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.

Degradation of Caffeine by Heterogeneous Photocatalysis Using ZnO with Fe and Ag

Abstract The organic compound caffeine when detected in environmental matrices such as surface waters and groundwater is considered as an emerging contaminant, in which its effects are still unknown. Therefore, in the present research, zinc oxide-based catalysts impregnated with iron and silver were prepared for the reaction of caffeine degradation by heterogeneous photocatalysis. The wet impregnation method with excess solvent was applied to the preparation of the materials, later they were characterized by adsorption of N2, X-ray diffraction and photoacoustic spectroscopy. Then, the photodegradation, photolysis and adsorption tests were carried out, in which it was observed that only the presence of the radiation or photocatalysts could not sufficiently degrade the caffeine, however when combined radiation with all the catalysts studied here presented degradation above 70% at the end of 300 minutes of the reaction, and the best catalyst studied was that containing 8% Ag in non-calcined ZnO. Thus, these results point out that the methodology employed in this research, both for the preparation of the catalysts and in the process of the photocatalysis reaction, was efficient in the degradation of the emerging contaminant, caffeine, which could later be used for a mixture of other contaminants.

Awareness on storage of drugs that should be protected from light among nursing professionals in a tertiary care teaching hospital

Background: Despite of prescribing and administration of drugs to the patient, handling of drugs with utmost care by proper storage and use helps the drug not to lose its potency when administered to a patient. Storage is an important aspect of the total drug control system. There is a need to increase awareness among nurse so as to avoid treatment failure. Exposure to light is a concern with numerous medications due to the potential for photodegradation or other chemical reactions that affect drug stability.Methods: This study was conducted on nursing professionals and students (BSc) students 1st year /2nd year, working in different departments of Inpatient and Outpatient in a tertiary care teaching hospital of RIMS Kadapa. The data was collected by using structured knowledge questionnaire on proper storage of drugs that should be protected from light which consists of 20 items, based on their answers score was given1-10.Results: Among 50, the highest number was occupied by staff nurses (28), followed by head nurses (12), student nurses (8) and the least was nursing officers (2). Majority of them were B.Sc. qualified (26), followed by general nursing (10). The M.Sc and diploma qualified nurses were seven and six in number respectively. Based on scoring they were classified as POOR (<5) 13, AVERAGE (5-10) 24, GOOD (>10) 13.Conclusions: In this study half of the nursing professionals have average knowledge on storage of light sensitive drugs irrespective of their experience, so there is a need to increase awareness on storage of light sensitive drugs.

Correlation Research on Photodegradation Products of Cobamamide / 中国药师

Objective:To research the correlation between the cobamamide photodegradation products in the visible light area at different wavelengths and the photodegradation rate intensity. Methods:The 40-minute illumination experiment was conducted for co-bamamide reference solution respectively at the wavelength of 400 nm,450 nm,500 nm,550 nm,600 nm,650 nm and 700 nm under the illumination of 50 Lx,100 Lx,200 Lx,300 Lx,400 Lx and 500 Lx,respectively. An HPLC method was used to detect the cobam-amide content after the irradiation, the contents and proportions of hydroxocobalamin and adenosine (two photodegradation products) were calculated and the two photodegradation products were confirmed by mass spectrum. Results:The main photodegradation products of cobamamide (impurity 1,adenosine and hydroxocobalamin) had the similar photodegradation tendency. Within the scope of 50 Lx-200 Lx,the illumination intensity affected the concentration ratio of hydroxocobalamin and adenosine obviously. Within the scope of 200 Lx-500 Lx,the illumination intensity showed smaller effect. Under the different wavelengths and photodegradation rate intensity, the content of hydroxocobalamin was higher than that of adenosine under the same experimental condition.Conclusion:This paper re-searched the cobamamide photodegradation products in the optimum dark condition. The method is accurate and reliable,which can be used for the control of photodegradation related substances of cobamamide.

Identification and determination of the photodegradation impurities in melphalan hydrochloride / 中国药科大学学报

This study was aimed to identify the photodegradation impurities (PD1 and PD2) in melphalan hydrochloride and establish a method for determining PD1 and PD2.The structures of the photodegradation impurities were inferred by LC-MS/MS.The impurities were confirmed by comparing with synthesized impurities.An HILIC method was established to determine PD1 and PD2.The method was carried out on an Atlantis HILIC column(4.6 mm × 150 mm,3 μm) with the mobile phase consisting of 0.1 mol/L ammonium formate (adjusted to pH 3.0 with formic acid) and acetonitrile (13∶ 87) at the flow rate of 1.0 mL/min.The column temperature was 35 ℃.The detection wavelength was 260 nm.PD1 and PD2 were characterized as 4-amino-L-phenylalanine hydrochloride and 4-(2-chloroethyl) amino-L-phenylalanine hydrochloride,respectively.Melphalan hydrochloride,PD1 and PD2 were separated completely under the HILIC condition.The established HILIC method can be used to determine the photodegradation impurities.

Characterization of Encapsulation Process of Avobenzone in Solid Lipid Microparticle Using a Factorial Design and its Effect on Photostability.

Avobenzone (AVO)liposphereswere obtained using as encapsulating material carnauba wax and applying the method of hot emulsification. A factorial design 23 was performed to optimize and recognize the influence of the initial amount of AVO, the stearyl alcohol (SA) and polysorbate (PS-20)concentrationsin the AVO loading, mean and D90 particle size. The results showed a variation of AVO loading between 1.8 and 20%, which was mainly affected by initial amount of AVO. The mean particle size D [4.3] ranged from 11.11 to 37.15 μm, this was affected by the levels of SA and PS-20, while D90 was influenced by three variables under study. Lipospheres highly loaded and under a narrow particle distribution was obtained when initial amount of AVO, SA and PS-20 were set in the maximum level. The study showed that the encapsulation process enhanced the photostability going from 31.5% for free AVO to 16.2% for the encapsulated AVO.

Photo-degradation effect on dissolved organic carbon availability to bacterioplankton in a lake in the upper Paraná river floodplain / Photo-degradation effect on dissolved organic carbon availability to bacterioplankton in a lake in the upper Paraná river floodplain

Dissolved organic carbon (DOC) is nowadays recognized as the main substrate and source of energy for aquatic microbial community. The great part of available organic carbon for bacterioplankton might be formed after photolytic degradation of humic material, which constitutes the major part of DOC in almost all natural waters. The effects of DOC photo-degradation were evaluated, as was its utilization by bacterioplankton, through a two-step experiment, one involving photo-degradation of DOC and the other bacterial growth on the photo-degraded substrate. Photo-degradation was responsible for the consumption of 19% of DOC, reduced SUVA254, an increase in the E2/E3 and E3/E4 ratios, in addition to modifications in the fluorescence spectra that indicated a rise in the labile fraction of DOC. However, these alterations on DOC were not reflected in differences in bacterioplankton growth, as shown by the fact that there were no significant differences in density, biomass, bacterial production, bacterial respiration and bacterial growth efficiency between treatment and control.

O carbono orgânico dissolvido (COD) é reconhecido atualmente como o principal substrato e fonte de energia para a comunidade microbiana aquática. Grande parte do COD biodisponível para o bacterioplâncton pode ser gerada após degradação fotolítica do material húmico dissolvido, que constitui a maior parte do carbono orgânico total. Neste trabalho foram avaliados os efeitos da fotodegração no COD de um ambiente húmico e a sua posterior utilização pelo bacterioplâncton, por meio de um experimento em duas etapas, uma de fotodegradação do COD e outra de crescimento microbiano sobre o substrato fotodegradado. A fotodegradação causou consumo de 19% do COD, diminuição na SUVA254, aumento nas razões E2/E3 e E3/E4 e modificações nos espectros de fluorescência apontando aumento da fração lábil. No entanto, as alterações no COD não se refletiram em diferenças no crescimento do bacterioplâncton, não havendo diferenças significativas com relação à densidade, biomassa, produção, respiração e eficiência de crescimento bacteriano.

Avaliação da fotoestabilidade de acetazolamida e loratadina e da capacidade de fotoproteção de seus complexos com ciclodextrinas / Assessing the photostability of acetazolamide and loratadine and the photoprotection capacity of its complexes with cyclodextrins

A fotoestabilidade é uma propriedade das moléculas que, quando utilizada como parâmetro farmacêutico, descreve como um fármaco responde à exposição à luz (solar ou artificial). No presente trabalho, foi avaliada a fotoestabilidade dos fármacos loratadina (LORA) e acetazolamida (ACZ) e de complexos LORA-ciclodextrinas. O estudo de fotoestabilidade de LORA (Capítulo 2) indicou que o fármaco é estável quando no estado sólido, porém, ocorre surgimento de coloração intensa. Por outro lado, quando em solução, observou-se degradação do fármaco, com surgimento de vários fotoprodutos denominados F1 a F15, dentre os quais foi possível identificar cinco compostos: F4 (C13H10N), F10 (C14H10CIN), F8 (C20H18CIN2O), F9 (C19H18CIN2) e F14 (C17H14CIN). A validação do método analítico CLAE, utilizado para quantificação de LORA em especialidades farmacêuticas (comprimidos e xaropes) é descrita no Capítulo 3. Na avaliação da fotodegradação forçada de formulações líquidas contendo LORA, foram degradados até 50% do fármaco. As formulações sólidas apresentaram-se fotoestáveis, observando-se perda de menos de 5% do fármaco. Não foram encontrados produtos de fotodegradação nas formulações, quando analisadas tal qual, obtidas do mercado. Dessa forma, as embalagens primárias garantiram sua estabilidade. A complexação de LORA com ciclodextrinas (Capítulo 4) mostrou-se um recurso bastante interessante para melhorar a fotoestabilidade do fármaco, uma vez que, após 12 horas de irradiação luminosa, é possível recuperar até 99% deste, quando na forma de complexo com γ-CD na proporção 1:1. Finalmente, o Capítulo 5 traz o método CLAE desenvolvido e validado para avaliação da acetazolamida (ACZ), o qual mostrou-se adequado para a quantificação do fármaco, obtendo-se ótima linearidade, precisão, exatidão e seletividade. Segundo as condições do guia Q1B, a ACZ se manteve estável quando submetida à radiação luminosa utilizando meios aquosos e no estado sólido. No entanto, a fotoestabilidade da ACZ foi afetada na presença de metanol, sendo possível quantificar três impurezas

Photostability is a property of molecules that, when used as a pharmaceutical parameter, can describe how a drug responds to exposure to light (either solar or artificial). In this study, the photostability of the drugs loratadine (LORA) and acetazolamide (ACZ), as well as LORA-cyclodextrin complexes, was evaluated. A study of the photostability of LORA (Chapter 2) indicated that the drug is stable in its solid form, however intense coloring does occur. On the other hand, when in solution form, degradation of the drug was observed, with the appearance of several photoproducts that we labled F1 to F15, among which it was possible to identify five compounds: F4 (C13H10N), F10 (C14H10CIN), F8 (C20H18CIN2O), F9 (C19H18CIN2) and F14 (C17H14CIN). The validation of the analytical method by HPLC, used for the quantification of LORA in pharmaceutical products (tablets and syrups) is detailed in Chapter 3. In the evaluation of forced photodegradation of liquid formulations containing LORA, up to 50% of the drug was degraded. The solid formulations proved to be photostable, with a loss of less than 5% of the drug. No photodegradation products were found in the formulations when they were analyzed "as is" (the way they were obtained from the commercial market). Accordingly, their primary packaging protected their stability. The complexation of LORA with cyclodextrins (Chapter 4) proved to be an effective resource for improving the photostability of the drug, since, after 12 hours of luminous radiation, it was possible to recover up to 99% of the drug, when in the complex form with γ-CD, in the proportion 1:1. Finally, Chapter 5 describes the HPLC method developed and validated for the evaluation of acetazolamide (ACZ), which proved to be adequate for the quantification of the drug, with the attainment of optimal linearity, precision, exactness and selectivity. According to the conditions of the Q1B guideline, ACZ was stable when subjected to luminous radiation using aqueous means and in its solid state. However, the photostability of ACZ was affected by the presence of methanol, and we were able to quantify three impurities

Estabilización de disoluciones acuosas de riboflavina por solapamiento espectral / Stabilization of aqueous solution of Riboflavin by spectral overlapping

Se evaluó la fotoestabilización de la riboflavina en disolución acuosa a través de solapamiento espectral. En estudios previos se determinó que la longitud de onda a 445 nm promueve la degradación de la riboflavina, por eso se escogieron los colorantes que mejor eficiencia de absorción presentaran a esta longitud de onda. El estudio de fotoprotección consistió en determinar y comparar las constantes de velocidad (k0) de las reacciones de fotodegradación de la riboflavina en disoluciones (80 µM) en presencia y ausencia de colorantes a diferentes concentraciones: tartrazina (40, 58, 71 y 187 µM), amarillo ocaso (80, 160, 442 y 1 600 µM) y amarillo de quinoleína (80,133, 160 y 1 600 µM). Las cinéticas se realizaron irradiando las muestras en una cámara de simulación solar a 250 W.m-2, a diferentes tiempos y cuantificando la riboflavina residual, mediante cromatografía líquida de alta resolución. Las constantes de velocidad (k0) se determinaron mediante el método integral. En ausencia de colorantes la fotodegradación de la riboflavina obedece a una cinética de orden cero (k0= 0,0012 mg.mL-1×min-1) con un 79,9 por ciento de degradación tras 20 min de exposición a la luz. En presencia de colorantes la estabilidad de la riboflavina mejora significativamente con el aumento de la concentración del colorante empleado; sin embargo, se encontró que el amarillo de quinoleína a bajas concentraciones (< 160 µM) incrementó la degradación de la riboflavina, mientras que en la concentración más alta estudiada, redujo 6 veces la k0, lo cual sugiere que interacciones químicas se están llevando a cabo. La mayor fotoprotección se obtuvo con el amarillo ocaso a la concentración legal permitida, donde la concentración de la riboflavina se mantuvo inalterada tras 30 min de irradiación. El estudio muestra que debido a la alta capacidad fotosensibilizante de la riboflavina, la técnica de fotoprotección por solapamiento espectral no se pueda usar de forma genérica, pues no solo se puede esperar un efecto fisicoquímico de solapamiento sino que pueden generarse interacciones fotoquímicas.

The photostabilization of Riboflavin (RF) in aqueous solution was evaluated through spectral overlap. Previous studies established that wavelength at 445nm promoted RF degradation; hence dyes that exhibited high absorption performance at 445 nm were selected. The photoprotection study consisted in determining and comparing the rate constants (k0) of the RF photodegradation reactions in solutions (80 µM), both in presence and absence of dyes at different concentrations: tartrazine (40, 58, 71 y 187 µM), sunset yellow (80, 160, 442 y 1 600 µM) and quinoline yellow (80, 133, 160 y 1600 µM).The kinetics were estimated by irradiating the samples in a solar simulation chamber at 250 W×m-2 and at different times; then the residual RF was quantified by HPLC method. The rate constants (k0) were determined by the integral method. When dyes are absent, the RF photodegradation is due to zero order kinetics (k0= 0.0012 mg×mL-1×min-1) with 79.9 percent degradation after 20 min of exposure to light. When dyes are present, the RF stability improves significantly with increasing concentration of the dye; however, it was found that quinoline yellow at low concentrations (<160 µM) increased the EF degradation, whereas at the highest studied concentration, k0 was reduced 6 times, suggesting that chemical interactions occurred. Most photoprotection was obtained from the sunset yellow at allowable concentration where RF concentration was unchanged after 30 min of irradiation. The study showed that the high photosensitizing capacity of riboflavin hindered the generic use of photoprotective technique through spectral overlapping, because physical-chemical effect of overlapping may be expected in addition to occurrence of photochemical interactions.

Stability study of azithromycin in ophthalmic preparations / Estudo de estabilidade de azitromicina em preparações oftálmicas

A stability study of azithromycin in ophthalmic preparations was developed by submission to different types of light, temperature and pH, using the biodiffusion assay (cylinder 3 x 3) for the quantifications. Bacillus subtilis, ATCC 9372, was used as test organism. The used concentration range was of 50 to 200 µg/mL. The study demonstrated that the drug suffered degradation when submitted to the ultraviolet light, germicide light, solar luminosity, acid solution, basic solution and hydrogen peroxide solution. The results were analyzed by the analysis of variance (ANOVA).

O estudo de estabilidade de azitromicina em preparações oftálmicas foi realizado após exposição a diferentes tipos de luz, temperatura e pH, utilizando o método de difusão em ágar (cilindros 3 x 3) para as quantificações. A faixa de concentração foi de 50 a 200 µg/mL. O estudo demonstrou que o fármaco sofreu degradação quando submetido às luzes ultravioleta, germicida e solar, e a soluções ácida, alcalina e de peróxido de hidrogênio. Os resultados foram analisados através da análise da variância (ANOVA).

Fotodegradación de las aguas residuales con pesticida Mertect en la industria bananera empleando Fotocatálisis con Dióxido de Titanio y Lámpara de Luz Ultravioleta / Degradation of waste waters from the banana industry by the use of photocatalysis with titanium dioxide and ultra violet light lamp

Introducción. Los pesticidas son compuestos químicos sintéticos que poseen la característica de ser persistentes, lo cual favorece la contaminación de las aguas, la incorporación a suelos, pastizales, vegetales y animales comestibles, los que al ser consumidos actúan como transportadores de los pesticidas facilitando su acumulación en los organismos vivos en todos los eslabones de la cadena trófica; es por esta razón que reviste importancia los procesos de degradación y descontaminación de este tipo de contaminantes. Objetivo. Evaluar la fotodegradación del pesticida Mertect empleando fotocatálisis con dióxido de titanio y lámpara de luz ultravioleta. Materiales y métodos. En la experimentación se utilizó una lámpara de luz ultravioleta, una cuba de vidrio para el almacenamiento de la solución del pesticida a degradar y una bomba que permitía la recirculación de la solución por el sistema de tratamiento; la degradación del pesticida se determinó mediante espectrofotometría ultravioleta/visible. Para el análisis de la información se empleo el diseño experimental factorial 2³, completamente balanceado. Resultados. El porcentaje de remoción más alto fue de 99,5%; este se obtuvo para dos condiciones experimentales: 50 mg/L de dióxido de titanio y 1 %v/v de peróxido de hidrógeno, y 100 mg/L de dióxido de titanio y 1 %v/v de peróxido de hidrógeno. Conclusión. Los procesos de oxidación avanzados son adecuados para la remoción y eliminación del pesticida Mertect en las aguas residuales de la industria bananera.

Introduction. Pesticides are synthetic chemical compounds with the characteristic of being persistent, thus helping to contaminate water and incorporating pollutants to the soils and to edible vegetables and animals that, when eaten, act as pesticide transporters, accumulating that pesticide in living organisms from all the links of the trophic chain. This is the reason for the great importance of the degradation and decontamination processes of this kind of pollutants. Objective. To evaluate the photodegradation of the Mertect pesticide by the use of photocatalysis with titanium dioxide and ultra violet light. Materials and methods. In the experiment, an ultra violet light lamp, a glass bucket to store the pesticide to be degraded and a bomb to recirculate the solution trough the treatment system were used. The degradation of the pesticide was determined by visible/ultraviolet spectrophotometry. For the information analysis the 2³ experimental factorial designs was used, under complete balance. Results. The highest removal percentage was 99.5%, obtained for two experimental conditions: 50 mg /L of titanium dioxide and 1% v/v of hydrogen peroxide, and 100mg/L of titanium dioxide and 1%v/ v of hydrogen peroxide. Conclusions. Advanced oxidation processes are adequate to remove and eliminate the Mertect pesticide in the waste waters from the banana industry.

Preparation of TiO2 Nano-materials and Photocatalytic Purification of Sewage / 环境与健康杂志

The recent research progress of photo-catalyzed degradation of organic pollutants by TiO2 is reviewed,the characteristics of hydrothermal method and the prepared processes of TiO2 were discussed,the photo-catalyzed mechanism under UV and visible light and the application of degradation of sewage using TiO2 nanomaterials from five aspects were described in this paper. The main problems existing in the studies of TiO2,the research directions,and the development prospects were also discussed.

Evidence for the possible involvement of the Superoxide radicals in the photodegradation of bilirubin.

The photodecomposition of bilirubin follows first order kinetics with a kB value of 12·5 × 10-3 min–1. In the presence of a model system generating superoxide anions, such as xanthine-xanthine oxidase, the kB value was 103 × 10-3 min-1 This ten-fold enhancement of kB value by xanthine-xanthine oxidase was abolished when the reaction mixture was supplemented with a superoxide ion scavenger___ superoxide dismustase. Further, known singlet oxygen quenchers like ß–carotene and bistidine did not prevent the enhancement of bilirubin oxidation by xanthinexanthine oxidase, thereby ruling out the obligatory conversion of superoxide anion to singlet oxygen. It is concluded that radical oxygen mediated bilirubin degradation might be a natural catabolic route for the bile pigment degradation during oxygen stress.