SmartAnalysis: A sustainable digital-image colorimetry method for ethanol determination in alcohol-based hand sanitizer / SmartAnalysis: Un método sostenible de colorimetría de imagen digital para la determinación de etanol en desinfectante de manos a base de alcohol

Introducción: El consumo de desinfectantes de manos a base de alcohol ha aumentado significativamente después de la pandemia causada por el SARS-CoV-2. A pesar de la conclusión de la emergencia sanitaria declarada por la OMS en 2023, la costumbre de desinfectar las manos con geles sanitizantes a base de etanol ha sido adoptada a nivel mundial por la población. Dado que los métodos generales descritos en los compendios oficiales para la de-terminación del etanol, como la cromatografía de gases o la destilación, son laboriosos y no específicos para geles que contienen carbómero, este trabajo propone un método alternativo basado em la colorimetría de imágenes digitales. Método: La imagen digital (proporcionada por la reacción etanol-fenolftaleína) fue capturada y transformada en una señal analítica basada en el sistema de colores Rojo-Verde-Azul. Las adquisiciones de imágenes se realizaron utilizando un smartphone Samsung Galaxy J6, y las señales se generaron mediante el programa gratuito Photometrix Pro®. El método fue validado de acuerdo con las directrices de la ICH y se aplicó en muestras comerciales. Además, el método propuesto fue evaluado por su impacto ambiental utilizando la herramienta Índice del Proceso Analítico Verde (GAPI). Se generaron pictogramas utilizando el programa gratuito ComplexGAPI®.Resultados: El canal verde mostró una respuesta lineal en las curvas de calibración para concentraciones de etanol que van desde el 5 hasta el 40 % (p/p) en medio ácido. El método demostró linearidad, precisión, exactitud y robustez. Conclusiones: El método propuesto presentó como principales ventajas el uso de dispositivos de bajo costo y fáciles de manejar, así como un consumo reducido de reactivos, de acuerdo con los principios de la química analítica verde. (AU)

Introduction: The consumption of alcohol-based hand sanitizers has increased significantly after the pandemic caused by SARS-CoV-2. Despite the conclusion of the health emergency declared by the WHO in 2023, the habit of sanitizing hands with ethanol-based gel sanitizers has been globally adopted by the population. Since general methods described in official compendia for ethanol determination such as gas chromatography or distillation are laborious and not-specific to carbomer-containing gels, this work proposes an alternative method based on digital image colorimetry. Method: The digital image (provided by ethanol-phenolphthalein reaction) was captured and transformed into an analytical signal based on the Red-Green-Blue system. The image acquisitions were performed using a Samsung Galaxy J6 smartphone, and the signals were generated using the Photometrix Pro® free program. The method was validated in accordance with ICH and applied in commercial samples. Additionally, the proposed method was eval-uated for its environmental impact using the Green Analytical Process Index (GAPI) tool. Pictograms were generated using the ComplexGAPI® free program. Results: Green channel exhibited a linear response in the calibration curves for ethanol concentrations ranging from 5 to 40 % (w/w) in acidic medium. The method showed linearity, precision, accuracy, and robustness. Conclusions: The proposed method presented as main advantages the use of low-cost and easy-to-handle devices and reduced reagent consumption, in accordance with green analytical chemistry principles. (AU)

Tadalafil and Sildenafil illicit association: Stability- indicating HPLC method, photodegradation kinetic and toxicological studies

Abstract The illicit market of counterfeit medicines containing sildenafil and tadalafil has been causing serious public health problems. Thus, further studies on this illicit association are needed. A stability-indicating HPLC method was developed for simultaneous determination of tadalafil (TAD) and sildenafil (SIL) using a C18 column (250 x 4.6 mm, 5 µm). Detection was achieved at 284 nm, for TAD, and 292 nm, for SIL. The method was considered to be specific, linear, precise, accurate, robust, and sensitive. In the photodegradation kinetic studies, the drugs showed a first-order reaction rate when isolated, and zero-order when associated. Toxicological assays demonstrated that the photodegraded drugs decreased cell viability in compared to non- degraded drugs, suggesting cytotoxic activity. Additional, mutagenic activity was not observed under the tested conditions. Photodegraded drugs, in association, depicted DNA damage index, suggesting genotoxic effects. The obtained results will be able to support the forensic intelligence laboratories, as well as to alert the population about the risk inherent to consuming counterfeit products.

Forced degradation studies and stability-indicating liquid chromatography method for determination of tirofiban hydrochloride and synthetic impurities / Estudo da degradação forçada e método indicativo da estabilidade por cromatografía líquida para determinação de cloridrato de tirofibana e impurezas sintéticas

SUMMARY This study aimed to develop and validate a stability-indicating liquid chromatography method for the determination of tirofiban hydrochloride and two synthetic impurities (impurity A and impurity C). The method utilizes a RP-18 column (250 mm x 4.6 mm; 5 µm) with the PDA detector for quantitation. A mixture of triethylamine 0.1% (acidified to pH 5.5 with phosphoric acid) and acetonitrile was used as the mobile phase at a flow rate of 1 mL min-1 with gradient elution. The method presented satisfactory linearity, precision, accuracy and robustness, as well as low limits of detection and quantification, which demonstrate sensitivity in the determination of tirofiban and impurities A and C. It was selective for the determination of the drug and impurities analysed, without interference of the degradation products generated under forced conditions, demonstrating the stability-indicating capacity of the proposed method. Tirofiban showed to be practically stable to oxidative (30% H2O2 for 24 h) and thermal (75 °C for 24 h) conditions, but presented degradation to UVA light and acid hydrolysis, obeying the first order kinetics for both. In this way, it can be used as a stability-indicating method in the quality control of the raw material of tirofiban hydrochloride, as well as of the finished product. The obtained results demonstrate the importance of deepening the studies in this area, to guarantee the quality of commercialized pharmaceutical products.

RESUMO Este estudo teve como objetivo desenvolver e validar método indicativo da estabilidade por cromatografía líquida para determinação de cloridrato de tirofibana e duas impurezas de síntese (impureza A e impureza C). O método utilizou coluna de fase reversa RP-18 (250 mm x 4,6 mm; 5 µm) e detector PDA para quantificação. A fase móvel foi composta por uma mistura de trietilamina 0,1% (acidificada com ácido fosfórico para pH 5,5) e acetonitrila, à vazão de 1 mL/min, no modo gradiente. O método apresentou linearidade, precisão, exatidão, robustez, bem como baixos limites de detecção e quantificação, demonstrando sensibilidade na determinação da tirofibana e impurezas A e C. O método apresentou seletividade na determinação do fármaco e das impurezas, sem interferência dos produtos de degradação gerados na degradação forçada da tirofibana, demonstrando sua capacidade indicativa de estabilidade. O fármaco apresentou-se estável a oxidação (H2O2 30% por 24 h) e a degradação térmica (75 °C por 24 h), mas degradou frente à luz UVA e hidrolise ácida, obedecendo cinética de primeira ordem para ambas. Dessa forma, pode ser utilizado como um método indicativo de estabilidade no controle de qualidade da matéria -prima do cloridrato de tirofibana, bem como no produto acabado. Os resultados obtidos demonstram a importância de aprofundar os estudos na área, com intuito de garantir a qualidade dos produtos farmacêuticos comercializados.

Validation of an analytical method by high-performance liquid chromatography and microbiological assay, biological safety and in silico toxicity for danofloxacin

Danofloxacin is a veterinary fluoroquinolone used to treat respiratory and gastrointestinal diseases of birds, pigs and cattle. The literature reviewed shows some analytical methods to quantify this fluoroquinolone, but microbiological and biological safety studies are limited. The analytical methods were validated by the Official Codes. The LC-DAD method was developed and validated using an RP-18 column, mobile phase containing a mixture of 0.3% triethylamine (pH 3.0) and acetonitrile (85:15, v/v). The microbiological assay was performed by agar diffusion method (3 x 3) and Staphylococcus epidermidis as a microorganism test. Forced degradation studies were performed in both methods. The minimum inhibitory concentration (MIC) was performed by test microdilution and toxicity studies were evaluated using in silico study, cell proliferation, cell viability test, micronuclei and comet assay. LC and a microbiological assay proved linear, accurate, precise, and robust to quantify danofloxacin, but only the LC method showed selectivity to quantify the drug in the presence of its degradation products. These results demonstrate that the LC method is suitable for stability studies of danofloxacin, but a microbiological assay cannot be used to quantify the drug due to the biological activity of the photoproducts. Ex-vivo cytotoxicity and theoretical and experimental genotoxicity were also observed.

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.

Evaluation of the influence of fluoroquinolone chemical structure on stability: forced degradation and in silico studies

ABSTRACT Fluoroquinolones are a known antibacterial class commonly used around the world. These compounds present relative stability and they may show some adverse effects according their distinct chemical structures. The chemical hydrolysis of five fluoroquinolones was studied using alkaline and photolytic degradation aiming to observe the differences in molecular reactivity. DFT/B3LYP-6.31G* was used to assist with understanding the chemical structure degradation. Gemifloxacin underwent degradation in alkaline medium. Gemifloxacin and danofloxacin showed more degradation perceptual indices in comparison with ciprofloxacin, enrofloxacin and norfloxacin in photolytic conditions. Some structural features were observed which may influence degradation, such as the presence of five member rings attached to the quinolone ring and the electrostatic positive charges, showed in maps of potential electrostatic charges. These measurements may be used in the design of effective and more stable fluoroquinolones as well as the investigation of degradation products from stress stability assays.

Stability-indicating liquid chromatographic and UV spectrophotometric methods for the quantification of ciprofibrate in capsules and tablets

This study describes the development and evaluation of stability-indicating liquid chromatographic (LC) and UV spectrophotometric methods for the quantification of ciprofibrate (CPF) in tablets and capsules. Isocratic LC separation was achieved on a RP18 column using a mobile phase of o-phosphoric acid (0.1% v/v), adjusted to pH 3.0 with triethylamine (10% v/v) and acetonitrile (35:65 v/v), with a flow rate of 1.0 mL min-1. Detection was achieved with a photodiode array detector at 233 nm. For the spectrophotometric analysis, ethanol and water were used as the solvent and a wavelength of 233 nm was selected for the detection. The methods were validated according to International Conference on Harmonization (ICH) guidelines for validating analytical procedures. Statistical analysis showed no significant difference between the results obtained by the two methods. The proposed methods were successfully applied to the CPF quality-control analysis of tablets and capsules.

Este estudo descreve o desenvolvimento e avaliação de método indicativo da estabilidade por cromatografia líquida (LC) e método por espectrofotometria UV para quantificação de ciprofibrato (CPF) em comprimidos e cápsulas. No método por cromatografia líquida as análises foram realizadas isocraticamente em coluna de fase reversa C18, utilizando fase móvel composta por ácido o-fosfórico (0.1% v/v) pH 3.0, ajustado com trietilamina (10% v/v), e acetonitrila (35:65 v/v), com fluxo de 1,0 mL min-1. A detecção foi realizada em detector de arranjo de diodos a 233 nm. Na análise espectrofotométrica, etanol e água foram utilizados como solventes e o comprimento de onda de 233 nm foi selecionado para a detecção do fármaco. Os métodos foram validados de acordo com as diretrizes do International Conference on Harmonization (ICH). A análise estatística não mostrou diferença significativa entre os resultados obtidos pelos dois métodos. Os métodos foram aplicados com sucesso para análises de controle de qualidade do ciprofibrato em comprimidos e cápsulas.

Identification, characterization and cytotoxicity in vitro assay of nitazoxanide major degradation product.

Stress studies of the broad-spectrum antiparasitic nitazoxanide were conducted in order to isolate and elucidate the major degradation product involved in thermal, acid, alkaline, oxidative and photolytic decomposition of the drug in solution and solid state. The major degradation product was identified and characterized using techniques namely LC-DAD, (1)H NMR, (13)C NMR, IR, and MS/MS. The stability of nitazoxanide raw material and nitazoxanide in tablets and in suspension powder was studied under different conditions and the results suggest the formation of the same deacetylated degradation product occur in all cases. This product was also studied in order to determine the preliminary cytotoxicity in vitro with mononuclear cells. Compared with nitazoxanide, the degradation product showed a higher cytotoxicity at a concentration of 40 µg mL(-1) after 48 h of incubation, under tested conditions. Therefore, stress studies showed that special care must be taken during the preparation, manufacture, and storage of this pharmaceutical drug.

Stability-indicating LC assay for butenafine hydrochloride in creams using an experimental design for robustness evaluation and photodegradation kinetics study.

A stability-indicating liquid chromatography method for the determination of the antifungal agent butenafine hydrochloride (BTF) in a cream was developed and validated using the Plackett-Burman experimental design for robustness evaluation. Also, the drug photodegradation kinetics was determined. The analytical column was operated with acetonitrile, methanol and a solution of triethylamine 0.3% adjusted to pH 4.0 (6:3:1) at a flow rate of 1 mL/min and detection at 283 nm. BTF extraction from the cream was done with n-butyl alcohol and methanol in ultrasonic bath. The performed degradation conditions were: acid and basic media with HCl 1M and NaOH 1M, respectively, oxidation with H(2)O(2) 10%, and the exposure to UV-C light. No interference in the BTF elution was verified. Linearity was assessed (r(2) = 0.9999) and ANOVA showed non-significative linearity deviation (p > 0.05). Adequate results were obtained for repeatability, intra-day precision, and accuracy. Critical factors were selected to examine the method robustness with the two-level Plackett-Burman experimental design and no significant factors were detected (p > 0.05). The BTF photodegradation kinetics was determined for the standard and for the cream, both in methanolic solution, under UV light at 254 nm. The degradation process can be described by first-order kinetics in both cases.

Determination of amlodipine in pharmaceutical dosage forms by liquid chromatography and ultraviolet spectrophotometry.

A liquid chromatography (LC) method and an ultraviolet (UV) spectrophotometric method were developed and validated for quantitative determination of amlodipine in tablets and compounded capsules. The isocratic LC analyses were performed on an RP18 column using a mobile phase composed of 0.1% (v/v) ortho-phosphoric acid (pH 3.0) -acetonitrile (60 + 40, v/v) at a flow rate of 1.0 mL/min. The UV spectrophotometric method was performed at 238 nm. The analytical methods were validated according to International Conference on Harmonization Guidelines. The calibration graphs were linear [correlation coefficient (r) > 0.999] in the studied concentration range of 10-30 microg/mL for LC and 10-35 microg/mL for UV spectrophotometry. The relative standard deviation values for intraday and interday precision studies were less than 2%, and the accuracy was greater than 98% for both methods. The specificity of the LC method was proved using forced degradation. Statistical analyses showed no significant difference between the results obtained by the 2 methods. The proposed methods are precise and accurate and can be applied directly and easily to the oral pharmaceutical preparations of amlodipine.

Liquid chromatographic determination of cetirizine in oral formulations.

The development and validation of a reversed-phase liquid chromatographic (LC) method for the determination of cetirizine dihydrochloride in oral formulations are described. An isocratic LC analysis was performed on a reversed-phase C18 column (250 x 4.6 mm id, 5 microm particle size). The mobile phase was 1% orthophosphoric acid solution, pH 3.0-acetonitrile (60 + 40, v/v), pumped at a constant flow rate of 1.0 mL/min. Measurements were made at a wavelength of 232 nm. The calibration curves were linear over the range of 10-30 microg/mL (r2 = 0.9999). The relative standard deviation (RSD) values for intraday precision were 0.94 and 1.43% for tablets and compounded capsules, respectively. The RSD values for interday precision were 0.13 and 0.82% for tablets and compounded capsules, respectively. Recoveries ranged from 97.7 to 101.8% for tablets and from 98.4 to 102% for compounded capsules. No interferences from the excipients were observed. Because of its simplicity and accuracy, the method is suitable for routine quality-control analysis for cetirizine in tablets and compounded capsules.