQuick, for efficient and high-recovery extraction of EV-miRNAs from samples. The miRQuick method involves adding positively charged substances to the sample, causing negatively charged EVs to quickly aggregate and precipitate. A membrane lysate is then added to extract only miRNA. The entire process can be completed within an hour using standard laboratory equipment. We validated the miRQuick method using various analytical techniques and compared its performance to other methods for plasma, urine and saliva samples. The miRQuick method demonstrated significantly higher performance than other methods, not only for blood plasma but also for urine and saliva samples. Furthermore, we successfully extracted and detected nine biomarker candidate miRNAs in the plasma of breast cancer patients using miRQuick. Our results demonstrate that miRQuick is a rapid and efficient method for EV-miRNA extraction with excellent repeatability, making it suitable for various applications including cancer diagnosis.

Drilling into "Quality by Design" Approach for Analytical Methods

The need for consistency in analytical method development reinforces the dependence of pharmaceutical product development and manufacturing on robust analytical data. The Analytical Quality by Design (AQbD), akin to the product Quality by Design (QbD) endows a high degree of confidence to the method quality developed. AQbD involves the definition of the analytical target profile as starting point, followed by the identification of critical method variables and critical analytical attributes, supported on risk assessment and design of experiment tools for the establishment of a method operable design region and control strategy of the method. This systematic approach moves away from reactive troubleshooting to proactive failure reduction. The objective of this review is to highlight the elements of the AQbD framework and provide an overview of their implementation status in various analytical methods used in the pharmaceutical field. These methodologies include but are not limited to, high-performance liquid chromatography, UV-Vis spectrophotometry, capillary electrophoresis, supercritical fluid chromatography, and high-performance thin-layer chromatography. Finally, a critical appraisal is provided to highlight how regulators have encouraged AQbD principles application to boost the prevention of method failures and a better understanding of the method operable design region (MODR) and control strategy, ultimately resulting in cost-effectiveness and regulatory flexibility.

Self-assembled super-small AIEgen nanoprobe for highly sensitive and selective detection of protamine and trypsin

Amphiphilic aggregation-induced emission (AIE) molecules show superior potential for fabricating novel ultrasmall nanoprobes. Here, an anionic dipyridyl tetraphenylethene (TPE) derivative is rationally designed and a super-small self-assembled AIEgen nanoprobe (TPE-2Py-SO₃NaNPs, ca. 2.48 nm) is thus conveniently constructed for the supersensitive detection of protamine and trypsin. In HEPES/DMSO solution (8 : 2, v/v, pH = 7.4), negatively charged TPE-2Py-SO₃NaNPs exhibited an AIE effect in the presence of positively charged protamine, presenting a fluorescence enhancement at 498 nm together with a large Stokes shift of 150 nm and a low detection limit of 8.0 ng mL^-1. In addition, the in situ formed TPE-2Py-SO₃Na/protamine nanocomposite can be dissociated by trypsin due to the highly selective degradation of protamine via enzymatic hydrolysis, achieving a detection limit for trypsin as low as 5.0 ng mL^-1.

Pharmacology of Heparin and Related Drugs: An Update

Heparin has been used extensively as an antithrombotic and anticoagulant for close to 100 years. This anticoagulant activity is attributed mainly to the pentasaccharide sequence, which potentiates the inhibitory action of antithrombin, a major inhibitor of the coagulation cascade. More recently it has been elucidated that heparin exhibits anti-inflammatory effect via interference of the formation of neutrophil extracellular traps and this may also contribute to heparin's antithrombotic activity. This illustrates that heparin interacts with a broad range of biomolecules, exerting both anticoagulant and nonanticoagulant actions. Since our previous review, there has been an increased interest in these nonanticoagulant effects of heparin, with the beneficial role in patients infected with SARS2-coronavirus a highly topical example. This article provides an update on our previous review with more recent developments and observations made for these novel uses of heparin and an overview of the development status of heparin-based drugs. SIGNIFICANCE STATEMENT: This state-of-the-art review covers recent developments in the use of heparin and heparin-like materials as anticoagulant, now including immunothrombosis observations, and as nonanticoagulant including a role in the treatment of SARS-coronavirus and inflammatory conditions.

In-use stability assessment of FDA approved metformin immediate release and extended release products for N-Nitrosodimethylamine and dissolution quality attributes

Metformin is a widely used first-line oral antidiabetic agent. TheFood and Drug Administration (FDA) confirmed the presence of the ofN-nitrosodimethylamine (NDMA) impurity, a carcinogenic, above the acceptable daily intake (ADI, 96 ng/day) in certain metformin products. The objective of the present study was to assess in-use stability of commercial metformin products for NDMA and dissolution quality attributes. Four immediate-release (M1-M4) and six extended-rerelease (M5-M10) metformin products were evaluated in the stability testing. All products were repacked in pharmacy vials and stored at 30 °C/75% RH for 12 weeks. Five products (M2, M3, M5, M7 and M10) had NDMA level above ADI limit (96 ng/day) before in-use stability exposure. NDMA in M2 (1164 ± 52.9 ng/tablet) and M3 (3776 ± 351.9 ng/tablet) products were 12 and 39 folds of ADI, respectively. Similarly, ER products, M5 (191 ± 94.1 ng/tablet), M7 (1473 ± 47.3 ng/tablet) and M10 (423 ± 55.8 ng/tablet) exhibited NDMA of 1.9, 15.3 and 4.4 folds of ADI, respectively. The impurity level significantly (p < 0.05) increased after 12-week stability exposure to 2.72, 2.47, 2.23 and 2.78 folds of initial values in M2, M3, M7 and M10. In summary, these findings suggested that carcinogenic impurity generation was affected by in-use stability condition exposure and it is expected that several more products currently in the market may also be recalled soon.

Experimental Design Approach for Quantitative Expressions of Simultaneous Quantification of Two Binary Formulations Containing Remogliflozin and Gliptins by RP-HPLC

The aim of this study was to develop a fast RP-HPLC method for simultaneous measurement of two antidiabetic formulations (vildagliptin + remogliflozin and teneligliptin + remogliflozin) under identical experimental conditions. Using the Box–Behnken approach and response surface design, the interaction and quadratic influence of three variable parameters, acetonitrile %, pH of the mobile phase, and flow rate, on resolution between the peaks were optimized. To forecast the resolution of peaks (2.7 and 6.5) for the three anti-diabetic medications, the design space with desirability function was used to find the optimal chromatographic conditions. Isocratic elution with 58:42 acetonitrile and phosphate buffer (20 mM KH2PO4, pH adjusted to 4.9 with orthophosphoric acid) over a Zorabx C18 HPLC column with a flow rate of 1.2 mL min−1 separated all three analytes in 2.5 min. In addition, the optimized HPLC process was validated using ICH recommendations. The devised HPLC method’s precision and accuracy were proven by the low percent relative standard deviation (0.60–1.65%), good percentage recovery (98.18–101.50%), and low percentage relative errors (0.20–1.82%). The method’s robustness was also proven by slightly varying the five separate parameters. Finally, the accuracy of the proposed HPLC approach was confirmed using a standard addition method for simultaneous determination of vildagliptin + remogliflozin and teneligliptin + remogliflozin from formulations. Furthermore, the findings demonstrated that experimental design can be successfully used to optimize chromatographic conditions with fewer runs. The devised HPLC method for simultaneous quantification of two binary combinations utilizing the same chromatographic conditions is fast, accurate, precise, and easy, and it might be utilized in laboratories for routine quality control investigations on both formulations.

Multivariate optimization and evaluation of quaternary mixture in bulk and co-formulated dosage forms by central composite design

Background

The current study describes the use of central composite design for multivariate optimization of resolution and retention time, taking into account different critical method parameters like organic phase, pH, flow rate, and wavelength for risk assessment. The chromatographic method for the assay of the most effective anti-viral regimen (EPCLUSA, DARVONI, and HARVONI) was developed. An experimental design was presented by sequential investigation of four independent parameters. The method was developed using XTERRA C18 (250 mm × 4.6 mm, 5 μm particle size) column in isocratic mode using potassium dihydrogen phosphate buffer (pH adjusted to 5) and acetonitrile (50:50 % v/v) as mobile phase at a flow rate of 1.0 ml/min and UV detection wavelength of 260 nm.

Results

The separation of four drugs with fine resolution and preferable retention times was achieved. Retention times of four drugs were found to be 2.96, 3.91, 7.15, and 11.94 min for daclatasvir, sofosbuvir, velpatasvir, and ledipasvir, respectively. The percentage accuracy of labelled claim was in the range of 99–102%, and the pooled %RSD for repeatability, precision, and accuracy was less than 2%.

Conclusion

The suggested method was applied for quantification and identification of studied drugs in tablets; the results agreed with the label claim and were validated according to the ICH guidelines. The optimized method can be used for pharmacokinetic and quality control studies.

Thrombus-specific theranostic nanocomposite for codelivery of thrombolytic drug, algae-derived anticoagulant and NIR fluorescent contrast agent

Thrombolysis is a standard treatment for rapidly restoring blood flow. However, the application of urokinase-type plasminogen activator (Uk) in clinical therapy is limited due to its nonspecific distribution and inadequate therapeutic accumulation. Precise thrombus imaging and site-specific drug delivery can enhance the diagnostic and therapeutic efficacy for thrombosis. Accordingly, we developed a P-selectin-specific, photothermal theranostic nanocomposite for thrombus-targeted codelivery of Uk and indocyanine green (ICG, a contrast agent for near-infrared (NIR) fluorescence imaging). We evaluated its capabilities for thrombus imaging and enzyme/hyperthermia combined thrombolytic therapy. Mesoporous silica-coated gold nanorods (Si-AuNRs) were functionalized with an arginine-rich peptide to create an organic template for the adsorption of ICG and fucoidan (Fu), an algae-derived anticoagulant. Uk was loaded into the SiO₂ pores of the Si-AuNRs through the formation of a Fu-Uk-ICG complex on the peptide-functionalized template. The Fu-Uk/ICG@SiAu NRs nanocomposite increased the photostability of ICG and improved its targeting/accumulation at blood clot sites with a strong NIR fluorescence intensity for precise thrombus imaging. Furthermore, ICG incorporated into the nanocomposite enhanced the photothermal effect of Si-AuNRs. Fu, as a P-selectin-targeting ligand, enabled the nanocomposite to target a thrombus site where platelets were activated. The nanocomposite enabled a faster release of Uk for rapid clearing of blood clots and a slower release of Fu for longer lasting prevention of thrombosis regeneration. The nanocomposite with multiple functions, including thrombus-targeting drug delivery, photothermal thrombolysis, and NIR fluorescence imaging, is thus an advanced theranostic platform for thrombolytic therapy with reduced hemorrhaging risk and enhanced imaging/thrombolysis efficiency. STATEMENT OF SIGNIFICANCE: Herein, for the first time, a P-selectin specific, photothermal theranostic nanocomposite for thrombus-targeted co-delivery of urokinase and NIR fluorescence contrast agent indocyanine green (ICG) was developed. We evaluated the potential of this theranostic nanocomposite for thrombus imaging and enzyme/hyperthermia combined thrombolytic therapy. The nanocomposite showed multiple functions including thrombus targeting and imaging, and photothermal thrombolysis. Besides, it allowed faster release of the thrombolytic urokinase for rapidly clearing blood clots and slower release of a brown algae-derived anticoagulant fucoidan (also acting as a P-selectin ligand) for prevention of thrombosis regeneration. The nanocomposite is thus a new and advanced theranostic platform for targeted thrombolytic therapy.

Development and Validation of an HPLC Method Using an Experimental Design for Analysis of Amlodipine Besylate and Enalapril Maleate in a Fixed-dose Combination

Objectives

The aim of this study was to develop and optimize a simple, cost-effective, and robust high-performance liquid chromatography (HPLC) method by taking an experimental design approach to the assay and dissolution analysis of amlodipine besylate and enalapril maleate from a fixed-dose combination tablet.

Materials and Methods

The chromatographic analysis was performed on a C18 column (4.6x250 mm id., particle size of 5 μm). The injection volume was 5 μL, and the detection wavelength was 215 nm. A Box-Behnken design was used to test the robustness of the method. The flow rate (1, 1.2, and 1.4 mL/min), column temperature (25°C, 30°C, and 35°C), methanol ratio of the mobile phase (5, 10, and 15%), and pH of the mobile phase (2.8, 3, and 3.2) were selected as independent variables. The method was validated according to International Conference on Harmonization guidelines. Dissolution of the tablets was performed by using USP apparatus 2 and analyzed using the optimized HPLC method. Multivariate linear regression analysis and ANOVA were used in the statistical evaluation.

Results

Linear models were fitted for all variables. The flow rate was the most significant factor affecting the APIs' concentrations. The optimized method included the following parameters: Column temperature of 25°C, 10% methanol as the mobile phase, pH of 2.95, and flow rate of 1.205 mL/min. Retention times were 3.8 min and 7.9 min for enalapril and amlodipine, respectively. The method was found to be linear in the range of 0.8-24 μg/mL (R² >0.999) and 1.6-48 μg/mL (R² >0.999) for amlodipine and enalapril, respectively. Both APIs were dissolved more than 85% within 10 min.

Conclusion

The experimental design was proved as a useful tool for the determination and separation of enalapril maleate and amlodipine besylate in dosage forms. The optimized method can be used for in vitro performance and quality control tests of fixed-dose tablet combinations containing enalapril maleate and amlodipine besylate.

Developing a Validated HPLC Method for Quantification of Ceftazidime Employing Analytical Quality by Design and Monte Carlo Simulations

BACKGROUND

Ceftazidime, a third-generation cephalosporin, is widely used in the treatment of lung infections, often given as "off-label" nebulization. There is a need to develop a sensitive and robust analytical method to compute aerodynamic properties of ceftazidime following nebulization.

OBJECTIVE

The current study entails development of a simple, accurate, and sensitive HPLC method for ceftazidime estimation, employing the principles of analytical quality-by-design (AQbD) and Monte Carlo simulations.

METHOD

Selection of critical material attributes (CMAs) affecting method performance was accomplished by factor screening exercises. Subsequently, the influential CMAs, i.e., mobile phase ratio and flow rate, were systemically optimized using a face-centered cubic design for the chosen critical analytical attributes (CAAs). The factor relationship(s) between CMAs and CAAs was explored employing a 3 D-response surface and 2 D-contour plots, followed by numerical as well as graphical optimization, for establishing the optimal chromatographic conditions. The obtained method operable design region was validated by Monte Carlo simulations for defect rate analysis.

RESULTS

The optimized HPLC conditions for estimating ceftazidime were acetonitrile to acetic acid solution (75:25) as mobile phase at a flow rate of 0.7 mL/min, leading to Rt of 4.5 min and peak tailing ≤2. Validation studies, as per International Conference on Harmonization Q2(R1) guidance, demonstrated high sensitivity, accuracy, and efficiency of the developed analytical method with an LOD of 0.075 and LOQ of 0.227 µg/mL. Application of this chromatographic method was extrapolated for determining aerodynamic performance by nebulizing ceftazidime at a flow rate of 15 L/min using a next-generation impactor. The study indicated superior performance, sensitivity, and specificity of the developed analytical system for quantifying ceftazidime.

CONCLUSIONS

Application of an AQbD approach, coupled with Monte Carlo simulations, aided in developing a robust HPLC method for estimationof ceftazidime per se and on various stages of impactor.

HIGHLIGHTS

(i) QbD-enabled development of robust RP-HPLC method for ceftazidime quantification, (ii) Analytical method optimization employing Risk Assessment and Design of Experiments, (iii) Design space verification and defect rate analysis using Monte Carlo simulations, (iv) Chromatographic method validation as per ICH Q2 R1 guidelines and (v) Quantitative estimation of ceftazidime on various stages of impactor.

Simultaneous separation of insulin and six therapeutic analogues on a mixed mode column: HPLC-UV method development and application

Human insulin and six most used therapeutic analogues are very similar in terms of retention on a reversed-phase column. Thus, the LC methods prescribed in the European Pharmacopoeia monographs for insulin and insulin analogues include many similar separation methods, which tend to be time consuming when separating individual products of insulins or are inadequate when handling a mixture. In this study, we present a simple, robust, versatile and accessible HPLC-UV separation method for identification and quantification of human insulin and its analogues in one run. The simultaneous separation and detection is possible by fine-tuning the mobile phase properties that affect the separation mechanism on a mixed mode column combining anion exchange and reversed-phase characteristics. Also developed was a simple and effective SPE sample cleaning procedure with insulin recoveries ranging from 80 to 100% for all analogues. On the other hand, the concentration of major excipients such as phenol and m-cresol fall below 1%. The two developed and validated separation methods differ in their compatibility with the use of a quaternary or binary pump, thus enabling sample characterisation independent of the HPLC solvent delivery system. The methods are compatible with the use of a mass spectrometric detector for an indisputable identification.

Analysis of Aspirin, Prasugrel and Clopidogrel in Counterfeit Pharmaceutical and Herbal Products: Plackett–Burman Screening and Box–Behnken Optimization

An isocratic reversed-phase high-performance liquid chromatographic method has been developed and validated for the simultaneous determination of aspirin, prasugrel HCl and clopidogrel bisulfate in the presence of clopidogrel-related compound (impurity-A) in focus on counterfeit. This method was used to determine counterfeited antiplatelet drugs in two substandard Indian pharmaceutical products sold on the market in Yemen and two traditional herbal medicines sold on the market in China. Thin layer chromatography and mass spectrometry of counterfeit herbal medicines have additionally been carried out to verify the identification of adulterants. Chromatographic separation was performed on Inertsil ® ODS-3 C18 (4.6 × 250 mm, 5 μm) with isocratic mobile phase elution containing a mixture of acetonitrile: (25 mM) potassium dihydrogen phosphate buffer, pH 2.7 adjusted with 0.1 M o-phosphoric acid (79: 21, v/v), at a flow rate of 1 mL/min and UV detection at 220 nm. Designs of experiment methodology, Plackett–Burman and Box–Behnken designs were used for the screening and optimization of the mobile phase composition. The method validation was also performed in accordance with the International Council on Harmonization (ICH) guidelines. The method developed for routine analysis was found to be sensitive, simple, accurate and highly robust. The results were statistically compared to reference methods using Student’s t-test and variance ratio F-test at P &lt; 0.05.

An anionic polyelectrolyte induced aggregate assembly of Thioflavin-T: A prospective platform for Protamine sensing

Protamine, a polycation, is biologically and medically relevant protein. Protamine exhibits a wide array of functions in biological processes like gene transfer, tissue and organogenesis, cell reproduction, etc. Medically, Protamine is the only clinically approved antidote for Heparin and is routinely used in various surgical interventions, and hence controlling Protamine dosing in patients is very crucial. Taking into account the medical significance of Protamine, designing simple, reliable and sensitive fluorescence sensors is highly desirable. In this work, we propose one such sensitive and reliable fluorescent sensor which is based on a template of dye-polyelectrolyte assembly constituting a molecular rotor dye, Thioflavin-T and an anionic synthetic polyelectrolyte, polystyrene sulfonate. The addition of Protamine, prompts drastic modulations in spectral features of dye-polyelectrolyte assembly which enables sensitive detection of Protamine in aqueous solution. Apart from sensitive detection, our sensing platform aids in highly selective sensing of Protamine compared to other proteins. Moreover, our sensor system is constructed on label-free, inexpensive, commercially available molecules posing as an advantage over other sensor systems which involve laborious synthesis protocols. Most importantly, our sensor template is able to sense Protamine in diluted serum sample, indicating the potential practical utility of our sensor system.

Experimental investigation on sludge dewatering using granulated blast furnace slag as skeleton material

The highly compressible nature of sludge and the presence of colloidal particles cause difficulties in sludge dewatering. Reducing the moisture content in secondary sludge is a key factor in reducing the capital costs, operational costs, and transportation costs in wastewater management. This investigation concerned the combined utilization of quicklime and granulated blast furnace slag (GBFS) to improve sludge dewatering. The experimental work included the initial characterization of the sludge and granulated blast furnace slag and evaluation of the dewatering ability of the treated sludge (CST, moisture content, turbidity, zeta potential, and heavy metal and biopolymer contents). Optimization using the Box-Behnken design (BBD) was carried out with various operational parameters, and the best performance was found to be at a pH of 10.2, a dose of 0.34 g/g DS, and a contact time of 14 min. A characterization study was carried out by scanning electron microscopy (SEM) in conjunction with EDS, X-ray diffractometry (XRD), and Fourier transform infrared spectroscopy (FTIR) to confirm the structural features (dense), elemental composition, and the presence of different functional groups. Hence, this study concluded that the use of quicklime with granulated blast furnace slag is suitable for conditioning during sludge dewatering. Graphical abstract.

Electrochemiluminescence resonance energy transfer between luminol and black phosphorus nanosheets for the detection of trypsin via the “off–on–off” switch mode

In this work, the electrochemiluminescence behavior of a luminol–H₂O₂ system was studied on a black phosphorus nanosheet modified electrode.

Micro/Nanoparticle Delivery Systems for Ocular Diseases

Micro- (MPs) and nanoparticles (NPs) have been recently studied for their application in ophthalmic drug delivery. These drug delivery systems are able to circumvent the ocular barriers that currently limit the efficacy of conventional treatments, as well as provide a more sustained release of drug, reducing the frequency of administration and increasing patient compliance. This review summarizes the recent trends in ophthalmic research from conventional treatment to the utilization of MPs and NPs as drug carriers.

Statistical optimization of preparing marine macroalgae derived activated carbon/iron oxide magnetic composites for sequestering acetylsalicylic acid from aqueous media using response surface methodologys

This study focuses on the optimization of synthetic conditions for preparing marine macroalgae-derived activated carbon/iron oxide magnetic composites (AC/Fe-MC) and its feasibility for the removal of acetylsalicylic acid from aqueous media. Response surface methodology coupled with a 3^k Box-Behnken design was applied to determine the optimal conditions (independent variables: impregnation ratio, activation temperature, and activation time) towards two response variables (production yield and adsorption capacity). According to the analysis of variance and numerical desirability function approaches, the optimal conditions were impregnation ratio of 2.62:1, activation temperature of 727 °C, and activation time of 129 min. Physicochemical properties of the prepared composite revealed that AC/Fe-MC possesses a porous structure and superparamagnetic property, which substantially contributed to the effective adsorption capacity and separation from the solution using an external magnetic field. Adsorption kinetics and equilibrium studies delineated that the pseudo-second-order and Sips isotherm models represent the adsorption behavior of AC/Fe-MC accurately. The maximum adsorption capacity of AC/Fe-MC was found to be around 127 mg/g at 10 °C, as fitted by Sips isotherm model, which is higher than that of other adsorbents reported in the literature. Intraparticle diffusion and Boyd models suggested that the adsorption process was mainly controlled by film diffusion mechanism. Lastly, thermodynamic and isosteric heat of adsorption analyses demonstrated that the adsorption process was controlled by physisorption and exothermic mechanisms.

Aggregation-induced emission enhancement of gold nanoclusters triggered by silicon nanoparticles for ratiometric detection of protamine and trypsin

Metal nanoclusters protected by glutathione (GSH) have attracted a wide attention due to the unique aggregation-induced emission (AIE) feature. However, the "trigger" effects of ethanol, temperature, pH values, and metal ions may restrict the application of these particles. In this work, the amino modified silicon nanoparticles (SiNPs) and GSH-capped gold nanoclusters (GSH-AuNCs) can self-assemble into well-defined spherical particles due to the electrostatic interaction. As a result, the unique aggregation-induced emission enhancement (AIEE) of GSH-AuNCs arises at 570 nm, and the SiNPs keep their own blue fluorescence at 450 nm, so a novel nanohybrid probe (SiNPs@GSH-AuNCs) with dual-emission property has been constructed. When protamine is added to SiNPs@GSH-AuNCs, the cationic protamine can compete with SiNPs and absorb onto the surface of GSH-AuNCs, which inhibits the self-assembly and leads to the fluorescence quenching of GSH-AuNCs; while trypsin can catalyze the hydrolysis of protamine, the self-assembly starts again, producing the AIEE recovery. In the whole process, the SiNPs act as an internal standard and their emission stays constant. By means of the fluorescence intensity ratios I₅₇₀/I₄₅₀, the linear range of protamine is from 0.15 to 3.00 μg mL^-1 with the limit of detection (LOD) of 0.07 μg mL^-1, and trypsin shows a linear response in the range from 10 to 100 ng mL^-1 with LOD of 4.50 ng mL^-1. Furthermore, this strategy exhibits good sensitivity and selectivity, and has been further validated by applying it for the determination of protamine and trypsin in serum samples.

Risk-based approach for method development in pharmaceutical quality control context: A critical review

Pharmaceutical regulatory bodies increasingly require the implementation of systematic approaches in pharmaceutical product development. Quality control methods play a key role in the control strategy of drugs manufacturing to assure their quality. A risk-based approach in the analytical method development is strongly recommended to ensure that the method performances fit the purpose of the method during its entire life-cycle. In the last decade, analytical quality by design (AQbD), as risk management oriented methodology, has been progressively integrated with method development for fulfilling this objective. This approach has successfully allowed the quality to be designed into the analytical processes by obtaining a deep understanding of the procedures. In this paper the AQbD workflow and its application in the development of methods to be used for pharmaceutical quality control have been treated and discussed. Recent publications regarding how AQbD has been applied in separation techniques were reviewed. The different development strategies have been also showcased, highlighting their advantages and disadvantages, in order to give a useful overview.

A headspace-gas chromatography method for isopropanol determination in warfarin sodium products as a measure of drug crystallinity

Coumadin® a nd s everal generic products of warfarin s odium (WS) contain the crystalline form (clathrate) in which WS and isopropanol (IPA) are associated in a 2:1 molar ratio. IPA is critical in maintaining the WS crystalline structure. Physicochemical properties of the drug and drug product may change when the crystalline drug transforms to amorphous form. A headspace-gas chromatography (HS-GC) method was developed and validated for IPA determination in the WS drug product. n-propanol (NPA) was used as internal standard and the method was validated for specificity, system suitability, linearity, accuracy, precision, range, limits of detection and quantification, and robustness. The method was specific, with good resolution between IPA and NPA peaks. Chromatographic parameters (retention time, IPA/NPA area ratio, tailing factor, theoretical plates, USP symmetry, capacity factor, selectivity and resolution) were consistent over three days of validation. The analytical method was linear from 2-200 μg mL-1 (0.1- 10 % IPA present in the drug product). LOD and LOQ were 0.1 and 2 μg mL-1, respectively. Accuracy at low (2 μg mL-1) and high (200 μg mL-1) IPA concentrations of the calibration curve was 103.3-113.3 and 98.9-102.2 % of the nominal value, resp. The validated method was precise, as indicated by the RSD value of less than 2 % at three concentration levels of the calibration curve. The method reported here was utilized to determine accurately and precisely the IPA content in in-house formulations and commercial products. In summary, IPA determination by HS-GC provides an indirect measure of WS crystallinity in the drug product. Nevertheless, it should be confirmed by another analytical method since IPA from the drug substance is not distinguishable from IPA that may be present outside the drug crystals in a dosage form when prepared by wet granulation with IPA.

Silver triangular nanoplates as an high efficiently FRET donor-acceptor of upconversion nanoparticles for ultrasensitive "Turn on-off" protamine and trypsin sensor

Silver triangular nanoplates (STNPs) as a high efficient fluorescence quenching reagent of upconversion nanoparticles (UCNPs) was used to constract a novel label-free fluorescence nanosensor for ultrasensitive detection of protamine and trypsin based on fluorescence resonance energy transfer (FRET) between STNPs and UCNPs. In this assay, the negatively charged STNPs can bind with positively charged UCNPs through electrostatic interaction, and then quenched the fluorescence of UCNPs. When protamine was added to the mixture of UCNPs-STNPs, the STNPs interacted with protamine and then detached from the surface of UCNPs and aggregated, which result in the recovery of the fluorescence of UCNPs. Trypsin could catalyze the hydrolysis of protamine and effectively quench the fluorescence recovered by protamine. By measuring the changes of the fluorescence of UCNPs, the concentrations of protamine and trypsin were determined. Under the optimized conditions, the linear response range was obtained from 10 to 500ng/mL, 5-80ng/mL and with the low detection limit of 3.1ng/mL and 1.8ng/mL for protamine and trypsin, respectively. Meanwhile, the nanosensor shows good selectivity, sensitivity and can be successfully applied to detection of protamine and trypsin in serum samples.

Determination of the stereoisomeric impurities of sitafloxacin by capillary electrophoresis with dual chiral additives

Because of the bioactivity against the human topoisomerase II, the stereoisomeric impurities of sitafloxacin should be controlled in the process of manufactory. In the present work, a capillary electrophoresis (CE) method was developed and validated for simultaneous determination of three stereoisomeric impurities of sitafloxacin. The separation with high resolution not only for the separation of enantiomers, but also for the separation of diastereoisomers was achieved by using a background electrolyte composed of dual chiral selectors, namely γ-cyclodextrin (γ-CD) and Cu²⁺-d-phenylalanine (D-Phe) complex. The combination of two chiral selectors is indispensable to gain a high separation selectivity due to the cooperativity effect of different chiral discrimination modes: inclusion complexation (γ-CD) and ligand exchange (Cu²⁺-d-Phe). The concentrations of γ-CD, Cu²⁺ and D-Phe were found to be critical to the separation. Because two chiral selectors were involved in the enantiomer separation system, multiple factors and their interaction should be simultaneously optimized by using the response surface methodology (RSM) with a face centred central composite design (FCCD). The obtained optimized separation conditions were as follows: 15mmol/L dipotassium hydrogenphosphate solution (pH 4.5) containing 15mmol/L D-Phe, 20mmol/L CuSO₄ and 20mmol/L γ-CD, separation voltage 15kV. The method was then validated and the robustness of the method was tested. Under the optimized conditions, as low as 0.1% (m/m) stereoisomeric impurities of sitafloxacin can be determined by the method.

An overview of experimental designs in HPLC method development and validation

Chemometric approaches have been increasingly viewed as precious complements to high performance liquid chromatographic practices, since a large number of variables can be simultaneously controlled to achieve the desired separations. Moreover, their applications may efficiently identify and optimize the significant factors to accomplish competent results through limited experimental trials. The present manuscript discusses usefulness of various chemometric approaches in high and ultra performance liquid chromatography for (i) methods development from dissolution studies and sample preparation to detection, considering the progressive substitution of traditional detectors with tandem mass spectrometry instruments and the importance of stability indicating assays (ii) method validation through screening and optimization designs. Choice of appropriate types of experimental designs so as to either screen the most influential factors or optimize the selected factors' combination and the mathematical models in chemometry have been briefly recalled and the advantages of chemometric approaches have been emphasized. The evolution of the design of experiments to the Quality by Design paradigm for method development has been reviewed and the Six Sigma practice as a quality indicator in chromatography has been explained. Chemometric applications and various strategies in chromatographic separations have been described.

Establishment and reliability evaluation of the design space for HPLC analysis of six alkaloids in Coptis chinensis (Huanglian) using Bayesian approach

Coptis chinensis (Huanglian) is a commonly used traditional Chinese medicine (TCM) herb and alkaloids are the most important chemical constituents in it. In the present study, an isocratic reverse phase high performance liquid chromatography (RP-HPLC) method allowing the separation of six alkaloids in Huanglian was for the first time developed under the quality by design (QbD) principles. First, five chromatographic parameters were identified to construct a Plackett-Burman experimental design. The critical resolution, analysis time, and peak width were responses modeled by multivariate linear regression. The results showed that the percentage of acetonitrile, concentration of sodium dodecyl sulfate, and concentration of potassium phosphate monobasic were statistically significant parameters (P < 0.05). Then, the Box-Behnken experimental design was applied to further evaluate the interactions between the three parameters on selected responses. Full quadratic models were built and used to establish the analytical design space. Moreover, the reliability of design space was estimated by the Bayesian posterior predictive distribution. The optimal separation was predicted at 40% acetonitrile, 1.7 g·mL(-1) of sodium dodecyl sulfate and 0.03 mol·mL(-1) of potassium phosphate monobasic. Finally, the accuracy profile methodology was used to validate the established HPLC method. The results demonstrated that the QbD concept could be efficiently used to develop a robust RP-HPLC analytical method for Huanglian.