Determination of omeprazole via fluorescence-quenching methodology; application to content uniformity testing

A new, proven, economical spectrofluorimetric approach has been used to determine the proton pump inhibitor omeprazole (OMP). This innovative technique is based on the ability of OMP to quench the native fluorescence of the mercurochrome dye in an acidic (pH 3.6) solution. Because it was discovered that quenching is proportional to the drug concentration, this dye was used as a sensor for OMP detection. The fluorescence intensity was measured at 518/540 nm, and its linear response ranged from 0.2-10.0 μg/mL with a linear coefficient of 0.9999. The computation yielded a limit of quantification (LOQ) of 0.20 μg/mL and a limit of detection (LOD) of 0.07 μg/mL. Every circumstance and element impacting the reaction product was examined in detail. Pharmacopeial standards carried out the validation. The approved method investigated several commercial preparations and formulations, and the results were favorably compared with those provided by a reference method. According to United States Pharmacopeia (USP) rules, content consistency for two distinct formulations was evaluated.

Stability indicating eco-friendly quantitation of terbutaline and its pro-drug bambuterol using quantitative proton nuclear magnetic spectroscopy

Quantitative 1H-NMR became an increasingly important issue in pharmaceutical analytical chemistry. This study used NMR spectroscopy to assay the bronchodilator drug terbutaline sulfate and its pro-drug bambuterol hydrochloride in pure form and pharmaceutical preparations. The technique proceeded using deuterium oxide (D2O) as an 1H-NMR solvent and phloroglucinol anhydrous as an internal standard (IS). Comparatively, to the phloroglucinol signal at 5.9 ppm, the resulting quantitative signals of the studied drugs were corrected. The terbutaline singlet signal at 6.3 ppm was chosen for quantification, while the bambuterol quantitative singlet signal was at 2.9 ppm. The two drugs were rectilinear over the concentration range of 1.0-16.0 mg/mL. LOD values were 0.19 and 0.21 mg/mL while LOQ values were 0.58 and 0.64 mg/mL for terbutaline and bambuterol respectively. The developed method has been validated according to the International Conference of Harmonization (ICH) regarding linearity, accuracy, precision, specificity, and robustness. A greenness profile assessment was applied, and the method proved to be green. The method enables the assay of the two drugs in pure drug and pharmaceutical preparations. The method also enables the assay of the two drugs in the presence of each other; thus, it is considered a stability-indicating method where terbutaline is an acid degradation product of bambuterol.

Investigating fluorogenic labelling of amine coupled with first-order derivative spectrofluorimetry as a versatile analytical methodology: Application to estimation of benoxinate in its eye drops

In this research, fluorogenic labelling followed by applying first-order derivative spectrofluorimetry for the developed fluorophore is discussed as an alternative, sensitive and selective analytical approach. Benoxinate, containing a primary amine and fluorescamine reagent were selected for the study. Then the proposed methodology relies on the reaction between the primary amine in benoxinate with fluorescamine that selectively reacts with primary amines to develop highly fluorescent products. The fluorescamine-benoxinate developed fluorophore is identified by its sharp first-order derivative peak at 465 nm following excitation at 386 nm in borate buffer, pH 8. The optimum reaction conditions were ascertained. Following ICH validation guidelines, the first order derivative of the relative fluorescence intensity for the developed fluorophore was linearly related to benoxinate concentration and ranged from 20.0 to 200.0 ng/mL with a detection limit of 3.36 ng/mL and a quantitation limit of 10.19 ng/mL, moreover, satisfying accuracy and precision values were obtained upon statistical analysis of results. The offered analytical method was successfully applied to quantify benoxinate in raw material and Benox® eye drops as a direct application to a commercial formulation.

Fast concurrent determination of guaifenesin and pholcodine in formulations and spiked plasma using first derivative synchronous spectrofluorimetric approach

Guaifenesin and pholcodine are frequently co-formulated in certain dosage forms. A new fast first derivative synchronous spectrofluorometric method has been used for their simultaneous analysis in mixtures. Here, first derivative synchronous spectrofluorometry enabled the successful simultaneous estimation of guaifenesin at 283 nm and pholcodine at 275 nm using a wavelength difference (Δλ) of 40 nm. The method was fully validated following International Council of Harmonization guidelines. For guaifenesin and pholcodine, linearity was determined within the corresponding ranges of 0.05-0.30 and 0.10-6.0 μg/ml. The two drugs were effectively analyzed using the developed approach in their respective formulations, and the results showed good agreement with those attained using reference methods. The method demonstrated excellent sensitivity, with detection limits down to 0.007 and 0.030 μg/ml and quantitation limits of 0.020 and 0.010 μg/ml for guaifenesin and pholcodine, respectively. Therefore, the procedure was successful in determining these drugs simultaneously in vitro in spiked plasma samples and syrup dosage form. The developed methodology also offered an environmentally friendly advantage by utilizing water as the optimal diluting solvent throughout the whole work. Different greenness approaches were investigated to ensure the method's ecofriendly properties.

Applications of deep eutectic solvents in microextraction and chromatographic separation techniques: Latest developments, challenges, and prospects

Deep eutectic solvents (DESs) have recently sparked considerable attention in a variety of scientific and technological fields. The unique properties of DESs include biodegradability, easy preparation, low cost, and tuneability, rendering them a new and prospective alternative to hazardous solvents. Analytical chemistry is one of the most appealing fields where DESs proved to be applicable in either sample preparation or chromatographic separation. This review summarizes the new horizons dedicated to the application of DESs in microextraction and chromatographic separation. The utilization of DESs in microextraction, in chromatography as mobile phase additives, and in chromatographic material preparation processes is outlined. The enhancements in chromatographic performance achieved using DESs and any potential explanations deduced from the experimental findings were primarily discussed. An additional brief discussion on DESs preparation, characterization, and properties is addressed in this work. Finally, current challenges and future trends are also presented, supplying evidence for distinct possibilities regarding new research approaches involving DESs. This review can represent a guide and stimulate further research in this field.

Synthesis, crystallographic, DNA binding, and molecular docking/dynamic studies of a privileged chalcone-sulfonamide hybrid scaffold as a promising anticancer agent

In the present study, a drug-like molecular hybrid structure between chalcone and sulfonamide moieties was synthesized and characterized. The structural peculiarities of the synthesized hybrid were further verified by means of single crystal X-ray crystallography. Furthermore, its biological activity as an anticancer agent was evaluated. The synthesized model of chalcone-sulfonamide hybrid 3 was found to have potent anticancer properties against the studied cancer cell lines. Hence, the in vitro binding interaction of hybrid 3 with Calf thymus DNA (CT-DNA) was studied at a simulated physiological pH to confirm its anticancer activity for the first time. This was investigated by applying different spectroscopic techniques, ionic strength measurements, viscosity measurements, thermodynamics, molecular dynamic simulation and molecular docking studies. The obtained results showed a clear binding interaction between hybrid 3 and CT-DNA with a moderate affinity via a minor groove binding mechanism. The binding constant (Kb) at 298 K calculated from the Benesi-Hildebrand equation was found to be 3.49 × 104 M-1. The entropy and enthalpy changes (ΔS0 and ΔH0) were 204.65 J mol-1 K-1 and 35.08 KJ mol-1, respectively, indicating that hydrophobic interactions constituted the major binding forces. The results obtained from molecular docking and dynamic simulation studies confirmed the minor groove binding interaction and the stability of the formed complex. This study can contribute to further understanding of the molecular mechanism of hybrid 3 as a potential antitumor agent and can also guide future clinical and pharmacological studies for rational drug design with enhanced or more selective activity and greater efficacy.[Figure: see text]Communicated by Ramaswamy H. Sarma.

Green versatile micellar electrokinetic chromatographic method for determination of six antimicrobial and anti-inflammatory drugs in combined dosage forms

A fast reliable micellar electrokinetic methodology was investigated for the concurrent quantitation of six antimicrobial and anti-inflammatory drugs, namely, ciprofloxacin, dexamethasone, metronidazole, ornidazole, spiramycin and tinidazole. The method has the merits of rapidity, precision, and sensitivity. The separation was carried out in less than 7 min by applying a basic background electrolyte consisting of 25 mM disodium tetraborate buffer, pH 9 containing 50 mM SDS at 25 kV using photodiode array detector at 230 and 315 nm. The internal standard used during analysis was cromolyn sodium and validation was carried out following ICH guidelines. The proposed method showed linear response over the range from 0.5 to 10.0 μg mL−1 reaching limits of detection and limits of quantitation in the ranges of 0.09–0.2 μg mL−1 and 0. 27–0.6 respectively. The method's greenness was estimated using the GAPI tool where excellent greenness was concluded. Co-formulated or single-ingredient commercial preparations were investigated and the results were statistically evaluated.

Green synthesized nitrogen-doped carbon quantum dots for the sensitive determination of larotrectinib in biological fluids and dosage forms: Evaluation of method greenness and selectivity

Recently, the kinase receptor inhibitor drug larotrectinib has been approved as a monotherapy for the treatment of patients with solid tumors containing the neurotrophic receptor tyrosine kinase gene fusion. In this paper, a novel sensitive spectrofluorimetric method was proposed for the determination of larotrectinib based on nitrogen-doped carbon quantum dots (N-CQDs) fluorescent probes. The proposed method is the first spectroscopic method for analysis of the cited drug, which is simple to implement and involves no pre-treatment steps or complicated techniques. The N-CQDs synthesis was performed by adopting a straightforward, fast, and environmentally friendly approach. It was achieved by means of a standard domestic microwave with inexpensive and readily available starting materials: orange juice (carbon source) and urea (nitrogen source). The synthesized N-CQDs were subjected to microscopic and spectroscopic characterization procedures. They were found to be stable with a sufficiently high fluorescence quantum yield (25.3%) and a small particle size distribution (2-5 nm). The motivation for the use of N-CQDs in this study arose from their excellent fluorescence intensities at 417 nm when excited at 325 nm. Larotrectinib was found to have a quantitative and selective quenching effect on the QDs fluorescence allowing for its sensitive determination. The drug's quenching mechanism was investigated and found to be of the static type. Under optimal conditions, the proposed approach permitted the determination of larotrectinib over the concentration interval of 5.0-28.0 µg/mL. The method showed sufficient sensitivity with a detection limit of 0.19 µg/mL and a quantitation limit of 0.57 µg/mL, enabling the determination of LARO in spiked human plasma samples. The approach's recovery percentage was found to be in the range of 99.09-100.73% for pure samples and 97.35-102.59% for plasma samples. The study also successfully applied the proposed approach to the commercial oral solution form of larotrectinib (Vitrakvi®) with high selectivity. Method greenness was further evaluated by adopting two metric tools, including the complementary green analytical procedure index (ComplexGAPI) and Analytical GREENNESS metric approach (AGREE), and it was confirmed to be excellent green. The proposed method was validated in accordance with the ICHQ2 (R1) recommendations and is considered an excellent candidate for potential application in the therapeutic monitoring of larotrectinib.

Green quality by design HPLC approach for the simultaneous determination of Bilastine and Montelukast

For the simultaneous estimation of two co-formulated antihistaminic drugs (Bilastine and Montelukast), a novel and eco-friendly reversed-phase HPLC approach with both diode array and fluorescence detection modes was designed. Rather than using the routine methodology, the Quality by Design (QbD) approach was adopted to speed up the method development and to test robustness of the method. To evaluate the effect of variable factors on chromatographic response, a full factorial design was used. The chromatographic separation was performed using isocratic elution on the C18 column. The mobile phase consists of 92% methanol, 6% acetonitrile, and 2% phosphate buffer with 0.1 (v/v) triethylamine adjusted to pH 3, it was pumped at a flow rate of 0.8 mL/min with an injection volume of 20 μL. The developed stability indicating HPLC approach was used to assess the stability of montelukast (MNT). It was subjected to a variety of stress conditions, including hydrolytic (acid-base), oxidative, thermal, and photolytic stress conditions. All of these conditions were found to have relevant degradation pathways. Under the described experimental conditions, MNT degradation followed pseudo-first-order kinetics. The kinetic parameters of its degradation (rate constant and t_1/2) were calculated and a proposal for the degradation pathway was postulated.

Insights on the in-vitro binding interaction between donepezil and bovine serum albumin

In this work, the binding mechanism between donepezil (DNP) and bovine serum albumin (BSA) was established using several techniques, including fluorimetry, UV- spectrophotometry, synchronous fluorimetry (SF), fourier transform infrared (FTIR), fluorescence resonance energy transfer (FRET) besides molecular docking study. The fluorescence quenching mechanism of DNP-BSA binding was a combined dynamic and static quenching. The thermodynamic parameters, binding forces, binding constant, and the number of binding sites were determined using a different range of temperature settings. Van't Hoff's equation was used to calculate the reaction parameters, including enthalpy change (ΔH^ο) and entropy change (ΔS^ο). The results pointed out that the DNP-BSA binding was endothermic. It was shown that the stability of the drug-protein system was predominantly due to the intermolecular hydrophobic forces. Additionally, the site probing method revealed that subdomain IIA (Site I) is where DNP and BSA's binding occurs. This was validated using a molecular docking study with the most stable DNP configuration. This study might help to understand DNP's pharmacokinetics profile and toxicity as well as provides crucial information for its safe use and avoiding its toxicity.

Insights into the spectrofluorometric determination of the neuromuscular blocker mivacurium chloride

Fluorescence spectroscopy is gaining interest in the analysis and quantitative determination of different drugs. This study was carried out to investigate the fluorometric properties of the short-acting muscle relaxant mivacurium in its pure form, injection, and human plasma. It is nondepolarizing skeletal muscle relaxant for intravenous (IV) administration. Mivacurium shows a strong native fluorescence in methanol at 317 nm after excitation at 230 nm (Method I). The critical parameters that may influence the fluorescence of this drug were carefully studied. A linear response between concentration and fluorescence was constructed over the concentration range: 20.0 to 400.0 ng/mL with determination coefficient (r²) equal to 0.9998. Additionally, the correlation coefficient of the linear relationship (r) was found to be 0.9999 with a slope = 2.196 and intercept = -16.61. Limits of quantitation and detection were calculated mathematically to be 17.45 and 5.75 ng/mL respectively. Further estimation of mivacurium in spiked human plasma was performed by construction of specific calibration curve and the obtained correlation coefficient was 0.9948. Moreover, the ability to determine mivacurium in the presence of commonly co-administered drugs were investigated including propofol and thiopental. Method II includes the determination of MVC in the presence of propofol utilizing the first derivative synchronous fluorescence spectroscopy. The results of method II indicated acceptable percentage recoveries from 98.88 to 100.75 %. Statistical evaluation of the results revealed satisfactory accuracy and precision.

A Novel Quantum Dots-Based Fluorescent Sensor for Determination of the Anticancer Dacomitinib: Application to Dosage Forms

One of the most promising drugs recently approved for the treatment of various types of cancer is dacomitinib, which belongs to the tyrosine kinase inhibitor class. The US Food and Drugs Administration (FDA) has recently approved dacomitinib as a first-line treatment for patients suffering from non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) mutations. The current study proposes the design of a novel spectrofluorimetric method for determining dacomitinib based on newly synthesized nitrogen-doped carbon quantum dots (N-CQDs) as fluorescent probes. The proposed method is simple and does not require pretreatment or preliminary procedures. Since the studied drug does not have any fluorescent properties, the importance of the current study is magnified. When excited at 325 nm, N-CQDs exhibited native fluorescence at 417 nm, which was quantitatively and selectively quenched by the increasing concentrations of dacomitinib. The developed method involved the simple and green microwave-assisted synthesis of N-CQDs, using orange juice as a carbon source and urea as a nitrogen source. The characterization of the prepared quantum dots was performed using different spectroscopic and microscopic techniques. The synthesized dots had consistently spherical shapes and a narrow size distribution and demonstrated optimal characteristics, including a high stability and a high fluorescence quantum yield (25.3%). When assessing the effectiveness of the proposed method, several optimization factors were considered. The experiments demonstrated highly linear quenching behavior across the concentration range of 1.0-20.0 μg/mL with a correlation coefficient (r) of 0.999. The recovery percentages were found to be in the range of 98.50-100.83% and the corresponding relative standard deviation (%RSD) was 0.984. The proposed method was shown to be highly sensitive with a limit of detection (LOD) as low as 0.11 μg/mL. The type of mechanism by which quenching took place was also investigated by different means and was found to be static with a complementary inner filter effect. For quality purposes, the assessment of the validation criteria adhered to the ICHQ2(R1) recommendations. Finally, the proposed method was applied to a pharmaceutical dosage form of the drug (Vizimpro^® Tablets) and the obtained results were satisfactory. Considering the eco-friendly aspect of the suggested methodology, using natural materials to synthesize N-CQDs and water as a diluting solvent added to its greenness profile.

Utility of a xanthene-based dye for determination of nilotinib using two spectroscopic approaches. Applications to bulk powder, capsules, and spiked human plasma

Novel, selective, facile, and precise spectroscopic approaches were validated to determine nilotinib hydrochloride, a tyrosine kinase inhibitor used to treat patients with chronic myeloid leukemia. These approaches depend on the reaction of the tertiary amine group of nilotinib with erythrosine B in the Britton-Robinson buffer at pH 4. Method I, depends on measuring the absorbance of the formed complex at 551 nm. The absorbance concentration plot showed linearity over the concentration range of 1.0 to 9.0 μg/ml. Method II, involved the measurement of the quenching of the native fluorescence of erythrosine B by adding nilotinib in an acidic medium. The fluorescence quenching of erythrosine B was measured at 549 nm after excitation at 528 nm. This approach showed excellent linearity in the concentration range of 0.04 to 0.7 μg/ml. The limit of detection values for Method I and Method II were 0.225 and 0.008 μg/ml, respectively, while the limit of quantitation values for Method I and Method II were 0.68 and 0.026 μg/ml, respectively. To get the optimal conditions, factors that may affect the formation of the ion-pairing complex were thoroughly examined. The two approaches were carefully validated following the International Conference of Harmonization (ICH Q2R1) guidelines. Statistical assessment of the results achieved using the suggested and previously published comparison approaches showed no significant difference. The approaches were successful in determining nilotinib in a pharmaceutical dosage form as well as spiked human plasma samples. The eco-friendly properties of the methods were evaluated by three different tools.

Investigation of facile spectroscopic approaches for rapid calycosin determination in invitro biological samples and pharmaceuticals; application to the content uniformity of capsules

Calycosin, the major bioactive isoflavonoid inAstragali Radix and an important anti-viral drug with a variety of pharmacological actions, is being determined by five different spectroscopic methods. Two spectrophotometric methods have been investigated including measuring the absorption spectra at λ^max = 270 nm and the first derivative spectra at λ = 288 nm for methods I and II, respectively. For the first time; the native fluorescence of calycosin is measured without adding any reagents. The fluorescence intensity was measured at 340 nm after excitation at 282 nm in method III. The fourth method involves the direct measuring of a first derivative spectrofluorimetric emission peak at 292 nm. In method V synchronous fluorescence spectra were recorded in methanol at Δλ = 70 nm. The linear range for the fluorescence-based methods was 0.05-1.0 µg/mL and for the UV-based methods was 0.5-10.0 µg/mL. The methods were validated per International Council of Harmonization (ICHQ2R1) guidelines. The limits of detection were found to be down to 0.11 and 0.12 µg/mL for the spectrophotometric methods, and 15.0, 18.0,16.0 ng/ mL, for the spectrofluorimetric approaches respectively, representing the high sensitivity. Accordingly, this permitted the quantitation of calycosin in spiked human plasma samples with satisfactory percentage recoveries (94.50.-102.50 %). The methods were utilized for calycosin analysis in different matrices including plasma and capsules with high precision and accuracy.

Rapid microwave-assisted synthesis of nitrogen-doped carbon quantum dots as fluorescent nanosensors for the spectrofluorimetric determination of palbociclib: application for cellular imaging and selective probing in living cancer cells

The current study introduces a spectrofluorimetric methodology for the assessment of palbociclib without the need for any pre-derivatization steps for the first time. This approach relied on the palbociclib quenching effect on the native fluorescence of newly synthesized nitrogen-doped carbon quantum dots (N-CQDs). An innovative, facile, and rapid microwave-assisted pyrolysis procedure was applied for the synthesis of N-CQDs using available and economic starting materials (the carbon source is orange juice and the nitrogen source is urea) in less than 10 minutes. Full characterization of the prepared QDs was carried out using various techniques. The prepared N-CQDs exhibited good fluorescence emission at 417 nm after excitation at 325 nm with stable fluorescence intensity and good quantum yield (29.3%). They showed spherical shapes and narrow size distribution with a particle size of around 2-5 nm. Different experimental variables influencing fluorescence quenching were examined and optimized. A good linear correlation was exhibited alongside the range of 1.0 to 20.0 μg mL^-1 with a correlation coefficient of 0.9997 and a detection limit of 0.021 μg mL^-1. The proposed methodology showed good selectivity allowing its efficient application in tablets with high percentage recoveries and low percentage RSD values. The mechanism of quenching was proved to be static by applying the Stern-Volmer equation at four different temperatures. The method was validated in accordance with ICHQ2 (R1) recommendations. Intriguingly, N-CQDs demonstrated good biocompatibility and low cytotoxicity, which permitted cellular imaging and palbociclib detection in living cancer cells. Therefore, the proposed method may have potential applications in cancer therapy and related mechanism research.

Utility of synchronous fluorimetry for the concurrent quantitation of metoprolol and ivabradine

Metoprolol combined with ivabradine have been determined up to nanogram level simultaneously relied on the synchronous fluorescence spectra. First derivative amplitudes of the synchronous spectrofluorimetric spectra are recorded at Δλ = 40 nm using ethanol as diluting solvent. Metoprolol can be measured at 286 nm which is the zero-crossing point of ivabradine, and the later can be measured at 296 nm. The calibration plots were found to be linear over the ranges of concentrations: 100.0-1000.0 ng/mL and 10.0-200.0 ng/mL for metoprolol and ivabradine, respectively. Validation of the procedure was performed using the International Council of Harmonization guidelines. Values of LODs were found to be 28.89, 2.80 ng/mL and LOQs were 87.56, 8.49 ng/mL for metoprolol and ivabradine, respectively. As the two drugs are co-administered safely and effectively to reduce heart rate, angina attacks, the current methodology is utilized for the concurrent analysis of them in their single ingredient pharmaceutical preparations, synthetic mixtures, and biological fluids. The designed method, being cost-effective and simple procedure, is the first method for metoprolol and ivabradine simultaneous analysis. The results agreed statistically with the comparison methods.

Doped Carbon Dots as Promising Fluorescent Nanosensors: Synthesis, Characterization, and Recent Applications

Abstract:

Carbon dots (CDs) have recently attracted attention as a new class of photoluminescent materials with promising optical, chemical, and electrical properties. They have been proposed for various applications, such as pharmaceutical sensing, biomarker detection, and cellular bioimaging, by virtue of their economical synthesis, cheap starting materials, water-solubility, excellent chemical stability, good biocompatibility, and low toxicity. Hetero-atom doping is a reliable and adaptable strategy for enhancing the photoluminescence, electrical, and structural characteristics of CDs. Herein, we present an update on heteroatom-doped CDs. Various modern synthetic routes are highlighted, ranging from synthetic processes to doping components. In addition, the optical and biological properties and the possible applications of heteroatom-doped CDs are discussed. This review (with 227 references) will provide an overview of recent advances in doped CDs and their expected future perspectives.

Spectroscopic strategies for quantitation of varenicline in pharmaceutical preparations and content uniformity testing

Herein, two new facile methods were examined for varenicline determination using erythrosine. The latter is a food additive that has been recently investigated as a fluorescent dye for the determination of drugs. In the first method, the fluorescence of erythrosine B was quenched quantitatively by increasing the concentration of varenicline through ion-pair complex formation. This linear response was a basis for the spectrofluorimetric method used for varenicline quantitation in pure and dosage forms. The quenching is correlated with the concentration linearly over the range of 0.4-4.0 µg ml^-1 at 550 nm after excitation at 528 nm with a correlation coefficient of 0.9993. Different parameters were investigated to reach the optimal conditions with the highest sensitivity and repeatability. The second method is depending on measuring the formed complex by spectrophotometry at 550 nm over the range of 1.0-10.0 µg ml^-1 with an excellent correlation coefficient of 0.9999. The suggested methods were validated consistently with ICH guidelines, with acceptable results. The procedures were used to test the uniformity of content of Champix tablets. By comparing with the previous spectroscopic method, there was no significant difference as revealed from the calculated Student t-test and variance ratio F-test values.

Utility of a novel turn-off fluorescence probe for the determination of tranilast, an adjunctive drug for patients with severe COVID-19

Tranilast (TR) could be investigated as a suitable anti-inflammatory and NLRP3 inflammasome inhibitor medication for the treatment of COVID-19 acute patients. Owing to its importance, our study was constructed for the determination of TR using a new, fast, sensitive, and reliable green spectrofluorimetric method. TR was quantified in this study by forming a complex with the acriflavine (AC) reagent. The reaction between TR and AC quenched the fluorescence of AC through the formation of an ion-association complex and the response was measured at 493 nm after excitation at 263 nm. It was observed that the quenching of the fluorescence of AC was linear (r = 0.9998) with the concentration of TR in the range of 1.0–15.0 μg mL⁻¹. The limit of detection was 0.224 μg mL⁻¹, and the limit of quantification was 0.679 μg mL⁻¹. The fluorescence quenching mechanism was carefully studied and was confirmed to be able to analyze TR in its pure form and its prepared pharmaceutical dosage form. To validate the method, the international conference of harmonization (ICH) Q₂R₁ guidelines were followed. The statistical assessment of the proposed and comparison methods revealed no significant differences between them. Moreover, the green criteria of the method were evaluated and confirmed.

Tranilast (TR) could be investigated as an anti-inflammatory and NLRP3 inflammasome inhibitor medication using acriflavine.

Implementation of HILIC-UV technique for the determination of moxifloxacin and fluconazole in raw materials and pharmaceutical eye gel

Hydrophilic interaction liquid chromatography (HILIC) has inherent merits over RP-HPLC in the analyzing of hydrophilic substances. Accordingly, an innovative HILIC-UV methodology is proposed for the simultaneous estimation of ethyl paraben (PRN), fluconazole (FLZ) and moxifloxacin hydrochloride (MOX) in raw materials and pharmaceutical eye gel. The separation process was conducted using Waters XBridge™ HILIC column (100 mm × 4.6 mm, 3.5 μm particle size) at room temperature. Isocratic mobile phase containing acetonitrile: 0.1% triethylamine buffer (90:10, v/v, pH 5.0), was pumped at flow rate 1.0 mL/min and detected at 260 nm. Under these optimized conditions, PRN, FLZ and MOX showed rectilinear relationships with the concentration ranges (0.5–6.0), (5.0–50.0) and (5.0–60.0) μg/mL, respectively. The developed method offered at least fivefold increase in sensitivity within shorter time than the reported methods. Three greenness assessment tools namely: Analytical eco-scale, GAPI and AGREE were exploited to investigate the method's impact on the environment and conduct a comparative study with the reported methods. International council of Harmonization (ICH) guidelines have been followed to calculate validation parameters. The statistical comparison between results of the suggested method and the comparison method showed no discrepancy confirming accuracy of the method.

Novel approaches of erythrosine B as a food dye-derived spectroscopic probe for assessing trospium chloride in raw material and dosage form

Two facile spectroscopic methodologies were designed for estimating trospium chloride (TPM) in raw material and tablets with high operational reliability and selectivity. The methods were based on employing erythrosine B (EB) as a spectroscopic tool for ion-pair complex formation with the drug. In a mild acidic medium of Britton Robinson buffer (BRB) (pH 4.0), the ionized hydroxyl group in the reagent interacted with the ionized amine in the studied drug. Method I was based on the spectrophotometric measuring of the absorbance of the reaction product at 557 nm. Method II was based on spectrofluorimetric measuring of the quenching effect of TPM on the inherent fluorescence of EB at 550 nm (λ_ex. =528 nm). The two methods showed linearity through ranges (1.0-10.0) and (0.5-10.0) μg/mL for methods I and II, respectively. The suggested methods were exploited for analyzing TPM in Trospamexin® tablets and showed good applicability. The designed systems were validated as per ICH guidelines. Experimental conditions were modulated to obtain the best sensitivities. The quenching mechanism was investigated and the quenching constant was computed relying on Stern-Volmer equation. Environmental impact was appraised using novel metric green tools, GABI and AGREE. The suggested systems excelled over other reported methods in terms of greenness, sensitivity and cost-effectiveness.

Exploring the molecular interaction of mebendazole with bovine serum albumin using multi-spectroscopic approaches and molecular docking

This article presents the binding interaction between mebendazole (MBZ) and bovine serum albumin. The interaction has been studied using different techniques, such as fluorescence quenching spectroscopy, UV–visible spectroscopy, synchronous fluorescence spectroscopy, fourier transform infrared, and fluorescence resonance energy transfer in addition to molecular docking. Results from Stern Volmer equation stated that the quenching for MBZ-BSA binding was static. The fluorescence quenching spectroscopic study was performed at three temperature settings. The binding constant (k_q), the number of binding sites (n), thermodynamic parameters (ΔH^ο, ΔS^ο and ΔG^ο), and binding forces were determined. The results exhibited that the interaction was endothermic. It was revealed that intermolecular hydrophobic forces led to the stabilization of the drug-protein system. Using the site marker technique, the binding between MBZ and BSA was found to be located at subdomain IIA (site I). This was furtherly approved using the molecular docking technique with the most stable MBZ configuration. This research may aid in understanding the pharmacokinetics and toxicity of MBZ and give fundamental data for its safe usage to avoid its toxicity.

Insights on the Quantitative Concurrent Fluorescence-Based Analysis of Anti-COVID-19 Drugs Remdesivir and Favipiravir

We hereby introduce a sensitive fast straightforward spectrofluorometric method for the estimation of remdesivir and favipiravir. The two drugs are prescribed in some regimens to treat COVID‐19 pandemic disease, which is caused by SARS‐CoV‐2. The method is based on the first derivative synchronous spectrofluorimetry approach for the measurement of remdesivir and favipiravir. This was accomplished at 251 nm and 335 nm respectively using the first derivative order at delta lambda of 140 nm. A linear response with a correlation coefficient 0.9994 was achieved between the concentration and the derivative amplitudes in the ranges of 20.0–100.0 ng ml⁻¹ and 40.0–100.0 ng ml⁻¹ for remdesivir and favipiravir, respectively. The methods were validated for different parameters as stated by the pharmacopeial rules and were applied successfully for estimation of the studied drugs in their synthetic mixtures and in spiked human plasma samples. No significant difference was observed between the proposed and comparison methods as revealed from the analysis of data.

Determination of pholcodine alone or in combination with ephedrine in human plasma using fluorescence spectroscopy

In this study, sensitive, facile, and cost-effective spectrofluorimetric approaches were developed for the determination of pholcodine and ephedrine. Method I is a novel spectrofluorimetric method depending on measuring the native fluorescence of pholcodine at 337 nm after excitation at 284 nm over a concentration range of 0.01-2.4 μg/mL. The method sensitivity reached quantitation and detection limits down to 10.0 and 5.0 ng/mL, respectively. Method II relied on the simultaneous estimation of pholcodine and ephedrine using synchronous fluorimetry for the first time. The cited drugs were measured concurrently at 286 and 304 nm for pholcodine and ephedrine, respectively at Δλ of 40 nm without interference. Excellent linear relationship between concentration and response was obtained over the ranges of 0.05-6.0 μg/mL and 0.02-1.0 μg/mL for pholcodine and ephedrine, respectively. The method showed distinct sensitivity and exhibited quantitation limits of 20.0 and 10.0 ng/mL and detection limits of 10.0 and 5.0 ng/mL, respectively. The method was successfully applied to the syrup dosage form. The two developed approaches were also applied to in-vitro plasma samples, showing good bioanalytical applicability and providing further insights for monitoring drug abuse. The proposed methods were validated according to ICHQ2(R1) guidelines. The proposed methodologies' greenness profiles were evaluated using two greenness assessment tools.

Micellar-Emphasised simultaneous determination of ivabradine hydrochloride and felodipine using synchronous spectrofluorimetry

Sensitive and green micellar spectrofluorimetric approach was applied for the simultaneous estimation of ivabradine hydrochloride (IVB) and felodipine (FLD) in ng/mL concentration range. The approach depended on measuring the first derivative synchronous peak amplitude (¹ D) of both drugs at ∆λ= 60 nm in tween-80 micellar system. The method was rectilinear alongside the concentration range (0.02-0.4) μg/mL and (0.05-1.0) μg/mL at 269.5 nm and 378.5 nm for of IVB and FLD, respectively. The proposed method was validated by following ICH guidelines. The method was successfully applied without interference for laboratory-prepared synthetic mixtures, single pharmaceutical preparation and within spiked biological fluids with acceptable percent recoveries. Comparing the performance of the suggested method with the comparison methods, showed no discrepancy. The method ecofriendly properties were evaluated by 3 different tools confirming an excellent green method.

Investigation of the fluorescence of benoxinate for facile determination in pure form, eye drops and aqueous humor

A new approach to determine the local anesthetic benoxinate spectrofluorimetrically was developed. It was found that benoxinate exhibits strong native fluorescence in ethanol at 371 nm after excitation at 297 nm. There was a linear response between the fluorescence intensity and the concentration of the studied drug over the range of 10.0-100.0 ng/ mL. The suggested spectrofluorimetric method was optimized and validated following the pharmacopoeial guidelines. The obtained results were fully discussed and statistically analyzed in relevance to a previous published spectroscopic method. The limit of quantification (LOQ) of the present method was 1.79 ng/mL. Inter-day and intra-day precision relative standard deviations were lower than 1.5%.Finally, the proposed methodology has been adopted for determination of benoxinate in aqueous humor with a mean percentage recovery 99.87 ± 1.66 as well as in the pharmaceutical eye drops with a mean percentage recovery 100.37 ± 1.32. The method is cost-effective and green as it depends in water and ethanol mainly.

Factorial design-assisted spectroscopic determination of oxybutynin hydrochloride

In this study, we have developed two facile spectroscopic methods for quantifying oxybutynin (OBT) hydrochloride in its pure form and tablets using design of experiments (DOEs). The spectroscopic methods depended on the ion-pair complex formation between the tertiary amino group in the drug and eosin in 0.2 M acetate buffer of pH 4. Method I involves spectrophotometric measurement of the absorbance of the developed complex at 550 nm and showed linearity through 1.0-10.0 µg ml-1. Method II involves spectrofluorometric measurement of the quenching influence of OBT on the native fluorescence of eosin (λ excitation/λ emission of 304/548 nm) and showed linearity through 1.0-6.0 µg ml-1. Critical parameters were identified through preliminary trials and optimized using the DOE. Additionally, the quenching mechanism was investigated and the pathway of the reaction was postulated. The fluorescence quenching constant and thermodynamic parameters were explored using the Stern-Volmer plot and Van't Hoff graph, respectively. Assessments conducted via analytical ecoscale revealed the 'excellent-greenness' of the methodology. The two methods have the potentials of being green and fast compared with other reported methods.

Green and sensitive spectrofluorimetric determination of Remdesivir, an FDA approved SARS-CoV-2 candidate antiviral; application in pharmaceutical dosage forms and spiked human plasma

Fluorescence spectroscopy has gained much attention over the last few years. Its advantages cover both analytical performance as well as ecological greenness. The quality control of pharmaceuticals requires sensitive, fast and economic methodologies to provide a high throughput at desirable costs. The low energy and decreased solvent consumption make this technique green as well as economic, and hence it is much preferred by pharmaceutical industries. Remdesivir is a recent antiviral, previously used for the treatment of Ebola virus infections, which was approved by the US-FDA in 2020 for treatment of infections caused by SARS-CoV-2 virus. Formulation and wide-scale production of this drug started recently and hence methodologies related to its quality control are highly required. A smart spectrofluorimetric method was validated as per the US-FDA guidelines for the facile estimation of Remdesivir. The assay of Remdesivir was based on its native fluorescence measurements at pH 4 and wavelengths of 244/405 nm. Calibration was achieved over the range of 1.0-65.0 ng mL^-1. Different variables affecting the proposed methodology were studied to achieve maximum sensitivity, at limits of detection and quantification of 0.287 and 0.871 ng mL^-1, respectively. The developed method is regarded as the first spectrofluorimetric one for the estimation of Remdesivir. The developed method was also utilized for the determination of the drug in its formulated IV infusion and in spiked human plasma. Statistical analysis verified that this method is accurate and reproducible. Moreover, the ecological impact of the developed procedures was evaluated on two recently reported assessment metrics, the Green Analytical Procedure Index (GAPI) and AGREE-analytical greenness metric, to emphasize the greenness of the procedure.

Studying the quenching resulted from the formation of an association complex between olsalazine or sulfasalazine with acriflavine

We report the detection and quantification of important ulcerative colitis drugs olsalazine (OLS) and sulfasalazine (SUL) by the spectrofluorometric method. The proposed method was optimized and validated by using the quenching effect on the acriflavine fluorescence. The method was applied on the detection and quantification of OLS and SUL under optimized conditions showing the calibration curves were linear (range: 1.0-10.0 µg ml-1), with correlation coefficients R 2 of 0.9999 for both drugs. The limits of detection (LOD) and quantification (LOQ) were 53 and 104 ng ml-1 for the OLS and 160 and 315 ng ml-1 for the SUL. This method permitted the analysis of OLS and SUL in their pure and pharmaceutical forms. The proposed spectrofluorimetric method was also evaluated against 'green' criteria and all the experimental results make it an eco-friendly and safe method for the detection of OLS and SUL.

Novel spectrofluorimetric technique for determination of amoxicillin and ethopabate in chicken tissues, liver, kidney, eggs, and feed premix

A new smart spectrofluorometric method was developed for the quantitation of amoxicillin and ethopabate simultaneously for the first time. The method is based on measuring their first derivative synchronous amplitudes in water at Δλ = 80 nm. The peak amplitudes were recorded at their crossing points; 240 nm for amoxicillin and 280 nm for ethopabate. The method is linear over the concentration ranges of 100.0-1,000.0 ng/ml for amoxicillin and 2.0-20.0 ng/ml for ethopabate. The limits of detection were 20.0 ng/ml and 0.58 ng/ml and limits of quantitation were 60.0 ng/ml and 1.92 ng/ml for amoxicillin and ethopabate, respectively. The method sensitivity permitted the determination of the two drugs below their maximum residue limit stated by the federal regulations. The developed method was applicable to the analysis of both drugs in the veterinary powders, feed premix, chicken tissues, liver, kidney, and eggs samples with percentage recoveries ranging 93.72-104.71%.

Green micellar solvent-free HPLC and spectrofluorimetric determination of favipiravir as one of COVID-19 antiviral regimens

Quality control (QC) of pharmaceutical products requires fast, sensitive as well as economic methodologies in order to provide high through output at low cost which are the main aspects considered by such economic facilities. Meanwhile, the ecological impacts must be considered by researchers to minimize the hazardous effects of research laboratories. Favipiravir (FAV) is an antiviral agent recently approved for treatment of COVID-19 infections during 2020 pandemic crisis, so the size of its production by international pharmaceutical corporations evolved dramatically within the past few months. Two novel simple, sensitive, and green methods were developed and validated for FAV determination based on solvent-free micellar LC and spectrofluorimetry techniques. To improve FAV native fluorescence, several factors were studied including solvent type, buffering, pH and added surfactants. The best sensitivity for FAV fluorescence was obtained in Britton-Robinson buffer (pH 4) at 436 nm after excitation at 323 nm within concentration range of 20–350 ng mL⁻¹. Another HPLC method was validated using C18-RP (5 µm, 250 × 4.6 mm) stationary phase and solvent-free mobile phase consisting of (0.02 M Brij-35, 0.15 M SDS, and 0.02 M disodium hydrogen phosphate, pH 5.0) isocratically eluted at a flow rate of 1 mL min⁻¹ and detection wavelength of 323 nm. LC method was validated across concentration range of 10–100 µg mL⁻¹ and FAV eluted in 3.8 min. The methods were validated according to the FDA guidelines and were applied successfully for determination of FAV in its marketed tablet dosage forms and in spiked human plasma samples. The proposed methods are eco-friendly since they are typically based on biodegradable reagents in aqueous solvent-free phases, which was proven by their assessment on two recent greenness metrics (GAPI and AGREE) to prove their eco-friendly properties.

New spectroscopic methods for determination of dexlansoprazole using mercurochrome

New spectroscopic methods were developed for dexlansoprazole estimation in capsule formulation based on the formation of a reaction between dexlansoprazole and Mercurochrome (MER) at pH 3.7. The formed complex was measured spectrophotometrically (Method I) at 557 nm and spectrofluorometrically (Method II) at 300 nm/538 nm, because the drug caused quantitative quenching of the native fluorescence of Mercurochrome. The spectrophotometric method was linear over the concentration 25-55 μg/ml with a limit of detection (LOD) of 1.15 μg/ml and a limit of quantification (LOQ) of 3.48 μg/ml. The spectrofluorometric method had a linear range 20-45 μg/ml with an LOD of 1.13 μg/ml and an LOQ of 3.45 μg/ml. The suggested methods were used to analyze capsules to test the interference from excipients and the data indicated good selectivity. Data obtained were statistically analyzed and were favourably good. The new methods are environmentally benign and depend on distilled water mainly as the diluting solvent. This property was confirmed by assessing their greenness.

Factorial design-assisted reversed phase-high performance liquid chromatography method for simultaneous determination of fluconazole, itraconazole and terbinafine

A 23 full factorial design model was used for the development of a new high performance liquid chromatography method with UV detection to estimate three antifungal drugs simultaneously. Fluconazole (FLU), itraconazole (ITR) and terbinafine (TRH) are co-administered for severe fungal infections. They have been determined using MOS-1 Hypersil C18 column and an isocratic eluent; methanol 95% and phosphate buffer 5% with 0.001% triethylamine. The pH was adjusted to 7, and the flow rate was 0.7 ml min-1. The three drugs were separated within less than 7 min at 210 nm. The developed method gave a linear response over 5-80 µg ml-1, 5-50 µg ml-1 and 1-50 µg ml-1 for FLU, ITR and TRH, respectively. It showed detection limits of 0.88, 0.29 and 0.20 µg ml-1 and quantification limits of 2.66, 0.88 and 0.60 µg ml-1 for the three drugs, respectively. The design of the experiment facilitated the optimization of different variables affecting the separation of the three drugs. The sensitivity of the designed method permitted the simultaneous estimation of ITR and TRH in spiked human plasma successfully.

Rapid fluorometric determination of ticagrelor in tablets and rat plasma: Application to pharmacokinetics study

The new antiplatelet drug ticagrelor has been determined based on its native fluorescence properties. These properties were studied and optimized to develop fast, simple and sensitive spectrofluorimetric method. The study included two approaches. The first approach is depending on measuring the native fluorescence at 300 nm after excitation at 222 nm. While the second approach combined synchronous and derivative scanning modes to measure ticagrelor at 286 nm using Δ λ = 100 nm. Ticagrelor was measured in aqueous solution starting from the concentration of 200 to 5000 ng/mL in both native and first derivative synchronous approaches. The developed methods were validated in accordance with ICH guidelines to be acceptable for quality control laboratories. Lowest concentrations that could be quantitated using the native and first derivative synchronous methods were 189 and 151 ng/mL while lowest detectable concentrations were 63 and 50 ng/mL, respectively. Moreover, the derivative synchronous fluorimetric approach was utilized to determine ticagrelor at 286 nm in presence of other commonly co- administered drugs and the results demonstrate the enhanced selectivity of the proposed method. The same approach was also used to determine ticagrelor in rat plasma with acceptable recoveries. A preliminary pharmacokinetic study in rats was conducted and could be used to monitor plasma ticagrelor levels in humans.

Combining derivative and synchronous approaches for simultaneous spectrofluorimetric determination of terbinafine and itraconazole

In this study, determination of terbinafine and itraconazole down to biological concentration level has been carried out. The determination is based on increasing the selectivity of the spectrofluorimetric technique by combining both derivative and synchronous spectrofluorometric approaches, which permits successful estimation of terbinafine at 257 nm and itraconazole at 319 nm in the presence of each other at Δλ of 60 nm. International Conference on Harmonization validation guidelines were followed to fully validate the method, and linearity was obtained for the two drugs over the range of 0.1-0.7 µg ml-1 for terbinafine and 0.5-4.0 µg ml-1 for itraconazole. Application of the method was successfully carried out in the commercial tablets with good agreement with the comparison spectrofluorometric methods. As the detection limits were down to 0.013 and 0.1 µg ml-1 and quantitation limits were 0.04 and 0.032 µg ml-1 for terbinafine and itraconazole, respectively; the in vitro determination of terbinafine and itraconazole in spiked plasma samples was applicable. The percentage recoveries in biological samples were 97.17 ± 4.54 and 98.75 ± 2.25 for terbinafine and itraconazole, respectively. Water was used as the optimum diluting solvent in the proposed methodology which adds an eco-friendly merit.

Use of eosin for green spectroscopic determination of mebendazole

New, sensitive, and reliable spectroscopic methods were constructed for the fast determination of the anthelmintic drug mebendazole. The methods depended on the reaction of the amino group in mebendazole with eosin in acidic medium forming an ion pair complex. The first method, Method I, relied on quenching of the native fluorescence of eosin after reaction with mebendazole at pH 3.7 using acetate buffer. Fluorescence quenching was measured at 538 nm after excitation at 518 nm. This method showed a linear response over the concentration range 5.0-20.0 μg/ml. The second method, Method II, was based on measuring the absorbance of the formed complex at 554 nm; the method showed good linearity from 7.0 to 22.0 μg/ml. Different parameters that influenced the formation of the reaction product were carefully investigated to reach the optimized conditions. A comparison between the proposed methods and a previous spectrophotometric method was carried out and there was no significant difference between them. The methods could be applied successfully to determine mebendazole in its tablet form. Moreover, the methods used water as diluting solvent, which made them compatible with the 'green' analytical chemistry principles. No organic solvents were used throughout the study.

Solvent-free mixed micellar mobile phases: An advanced green chemistry approach for reversed-phase HPLC determination of some antihypertensive drugs

Minimizing the amount of organic solvents without loss in chromatographic performance has been an important step toward greening analytical methodologies. Mobile-phase composition is the key for maintaining separation efficiency in liquid chromatography while decreasing the procedure hazardousness. If sodium dodecyl sulfate is mixed with Brij-35 in the mobile phase, they could be used as a green alternative for using organic modifiers. In this research, the effect of changing the relative amounts of both surfactants was studied on the chromatographic performance and separation efficiency of ten antihypertensive drugs belonging to different categories. The use of surfactants has many advantages including low cost and toxicity, safe environmental disposal, unique selectivity besides high solubilization capabilities. The optimum separation was maintained using a mobile phase (0.01 M Brij-35, 0.08 M sodium dodecyl sulfate and 0.01 M sodium dihydrogen phosphate/pH 5) on reversed-phase C18 core-shell column at flow rate 1.5 mL/min and temperature 30°C. The method was successfully applied for the determination of the drugs in various marketed dosage forms. International Conference of Harmonization guidelines were followed to validate the developed method. Additionally, the method was verified on the Green Analytical Procedure Index in regards to the greenness and found to be an excellent green alternative method.

Assessment of lipophilicity of newly synthesized celecoxib analogues using reversed-phase HPLC

BACKGROUND

Lipophilicity is a physicochemical property of an essential importance in medicinal chemistry; therefore, fast and reliable measurement of lipophilicity will affect greatly the drug discovery process.

RESULTS

A series of N-benzenesulfonamide-1H-pyrazoles, oximes and hydrazones as celecoxib analogues was investigated with regard to their retention behavior using reversed-phase high performance liquid chromatography (RP-HPLC). The mobile phases employed for this study consist of a mixture of water and methanol in different proportions. In addition, the stationary phase utilized for this separation was C18 silanized silica gel and using 200 nm as a detection wavelength. The retention behavior of the investigated compounds was determined based on practical determination of log k at different concentrations of methanol (as an organic modifier) in the mobile phase ranging from 60 to 80%. It was observed that the retention of these compounds (expressed as log k) decreased in a linear manner with increasing the concentration of methanol. High correlation coefficients (more than 0.90 in most cases) were obtained for the relationship between the volume fraction of the organic solvent and the retention values represented as log k w. A comparative evaluation was carried out between chromatographically-obtained lipophilicity parameters (represented as lipophilicity chromatographic index log k w or isocratic chromatographic hydrophobicity index, φ 0) and the computationally calculated log P values (miLogP, ALOGP, ACD/Labs and ALOGPs).

CONCLUSION

It was found that a good correlation exists between the experimental and computed log P values. In the future, these results can give a deep insight about the anti-inflammatory and analgesic activity of the newly synthesized compounds.

Synchronous fluorescence as a green and selective tool for simultaneous determination of bambuterol and its main degradation product, terbutaline

A green, sensitive and cost-effective method is introduced in this research for the determination of bambuterol and its main degradation product, terbutaline, simultaneously, relying on the synchronous spectrofluorimetric technique. First derivative synchronous spectrofluorimetric amplitude is measured at Δλ = 20 nm, so bambuterol can be quantitated at 260 nm, and terbutaline can be measured at 290 nm, each at the zero crossing point of the other. The amplitude-concentration plots were linear over the concentration ranges of 0.2-6.0 µg ml-1 and 0.2-4.0 µg ml-1 for both bambuterol and terbutaline, respectively. Official guidelines were followed to calculate the validation parameters of the proposed method. The low values of limits of detection of 0.023, 0.056 µg ml-1 and limits of quantitation of 0.071, 0.169 µg ml-1 for bambuterol and terbutaline, respectively, point to the sensitivity of the method. Bambuterol is a prodrug for terbutaline, and the latter is considered its degradation product so the established method could be regarded as a stability-indicating one. Moreover, the proposed method was used for the analysis of bambuterol and terbutaline in their single ingredient preparations and the results revealed statistical agreement with the reference method. The suggested method, being a simple and low-cost procedure, is superior to the previously published methods which need more sophisticated techniques, longer analysis time and highly toxic solvents and reagents. It could be considered as an eco-friendly analytical procedure.

Simultaneous HPLC Determination of Cisatracurium and Propofol in Human Plasma via Fluorometric Detection

The proposed method describes a high performance liquid chromatographic method with fluoremetric detection for the determination of cisatracurium (CIS) and propofol (PRP) simultaneously, which are co-administered as a pre-operative injection mixture. The separation of the two drugs was achieved using monolithic column (100 mm and 4.6 mm internal diameter) and mixture of methanol and 0.1 M phosphate buffer in the ratio of 80:20 (v/v) at pH 4.5 as a mobile phase. The fluorescence detection was carried out at 230/324 nm. The procedure showed good linearity through the concentration ranges of 0.01-1.00 μg/mL and 0.1-3.0 μg/mL with limits of detection of 0.002, 0.030 μg/mL and limits of quantification of 0.006, 0.100 μg/mL for CIS and PRP, respectively. Simultaneous determination of CIS and PRP in spiked human plasma samples was additionally executed and the results were satisfactory precise and accurate.

Simultaneous determination of cetirizine, phenyl propanolamine and nimesulide using third derivative spectrophotometry and high performance liquid chromatography in pharmaceutical preparations

Background

The combination between cetirizine (CET), phenylpropanolamine (PPA) and nimesulide (NMS) under trade name Nemeriv Cp tablet is prescribed for nasal congestion, cold, sneezing, and allergy. Among all published methods for the three drugs; there is no reported method concerning estimation of CTZ, PPA and NMS simultaneously and this motivates us to develop new and simple methods for their assay in pure form and tablet preparations.

Results

Two new methodologies were described for the simultaneous quantification of cetirizine (CTZ), PPA and NMS. Spectrophotometric procedures relies on measuring the amplitudes of the third derivative curves at 238 nm for CTZ, 218 nm for PPA and 305 nm for NMS. The calibration graphs were rectilinear over the ranges of 8–90 µg/mL for CTZ, 20–100 µg/mL for PPA and 20–200 µg/mL for NMS respectively. Regarding the HPLC method; monolithic column (100 mm × 4.6 mm i.d) was used for the separation. The used mobile phase composed of 0.1 M phosphate buffer and methanol in the ratio of 40:60, v/v at pH 7.0. The analysis was performed using UV detector at 215 nm. Calibration curves showed the linearity over concentration ranges of 5–40, 10–100 and 10–120 µg/mL for CTZ, PPA and NMS.

Conclusion

Application of the proposed methods to the laboratory prepared tablets was carried out successfully. The results were compared with those obtained from previously published methods and they were satisfactory.Graphical abstract

Simultaneous Determination of Cromolyn Sodium Combined Dosage Forms Using Isocratic HPLC Method

A simple and selective reversed-phase high-performance liquid chromatography method was developed for the estimation of cromolyn sodium (CRM) with either oxymetazoline hydrochloride (OMZ) or xylometazoline hydrochloride (XMZ) in their binary mixtures. The method is based on the simultaneous separation of each drug in a reversed-phase Waters symmetry^® C18 column (250 mm × 4.6 mm intradermally, 5-µm particle size) at 25°C. Elution was performed with a mobile phase consisting of methanol : 0.1 M phosphate buffer (60:40, v/v, pH 4.0). Quantitation was achieved with ultraviolet detection at 220 nm. The method could determine the three drugs, with linearity, in the range of 2.0-100.0 µg/mL for CRM and 0.8-8.0 µg/mL for OMZ and for XMZ. Aspirin was used as internal standard. Optimization of the separation in terms of mobile phase composition is critical to the method development, which is discussed in detail. The suggested procedure was successfully applied to the analysis of the studied drugs in their nasal preparations. Statistical evaluation of the data obtained by the proposed and comparison methods revealed good accuracy of the proposed method.