Empagliflozin: Validation of Stability-Indicating LC Method and in silico Toxicity Studies

A new stability-indicating liquid chromatography method was developed for the quantification of empagliflozin and two synthetic impurities. The chromatographic conditions included Spherisorb® RP-18 column (150 × 4.6 mm, 5 μm) with a PDA detector, using acetonitrile and formic acid (pH 4.0) as mobile phase in gradient elution and flow-rate of 1.2 mL·min-1. The gradient increasing from 51 to 100% acetonitrile until 11.00 min, followed by decreasing the solvent from 100% to the initial ratio from 11.01 to 15.00 min. The method was validated according to International Council of Harmonization guidelines. The LOD and LOQ values for impurities A and B were 35 and 15 ng·mL-1, respectively, (for LOD) and 115 and 35 ng.mL-1, respectively (for LOQ). The method was linear in the range of 80-140, 115-1150 and 35-350 ng·mL-1 for EMPA, impurities A and B, respectively, and the correlation coefficient were > 0.999 in all situations, indicating the method good linearity. The developed method showed a good recovery for empagliflozin and added impurities. The method has proven to be precise, demonstrated values less than 2.0% to empagliflozin and 5.0% to synthetic impurities, robust and selective with no interference from other products in the determination of analytes. The in silico toxicity prediction suggested that the impurities do not present any toxicity risk for the parameters evaluated.

Bilastine: stability-indicating a method using environmentally friendly by reversed-phase high-performance liquid chromatography (RP-HPLC)

This study describes the development and validation of a new environmentally friendly analytical method for the determination of bilastine in coated tablets and the evaluation of its capacity to be stability-indicating as well. The ecofriendly analytical method was validated by specificity, linearity, accuracy, precision and robustness by reversed-phase high-performance liquid chromatography (RP-HPLC) according to International Conference on Harmonization guidelines (ICH) and Association of Official Analytical Chemists (AOAC). Isocratic LC separation was achieved on a RP18 column using a mobile phase of sodium dihydrogen phosphate aqueous buffer solution adjusted to pH (6.0 ± 0.1) with o-phosphoric acid (85% v/v) and triethylamine (0,3% v/v) and ethanol (EtOH) in the following proportions (60:40 v/v), at a flow rate of 1.0 mL·min-1 at temperature-controlled at 30 °C. The analytical method showed selectivity, good recovery and precision (intra- and inter-day), robustness, and linear over a range from 5.0 to 50 μg·mL-1.

A Review of Characteristics, Properties, Application of Nanocarriers and Analytical Methods of Luliconazole

Luliconazole is an imidazole agent, used for the treatment of fungi infection, especially dermatophytes. The mechanism of action of the drug consisting in inhibits sterol 14α-demethylase which interferes with ergosterol biosynthesis. Due to low aqueous solubility and highly lipophilic, there is a need to develop drug delivery systems (nanocarriers) capable to increase the solubility, permeability, and skin retention of luliconazole, and promote a better therapeutic effect. In this context, this review presents characteristics, properties, nanocarriers, and analytical methods used for luliconazole. From the analyzed studies, the majority reports the use of RP-HPLC techniques for luliconazole determination, but also are cited spectrophotometric UV methods. The luliconazole has been qualitatively and quantitatively analyzed in different matrices, such as raw material and pharmaceutical formulations, however, in this review, only one study was found with the luliconazole quantification biological matrix, demonstrating the lack of studies related to the quantification of the drug in biological matrices. The drug quantification in different matrices by analytical methods is of great importance since they assist in the control of the quality, efficacy, and safety of the medicine.

Multiresidue Analytical Method for Pesticides in Soybean Extract

Developed and validated a fast, simple and effective method based on the use of DLLME technique and determination by GC-MS of 26 pesticides in SE. To carry out the extraction of the pesticides of the matrix, 70 μL of mix of pesticides (1.5 μg/mL) was added to 5.0 mL of SE, containing 1.0 g of sodium chloride and 3.0 mL of acetonitrile. The results of validation were suitable. The calibration curve was linear in the range of 0.500-5.0 μg/mL. The method showed a limit of detection and quantification of 0.17 μg/mL and 0.50 μg/mL, respectively. The recovery recovering between 47% and 115%, with relative standard deviation (RSD) of <20% for fortification levels (range of 1.0-3.0 μg/mL). The method validated can be applied for routine analysis in soy-based drinks, considering it is fast, easy to perform and has satisfactory validation results.

Bilastine: Quantitative Determination by LC with Fluorescence Detection and Structural Elucidation of the Degradation Products Using HRMS

BACKGROUND

A liquid chromatography (LC) stability-indicating method was developed and validated for the quantitative determination of bilastine in coated tablets.

OBJECTIVE

The procedure was validated for specificity, linearity, robustness, precision, and accuracy. Plackett-Burmann experimental design was used to determine the robustness of the method.

METHOD

Chromatographic separation was performed on a Shim-pack® RP-18 column with fluorescence detection. The degradation products formed under oxidative conditions were isolated and identified using high-resolution mass spectrometry (HRMS). In silico prediction of degradation products and in silico toxicity studies were also performed.

RESULTS

The LC method presented good recovery and precision (intraday and interday), the response was linear in a range of 0.20 to 0.70 μg mL-1, and the results demonstrated the robustness of the analytical method under the evaluated conditions.

CONCLUSIONS

The degradation products were identified as benzimidazole (DP1) and amine N-oxide of bilastine (DP2). The results for the toxicity studies demonstrated the high mutagenic potential of DP1 and hepatotoxicity and hERG I inhibitor effects of DP2.

HIGHLIGHTS

Bilastine degradation products were identified as benzimidazole and amine N-oxide using HRMS.

Biological Safety Studies and Simultaneous Determination of Linagliptin and Synthetic Impurities by LC-PDA

A stability-indicating LC method was developed for quantification of linagliptin (LGT) and three synthetic impurities. The method utilizes a Thermo Scientific® RP-8 column (100 mm × 4.6 mm; 5 μm) with the PDA detector for quantitation of impurities. A mixture of 0.1% formic acid with pH 3.5 (A) and acetonitrile (B) was used as the mobile phase at a flow rate of 0.6 mL·min^-1 with gradient elution. The percentage of mobile phase B increases from 30% to 70% over 5 min and decreases from 70% to 30% between 5 and 8 min. The method was validated according to International Council for Harmonization (ICH) guidelines. The LOD values obtained were 0.0171 μg·mL^-1 and 0.015 μg·mL^-1 for LGT and impurities, respectively. The LOQ values were 0.06 μg·mL^-1 for LGT and impurities. In all cases, the correlation coefficients of LGT and impurities were >0.999, showing the linearity of the method. The % recovery of the LGT and added impurity were in the range of 92.92-99.79%. The precision of the method showed values less than 1.47% for LGT and less than 4.63% for impurities. The robustness was also demonstrated by small modifications in the chromatographic conditions. The selectivity was evidenced because the degradation products formed in stress conditions did not interfere in the determination of LGT and impurities. Toxicity prediction studies suggested toxicity potential of the impurities, which was confirmed using biological safety studies in vitro.

Stability Study of Finasteride: Stability-Indicating LC Method, In Silico and LC-ESI-MS Analysis of Major Degradation Product, and an In Vitro Biological Safety Study

Stability studies of the pharmaceutically important compound finasteride were conducted in order to evaluate decomposition of the drug under forced degradation conditions. A simple stability-indicating liquid chromatography method was developed and validated for the evaluation of finasteride and degradation products formed in pharmaceutical preparations and the raw material. Isocratic LC separation was achieved on a C18 column using a mobile phase of o-phosphoric acid (0.1% v/v), adjusted to pH 2.8 with triethylamine (10% v/v) and acetonitrile (52:48 v/v), with a flow rate of 1.0 mL min-1. The alkaline degradation kinetics of the drug were also evaluated and could be best described as second-order kinetics under the experimental conditions applied for the tablets and raw material. Based on in silico studies and molecular weight confirmation, a comprehensive degradation pathway for the drug and the identity of its major product could be suggested without complicated isolation or purification processes. Furthermore, a biological safety study was performed to evaluate the effect of the degraded sample in relation to the intact molecule. The results showed that the degraded sample affected the cell proliferation. Therefore, these studies show that special care must be taken during the manipulation, manufacture and storage of this pharmaceutical drug.

UV SPECTROPHOTOMETRIC METHOD FOR QUANTITATIVE DETERMINATION OF BILASTINE USING EXPERIMENTAL DESIGN FOR ROBUSTNESS

Bilastine is a novel nonsedative H1-receptor antagonist, which may be used for the symptomatic treatment of chronic idiopathic urticaria (CU). This study describes the validation of an UV spectrophotometric method for quantitative determination of bilastine in tablets using 0.1 mol L-1 HCl as solvent. The method was specific, linear, precise, exact and robust at 210 nm, confirming that the method is fast and useful to the routine quality control of bilastine in tablets. The validate method was compared to liquid chromatography (HPLC), which was previously developed and validated to the same drug, and no significative difference between the methods using Student´s t test was found to bilastine quantitation.

Structural elucidation of gemifloxacin mesylate degradation product

Gemifloxacin mesylate (GFM), chemically (R,S)-7-[(4Z)-3-(aminomethyl)-4-(methoxyimino)-1-pyrrolidinyl]-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid methanesulfonate, is a synthetic broad-spectrum antibacterial agent. Although many papers have been published in the literature describing the stability of fluorquinolones, little is known about the degradation products of GFM. Forced degradation studies of GFM were performed using radiation (UV-A), acid (1 mol L(-1) HCl) and alkaline conditions (0.2 mol L(-1) NaOH). The main degradation product, formed under alkaline conditions, was isolated using semi-preparative LC and structurally elucidated by nuclear magnetic resonance (proton - (1) H; carbon - (13) C; correlate spectroscopy - COSY; heteronuclear single quantum coherence - HSQC; heteronuclear multiple-bond correlation - HMBC; spectroscopy - infrared, atomic emission and mass spectrometry techniques). The degradation product isolated was characterized as sodium 7-amino-1-pyrrolidinyl-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylate, which was formed by loss of the 3-(aminomethyl)-4-(methoxyimino)-1-pyrrolidinyl ring and formation of the sodium carboxylate. The structural characterization of the degradation product was very important to understand the degradation mechanism of the GFM under alkaline conditions. In addition, the results highlight the importance of appropriate protection against hydrolysis and UV radiation during the drug-development process, storage, handling and quality control.

Gemifloxacin mesylate (GFM): dissolution test based on in vivo data

Gemifloxacin mesylate (GFM) is a synthetic, broad-spectrum, fluoroquinolone antibacterial agent. It is different from other class members because it achieves adequate plasma concentrations to inhibit both topoisomerase IV and gyrase. The aim of this study was to develop and validate a dissolution test for GFM in coated tablets, using a simulated absorption profile based on in vivo data obtained from the literature. The fraction and percentage of the dose absorbed were calculated using model-dependent Loo-Riegelman approach for two compartments. The best in vitro dissolution profile was obtained using 900 mL of pH 6.0 phosphate buffer as a dissolution medium at 37 °C ± 0.5 °C and paddles at 50 rpm. The in vitro dissolution samples were analyzed using a liquid chromatography method, and the validation was performed according to USP 34 (2011). The method showed specificity, precision, accuracy, robustness and linearity. Under these conditions, a level-A in vitro-in vivo correlation was suggested (r = 0.9926). The prediction errors were calculated to determine the validity and accuracy of the suggested correlation. The dissolution test can be used to evaluate the dissolution profile of GFM-coated tablets and minimize the number of bioavailability studies as part of new formulation development.

Levodopa microparticles for pulmonary delivery: photodegradation kinetics and LC stability-indicating method

Levodopa, (S)-2-amino-3-(3,4-dihydroxyphenyl) propanoic acid, is still considered the gold standard treatment for Parkinson's disease. However, oral levodopa shows poor pharmacokinetics and its efficacy becomes problematic with the progression of the disease. Pulmonary delivery using the association of the polymers: chitosan, hyaluronic acid and HPMC, represents a novel approach to overcome this problem. A stability-indicating liquid chromatography method for the quantitative determination of levodopa microparticles for pulmonary delivery was developed as well as its photodegradation kinetics in solution. The developed and validated method was applied for the analyses of the novel formulation as well as for protocols of stability studies.

Photodegradation kinetics, cytotoxicity assay and determination by stability-indicating HPLC method of mianserin hydrochloride

A stability-indicating HPLC method for the determination of mianserin hydrochloride in coated tablets was developed and validated. Also, drug photodegradation kinetics and cytotoxicity were determined. Chromatographic analyses were performed in an Ace RP-18 octadecyl silane column (250 mm x 4.6 mm i.d., particle size 5 microm) maintained at ambient temperature (25 degrees C). The mobile phase was composed of methanol, 50 mM monobasic potassium phosphate buffer and 0.3% triethylamine solution adjusted to pH 7.0 with phosphoric acid 10% (85:15, v/v) in isocratic mode at a flow rate of 1.0 mL x min(-1). The performed degradation conditions were: acid and basic media with HCl 1.0 M and NaOH 1.0 M, respectively, oxidation with H2O2 3% and the exposure to UV-C light. No interference in the mianserin hydrochloride elution was verified by degradation products formed. Linearity was assessed and ANOVA showed non-significant linearity deviation (p > 0.05). Adequate results were obtained for repeatability, intermediate precision, accuracy and robustness. The photodegradation kinetics of mianserin hydrochloride was evaluated in methanol. The degradation of mianserin could be better described as zero order kinetic (r = 0.9982). The UV-C degraded samples of mianserin hydrochloride were also studied in order to determine the preliminary cytotoxicity in vitro against mononuclear cells.

Degradation kinetics of telithromycin determined by HPLC method

The degradation kinetics of the antibiotic telithromycin using a stability-indicating high-performance liquid chromatography (HPLC) method is demonstrated. The photodegradation is performed by UVC lamp-254 nm (15W), installed in a chamber internally coated with mirrors, where telithromycin solutions prepared from coated tablets are placed in quartz cells. To promote oxidation, the reaction between the telithromycin solution and 3% hydrogen peroxide solution is carried out. The kinetics parameters of order of reaction and the rate constants of the degradation are determined for both conditions. The degradation process of telithromycin can be described by first-order kinetics under both experimental conditions used in this study. The results reveal the photo and oxidation lability of the drug and confirm the reliability of HPLC method for telithromycin in the presence of its degradation products.