Development of eco-friendly spectrophotometric methods for analysis of metformin hydrochloride and linagliptin in presence of metformin toxic impurity in their pure and dosage forms: Validation, practicality and greenness studies.

Metformin is considered as type 2 diabetes first line treatment according to American Diabetes Association and European Association. But, in some cases, di- or tri - therapy should be prescribed for glycemic management, prevention of the maximum dose side effects and induced effectiveness. Co-administration of Linagliptin with metformin has many benefits on diabetic patients such as decrease the possibility of hypoglycemia. For the first time, novel and reliable techniques were developed and verified for the concurrent quantification of metformin hydrochloride and linagliptin, while accounting for the existence of metformin toxic impurity 1-cyanoguanidine in their pure and dosage forms. Method (A) utilizes the zero-order spectrophotometric approach to quantitatively determine the concentration of linagliptin. The measurements are performed at a wavelength of 295 nm. The double divisor derivative ratio spectrophotometric method is used in Method (B) to measure the amounts of metformin and cyanoguanidine at 252 nm and 219 nm wavelengths, respectively. The spectrophotometric method (C) for determining metformin and cyanoguanidine at 252 nm and 223 nm, respectively, is based on the single divisor derivative ratio-zero crossing technique. The obtained findings were subjected to statistical comparison with the reported method, revealing no statistically significant differences. The Green Analytical Procedure Index (GAPI) and Analytical GREEnness Metric approach (AGREE) determined that these approaches had a high degree of environmental friendliness. Additionally, the proposed strategy was deemed to be practical according to the Blue Applicability Grade Index (BAGI) assessment tool.

Development of environmentally friendly catalyst Ag-ZnO@cellulose acetate derived from discarded cigarette butts for reduction of organic dyes and its antibacterial applications.

The release of harmful organic dyes from different industries besides its degradation products is a major contributor to environmental contamination. The catalytic reduction of these organic pollutants using nanocomposites based on polymeric material presents potential advantages for the environment. In this study, novel nanocomposite based on cellulose acetate (CA)-derived from discharged cigarette butts and zinc oxide nanoparticles (ZnO NPs) was prepared utilizing a very simple and low-cost solution blending method and used as support for silver nanoparticles (Ag NPs). A simple reduction method was used to anchor different percentages of Ag NPs on the ZnO@CA nanocomposite surface via utilizing sodium borohydride as a reducing agent. The Ag-ZnO@CA nanocomposite was characterized using X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The TEM analysis showed spherical Ag NPs, with an average diameter of ∼17.6 nm, were uniformly anchored on the ZnO@CA nanocomposite surface. The prepared nanocomposites were evaluated as catalysts for the reduction of organic dyes in water. It was found that 10 % Ag-ZnO@CA nanocomposite showed a remarkable reduction of Rhodamine B (RhB), Rhodamine 6G (Rh6G), Methylene Blue (MB), and Sunset Yellow (SY) dyes in short time. In the presence of this nanocomposite, the rate constant, kapp values for RhB, Rh6G, MB, and SY were 0.3498 min-1, 1.51 min-1, 0.2292 min-1, and 0.733 min-1, respectively. This nanocomposite was recovered and reused in five successive cycles, with a negligible loss of its activity. Furthermore, the nanocomposites demonstrated moderate antibacterial activity toward Staphylococcus aureus and Escherichia coli. Thus, this study directed attention on recycling of waste material to a valuable nanocomposite and its applications in environmental protection.

Development and validation of an eco-friendly HPLC-UV method for determination of atorvastatin and vitamin D3 in pure form and pharmaceutical formulation.

Statin-associated muscle symptoms are considered as obvious adverse effects of prolonged statin therapy such as myopathy, myalgia, and rhabdomyolysis. These side effects are associated with vitamin D3 deficiency and can be adjusted by amendment of serum vitamin D3 level. Green chemistry aims to decrease the harmful effects of analytical procedures. Here we have developed a green and eco-friendly HPLC method for the determination of atorvastatin calcium and vitamin D3. The two drugs were separated in less than 10 min on Symmetry column C18 (100 × 4.6 mm, 3.5 µm) using a mixture consisting of 0.1% ortho-phosphoric acid (OPA) (pH = 2.16) and ethanol as the mobile phase in gradient manner. We have used Green Analytical Procedure Index (GAPI) tools and the Analytical GREEnness Metric Approach (AGREE) for assessment of the greenness of our proposed method. The method proved linearity over concentration ranges of (5-40) and (1-8) µg/ml with low limit of detection of 0.475 and 0.041 µg/ml for atorvastatin calcium and vitamin D3 respectively. The method was successfully validated in accordance with ICH instructions and utilized for determination of the drugs of interest either in pure form or in their pharmaceuticals.

Cost-effective, green HPLC determination of losartan, valsartan and their nitrosodiethylamine impurity: application to pharmaceutical dosage forms.

Angiotensin-converting enzyme inhibitors are one of the most widely used anti-hypertensive drugs which are used to reduce hypertension. In 2018, the United States Food and Drug Administration together with the European Medicine Agency declared the presence of carcinogenic nitrosamine impurities such as nitrosodiethylamine (NDEA) in some of the products, including valsartan (VLS) and losartan (LOS), and drugs' recall procedures were started. Thus, they should be controlled to be below the acceptable cancer risk level to ensure safety of the pharmaceutical products. Therefore, sensitive and reliable analytical methods were required for detection and quantitation of NDEA in bulk and finished drug products. Green analytical chemistry has received great interest to minimize the amount of organic solvents consumed without loss in chromatographic performance. A green and sensitive HPLC method was developed for the determination of NDEA in LOS and VLS using mobile phase of 0.02 M ammonium acetate adjusted to pH 7.2 and ethanol in gradient manner. Limits of detection and limits of quantification for NDEA were estimated to be 0.2 and 0.5 µg ml-1, respectively. The standardized limits of NDEA impurity in drug substances were set as 0.56 ppm, which indicates the feasibility of its determination by the proposed conventional method without need for expensive instrumentations (e.g. MS/MS detectors) that are not found in most pharmaceutical quality control laboratories.

Spectral analysis of severely overlapping spectra based on newly developed mathematical filtration techniques and ratio spectra manipulations: An application to the concurrent determination of dapoxetine and sildenafil in combined dosage form.

BACKGROUND: Dapoxetine hydrochloride (DAP) and sildenafil citrate (SIL) have proven clinically effective in the treatment of comorbid conditions like erectile dysfunction and premature ejaculation. The analysis of DAP and SIL combinations represents a challenge because of the severe overlap of these compounds' spectra. Six newly developed methods were proven effective for resolving such a challenging overlap. They also exhibited the advantage of simplicity as they depend on the zero-order spectrum and only require simple mathematical handling. OBJECTIVE: We suggested six simple, precise, and sensitive spectrophotometric methods based on mathematical filtration techniques and ratio spectra manipulations to resolve the spectra of DAP and SIL in their bulk and combined pharmaceutical dosage form and estimate the relevant individual concentrations. METHODS: The first three methods were based on the zero-order range and involved modest mathematical manipulations. They are the induced dual-wavelength, Fourier self-deconvolution, and absorptivity factor spectrophotometric methods. Three other methods that are based on ratio spectra manipulation were developed: ratio difference, mean centering of the ratio spectra, and derivative ratio spectrum. RESULTS: We determined the performance of the suggested methods for estimating DAP and SIL in their laboratory mixtures and their combined pharmaceutical dosage form. The linear ranges for DAP and SIL were 1-40 µg/ml and 2-60 µg/ml, respectively. The detection limits were in the 0.18-1.10 µg/ml range for DAP and in the 0.68-1.11 µg/ml range for SIL. The developed methods were validated as per the ICH guidelines for linearity, detection limit, quantitation limit, selectivity, precision, and accuracy. Normal probability, interval, and Tukey's simultaneous significant difference plots were utilized to confirm and better visualize the analysis of variance test results. Statistically, no significant difference was observed to exist between results obtained from the hereby developed and the previously reported methods.

Smart UV spectrophotometric methods based on simple mathematical filtration and classical methods for the simultaneous determination of tamsulosin and solifenacin: A comparative study of efficacy and spectral resolution.

Treatment protocols combining tamsulosin and solifenacin proved better management of the complicated urinary tract symptoms. The pharmaceutical preparations of tamsulosin and solifenacin suffered from the high difference in their ratio, 0.4 mg tamsulosin and 6 mg solifenacin, and strong spectral overlap. Here, we developed four simple, accurate and selective spectrophotometric methods based on simple mathematical manipulations. These methods require the simplest mathematical filtration using short steps performed using built-in functions of the spectrophotometer operating software utilizing zero-order or derivative spectra. These methods are namely absorption correction method (ACM), induced dual-wavelength (IDW), absorptivity factor method (AFM) and first derivative method (D1). The linear ranges were 15-70 µg/ml and 100-1200 µg/ml for TAM and SFN, respectively. The limits of quantitation were in the range of 3.8-4.05 µg/ml and 23.34-59.05 µg/ml, while the limits of detection were in the range of 1.25-1.34 µg/ml and 7.7-24.6 µg/ml for TAM and SFN, respectively. All validation parameters investigated as per ICH guidelines. A statistical comparison executed for the proposed methods with each other and with the reported methods showed no significant difference between the proposed and the reported methods.

An enhanced first derivative synchronous spectrofluorimetric method for determination of the newly co-formulated drugs, amlodipine and celecoxib in pharmaceutical preparation and human plasma.

BACKGROUND: A new combination of amlodipine and celecoxib has been recently introduced in order to relieve the symptoms of osteoarthritis and help treat hypertension that commonly associated with osteoarthritis. OBJECTIVE: The current study is the first to develop and optimize a sensitive, simple and accurate first derivative synchronous spectrofluorimetric method for the simultaneous determination of amlodipine and celecoxib in bulk powder, pharmaceutical preparation and spiked human plasma. METHOD: The method implies the use of synchronous methodology using Δλ = 100 nm and measuring the fluorescence amplitudes of the first derivative each at the zero-crossing point of the other. For amlodipine and celecoxib, the emission wavelengths were at 455 nm and 368 nm, after excitation at 367 nm and 264 nm, respectively. RESULTS: The method was found to be linear over a wide concentration ranges of (5-600 ng/ml), (100-2000 ng/ml) with lower limits of detection of (1.16 ng/ml) and (17.16 ng/ml) for amlodipine and celecoxib, respectively. Enhancement of the fluorescence intensity was achieved by complex formation between the studied drugs and the surfactant sodium dodecyl sulfate and optimizing other experimental conditions. The method was further extended for application for determination of the studied drugs in spiked human plasma with excellent % recoveries of (95.20 ± 6.095) and (98.67 ± 6.394) for amlodipine and celecoxib, respectively. Validation of the method was successfully implemented according to recommendations delivered by guidelines of the International Conference on Harmonization.

Development of a micelle-enhanced high-throughput fluorometric method for determination of niclosamide using a microplate reader.

The present paper describes the development and validation of a simple and sensitive micelle-enhanced high-throughput fluorometric method for the determination of niclosamide (NIC) in 96-microwell plates. The proposed method is based on the reduction of the nitro group of niclosamide to an amino group using Zn/HCl to give a highly fluorescent derivative that was developed simultaneously and measured at λem 444 nm after excitation at λex 275 nm. Tween-80 and carboxymethylcellulose (CMC) have been used as fluorescence enhancers and greatly enhanced the fluorescence by factors of 100-150%. The different experimental conditions affecting the fluorescence reaction were carefully investigated and optimized. The proposed method showed good linearity (r2 ≥ 0.9997) over the concentration ranges of 1-5 and 0.5-5 µg/ml with lower detection limits of 0.01 and 0.008 µg/ml and lower quantification limits of 0.04 and 0.03 µg/ml on using Tween-80 and or CMC, respectively. The developed high-throughput method was successfully applied for the determination of niclosamide in both tablets and spiked plasma. The capability of the method for measuring microvolume samples made it convenient for handling a very large number of samples simultaneously. In addition, it is considered an environmentally friendly method with lower consumption of chemicals and solvents.

Development of High-Throughput Method for Measurement of Vascular Nitric Oxide Generation in Microplate Reader.

BACKGROUND: Despite the importance of nitric oxide (NO) in vascular physiology and pathology, a high-throughput method for the quantification of its vascular generation is lacking. OBJECTIVE: By using the fluorescent probe 4-amino-5-methylamino-2',7'-difluorofluorescein (DAF-FM), we have optimized a simple method for the determination of the generation of endothelial nitric oxide in a microplate format. METHODS: A nitric oxide donor was used (3-morpholinosydnonimine hydrochloride, SIN-1). Different factors affecting the method were studied, such as the effects of dye concentration, different buffers, time of reaction, gain, and number of flashes. RESULTS: Beer's law was linear over a nanomolar range (1-10 nM) of SIN-1 with wavelengths of maximum excitation and emission at 495 and 525 nm; the limit of detection reached 0.897 nM. Under the optimized conditions, the generation of rat aortic endothelial NO was measured by incubating DAF-FM with serial concentrations (10-1000 µM) of acetylcholine (ACh) for 3 min. To confirm specificity, Nω-Nitro-l-arginine methyl ester (l-NAME)-the standard inhibitor of endothelial NO synthase-was found to inhibit the ACh-stimulated generation of NO. In addition, vessels pre-exposed for 1 h to 400 µM of the endothelial damaging agent methyl glyoxal showed inhibited NO generation when compared to the control stimulated by ACh. CONCLUSIONS: The capability of the method to measure micro-volume samples makes it convenient for the simultaneous handling of a very large number of samples. Additionally, it allows samples to be run simultaneously with their replicates to ensure identical experimental conditions, thus minimizing the effect of biological variability.

High performance liquid chromatography for simultaneous determination of xipamide, triamterene and hydrochlorothiazide in bulk drug samples and dosage forms.

A novel, simple and robust high-performance liquid chromatography (HPLC) method was developed and validated for simultaneous determination of xipamide (XIP), triamterene (TRI) and hydrochlorothiazide (HCT) in their bulk powders and dosage forms. Chromatographic separation was carried out in less than two minutes. The separation was performed on a RP C-18 stationary phase with an isocratic elution system consisting of 0.03 mol L(-1) orthophosphoric acid (pH 2.3) and acetonitrile (ACN) as the mobile phase in the ratio of 50:50, at 2.0 mL min(-1) flow rate at room temperature. Detection was performed at 220 nm. Validation was performed concerning system suitability, limits of detection and quantitation, accuracy, precision, linearity and robustness. Calibration curves were rectilinear over the range of 0.195-100 µg mL(-1) for all the drugs studied. Recovery values were 99.9, 99.6 and 99.0 % for XIP, TRI and HCT, respectively. The method was applied to simultaneous determination of the studied analytes in their pharmaceutical dosage forms.

Utility of 4-chloro-7-nitrobenzofurazan (NBD-CI) for the Spectrophotometric and spectrofluorometric determination of several antihistamine and antihypertensive drugs.

New, sensitive, and selective spectrophotometric and spectrofluorometric methods have been developed for determination of clemastine hydrogen fumarate (Clem), loratadine (Lor), losartan potassium (Los), and ramipril (Ram) in both pure form and pharmaceutical formulations using 4-chloro-7-nitrobenzofurazan (NBD-CI), which is a highly sensitive chromogenic and fluorogenic reagent. The relation between absorbance at 470, 467, 471, and 469 nm and the concentration was linear over the ranges 5-35, 10-100, 10-90, and 10-120 microg/mL for Clem, Lor, Los, and Ram, respectively. The complexation products were also measured spectrofluorometrically at the emission wavelength 535 nm for Clem, Lor, and Ram and at 538 nm for Los with excitation at 477 and 452 nm for Clem and Lor, respectively, and 460 nm for both Los and Ram. The fluorescence intensity was directly proportional to the drug concentration over the ranges 0.05-0.5, 5-20, 1-6, and 2-15 microg/mL for Clem, Lor, Los, and Ram, respectively. The methods were successfully applied for the determination of the studied drugs in pharmaceutical dosage forms with excellent recovery.