Novel spectrofluorimetric approach for determination of ledipasvir through UV-irradiation: application to biological fluids, pharmacokinetic study and content uniformity test

Development of Eco-Friendly Scattering and Fluorimetric Methods for the Determination of Clemastine Through Its Interaction with Eosin Y: Assessment of Whiteness, Blueness, and Greenness Tools

For the first time, clemastine was estimated in this work utilizing two validated resonance Rayleigh scattering (RRS) and fluorimetric methods. The methods relied on forming an association complex in an acidic medium between eosin Y reagent and clemastine. In the spectrofluorimetric approach, the investigated drug was quantified by quenching the fluorescence-emission intensity of eosin Y at 543.5 nm. The RRS method relied on enhancing the RRS spectrum at 331.8 nm, which is produced when eosin Y interacts with clemastine. Suitable conditions were established for the reaction to achieve maximum sensitivity. The linear values obtained from the spectrofluorimetric approach and the RRS method fall into the ranges of 0.2-1.5 µg mL- 1 and 0.25-2.0 µg mL- 1, respectively. It was established that the detection limits for these methods were 0.045 µg mL- 1 and 0.059 µg mL- 1, respectively. The developed methodologies yielded acceptable recoveries when used to estimate the quantity of clemastine in its pharmaceutical tablet dosage form. Regarding the use of greener solvents that were chosen, the suggested and reported methods were compared with the help of the Green Solvents Selecting (GSST) tool for assessing hazardous solvents to achieve sustainability. Furthermore, analytical Eco scale and comprehensive assessments of whiteness, blueness, and greenness were carried out utilizing Modified NEMI, ComplexGAPI, and AGREE evaluation tools. Additionally, recently developed tools such as BAGI and RGB 12 were applied to assess the blueness and the whiteness of the suggested methods.

In-vivo microwave-aided spectrofluorimetric characterization of teneligliptin-loaded solid dispersion adsorbate using quality by design approach

This study developed a microwave-aided spectrofluorimetric method for in-vivo characterizing teneligliptin-loaded solid dispersion adsorbate (TNG-SDA) using a quality by design approach. The microwave-aided chemical reaction was applied for derivatization of non-fluorescent teneligliptin with NBD-Cl (7-chloro-4-nitrobenzoxadiazole). TNG-SDA was prepared to enhance the solubility and bioavailability of teneligliptin, a BCS (Biopharmaceutical Classification System) class II drug. The method utilized environmentally friendly solvents and employed analytical quality by design principles for optimization. Critical method parameters were identified through failure mode impact analysis and optimized using response surface modelling. The fluorescence spectra of teneligliptin exhibited linearity across the concentration range of 50-250 ng/mL, with a correlation coefficient of 0.9978. The developed method was found to be accurate, precise, robust, specific and sensitive for estimation of teneligliptin. The method was applied to evaluate in vitro dissolution, pharmacokinetics, and pharmacodynamic of TNG-SDA compared to commercial formulations. Results showed significant improvements in teneligliptin solubility and bioavailability with the developed SDA. The microwave-aided derivatized fluorescent product was characterized by mass spectrometry. The method demonstrated environmental sustainability, robustness, sensitivity, cost-effectiveness, and user-friendliness when evaluated using white analytical chemistry approaches. It provided a sensitive and green alternative to existing hyphenated techniques for nanogram-level teneligliptin detection in pharmacokinetic studies.

Design of new boron-doped carbon dots for nano-level assay of nebivolol in human plasma and commercial products; Application to greenness assessments

Recently, nanomaterials have attracted a lot of attention due to their potential as effective fluorescent nano-sensor probes. They were distinguishing substitutes for other luminescent techniques, such as fluorescent dyes and luminous derivatization, because of their affordability, environmental friendliness, and special photocatalytic properties. In the suggested work, a straightforward method was used to create boron and nitrogen carbon dots (B@CDs) with a good quantum yield value of 31.15 % utilizing boric acid and di-sodium EDTA. For the purpose of characterizing QDs, a variety of instruments were employed, such as transmission electron microscopy, fluorescence spectroscopy, X-ray FTIR, and UV-VIS spectroscopy. Nebivolol (NEB) is a cardiovascular medication used globally to treat congestive heart failure and hypertension, is in the meantime. For this reason, a brand-new, environmentally friendly analytical technique was created to determine the amount of human plasma, uniformity test, and commercial nebivolol (NEB) tablets. After gradually adding NEB, the response of B@CQDs was enhanced at 438 nm (excitation at 371 nm). The calibration graph ranged between 20 and 500 ng mL-1 with a quantification limit (LOQ) of 2.50 ng mL-1 and a detection limit (LOD) of 0.82 ng mL-1.

Bioanalytical Validated Spectrofluorimetric Method for the Determination of Prucalopride succinate in Human Urine Samples and Its Greenness Evaluation

An economical & eco-friendly spectrofluorometric method has been developed for the determination of prucalopride succinate (PRU) in human urine on the basis of the drug's native fluorescence. The type of solvent and the wavelengths of excitation and emission have been carefully selected for optimal experimental conditions. In deionized water, the fluorescence intensity was measured at λ emission 362 nm upon excitation at 310 nm. This bio-validated method was carried out using 30uL urine without any preliminary steps. The calibration curve for prucalopride succinate shows a linear relationship in a concentration range of 0.75-5.5 µg/mL. Accuracy and precision were obtained using 4 quality control samples which are: 0.75 μg/ mL (LLOQ), 2.25 μg/mL (QCL), 2.5 μg/mL (QCM) & 4.125 µg/mL (QCH). The validation of this proposed technique obeys European Medicines Agency (EMA) Guidelines for validating bioanalytical methods and the greenness assessment was evaluated according to the Analytical GAPI approach.

In-depth investigation of the Silymarin effect on the pharmacokinetic parameters of sofosbuvir, GS-331007 and ledipasvir in rat plasma using LC-MS

The use of complementary medicine (CMD) for liver support in Hepatitis C virus (HCV) patients sometimes coincides with the administration of oral antiviral drugs to eradicate the virus. This calls for a deep investigation of CMD effects on the pharmacokinetic parameters of these drugs to ensure their safety and efficacy. Silymarin (SLY), as a CMD, was selected to be given orally to healthy male rats with sofosbuvir (SFB) and ledipasvir (LED), a common regimen in HCV treatment. A new and sensitive LC-MS method was validated for the bioassay of SLY, LED, SFB and its inactive metabolite, GS-331007, in spiked plasma with lower limits of quantitation of 10, 1, 4 and 10 ng/ml, respectively. Moreover, the method was further applied to conduct a full pharmacokinetic profile of SFB, GS-331007 and ledipasvir with and without SLY. It was found that co-administration of SLY may expose the patient to unplanned high serum concentrations of SFB and LED. This could be accompanied by a decrease in SFB efficacy, potentially leading to therapeutic failure and the emergence of viral resistance.

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.

Spectrofluorimetric Determination of the Anti-Covid 19 Agent; Remdesivir in Vials and Spiked Human Plasma

Following the sudden widespread of the novel coronavirus (COVID‐19) which first appeared in Wuhan city. Remdesivir (REM) was the first medicine licensed by the US Food and Drug Administration (FDA) for COVID‐19 infected hospitalized patients. Hence, there was an urgent demand for the optimization of efficient selective and sensitive methods to be developed for the determination of REM in pharmaceuticals as well as biological samples. A sensitive and simple green spectrofluorimetric method has been developed to determine REM in pharmaceutical formulation, in addition to, spiked human plasma. The technique involves measuring the native fluorescence of REM in distilled water at 410 nm followed by excitation at 241 nm, giving a linear relationship over the range 50.00–500.00 ng/mL, and then improving the sensitivity of REM through micellar formation using 2.00% w/v sodium dodecyl sulfate (SDS). A linear relationship has been obtained over the range 10.00–350.00 ng/mL having detection and quantitation limits of 2.34 and 7.10 ng/mL, respectively. Different analytical parameters have been carefully studied. A validation study has been conducted successfully in accordance with the FDA and the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines. The developed methods' greenness was assessed utilizing a greenness profile and analytical eco‐scale standards. Both methods were discovered to be environmentally friendly and could be successfully used for the determination of the studied drugs in pharmaceutical formulation and human plasma with good accuracy and high precision. As a result, the developed spectrofluorimetric methods could be ideally suited for determination of REM in quality control and medicinal laboratories.

Computational design for eco-friendly visible spectrophotometric platform used for the assay of the antiviral agent in pharmaceutical dosage form

Nowadays, the analytical community is focusing on developing new analytical methods that incorporate principles of green analytical chemistry to reduce adverse impacts on the environment and humans. In this study, we focused specifically on establishing a correlated connection between theoretical and experimental applications via developing green, and eco-friendly visible spectrophotometric methods. These methods were relied on charge-transfer complexation (CTC) between ledipasvir and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), or chloranilic acid (CA) for sensitive colorimetric analysis of ledipasvir in the presence of sofosbuvir (Sofolanork plus®). The results were evaluated as modern computational chemistry using molecular modeling technology. At ambient temperature, the reactions for DDQ and CA took 15 and 10 min, respectively, to produce a purple red-colored solution with DDQ absorbing maximally at 588 nm and a purple-colored solution with CA absorbing maximally at 522 nm. Linearity was achieved for ledipasvir utilizing DDQ and CA in the concentration ranges of 8-80 µg.mL^-1 and 40-400 µg.mL^-1, respectively. The precision and accuracy of the methods mentioned were determined. Finally, the results were statistically compared to a previously published spectrophotometric technique, and no significant differences were found.

Two facile approaches based on association complex with erythrosine-B for nano-level analysis of duloxetine: application to content uniformity

Duloxetine is an antidepressant that exhibits its action by preventing the reuptake of serotonin and norepinephrine by neurons. In this analytical study, we developed two facile, sensitive methods for duloxetine analysis. Both methods rely on the formation of binary association complex between erythrosine-B and duloxetine in an acidic medium using spectrofluorimetric and resonance Rayleigh scattering (RRS) techniques. Spectrofluorimetric method simply uses the quenching property of the formed complex on the native fluorescence of erythrosine-B at an emission wavelength of 557.2 nm (λ ex = 528.6), while RRS is based on detecting the enhancement in the RRS signal at 357.2 nm. The proposed methods have been validated according to the International Conference on Harmonization guidelines. The approaches provide linear assay of duloxetine hydrochloride over 0.1-2.4 µg ml-1 and 0.2-2.0 µg ml-1 for spectrofluorimetric and RRS methods, respectively. Variables affecting methods and complex formation were studied and optimized. The limit of detection values were 0.03 and 0.056 µg ml-1 for spectrofluorimetric and RRS methods, respectively. Both approaches were applied with acceptable results for formulation analysis and evaluation of cymbatex capsule content uniformity.

Innovative Thin-Layer Chromatography/Fluorescence Detection Approach for Sensitive and Specific Determination of Ledipasvir in Rats' Feces and Pharmaceutical Dosage Form

An innovative thin-layer chromatography method coupled with the fluorescence detection was developed for a specific estimation of ledipasvir. The separation was achieved on plates of silica gel 60 F254 using ethylacetate: hexane: acetonitrile: triethylamine; (6: 3.5: 1.5: 0.5, $\mathrm{v}/\mathrm{v}/\mathrm{v}/\mathrm{v}$) as a mobile phase system. The method involved the exposure of the developed thin-layer chromatography plate of ledipasvir to strong ultraviolet irradiation, resulting in a great enhancement in the fluorescence properties of ledipasvir. The irradiated plates were scanned after the excitation at 315 $\mathrm{nm}$. The method provided a sufficient separation of ledipasvir from sofosbuvir with ${R}_F$values of 0.28 and 0.36 for ledipasvir and sofosbuvir, respectively. The developed procedures were validated based on guidelines from the International Conference on Harmonization and Food and Drug Administration guidelines. The calibration curve was linear over the range of 5-50 $\mathrm{ng}/\mathrm{band}$. The excellent analytical features of the proposed method allow to the specific determination of ledipasvir in pharmaceutical tablets without interference from sofosbuvir or excipients. As the main elimination route for ledipasvir is via the fecal excretion (86%), the method was applied for the estimation of ledipasvir in fecal specimens with adequate recovery. In addition, the proposed method was applied for testing the content uniformity of ledipasvir in the pharmaceutical tablets.

A Review on Analytical Strategies for the Assessment of Recently Approved Direct Acting Antiviral Drugs

Human beings are in dire need of developing an efficient treatment against fierce viruses like hepatitis C virus (HCV) and Coronavirus (COVID-19). These viruses have already caused the death of over two million people all over the world. Therefore, over the last years, many direct-acting antiviral drugs (DAADs) were developed targeting nonstructural proteins of these two viruses. Among these DAADs, several drugs were found more effective and safer than the others as sofosbuvir, ledipasvir, grazoprevir, glecaprevir, voxilaprevir, velpatasvir, elbasvir, pibrentasvir and remdesivir. The last one is indicated for COVID-19, while the rest are indicated for HCV treatment. Due to the valuable impact of these DAADs, larger number of analytical methods were required to meet the needs of the clinical studies. Therefore, this review will highlight the current approaches, published in the period between 2017 to present, dealing with the determination of these drugs in two different matrices: pharmaceuticals and biological fluids with the challenges of analyzing these drugs either alone, with other drugs, in presence of interferences (pharmaceutical excipients or endogenous plasma components) or in presence of matrix impurities, degradation products and metabolites. These approaches include spectroscopic, chromatographic, capillary electrophoretic, voltametric and nuclear magnetic resonance methods that have been reported during this period. Moreover, the analytical instrumentation and methods used in determination of these DAADs will be illustrated in tabulated forms.

Resonance Rayleigh scattering and spectrofluorimetric approaches for the selective determination of rupatadine using erythrosin B as a probe: application to content uniformity test

In this study, spectrofluorimetric and resonance Rayleigh scattering techniques were applied for the first time for determination of rupatadine through two validated methods. The proposed methods were based on a facile association complex formation between rupatadine and erythrosin B reagent in acidic medium. Spectrofluorimetric determination relied on the quenching effect of rupatadine on the fluorescence intensity of erythrosin B at 556 nm (excitation = 530 nm). Conversely, the resonance Rayleigh scattering (RRS) method relied on enhancement in the resonance Rayleigh scattering spectrum of erythrosin B at 344 nm after the addition of rupatadine. The developed methods produced linear results over ranges 0.15-2.0 μg/ml and 0.1-1.5 μg/ml, with detection limits of 0.030 μg/ml and 0.018 μg/ml for the spectrofluorimetric method and the RRS method, respectively. All reaction conditions for rupatadine-erythrosin B formation were optimized experimentally and both methods were validated according to International Council for Harmonisation guidelines. The developed methods were applied to estimate rupatadine content in its pharmaceutical tablet dosage form with acceptable recoveries. Furthermore, a content uniformity test for the commercial rupatadine tablets was successfully applied by the suggested spectroscopic methods according to United States Pharmacopeia guidelines.

Micelle sensitized synchronous spectrofluorimetric approaches for the simultaneous determination of simeprevir and ledipasvir: Application to pharmaceutical formulations and human plasma

Simeprevir (SMV) is commonly co-administered with ledipasvir (LDS) and sofosbuvir (SOF) as an effective combination regimen for treatment naive hepatitis C virus infected patients. In the present study, two spectrofluorimetric approaches were combined together for the development of highly sensitive, rapid, simple and accurate method for simultaneous quantification of SMV and LDS. The native fluorescence intensity values of SMV and LDS were enhanced by the addition of Tween-80 micellar system, while second derivative of the synchronous fluorescence intensity of the drugs at Δλ = 120 nm enabled the determination of both drug concomitantly. Different experimental parameters affecting the synchronous fluorescence of the cited drugs were carefully evaluated for their optimization. The peak amplitudes of the second derivative synchronous fluorimetry were measured at 429 nm for SMV and at 417 nm for LDS. The fluorescence-concentration plots were rectilinear over the range of 60-1500 and 36-540 ng mL^-1 with lower detection limits of 9.0 and 6.0 ng mL^-1 and quantification limits of 27.0 and 17.0 ng mL^-1 for SMV and LDS respectively. The method was successfully applied for the determination of both drugs in their pure forms as well as their pharmaceutical products and human plasma without any significant interference. Statistical comparison with the reported method revealed excellent accuracy and precision of the proposed method.

Thin-layer chromatography/fluorescence detection approach for sensitive and selective determination of hepatitis C virus antiviral (velpatasvir): application to human plasma

A validated thin-layer chromatography (TLC) method combined with fluorescence detection mode was developed for the selective determination of a recently approved anti-hepatitis C virus (HCV) drug (velpatasvir). The separation was performed on silica gel 60 F₂₅₄ plates using ethylacetate:methanol:triethylamine (48:1.5:1.0, v/v/v) as a mobile phase. Plates were scanned in the fluorescence mode after excitation at 335 nm. This method provided an excellent separation of velpatasvir from sofosbuvir with R_F values of 0.22 and 0.46 for velpatasvir and sofosbuvir, respectively, after scanning the developed plates in the ultraviolet detection mode at 335 nm. The calibration curve was linear over the range 4-40 ng/band with a correlation coefficient of 0.9994. The developed procedure was validated according to ICH guidelines with a detection limit of 1.30 ng/band and quantitation limit of 3.95 ng/band. The suggested method could selectively determine velpatasvir with high sensitivity in a synthetic tablet powder containing a co-formulated anti-HCV drug (sofosbuvir) without any interference from excipients or sofosbuvir. In addition, the method was successfully applied for determination of velpatasvir in spiked human plasma with adequate % recovery.

Micellar-based spectrofluorimetric method for the selective determination of ledipasvir in the presence of sofosbuvir: application to dosage forms and human plasma

A fast, low-cost, sensitive, and selective spectrofluorimetric method for the determination of ledipasvir was developed and validated. The method is based on an enhancement in the native fluorescence intensity of ledipasvir by 500% of its original value by the formation of hydrogen bonds between the cited drug and Tween-20 in the micellar system (pH = 5.0). All fluorescence measurements were carried out at 425 nm and 340 nm for emission and excitation wavelengths, respectively. A linear relationship between the concentration of ledipasvir and the observed fluorescence intensity was achieved in the range of 0.1-2.0 μg ml^-1 with 0.028, 0.084 μg ml^-1 , for detection and quantitation limits, respectively. The acquired selectivity and sensitivity using the proposed method facilitate the analysis of ledipasvir in spiked human plasma with sufficient percentage recovery (95.36-99.30%). The proposed method was developed and validated according to International Council for Harmonisation (ICH) guidelines. Moreover, the cited drug was successfully determined in its pharmaceutical dosage form using the proposed method. In addition, the validity of the proposed results was statistically confirmed using Student's t-test, variance ratio F-test, and interval hypothesis test.