Liquid Chromatographic Assay Research Articles

A practical approach to estimate analytical method variability from routine testing

The performance of analytical test methods is critical to ensure decisions that affect efficacy and quality of pharmaceutical products are based on accurate and reliable results. As described in USP <1220> and advocated for in ICH Q14, continued verification of critical method attributes linked to bias and precision is essential to ensure method performance throughout the lifecycle of an analytical test method. As continued verification programs for analytical methods within the pharmaceutical industry mature, additional monitoring tools are required to deliver robust and cost-effective verification programs. Herein, a novel methodology is presented to evaluated analytical method variability directly from results generated during routine method execution. The implementation of the methodology is demonstrated for a small molecule liquid chromatographic assay method utilizing a single-point external reference calibration. Approaches to reduce the required data to be collected and broaden the applicability of the methodology to a wide range of analytical methods is described. Finally, the application of the methodology to method development activities is discussed to aid in the identification of variability sources and effectively select replication strategies, thus allowing a holistic understanding of method variability throughout the entirety of the method lifecycle.

Development and validation of RP-HPLC method for estimation of anti- hypothyroidism drug in capsule dosage form

A simple, accurate, sensitive and precise Reverse Phase-High Performance Liquid Chromatographic assay method for estimation of Levothyroxine sodium in dosage form was successfully developed. The chromatographic separation was performed on Welch Ultisil XB-CN, 150 x 4.6 mm, 5µm. column. The mobile phase consists of 0.05% OPA Buffer solution, and Acetonitrile in the ratio of 72:28, v/v. Mobile phase was delivered at a flow rate of 1.0 ml/min. Samples were injected 50 μL the column temperature was kept at 40 0C and sample temperature 150C. The wavelength 221 nm were selected for the evaluation of the chromatogram. The retention time of the drug was found to be 3.7 min. The developed method was found to be linear in a concentration range of 5-15 μg/ml of the drug (r2= 0.999). The low value of % RSD indicates reproducibility of the method. Thus this method can be used for routine analysis of pomalidomide in formulation and to check the stability of bulk samples.

A simple high-performance liquid chromatographic assay for concurrent quantification of lumefantrine and efavirenz in human plasma from malaria–HIV co-infected individuals

BackgroundAs per current treatment guidelines, artemether-lumefantrine and efavirenz-based antiretroviral therapy are recommended drugs for falciparum malaria and human immunodeficiency virus (HIV) infections, respectively. A liquid chromatography-ultraviolet detection method for simultaneous quantification of lumefantrine and efavirenz was developed and validated for efficacy and pharmacokinetic clinical studies. Lumefantrine and efavirenz were separated using a 100 × 4.6 mm × 3 µm Fortis C18 chromatographic column, and a multistep gradient mobile phase. Calibration curves were obtained with a series of standard solutions containing known concentrations of the chemical reference of both analytes prepared concomitantly in drug-free plasma. The assay was validated within the calibration ranges of 78.125–20,000 ng/mL for lumefantrine and 187.15–24,000 ng/mL for efavirenz. Stability assessment was carried out with or without heating the quality control sample to 58 °C for 45 min. The method was employed to measure the plasma concentrations of lumefantrine and efavirenz in a study conducted among malaria-HIV co-infected patients.ResultLumefantrine and efavirenz were well separated from each other and from the biological matrix. The method demonstrated a good recovery of 72.64% for lumefantrine and 117.17% for efavirenz. The intra- and inter-day accuracy presented as 95.36–105.14% for lumefantrine and 104.11–115% for efavirenz and precision ranged from 1.15 to 6.45% for lumefantrine and 0.43 to 13.12 for efavirenz, were within ± 15% at the three quality control levels. The analytes from both quality control lots and samples collected from HIV-malaria co-infected individuals were found to be stable post-deactivation of infectious virus by heating to 58 °C for 45 min.ConclusionThe assay is accurate, precise and shown to simultaneously measure the lumefantrine and EFV in human plasma.

A simple high-performance liquid chromatographic assay for lumefantrine in plasma in the presence of efavirenz-based antiretroviral therapy

A simple high-performance liquid chromatographic assay for lumefantrine in plasma in the presence of efavirenz-based antiretroviral therapy

Quality by Design based pareto charts responses Evaluation approach for a Validated Stability-indicating RP-HPLC assay Method for sunitinib and its process related impurities in Oral Dosage Forms

For sunitinib (SUN) and its associated impurities, a simple and rapid stability-indicating liquid chromatographic assay technique was developed. The SUN related impurities in the completed oral dose forms were detected and assessed utilizing the high-pressure liquid chromatography with help of analytical quality by design (AQbD) approach. Impurity quantification necessitates a more comprehensive approach to analytical technique generation. The pareto charts evaluation technique, that is dependent on quality by design, enables for the evaluation of many analytical aspects and their consequences with a small series of investigations. A spiked sample mixture was separated to six specified known SUN impurities as well as undefined degradation products with significant chromatographic resolution. The separation was undertaken on a column of C18 (150 mm x 4.6 mm, 3.5 µm) with a mobile phase flow volume of 1.0 ml in a minute in a gradient elution manner. The mobile phase component A was composed of 20 mM KH2PO4 (pH 7.0), while the mobile phase component B was acetonitrile. Compound detection was conducted out at 268 nm, with the column temperature kept fixed at 40 oC. Stress degradation samples were subjected to oxidation, acid, base, thermal, and photolysis consistent with the endorsements of “International Conference on Harmonization” (Q2) methodology. The established method for SUN and its associated impurities assessment was validated as stability indicating, precise, robust, specific, rugged, and accurate.

Development and Validation of Stability Indicating RP-HPLC Method for Quantitative Estimation of Enzalutamide in Enzalutamide Capsules Dosage Form

Objectives: A precise, accurate and selective stability-indicating reverse phase high performance liquid chromatographic assay method has been developed for the quantitative estimation of Enzalutamide in Enzalutamide capsules dosage form. Materials and Methods: The separation was achieved by using a stationary phase Waters X-Bridge Shield RP18 (150 x 4.6 mm, 3.5μ) and the mobile phase consisted of perchloric acid buffer and acetonitrile in the proportion of (20:80 volume/volume). The run velocity was 1.2 mL/min. Enzalutamide was identified using UV detector at the wavelength of 210 nm. Column oven temperature 25°C and sample cooler temperature 25°C and infused quantity 20 μL, run time was 15 min. Results: As there is no meddling flanked by blank and placebo at the retention time of Enzalutamide. Degradation study results were shown significant degradation was observed in acid and oxidation (peroxide) stress condition. Hence it can be concluded that Enzalutamide is sensitive to acid and oxidation. To obtain system precision, a study was conducted with six replicate injections. %RSD was estimated from the peak areas of Enzalutamide establish to be 0.55% correspondingly. The relative standard deviation for method exactitude was establish to be 0.55%. The suggested HPLC technique was linear over the range of 100.6-301.8 μg/mL, the correlation coefficient was establish to be 0.9999. The accuracy studies were shown as % recovery for Enzalutamide 50% to150% level. The limit of % recovered revealed is in the assortment of 98 and 102% and the consequences obtained were establish to be within the limits. Hence the technique was establish to be accurate. The solution steadiness of the standard and samples are stable upto 48 hr on a bench top and refrigerator (2-8°C). The method is robust for changes like flow rate and column oven temperature. Performed the filter validation for sample solution 0.45 μm PVDF and 0.45 μm Nylon filterers are suitable for filtration. The method has validated as per ICH guidelines and all the validation parameters are satisfy the ICH Q2 specification acceptance limits. Conclusion: The developed method was validated for an assortment of parameters as per ICH guidelines like accuracy, precision, linearity, specificity, system suitability, solution stability and robustness. The consequences obtained were within the acceptance criteria. So, it can be concluded that the urbanized technique is simple, precise, cost-effective, eco-friendly, and safe and can be successfully employed for the routine analysis of Enzalutamide in bulk and pharmaceutical dosage forms.

Serum Androgen Metabolites Correlate with Clinical Variables in African and European American Men with Localized, Therapy Naïve Prostate Cancer.

Dihydrotestosterone (DHT) and testosterone (T), which mediate androgen receptor nuclear translocation and target gene transcription, are crucial androgens and essential molecular triggers required for the proliferation and survival of prostate cancer cells. Therefore, androgen metabolism is commonly targeted in the treatment of prostate cancer. Using a high-pressure liquid chromatographic assay with tandem mass spectral detection, we determined the serum levels of metabolites produced during DHT/T biosynthesis in African American (AA) and European American (EA) men with localized, therapy naïve prostate cancer. Serum progesterone and related metabolites were significantly lower in AA men than in EA men, and these differences were associated with rapid disease progression. Multivariate analysis revealed significant differences between a subset of intermediate androgen metabolites between AA and EA men and between men with <=3 + 4 and >=4 + 3 Gleason score disease. AA men have a significantly higher frequency of single nucleotide polymorphisms in CYP11B1 and CYP11B2, enzymes that regulate corticosterone-aldosterone conversion. Finally, higher levels of T and pregnenolone were associated with a lower risk of progression-free survival only in AA men. This work provides new insight into androgen metabolism and racial disparities in prostate cancer by presenting evidence of dysregulated androgen biosynthesis in therapy naïve disease that correlates with clinical variables.

A new simple liquid chromatographic assay for gentamicin in presence of methylparaben and propylparaben

AbstractGentamicin sulfate is a potent broad spectrum aminoglycoside antibiotic which is used against Gram-positive and Gram-negative bacteria. A simple, isocratic HPLC method for separation, identification and determination of gentamicin and parabens (methylparaben and propylparaben) was developed and validated. To our knowledge there is no report about simultaneous determination of those three analytes in pharmaceutical products. The optimum chromatographic conditions were achieved on CN column with a mobile phase consisting of 0.15% triethylamine in 10 mM KH2PO4 aqueous solution (final pH 3.0 adjusted with H3PO4) and methanol in the ratio 70:30 (v/v), providing selective quantification of analytes within 5 min. The method was successfully validated according to ICH guidelines acceptance criteria in terms of selectivity, linearity, accuracy, precision and robustness. The linearity of the method was proved in defined concentrations ranges for gentamicin (0.32–1.04 mg mL−1), methylparaben (0.0072–0.0234 mg mL−1) and propylparaben (0.0008–0.0026 mg mL−1). Relative standard deviations calculated for all analytes in precision testing were &lt;2% (analysis repeatability) and &lt;3% (intermediate precision). Recovery values were between 98.87% and 101.67%. Chromatographic parameters are not significantly influenced by small variations of column temperature, pH and molarity of KH2PO4. Finally, the method was successfully applied for quantitative determination of gentamicin and parabens in commercially available solution for injection. Proposed HPLC method is found to be promising in terms of simplicity, analysis times and non-use of derivatization and ion-pair agents.

Development and validation of a stability-indicating high performance liquid chromatographic assay for determination of cariprazine in bulk form and in drug product

The aim of the present study is to develop a stability indicating high performance liquid chromatographic method for the determination of cariprazine in bulk substance and in drug product. The chromatographic separation was carried out using a Phenomenex Kinetex® C18 column (5μm, 250×4.6mm) and a mobile phase consisting of acetonitrile-potassium dihydrogen orthophosphate buffer (pH 4; 50mM) (30:70, v/v), at a flow rate of 1mlmin -1 and UV detection at 248nm. The column was maintained at 25°C and an injection volume of 20μL was used. Stress testing of cariprazine bulk substance and drug product was performed according to the International Conference on Harmonization (ICH) Q1A (R2) guideline. Various stress conditions were tested including acidic, alkaline and neutral hydrolysis, humidity, oxidation, dry heat and photolysis. A total of three degradation products (DPs) were formed. Among them two DPs were successfully characterized with the liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis.

Development and Validation of New RP-HPLC Method for Estimation of Pramipexole Dihydrochloride in Bulk and Pharmaceutical Formulation

A novel high-performance liquid chromatographic assay method was developed and validated for the quantitative determination of the anti-Parkinson agent pramipexole dihydrochloride monohydrate in bulk and its tablet dosage form. In this perspective, the chromatographic separation was accomplished on Eclipse XDB-12 C18 (150 mm x 4.6 mm, 5 μm particle size) column using UV detection at 263 nm. The mobile phase consisted of distilled water: acetonitrile (10: 90 v/v), run at a flow rate of 1.0 mL/min with isocratic elution. The method was validated in accordance with ICH guidelines by evaluating the system suitability, linearity, limits of detection (LOD) and quantitation (LOQ), precision, accuracy, specificity, selectivity and short-term stability. Our findings revealed that retention time for pramipexole dihydrochloride was found to be 5.2 minutes. The linearity range was established between 6.25-225.0 μg/mL with a mean recovery of 101.26 % ± 0.56. The limits of detection and quantification were determined to be 4.18 μg/mL and 12.66 μg/mL, respectively, indicating that the method is very sensitive. Intra and inter-day precision were within acceptable limits (RSD

Phytochemical investigations and development of ethosomal gel with Brassica oleraceae L. (Brassicaceae) extract: An innovative nano approach towards cosmetic and pharmaceutical industry

The study was aimed to develop and characterize plant extract (Brassica oleraceae) loaded ethosomal gel for the valuation of cosmeceutical applications with a credence that botanical extracts have a greater capability to be employed in the formulation of advanced pharmaceuticals. Phytochemical profiling via FT-IR analysis, total bioactive contents of different polarity extracts (ethanol, dichloromethane, ethyl-acetate and chloroform) and quantification by using High Performance Liquid Chromatographic (HPLC) assay was carried out. Capabilities against oxidative stress were prodded through 2, 2-Diphenyl-1-picrylhydrazyl (DPPH), reduction potential analyses. Besides this, a correlation amongst total bioactive contents (TPC/TFC) and antioxidant potentials (biological activities) was studied by multi-variate statistical analysis. An augmented ethosomal preparation, after characterization and stability studies was incorporated to the gel matrix of Carbopol-940; Test/ EG (Ethosomal gel) with a Control/NEG (Non-ethosomal gel) formulation. Both formulations were then subjected to in-vitro characterization (organoleptic evaluation, pH, conductivity and rheology) of 90 days. By permeation studies flux (μg/cm2/hr); enhancement ratio was calculated and characterization of release data was done by using different kinetic models. The plant extracts revealed the presence of different functional groups along with 39.6 ± 0.5 mgGAE/g; 26.56 ± 0.4 mgQE/g phenolic and flavonoid contents, respectively; HPLC assay confirmed the existence of Quercetin, Gallic, Caffiec, Benzoic, Syringic and Sinapic Acids with highest antioxidant activity of 87.75% ± 1.18 in hydro-alcoholic fraction. Optimized ethosomal formulation exhibited entrapment efficiency of 68.57 ± 1.25, smallest vesicle size of 228.6 ± 1.17 nm with − 21.3 ± 0.15, zeta potential and a homogeneous size distribution of 0.233 ± 0.02. Significant results were obtained after in-vitro characterization. Both formulations followed Korsmeyer-peppas model with flux 35.499 and 21.731 μg/cm2/hr respectively and enhancement ratio 1.63. Thus, a stable ethosomal loaded gel of Brassica oleraceae extract was successfully developed and characterized for cosmeceutical potential.

Development and Validation of Fast and Robust Stability Indicating RP-HPLC Method for Simultaneous Estimation of Tolperisone Hydrochloride and Etoricoxib in Pharmaceutical Dosage Form

Objectives: A precise, accurate and selective stability-indicating reverse phase high performance liquid chromatographic assay method has been developed for the simultaneous quantitative determination of Tolperisone hydrochloride and Etoricoxib in tablets. Methods: The chromatographic separation of drugs was attained by using Eclipse plus C18 (150 mm × 4.6 mm, Agilent 5µm) column at room temperature. The composition of mobile phase was mixture of 0.035M triethylamine (pH 3.0 adjusted with orthophosphoric acid) and acetonitrile in ratio of 70:30 v/v and flow rate of mobile phase 1.0 ml/min with isocratic elution. The signal of eluents was observed at 290 nm by using diode array detector. Results: The retention time of Tolperisone hydrochloride and Etoricoxib were found to be 2.826 min and 7.566 min, respectively. The linearity ranges for both drugs were found to be 5-15 μg/ml and the percent recoveries were found to be 99.39% and 99.15% for Tolperisone hydrochloride and Etoricoxib respectively. Various forced degradation conditions, such as alkali hydrolysis, acid hydrolysis, thermal degradation, photolytic degradation, and oxidative degradation, were applied to the drug ingredients and drug formulation. The degradants were efficiently separated from the drugs by using optimized chromatographic conditions. The developed method was validated as per recommendation parameters of International council on harmonization guidelines Q2(R1). Conclusion: The validation parameters indicate that the drug substances were efficiently separated from its degradants and developed method can be routinely applied for the simultaneous quantitative determination of Tolperisone hydrochloride and Etoricoxib in combined tablet formulation in the quality control laboratory.

Validation and application of a simple and rapid stability-indicating liquid chromatographic assay for the quantification of caffeine from human saliva

A clinical trial is currently underway to examine the efficacy of using caffeine citrate to prevent intermittent hypoxemia in late preterm neonates. Determining caffeine concentration using saliva in this population would be preferable as it is less invasive than plasma sampling, but a suitable method of analysis is required. This paper presents the development and validation of a rapid, efficient and reproducible stability-indicating high-performance liquid chromatography (HPLC) method and extraction protocol for the quantification of caffeine present in saliva. The stability of extemporaneously prepared caffeine citrate solutions (at 20–25 °C) was determined, along with the stability of caffeine spiked saliva samples (at 20–25 and 2–8 °C), to ensure the suitability of the developed method in the analysis of clinical trial samples. Protein precipitation using acetonitrile ensured the complete removal of salivary proteins and resulted in extraction recovery of ≥95% for all samples. The HPLC assay following extraction was linear (R 2>0.99) over the range 0.3–50 µg/mL (lower limit of quantification 0.3 µg/mL). The accuracy of the quality control samples was 94–100% and the relative standard deviation (RSD) was <7% for all samples. Caffeine-spiked saliva samples were stable for three freeze-and-thaw cycles pre-extraction and up to 72 hr post-extraction. The extraction and HPLC methods described were thus suitable for the analysis of clinical trial samples from the Latte Dosage Trial. All caffeine solutions were physically and chemically stable, with concentrations at the end of the three-month test period being within 4% of the baseline concentrations, indicating appropriateness for use as clinical trial medications.

Heavy metal contamination and antibiotic residues in poultry feed and meat in Bangladesh

Presence of harmful contaminants and residues in poultry feed and meat have serious public health consequence. This study was carried out to identify and quantify antibiotic residues, heavy metals and toxins in poultry feed and meat in the two selected poultry production belts of Bangladesh. A total of 94 broiler feed samples and 60 broiler meat samples were collected and tested by Thin Layer Chromatography (TLC), High Performance Liquid Chromatography (HPLC) and Enzyme-linked Immunosorbent Assay (ELISA) for identification and quantification of the parameters. Antibiotic residues were detected in 18.89% of the feed samples, whereas, there were no toxin (Aflatoxin) positive samples. Among the antibiotic positive samples, Oxytetracycline (OTC) was found predominant and detected in 12.22% cases. The mean concentrations of Cadmium (Cd), Lead (Pb), Chromium (Cr) were found as 0.04 mg/kg, 1.28 mg/kg and 2.55 mg/kg respectively in feed samples. In the case of meat samples, the mean concentration of OTC, Ciprofloxacin (CIP), and Tetracycline (TCL) residues were found 8.67 ppb, 7.18 ppb and 0.81 ppb accordingly. The highest mean concentration of Oxytetracycline (OTC) (10.15 ppb) was found in samples collected from local poultry sellers, whereas, the highest mean concentration of Tetracycline (TCL) (1.35 ppb) and Ciprofloxacin (CIP) (10.62 ppb) were observed in the samples obtained from local farm. The highest percentage of TCL and CIP (64% and 48% respectively) were found in samples collected from local farm. Chlortetracycline (CTC) was found predominant (70%) in samples collected from Contract farms. On the other hand, out of 60 meat samples, Cd and Cr were detected in only one meat sample with concentration of 56.41 mg/kg and 14.44 mg/kg respectively. Lead was not detected in any of the meat samples. Asian Australas. J. Food Saf. Secur. 2021, 5 (2), 71-78

HPLC with fluorescence detection for the bioanalysis and pharmacokinetic study of Doxorubicin and Prodigiosin loaded on eco-friendly casein nanomicelles in rat plasma

A rapid, efficient, and sensitive liquid chromatographic assay hyphenated to fluorometric detector (HPLC-FLD) was developed and validated for the determination of doxorubicin (DXR) and prodigiosin (PDG) in rat plasma. The sample pre-treatment involves a protein precipitation with acetonitrile with satisfying extraction efficiency (98% and 85% for DXR and PDG, respectively). The chromatographic separation was accomplished using stationary phase: Agilent Zorbax Eclipse plus-C18 analytical column (250 × 4.6 mm, 5 μm) and gradient eluting mobile phase of ammonium acetate (pH = 3), acetonitrile and methanol with programmed fluorescence detection. As the proposed method has been validated, it was subsequently implemented to evaluate DXR and PDG loaded on novel eco-friendly Casein nano drug delivery system after intravenous injection in healthy rats. A comparative pharmacokinetics’ study was carried out in rats for DXR in free form, DXR alone entrapped in the nanomicelle and DXR with PDG entrapped in the nano micelle. After testing the differences in pharmacokinetic parameters of the different formulations using ANOVA, the results showed insignificant differences among the tested parameters. This indicates that the presented nanomicelle delivery system has succeeded to incorporate PDG and DXR in a hydrophilic, safe, and potent formulation. This novel nanomicelle has negligible effect on the distribution and elimination of DXR.

A NOVEL VALIDATED HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC STABILITY-INDICATING ASSAY METHOD IN REVERSE PHASE FOR ESTIMATION OF HYDROXYPROGESTERONE CAPROATE IN AN INJECTABLE FORMULATION.

A high-performance liquid chromatographic stability-indicating assay method in reverse-phase has been developed and validated for the quantitative measurement of Hydroxyprogesterone corporate in injectable formulation prepared in castor oil base containing excipient benzyl benzoate as preservative. The reverse-phase method was developed by using Sunfire C18 column having dimensions (150 x 4.6 mm x 5μm) with a mobile phase[A] comprised of water, acetonitrile, and Methanol mixed in 40:30:30 v/v ratio and mobile phase [B] comprised of water, acetonitrile, and Methanol mixed in 20:40:40 v/v ratio pumped gradient program at a flow rate of 1.0 ml/min where the thermostat of the column oven controlled at 30°C and sample compartment at 5°C. The injection volume is set at 20μL. Hydroxyprogesterone corporate has a retention time of 10 minutes with UV detection at 240 nm. The detector was showing linear response in a range of 0.25 μg/ml to 150 μg/ml for Hydroxyprogesterone corporate. The guidelines of the International Conference on Harmonization on guidance for industry (2005) validation of analytical procedures, text, and methodology Q2(R1) were followed for the validation of this novel method. For quantification of Hydroxyprogesterone corporate the developed method was found to be genuinely exact precise, accurate, linear, robust, rugged, stable. and cost-effective.

Momordica Charantia Polysaccharides Attenuates MPP+-Induced Injury in Parkinson’s Disease Mice and Cell Models by Regulating TLR4/MyD88/NF-κB Pathway

Objective. To investigate the potential role of Momordica charantia polysaccharides (MCPs) in Parkinson’s disease (PD) and reveal the molecular mechanism of its function. Method. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridinium (1-methyl-4-phenylpyridinium, MPP+) were used to establish PD mice and cell models. The mice and cells were divided into 4 groups: Control group, Control+MCPs group, PD group, and PD+MCPs group. Pole climbing experiment and Rotarod experiment were used to observe the coordination ability of mice. High-performance liquid chromatography and enzyme-linked immunosorbent assay (ELISA) were used to determine neurotransmitters and metabolites, inflammatory factors TNF-α and IL-1β, oxidative stress-related markers SOD, MDA, and GSH in striatum tissues. Western blot was used to determine the protein levels of tyrosine hydroxylase (TH), oxidative stress-related protein Cytochrome C (Cytochrome C), and apoptosis-related proteins Bcl-2, Bax, and cleaved Caspase-3 in tissues and cells. Moreover, flow cytometry, PI staining, and fluorescence were used to observe cell apoptosis. Finally, the activation effect of MCPs on TLR4/MyD88/NF-κB signaling pathway was observed and verified. Results. Compared with the Control group, MPTP treatment can induce brain damage in mice (all P &lt; 0.05 ), change the metabolic state of neurotransmitters (all P &lt; 0.05 ), induce inflammation (all P &lt; 0.05 ), and induce apoptosis and the occurrence of oxidation reaction (all P &lt; 0.05 ); however, MCPs treatment can significantly reverse the above changes (all P &lt; 0.05 ). In cell models, studies have found that MCPs can play a protective role by regulating the activation state of TLR4/MyD88/NF-κB pathway. Conclusion. This study found that the application of MCPs therapy can play anti-inflammatory, antioxidative stress, and antiapoptotic effects in PD by regulating the activation of the TLR4/MyD88/NF-κB pathway.

Development and Validation of Q-Absorbance Ratio by UV-Spectrophotometric Method for Simultaneous Estimation of Metformin and Empagliflozin in Bulk and Combined Dosage Form

Advantages of simultaneous stability studies are the identification of new degradation products, to understand mutual induction and/or inhibition of rates of degradation and to analyze the degradation products of both drugs. Various ultraviolet spectroscopic and high performance liquid chromatographic assay methods were reported for the estimation of metformin, sitagliptin, pioglitazone, glimepiride and simvastatin individually and in combination with other drugs. All the above reported methods were based on the estimation of metformin, sitagliptin, pioglitazone, glimepiride and simvastatin alone or in combination with other drugs. The degradation products were generated and successfully separated by the developed and validated high performance liquid chromatographic methods for the estimation of the selected anti-diabetic drug combinations. The aim of the study was to develop and validate of Q-Absorbance Ratio UV-Spectrophotometric Method for Simultaneous Estimation of Metformin and Empagliflozin in Bulk and Combined Dosage Form.&#x0D; Keywords: Metformin, Method Development, Validation, Empagliflozin, UV-Spectrophotometer.

Development and Validation of a Chiral Liquid Chromatographic Assay for Enantiomeric Separation and Quantification of Verapamil in Rat Plasma: Stereoselective Pharmacokinetic Application.

A novel, fast and sensitive enantioselective HPLC assay with a new core–shell isopropyl carbamate cyclofructan 6 (superficially porous particle, SPP) chiral column (LarihcShell-P, LSP) was developed and validated for the enantiomeric separation and quantification of verapamil (VER) in rat plasma. The polar organic mobile phase composed of acetonitrile/methanol/trifluoroacetic acid/triethylamine (98:2:0.05: 0.025, v/v/v/v) and a flow rate of 0.5 mL/min was applied. Fluorescence detection set at excitation/emission wavelengths 280/313 nm was used and the whole analysis process was within 3.5 min, which is 10-fold lower than the previous reported HPLC methods in the literature. Propranolol was selected as the internal standard. The S-(−)- and R-(+)-VER enantiomers with the IS were extracted from rat plasma by utilizing Waters Oasis HLB C18 solid phase extraction cartridges without interference from endogenous compounds. The developed assay was validated following the US-FDA guidelines over the concentration range of 1–450 ng/mL (r2 ≥ 0.997) for each enantiomer (plasma) and the lower limit of quantification was 1 ng/mL for both isomers. The intra- and inter-day precisions were not more than 11.6% and the recoveries of S-(−)- and R-(+)-VER at all quality control levels ranged from 92.3% to 98.2%. The developed approach was successfully applied to the stereoselective pharmacokinetic study of VER enantiomers after oral administration of 10 mg/kg racemic VER to Wistar rats. It was found that S-(−)-VER established higher Cmax and area under the concentration-time curve (AUC) values than the R-(+)-enantiomer. The newly developed approach is the first chiral HPLC for the enantiomeric separation and quantification of verapamil utilizing a core–shell isopropyl carbamate cyclofructan 6 chiral column in rat plasma within 3.5 min after solid phase extraction (SPE).

High performance liquid chromatographic assays with UV-detection for evaluation of inhibitors of acetylcholinesterase and butyrylcholinesterase

Acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) are considered as viable targets in the treatment of Alzheimer’s disease and other dementias. However, since clinically used AChE or dual AChE/BuChE inhibitors only provide some symptomatic treatment and lose their therapeutic effectiveness over time, in the last years an intensive search for multi-target compounds has started, which address additional targets besides AChE and BuChE, like endocannabinoid degrading enzymes. For the evaluation of the AChE and BuChE inhibitory potency of the test compounds in such drug development projects, usually the traditional Ellman’s method is used. Since this method has some analytical drawbacks, we have developed alternative robust HPLC/UV based assays using pyridin-2-ylmethyl acetate as substrate for AChE and benzoylcholine for BuChE. The enzyme products pyridin-2-ylmethanol and benzoic acid, respectively, were determined by reversed phase HPLC adding the ion pair reagent sodium octane-1-sulfonate to the mobile phase in case to the polar pyridine derivative. AChE from electric eel, human recombinant AChE and BuChE from equine serum were employed as enzymes. For method validation, the IC50-values of the known AChE and BuChE inhibitors physostigmine, rivastigmine and tacrine were measured. The obtained data were within the very wide range of the IC50-values given in the literature for these compounds.