Development of sensitive spectrofluorometric approach based on formation of pyrrolidone derivative for determination of linagliptin through condensation reaction with ninhydrin and phenylacetaldehyde: Application to content uniformity and real plasma.

The new drug linagliptin belongs to the class of dipeptidyl peptidase-4 enzyme inhibitors. Linagliptin is used to treat type 2 diabetes and is taken orally either alone or in combination with other drugs. In this instance, a new, simple, and economical technique for analyzing linagliptin was developed by the effective use of a pyrrolidone derivative. The primary amine group of linagliptin permits its condensation with ninhydrin (0.14% w/v) to produce a fluorescent product in the presence of phenylacetaldehyde (0.02% v/v). All experimental parameters were carefully examined and adjusted in order to monitor the generation of the pyrrolidone derivative at excitation and emission wavelengths of 385 and 475 nm, respectively. The calibration graph was made by plotting the intensity of the fluorescence in relation to linagliptin concentration. A significant linearity was found for values ranging from 20 to 460 ng/mL. The process's validity has been verified by a thorough assessment of the instructions provided by the International Conference on Harmonization (ICH). The results indicate excellent uniformity with a reference method, showing that there is no substantial difference in precision and accuracy. The proposed approach was utilized for determining linagliptin in real rat plasma successfully owing to its high sensitivity. Additionally, the proposed approach was evaluated using the Eco-Scale evaluation tool and showed a high degree of eco-friendliness (86/100).

A Highly Sensitive Inclusion Complex Based Spectrofluorimetric Method for the Determination of Certain Sodium Glucose Cotransporter-2 Inhibitors: Greenness Assessment and Application to Different Biological Fluids.

This study introduces a remarkably simple, green, and highly sensitive inclusion complex based spectrofluorimetric method for analyzing two sodium glucose cotransporter-2 (SGLT2) inhibitors: empagliflozin (EGF) and dapagliflozin (DGF). The method utilizes beta-cyclodextrin (ß-CD) complexation to enhance the native fluorescence of EGF and DGF in aqueous solutions, resulting in 11.0-fold and 9.0-fold intensity increases, respectively. Fluorescence measurements were conducted at 301 nm emission following 230 nm excitation for both drugs. The method demonstrates excellent linearity (0.9994 for EGF and 0.9993 for DGF) over concentration ranges of 5.0-250.0 ng/mL and 10.0-300.0 ng/mL, with low detection limits of 1.05 and 1.38 ng/mL for EGF and DGF, respectively. The method's versatility was validated through successful application in pharmaceutical formulations, content uniformity testing, and biological fluids. This eco-friendly approach primarily uses water as a solvent and requires minimal reagents. The method's environmental impact was comprehensively evaluated using the analytical eco-scale, green analytical procedure index (GAPI), and analytical greenness metric (AGREE).

NiFe-based Prussian blue analogue nanopolygons hybridized with functionalized glyoxal polymer as a voltammetric platform for the determination of amisulpride in biological samples.

A novel voltammetric platform based on pencil graphite electrode (PGE) modification has been proposed, containing bimetallic (NiFe) Prussian blue analogue nanopolygons decorated with electro-polymerized glyoxal polymer nanocomposites (p-DPG NCs@NiFe PBA Ns/PGE). Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV) were utilized to investigate the electrochemical performance of the proposed sensor. The analytical response of p-DPG NCs@NiFe PBA Ns/PGE was evaluated through the quantity of amisulpride (AMS), one of the most common antipsychotic drugs. Under the optimized experimental and instrumental conditions, the method showed linearity over the range from 0.5 to 15 × 10-8 mol L-1 with a good correlation coefficient (R = 0.9995) and a low detection limit (LOD) reached, 1.5 nmol L-1, with excellent relative standard deviation for human plasma and urine samples. The interference effect of some potentially interfering substances was negligible, and the sensing platform demonstrated an outstanding reproducibility, stability, and reusability. As a first trial, the proposed electrode aimed to shed light on the AMS oxidation mechanism, where the oxidation mechanism was monitored and elucidated using the FTIR technique. It was also found that the prepared p-DPG NCs@NiFe PBA Ns/PGE platform had promising applications for the simultaneous determination of AMS in the presence of some co-administered COVID-19 drugs, which could be attributed to the large active surface area, and high conductivity of bimetallic nanopolygons.

In vitro and In silico assessment of antischistosomal activities of ethanolic extract of Cornulacamonacantha.

Schistosomiasis is the second most prevailing parasitic disease worldwide. Although praziquantel is considered an effective drug in the treatment against schistosomiasis to some extent, there is an emerging drug resistance that widely recorded. Therefore, there is an urgent need to develop effective and safe anti-schistosomal drugs. In this study, Cornulaca monacantha (C. monacantha), a sub-saharan plant, was extracted using aqueous ethanol and characterized by High-Performance Liquid Chromatography (HPLC). Major constituents of the extract are belonging to flavonoids, tannins and phenolic glycosides. Worms' viability and surface morphology of Schistosoma mansoni (S. mansoni) adult worms treated with the extract were assessed using in vitro viability assay, Scanning Electron Microscopy (SEM), and histological examination. The extract (80-350 µg/ml) reduced viability percentage of worms by 40-60% and caused degeneration of both oral and ventral suckers, tegumental, sub-tegumental and muscular damage. Molecular docking approach was utilized to assess the binding affinities of the extracted compounds with S. mansoni alpha-carbonic anhydrase (SmCA), an essential tegument protein. Pharmacokinetic analysis using SwissADME showed that 7 compounds have high drug similarity. This study confirms the in vitro schistomicidal activity of C. monacantha extract against S. mansoni adult worms and suggests potential SmCA inhibition.

Ultrasensitive green spectrofluorimetric approach for quantification of Hg(II) in environmental samples (water and fish samples) using cysteine@MnO2 dots.

Mercury (Hg2+ ) is a natural element present in foods such as fish, water and soil. Exposure to mercury leads to severe toxic effects on the nervous, digestive, and immune systems. Here, a novel, green, and environmentally friendly fluorescent probe decorated with cysteine/MnO2 quantum dots (Cys@MnO2 QDs) was synthesized. This synthesis was carried out using a simple ultrasound technique with the aid of cysteine for fabricating Cys@MnO2 QDs to estimate Hg levels in fish and water samples. In this morphological study, Cys@MnO2 QDs were fully characterized using high-resolution transmission electron microscopy, zeta potential analysis, fluorescence, ultraviolet-visible and infrared spectroscopy. The fluorescence of the synthesized Cys@MnO2 QDs was significantly quenched by gradually increasing the Hg(II) concentration. The quenching mechanism based on the Hg-S bonds strengthened the utility of the Cys@MnO2 QDs as a novel luminescent nanoprobe. The estimation of Hg was linear in the concentration range 0.7-100.0 ng mL-1 with a limit of quantitation equal to 0.30 ng mL-1 . The Cys@MnO2 QDs are fluorescent probes with various benefits such as speed, ease of use, cost- effective, and being environmentally friendly; they are easily applied in food manufacturing and for public health improvement.

Hematological, biochemical, genotoxic, and histopathological changes induced by pyridaben.

The current work examined the genotoxic effects of pyridaben (PDB) in male Sprague Dawley rats. Twenty Sprague Dawley rats were divided into four equal groups; the first group was used as a control group; the other three groups were exposed to 19, 28.5, and 57 mg/kg b.w PDB by oral gavage for 4 weeks. Blood samples were collected for hematological and biochemical parameters; femoral bone marrow was flushed for chromosomal aberrations (CA) assay and liver samples were used for the analysis of gene expression of IL-6 and Casp-3 as well as histopathological and immunhistochemical investigation for Casp-3. The results showed that PDB exposure lead to non-significant changes in hematological parameters in all PDB administrated groups while malondialdehyde, glutathione peroxidase, aspartate aminotransferase, and alkaline phosphatase were significantly increased in 19 and 57 mg/kg PDB doses groups Also, gene expression of IL-6 and Casp-3 revealed a significant increase in 28.5 and 57 mg/kg PDB doses groups as compared with the control. However, there was no significant change in the percentage of CAs in bone marrow cells in all PDB-exposed groups. The histopathological and immunhistochemical examination showed focal areas of inflammatory cellular infiltration with fibrosis in 57 mg/kg b.w PDB dose group accompanied by the severe positive reaction of caspase3 in the liver.

Zinc(II) complexation strategy for ultra-sensitive fluorimetric estimation of molnupiravir: Applications and greenness evaluation.

The endemicity of the pandemic coronavirus disease 2019 (COVID-19) infection proved to be transitional only. Spikes are forming again in 2023, and high expectations are returning for reinfections and viral mutations. Molnupiravir (MOL) has been approved as an oral antiviral drug for the treatment of the COVID-19 causative virion. Therefore, the development of an ultrasensitive, instantaneous, and cost-effective method for the quantification of MOL in real plasma samples and formulated dosage form are mandatory. The proposed approach is based on the synthesis of a MOL metal-chelation product. MOL as a ligand was chelated with 1.0 mM zinc(II) in an acetate buffer (pH 5.3). After illumination at 340 nm, the intensity of the MOL fluorescence measured at 386 nm was increased by about 10-fold. The linearity range was found to be from 60.0 to 800.0 ng mL-1 with limit of quantitation (LOQ) of 28.6 ng mL-1 . Two methods were utilized for measuring the greenness of the proposed method (Green Analytical Procedure Index [GAPI] and analytical greenness metric [AGREE] methods), with results equal to 0.8. The binding stoichiometry of MOL with the zinc(II) ion was found to be 2:1. All the experimental parameters were optimized and validated using International Conference on Harmonization (ICH) and United States Food and Drug Administration (US-FDA) recommendations. Furthermore, the fluorescent probes were successfully utilized in real human plasma with high percentages of recovery (95.6%-97.1%) without any matrix interferences. The mechanism of fluorescent complex formation was confirmed using 1 H NMR in the presence and absence of Zn(II). The method was further utilized for testing content uniformity of MOL in its marketed capsule dosage forms.

The role of sodium lauryl sulfate on formulation of directly compressed tablets containing simvastatin and aspirin: Effect on drugs dissolution and gastric mucosa.

According to the American College of Cardiology/American Heart Association (ACC/AHA), both aspirin and statin are used in the primary prevention of cardiovascular diseases. Aspirin (ASA) is contraindicated if there is gastrointestinal bleeding because it will exaggerate the condition. In this study, the effect of surfactant; sodium lauryl sulfate (SLS), in enhancing the in vitro dissolution of simvastatin (SIM) and ASA, as well as gastric irritation and upset, was studied. Oral tablets containing both ASA and SIM with and without the SLS were manufactured using the direct compression technique. The prepared tablets were characterized with respect to hardness, friability, uniformity of dosage units, in vitro disintegration, and dissolution. The effect of the addition of SLS in reducing the in vivo irritation and protection of gastric mucosa were also investigated. The results showed that the compressed tablets possessed sufficient hardness, acceptable friability, and are uniform with respect to disintegration, drugs contents, and tablet weight. The results showed that SIM alone exhibited a gastroprotective effect on the induced irritation. In addition, the incorporation of the SLS in the tablets containing SIM and ASA significantly enhanced the dissolution rates of both drugs and significantly decreased the gastric irritation and the ulcer index. The ulcer index of aspirin was decreased from 2.3 for tablets manufactured without SLS to 0.8 for tablets containing SLS. In a conclusion, the addition of pH modifier surfactant; SLS could enhance the dissolution rate of poorly soluble acidic drugs, reduce gastric upset and irritation without any effect on the main characters of the tablets. Moreover, the addition of SLS is very useful in improving the therapeutic activities and reducing the side effects of ASA and SIM for patients who require long-term administration of these drugs.

Surgical castration versus chemical castration in donkeys: response of stress, lipid profile and redox potential biomarkers.

BACKGROUND: Castration is a husbandry practice raising important questions on the welfare and physiological status of farm animals. Searching for effective castration methods that minimally compromise the body physiology is worthy of attention. Therefore, this study aimed to evaluate the differential response of biological systems in donkeys to surgical castration versus the chemical one by CaCl2 with special emphasis on stress, lipid profile, and oxidative stress biomarkers. Donkeys were divided randomly and equally into two groups; the chemical (Ch) and surgical (S) groups (n = 6). The Ch group was chemically castrated by intratesticular injection of 20% CaCl2 dissolved in absolute ethanol. Blood samples were collected prior to castration and at 15, 30, 45, and 60 days after the beginning of experiment. RESULTS: Surprisingly, the Ch group at the end of the experiment was characterized by significantly higher cortisol level compared to the S group. TC and LDL-C levels in the S group significantly decreased at day 45, while TG levels significantly increased at days 45 and 60 in comparison with day 0. HDL-C levels at days 30 and 60 in the Ch group significantly increased in comparison with day 0. At day 30 post-castration, HDL-C was significantly higher and LDL-C was significantly lower in the Ch group than the S group. A significant elevation in TC and LDL-C was observed at day 45 and in HDL-C at the end of experimental duration in the Ch group when compared with the S group. TPX level was significantly lower and TAC was significantly higher in the Ch group at day 45 than the S group. CONCLUSION: Surgical castration evoked less stress and minor changes in lipid profile and oxidant/antioxidant balance relative to chemical castration by intratesticular 20% CaCl2 dissolved in absolute ethanol.

Applicability of ninhydrin as a fluorescent reagent for estimation of teicoplanin in human plasma using salting-out assisted liquid-liquid extraction technique.

The applicability of ninhydrin, a widely used derivatizing reagent, for determination of teicoplanin (TEIC) in its pure form, pharmaceutical vials, and in human plasma was investigated. The presented spectrofluorimetric method was based on a condensation reaction between ninhydrin and the primary amine group existing in TEIC (in the presence of phenylacetaldehyde) to produce a highly fluorescent product detected at 460 nm (λex ,390 nm). Calibration plots were constructed in the concentration range 60-600 ng mL-1 with a good correlation coefficient of 0.9998 and a low detection limit of 10.84 ng mL-1 . The method was subjected to a bioanalytical validation study according to US-FDA recommendations. The proposed method was applied for analysis of TEIC in commercial vials with high recovery result 101.88 ± 1.11%. In addition, the method was utilized efficiently for detection of TEIC in human plasma using salting-out assisted liquid-liquid extraction technique (SALLE) with a recovery range from 96.71 ± 1.08% to 97.71 ± 0.86%. SALLE is an effective approach used for extraction of TEIC from human plasma without interferences using ammonium sulphate. The proposed method is highly recommended to monitor TEIC in clinical laboratory samples and therapeutic drug monitoring systems.

Highly sensitive UHPLC-DAD method for simultaneous determination of two synergistically acting antiepileptic drugs; levetiracetam and lacosamide: Application to pharmaceutical tablets and human urine.

A simple and highly sensitive ultra-high-performance liquid chromatographic-diode array (UHPLC-DAD) detection method was developed and validated for the simultaneous estimation of levetiracetam (LEV) and lacosamide (LAC). It was clinically proven that the combination of LEV and LAC exhibits a synergistic effect against refractory seizures in mice, which was the motivation for the analysis of this binary mixture both in bulk and in human urine samples. The binary mixture was resolved on a Hypersil BDS C18 analytical column, utilizing a mobile phase of 0.050 mol L-1 phosphate buffer (pH 5.60), methanol and acetonitrile in the ratio (80:10:10 v/v/v) using catechol as an internal standard. The mobile phase was pumped at a flow rate of 1.2 mL min-1 with diode array detection at 205 nm for both drugs and 270 nm for IS. Calibration curves were linear with correlation coefficient >0.9990 over the studied concentration range of 0.1-70.0 µg mL-1 for both drugs. The developed method was reproducible with low relative standard deviation values for intra- and inter-day precision (<2.0%). Both drugs were determined in bulk, pharmaceutical formulations and human urine samples without any interference from complex matrices.

Development of sensitive benzofurazan-based spectrometric methods for analysis of spectinomycin in vials and human biological samples.

Spectinomycin hydrochloride (SPEC) is an aminoglycoside antibiotic that has a broad spectrum against several bacterial strains of humans and veterinary infections. However, SPEC lacks a fluorophore or chromophore and this lack makes its analysis a challenge. Our study provides a simple, sensitive and low-cost spectrofluorimetric/spectrophotometric method based on the reaction between secondary amine groups and a benzofurazan reagent using borate buffer (pH 9.2). The yielding compound was measured fluorimetrically at 530 nm (excitation at 460 nm) with colorimetry at 410 nm. The calibration curves ranged from 30 to 400 ng ml-1 and from 0.2 to 6 µg ml-1 for spectrofluorimetric and spectrophotometric analyses, respectively. The limits of detection were calculated to be 4.15 ng ml-1 and 0.05 µg ml-1 for spectrofluorimetric and spectrophotometric processes, respectively. The ultra-affectability and high selectivity of the proposed method permitted analysis of SPEC in the dosage form and in human plasma samples, with good recoveries of about 101.19 and 97.11%, respectively, without any matrix interference. The proposed strategy was validated using International Conference on Harmonization standards and validated bioanalytically using USFDA recommendations.

Utility of the fluorogenic characters of benzofurazan for analysis of tigecycline using spectrometric technique; application to pharmacokinetic study, urine and pharmaceutical formulations.

Tigecycline (TIGE) is the newest tetracycline derivative antibiotic with low toxicity, it is used for management of infectious diseases caused by Gram-positive and Gram-negative bacteria. Hence, an efficient, selective and sensitive method was developed for analysis of TIGE in commercial formulations, human plasma and urine. The spectrofluorimetric technique based on the reaction of secondary amine moiety in TIGE with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in slightly alkaline medium producing a highly fluorescent product measured at 540 nm (λex at 470 nm) after heating for 15 min at 75°C. The proposed strategy was upgraded and approved by ICH rules and bio-analytical validated using US-FDA recommendations. A linear relationship between fluorescence intensity and TIGE concentration was observed over the concentration range 40-500 ng mL-1 with limit of quantification (LOQ) 21.09 ng mL-1 and limit of detection (LOD) 6.96 ng mL-1 .The ultra-affectability and high selectivity of the proposed strategy permits analysis of TIGE in dosage form, human plasma and urine samples with good recovery ranged from 97.23% to 98.72% and from 99.36% to 99.80% respectively, without any interfering from matrix components. Also, the developed strategy was used to examine the stability of TIGE in human plasma and applied for pharmacokinetic investigation of TIGE.

Modification of N,S co-doped graphene quantum dots with p-aminothiophenol-functionalized gold nanoparticles for molecular imprint-based voltammetric determination of the antiviral drug sofosbuvir.

A molecularly imprinted polymer (MIP) was developed for the electrochemical determination of the antiviral drug sofosbuvir (SOF). The MIP was obtained by polymerization of p-aminothiophenol (p-ATP) on N,S co-doped graphene quantum dots (N,S@GQDs) in the presence of gold nanoparticles to form gold-sulfur covalent network. The presence of quantum dots improves the electron transfer rate, enhances surface activity and amplifies the signal. The nanocomposites were characterized by FTIR, TEM, EDX, and SEM. The electrochemical performance of the electrode was investigated by differential pulse voltammetry and cyclic voltammetry. The sensor uses hexacyanoferrate as the redox probe and is best operated at a potential of around 0.36 V vs. Ag/AgCl. It has a linear response over the concentration range of 1-400 nM SOF, with a detection limit of 0.36 nM. Other features include high selectivity, good reproducibility and temporal stability. The sensor was applied to the determination of SOF in spiked human plasma. Graphical abstract Novel sofosbuvir imprinted p-ATP polymer was synthesized by the aid of gold nanoparticles on N,S co-doped graphene quantum dots as a good conductive support. The imprinted polymer was used for detection of sofosbuvir in real samples by using the ferri/ferrocyanide redox probe.

Montelukast modifies simvastatin-induced myopathy and hepatotoxicity.

Montelukast (MNK) has prominent anti-inflammatory and antioxidant activities. It can protect the liver in different hepatotoxic models in animals. Simvastatin (SMV) is one of commonly used lipid lowering drugs for treatment of dyslipidemia in order to reduce cardiovascular disease. It has severe side effects such as myopathy and hepatotoxicity. The aim of the present study is to investigate the possible effect of MNK on SMV-induced myopathy and hepatotoxicity. Four groups of male rats: control group which received saline via stomach tube, MNK treated group (received 10 mg/kg/day MNK via stomach tube), SMV treated group (received 30 mg/kg/day SMV via stomach tube), and MNK + SMV (combination) group which received both MNK and SMV. All animals were treated for 14 days before obtaining blood and tissue samples. SMV has both hepatotoxic effects and myopathy. SMV caused a significant increase in myoglobin, creatinine kinase, ALT, AST, ALP, and bilirubin but, it decreased total proteins, globulin and albumin levels. Co-treatment of SMV and MNK increased the antioxidant activity significantly. MNK modifies partially the myopathic changes and hepatotoxic effect of SMV. Co-administration of MNK and SMV decreased their toxic potentials on the liver, skeletal muscles, and kidney. They have antioxidant activities when given together that produce muscle and hepatic protective effects.

Mucoadhesive tablets for the vaginal delivery of progesterone: in vitro evaluation and pharmacokinetics/pharmacodynamics in female rabbits.

OBJECTIVE: To develop mucoadhesive tablets for the vaginal delivery of progesterone (P4) to overcome its low oral bioavailability resulting from drug hydrophobicity and extensive hepatic metabolism. METHODS: The tablets were prepared using mixtures of P4/Pluronic® F-127 solid dispersion and different mucoadhesive polymers. The tablets physical properties, swelling index, mucoadhesion and drug release kinetics were evaluated. P4 pharmacokinetic and pharmacodynamic properties were evaluated in female rabbits and compared with vaginal micronized P4 tablets and intramuscular (IM) P4 injection, respectively. RESULTS: The tablets had satisfactory physical properties and their swelling, in vitro mucoadhesion force and ex vivo mucoadhesion time were dependent on tablet composition. Highest swelling index and mucoadhesion time were detected for tablets containing 20% chitosan-10% alginate mixture. Most tablets exhibited burst release (∼25%) during the first 2 h but sustained the drug release for ∼48 h. In vivo study showed that chitosan-alginate mucoadhesive tablets had ∼2-fold higher P4 mean residence time (MRT) in the blood and 5-fold higher bioavailability compared with oral P4. Further, same tablets showed 2-fold higher myometrium thickness in rabbit uterus compared with IM P4 injection. CONCLUSION: These results confirm the potential of these mucoadhesive vaginal tablets to enhance P4 efficacy and avoid the side effects associated with IM injection.

Evaluation of chemical castration with calcium chloride versus surgical castration in donkeys: testosterone as an endpoint marker.

BACKGROUND: For the last few years, researchers have been interested in developing a method for chemical sterilization which may be a better alternative to surgical castration. An ideal chemical sterilant would be one that effectively arrests spermatogenesis and androgenesis as well as libido with absence of toxic or other side effects. Calcium chloride in various solutions and concentrations has been tested in many animal species, but few studies have been evaluated it in equines as a chemical sterilant. So, the objective of this study was to evaluate the clinical efficacy of chemical castration with 20% calcium chloride dissolved in absolute ethanol in comparison with surgical castration in donkeys based on the changes in the serum testosterone level and the histopathological changes in treated testes. METHODS: Twelve clinically healthy adult male donkeys were used in this study. Donkeys were divided randomly and equally into two groups: a surgical (S) group (n = 6) and a chemical (C) group (n = 6). Animals in the (S) group were subjected to surgical castration while those in the (C) group received a single bilateral intratesticular injection of 20% calcium chloride dissolved in absolute ethanol (20 ml/testis). Animals were kept under clinical observation for 60 days. Changes in animals' behavior and gross changes in external genitalia were monitored daily. Serum concentrations of testosterone were measured prior to treatment and at 15, 30, 45 and 60 days post-treatment. Testicles in the (C) group were examined histopathologically at the end of the experiment. RESULTS: Chemical castration with intratesticular calcium chloride vs. surgical castration failed to reduce serum concentrations of testosterone throughout the whole duration of the study; however it induced orchitis that was evident by focal necrotic areas in seminiferous tubules, cellular infiltration of neutrophils, proliferative intertubular fibrosis with a compensatory proliferation of Leydig cells. Donkeys tolerated the intratesticular injection of calcium chloride. There were no detectable changes in the general health status of the animals with the exception of swelling in external genitalia, scrotal ulcerations and fistulas. Food and water consumption and the gait of animals remained unaffected. CONCLUSION: Intratesticular calcium chloride can't be considered an effective method for chemical castration in donkeys.

An Innovative Polymer-Based Electrochemical Sensor Encrusted with Tb Nanoparticles for the Detection of Favipiravir: A Potential Antiviral Drug for the Treatment of COVID-19.

An innovative polymer-based electro-sensor decorated with Tb nanoparticles has been developed for the first time. The fabricated sensor was utilized for trace determination of favipiravir (FAV), a recently US FDA-approved antiviral drug for the treatment of COVID-19. Different techniques, including ultraviolet-visible spectrophotometry (UV-VIS), cyclic voltammetry (CV), scanning electron microscope (SEM), X-ray Diffraction (XRD) and electrochemical impedance spectroscopy (EIS), were applied for the characterization of the developed electrode TbNPs@ poly m-THB/PGE. Various experimental variables, including pH, potential range, polymer concentration, number of cycles, scan rate and deposition time, were optimized. Moreover, different voltammetric parameters were examined and optimized. The presented SWV method showed linearity over the range of 10-150 × 10-9 M with a good correlation coefficient (R = 0.9994), and the detection limit (LOD) reached 3.1 × 10-9 M. The proposed method was applied for the quantification of FAV in tablet dosage forms and in human plasma without any interference from complex matrices, obtaining good % recovery results (98.58-101.93%).

Emphasis on the incorporation of Tropaeolin OO dye and silver nanoparticles for voltammetric estimation of flibanserin in bulk form, tablets and human plasma.

A novel electrochemical sensor based on the electro-deposition of silver nanoparticles (AgNPs) on Tropaeolin OO (poly-TO) layers over pencil graphite electrode (PGE) surface was fabricated for the first time for voltammetric determination of flibanserin (FBS); a drug enhances female sexual performance. Further characterization studies using cyclic voltammetry (CV), square wave voltammetry (SWV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were conducted. The AgNPs synergistic effect on poly-TO layers facilitates the FBS electro-oxidation in phosphate buffer solution (pH 6.0) and its determination in bulk form, tablets and in human plasma. Following ICH guidelines, validation of the proposed SWV method for FBS analysis was successfully achieved using the fabricated sensor (AgNPs@poly-TO/PGE). Under the optimal instrumental and experimental conditions, the anodic oxidation peak current was directly proportional to FBS concentration in the range from 0.1 to 8.5 µmol L-1 with low detection and quantitation limits (0.0286 and 0.0867 µmol L-1, respectively). High sensitivity, selectivity as well as easiness of fabrication are the main advantages of the modified sensor.