Buffer Solution pH Research Articles

Comparative Dissolution Study of Ciprofloxacin Hydrochloride-sustained Release Tablets by Using Carbopol-934 and Guar Gum Polymers

Aims: This study aimed to identify the potential release of the drug from the tablet dosage form using Carbopol-934 and Guar Gum polymers at different concentration ratios. Objective: The objective of this study was to determine the cumulative percentage of ciprofloxacin hydrochloride released from different polymers. Method: We formulated ciprofloxacin hydrochloride sustained-release tablets with Carbopol-934 and Guar gum using the wet granulation method. For the formulation of sustained-release ciprofloxacin hydrochloride tablets, both polymers were mixed in varying ratios. The tablets were examined for pre-formulation studies, including the angle of repose, bulk density, compressibility index, and physiological properties, such as variations in weight, friability, and drug content. For postformulation studies, such as the in vitro study, the in vitro release of the drugs was evaluated in a phosphate buffer solution (pH 7.4) for 8 h. However, the physiological properties of ciprofloxacin hydrochloride tablets were limited due to their liberality. Results: The tablets containing guar gum (Batches B-I and B-II) showed better drug content than other polymer-based batches, such as Carbopol-934 (Batch A-I, A-II) and a mixture of both polymer Carbopol-934 and Guar gum (Batch C-I, C-II). Sustained drug release was observed in the guar gum polymer-based tablets (Batch B-II). It was observed that the dissolution profile of ciprofloxacin hydrochloride tablets formed using different polymers showed an increase in the polymer ratio, which can be related to the increase in drug release. Conclusion: From this study, we can conclude that the ciprofloxacin hydrochloride drug release percentage was maximum when guar gum polymer was used in the tablet dosage form.

Method development and validation of an analytical quality by design ultrafast liquid chromatographic method for the determination of bedaquiline from pharmaceutical bulk and nanoemulsions.

Bedaquiline (BDQ) is a drug used to treat multidrug-resistant tuberculosis (MDR-TB). It exhibits exposure-dependent efficacy in eliminating Mycobacterium tuberculosis (Mtb). An easy, efficient and precise reverse-phase ultrafast liquid chromatography (RP-UFLC) method was developed to validate the free base of the antitubercular medication BDQ. BDQ was separated using a 10:90 v/v mobile phase of ammonium acetate buffer solution (pH = 5.4) and high-performance liquid chromatography-grade methanol, with a flow rate of 1.5mL/min and a UV detection wavelength of 226 nm. By using the Box-Behnken design (BBD) and response surface methodology (RSM), the method was optimised by varying critical analytical attributes (CAA) and critical performance attributes (CPAs) namely ammonium acetate fraction (%), flow rate (ml/min), buffer system molarity (M) and pH. BDQ was eluted at 7.5min utilising isocratic elution. The method was linear in the concentration range of 0.5-300 μg/mL with limit of detection values of 0.039 μg/mL and limit of quantification of 0.12 μg/mL. The results indicate that this validated method can be used as an alternative method for assay of BDQ.

Fast production of highly sensitive nanotextured nonwovens for detection of volatile amines, bacterial growth, and pH monitoring: New tools for real-time food quality monitoring

An efficient manufacturing of colorimetric nonwoven indicators represents a promising alternative to enable applications of such materials in food quality monitoring. The objective of this study is to use the solution blow spinning technique (SBS) to rapidly produce colorimetric nonwoven indicators based on polycaprolactone, incorporating natural or synthetic pH indicators to detect volatile amines, bacterial growth and monitor pH. Produced via the SBS method, these indicators were characterized aiming their physical, mechanical, thermal, and spectroscopic properties, evaluating their efficacy in detecting amines, monitoring bacterial growth, and pH, as well as assessing color stability during storage. The thermal stability and mechanical properties of the nonwovens practically always increased with the incorporation of natural and synthetic indicators. When exposed to volatile amines, the nonwoven indicators, particularly those embedded with bromophenol blue, displayed remarkable color change abilities in the presence of five volatile amines. These smart nonwovens in direct contact with E. coli K-12 or its volatiles in 24 h changed their color perceptible to the naked eye. The nanofiber nonwovens displayed visible color changes (ΔE ≥ 3) in response to buffer solutions (pH between 3 and 10). The smart nonwovens rapidly produced by the solution blow spinning method prove to be a promising tool for real-time monitoring of food freshness.

In Situ FT-IR Spectroelectrochemistry Reveals Mechanistic Insights into Nitric Oxide Release from Ruthenium(II) Nitrosyl Complexes.

Ruthenium(II) tetraamine nitrosyl complexes with N-heterocyclic ligands are known for their potential as nitric oxide (NO•) donors, capable of releasing NO• through either direct photodissociation or one-electron reduction of the Ru(II)NO+ center. This study delivers a novel insight into the one-electron reduction mechanism for the model complex trans-[RuII(NO)(NH3)4(py)]3+ (RuNOpy, py = pyridine) in phosphate buffer solution (pH 7.4). In situ FT-IR spectroelectrochemistry reveals that the pyridine ligand is readily released upon one-electron reduction of the nitrosyl complex, a finding supported by nuclear magnetic resonance spectroscopy (1H NMR) and electrochemistry coupled to mass spectrometry (EC-MS), which detect free pyridine in solution. However, direct evidence of NO• release from RuNOpy as the primary step following reduction was not observed. Interestingly, FT-IR results indicate that the isomers of the nitrosyl complex, cis-[Ru(NO)(NH3)4(OH)]+ and trans-[Ru(NO)(NH3)4(OH)]+, are formed following reduction and pyridine labilization, initiating an outer-sphere electron transfer process that triggers a chain electron transfer reaction. Finally, nitric oxide is liberated as an end product, arising from the reduction of the hydroxyl isomer complexes cis-[Ru(NO)(NH3)4(OH)]2+ and trans-[Ru(NO)(NH3)4(OH)]2+. This study provides new insights into the reduction mechanism and transformation pathways of ruthenium nitrosyl complexes, contributing to our understanding of their potential as NO• donors.

PH Determination of Acetic Acid-Sodium Acetate Buffer: An Application of Henderson-Hasselbalch Equation at Room Temperature

In article, we have reported the applying of Henderson-Hasselbalch equation in determination of pH of acetic acid and sodium acetate buffer solutions at about 298 Kelvin as room temperature. In preparation of these buffer solutions, we have taken 1.5 ml of glacial acetic acid into 100 ml of standard flask for making up 0.2M of acetic acid solution, and 0.64 gm of sodium acetate were dissolved into 100 ml distilled water. Now, we taken 36.2 ml prepared solution of sodium acetate into 100 ml of standard flask and added 14.8 ml of prepared acetic acid to make its volume 100 ml by using of distilled water, it is a buffer. In measuring of pH of prepared buffer solutions, we have been using a calibrated digital pen pH meter for accurate and quick reading. In observation, the pH of buffer solutions a quite fluctuation was appeared. But, it has gradually raised by adding small amount of basic 5N NaOH solution into buffer sample, and, an adjusted pH was being to 4.7 as well.

Electrospun Nanofiber Dopped with TiO2 and Carbon Quantum Dots for the Photocatalytic Degradation of Antibiotics

Novel photocatalysts were synthesized through the association of carbon quantum dots (CQDs) with commercial (P25) titanium dioxide (TiO2) by sonication. The resulting TiO2/CQDs composite was then incorporated into the polyamide 66 (PA66) biopolymer nanofibers using the electrospinning technique, considering a composite nanoparticles-to-polymer ratio of 1:2 in the electrospinning precursor solution. The produced nanofibers presented suitable morphology and were tested for the photocatalytic degradation under simulated solar radiation of 10 mg L−1 of amoxicillin (AMX) and sulfadiazine (SDZ), in phosphate buffer solution (pH 8.06) and river water, using 1.5 g L−1 of photocatalyst. The presence of the photocatalyst increased the removal of AMX in phosphate buffer solution by 30 times, reducing the AMX degradation half-life time from 62 ± 1 h (without catalyst) to 1.98 ± 0.06 h. Moreover, SDZ degradation half-life time in phosphate buffer solution was reduced from 5.4 ± 0.1 h (without catalyst) to 1.87 ± 0.05 h in the presence of the photocatalyst. Furthermore, the PA66/TiO2/CQDs were also efficient in river water samples and maintained their performance in at least three cycles of SDZ photodegradation in river water. The presented results evidence that the produced photocatalyst can be a promising and sustainable solution for antibiotics’ efficient removal from water.

Elucidating the effect of strain path-dependent crystallographic texture evolution on the electrochemical behavior of nanostructured AA2024 aluminum alloy

This research provides insight into the effect of strain path-dependent texture evolution on the electrochemical behavior of nanostructured AA2024 aluminum alloy in a phosphate buffer solution (pH = 8.3). To achieve this, AA2024 alloy sheets were processed using two methods: accumulative roll bonding (ARB) and cross accumulative roll bonding (CARB), i.e., rotating the sheets 90° around the normal direction (ND) axis between each cycle. The ARB-processed AA2024 alloy exhibited a pancake-shaped structure and included texture components of Copper {112}<111>, Brass {011}<211>, P {110}<221>, and S {123}<634>. Meanwhile, the CARB-processed AA2024 alloy had extremely fine and equiaxed nano-grains (< 100 nm) and texture components of S {123}<634>, Brass {011}<211>, Goss {011}<100>, Rotated Cube {001}<110>, and P {110}<221> after eight cycles. Electrochemical studies demonstrated an increase in corrosion current density due to high imposed strains in the ARB route, which in effect made the conditions of passive layer formation more difficult and lowered the corrosion resistance. Additionally, achieving a more uniform distribution of extremely fine grains and {011} orientation textures such as Brass {011}<211>, Goss {011}<100>, and P {110}<221> texture components in the CARB route, provided ideal conditions for forming oxide passive films with superior protection properties compared to ARB. These unique findings can contribute to the broader application of crystallographic-orientation-dependent electrochemical behavior of alloys in the field of corrosion management.

A pH Measurement of Acetic Acid-Sodium Acetate Buffer Solutions Using a pH Meter at Ambient Temperature

In article, we have reported the preparation of acetic acid-sodium acetate buffer solutions and determined its pH by using pH meter at about 25˚ C, as room temperature. In preparation of buffer solutions, firstly, we have taken 1.5 ml of glacial acetic acid into 100 ml of standard flask for making up 0.2M of acetic acid solution, and 0.64 gm of sodium acetate were dissolved into 100 ml distilled water. Then, taken 36.2 ml prepared solution of sodium acetate into 100 ml of standard flask and added 14.8 ml of prepared acetic acid to make its volume 100 ml by using distilled water, it is a buffer. In measuring the pH of prepared buffer solutions, we have been using a calibrated digital pen pH meter for quick resolution of reading with accuracy. The pH of acetic acid-acetate buffer solutions have gradually raised by adding small quantity of 5N NaOH solution into buffer sample, and adjusted pH was being to 4.7.

Electrochemical sensing of gatifloxacin using Ag2S/RGO nanocomposite

As a widely-used fluoroquinolone antibiotics, 1-Cyclopropyl-6-fluoro-8-methoxy-7-(3-methyl-1-piperazinyl)-4-oxo-1,4-dihydro-3-quinolinecarboxylic acid (gatifloxacin, GAT) has aroused much concern recently and it is of great importance to realize the accurate and efficient detection. Herein, the silver sulfide/reduced graphene oxide composite (Ag2S/RGO) was synthesized with one-pot method and was coated on the glassy carbon electrode to develop an effective electrochemical sensor for GAT. After the optimization of the size of Ag2S, the pH of buffer solution, and the scanning rate, the Ag2S/RGO modified electrode exhibits good linear relationship to GAT within wide ranges of 0.2 µM − 20 µM and 20 µM − 250 µM with a detection limit of 0.0667 µM. Besides, the proposed sensor shows good selectivity to GAT versus multiple interferences, including organic compounds, ions, and other antibiotics. At last, the proposed sensor was successfully applied in the GAT analysis in various real samples (including shrimp, fish, and chicken) with satisfying recoveries of 91.8 % − 102.4 %. In general, the proposed Ag2S/RGO-based electrochemical sensor provides a novel strategy for the GAT analysis, which is of significance for the development of efficient analytical techniques for antibiotics.

Development of carboxymethyl cellulose/starch films enriched with ZnO-NPs and anthocyanins for antimicrobial and pH-indicating food packaging

Active packaging, which can monitor food freshness and extend the shelf life, has gained significant attention in recent years. This study aims to develop a novel carboxymethyl cellulose (CMC)/starch/anthocyanins/ZnO active films with enhanced properties and specific functionalities. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) revealed that the addition of anthocyanins and nano-ZnO particles (ZnO-NPs) led to heterogeneous microstructures and a slight decrease in the crystallinity. Fourier transform infrared spectroscopy (FTIR) indicated that there were no chemical interactions among film components. Active films containing ZnO-NPs exhibited improved ductility, as well as enhanced light barrier and water resistance properties. Notably, a shift from hydrophilic to hydrophobic behavior of the films was observed with high ZnO-NP content, as evidenced by a significant increase in the water contact angle (from 63.44° to 114.22°). Furthermore, the presence of only 1 % ZnO-NPs resulted in efficient inhibition of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) growth. Moreover, active films containing both anthocyanins and ZnO-NPs were highly sensitive to pH changes in buffer solutions (pH 2–11). Based on the results, a recommended film formulation for future active packaging applications is a 80:20 CMC/starch blend with 3 % ZnO-NPs and 0.1 g anthocyanins.

Mn3O4-FeS2/Fe2O3 composite as peroxidase-mimics for the degradation of Bisphenol A

Due to the benefits of artificial peroxidase-like enzymes, Flower-like Mn3O4-FeS2/Fe2O3 composites with multiple active sites prepared by a one-step solvothermal method.The synergistic cyclic reaction between Mn and Fe on the catalyst surface enhances the generation of active radicals, which together promote the efficient degradation of BPA. In the presence of hydrogen peroxide (H2O2), Mn3O4-FeS2/Fe2O3 could generate hydroxyl radicals (·OH) and superoxide radicals (·O2-) in buffer solution of pH=4.5 and catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxidation products (ox TMB). The steady-state kinetic constants (Km) of TMB and H2O2 were obtained by Michaelis-Menten and Lineweaver-Burk models, which are 1.34 mM and 1.00 mM, respectively. This reveals the nice catalytic efficiency of Mn3O4-FeS2/Fe2O3 as enzyme mimics. Under the condition of 10 mg Mn3O4-FeS2/Fe2O3 catalyst, 100 μL H2O2 and pH = 4.5, the degradation efficiency of Bisphenol A (BPA) reaches 100 % when treating 40 mL of 50 mg L−1 BPA for 30 min at room temperature. Moreover, after 5 cycles of degradation, the BPA degradation efficiency of 85.8 % was still maintained. Therefore, the as-prepared Mn3O4-FeS2/Fe2O3 sample could potentially be applied in wastewater treatment.

Transformation of waste thermocol into activated carbon for electrochemical detection of ammonia in an aqueous solution

In this study, waste thermocol sheets are used to synthesize activated carbon (AC) for the electrochemical detection of ammonia in an aqueous solution. The AC is characterized for its morphology, structure, and chemical composition via standard characterization techniques. AC shows promise for detecting ammonia in aqueous solutions due to its high adsorption capacity from large surface area and porosity. The electrochemical approach used to detect ammonia (NH3) in electrolyte solutions uses an AC electrode and is based mostly on the electro-oxidative conversion of ammonia species at the electrode's interface. AC electrodes fabricated on flexible conductive fabric (CF) are used for the electrochemical detection of ammonia at pH 6. The electrochemical sensing of ammonia in aqueous solutions involves its oxidation on the electrode's surface. Cyclic Voltammetry (CV) experiments were conducted over a pH range of 5 to 8, revealing optimal current responses at pH 6. Therefore, phosphate-buffered saline (PBS) at pH 6.0 was employed for all electrochemical analyses. Various concentrations of ammonia (10–100 ppm) were investigated within a voltage window of −0.3 V to 0.3 V, with current signals increasing proportionally with ammonia concentration. The limits of detection (LOD) and quantification (LOQ) were determined to be 28.55 ppm and 86.54 ppm, respectively. An incubation period of 3 min was observed for ammonia concentrations ranging from 0 to 40 ppm. Selectivity evaluations were conducted by assessing interference effects from ethanol (E), methanol (M), toluene (T), and uric acid (UA), revealing ammonia's distinctive peak, indicative of superior selectivity. Notably, the electrode exhibited remarkable stability, retaining approximately 95 % of the original signal over a 5-week duration. The reproducibility of the fabricated electrodes shows significant results. The repeatability was performed at room temperature in a buffer solution of pH 6 and at a 40-ppm concentration of ammonia and has shown almost similar results. Therefore, the fabricated AC sensing electrode has shown prominent stability, reproducibility, and repeatability. These sensing electrodes can be very beneficial for sensing applications.

Chrysophanol‐Loaded Composites with Xanthan Gum/Polycaprolactone for Drug Release Enhancement

AbstractThis work focused on synthesizing novel chrysophanol‐loaded composites with varied ratios of polycaprolactone/xanthan gum to enhance the release of chrysophanol. The characteristics of the obtained composites were analyzed by infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry, rhermogravimetric analysis and dynamic light scattering methods. The xanthan gum/polycaprolactone/chrysophanol (XPC) composites were obtained in the powdery form with particle sizes ranging from 80–100 nm. The results of hydrophilic and hydrophobic tests of the composites were discussed. Chrysophanol, polycaprolactone and xanthan gum can interact and are compatible to each other. XPC composites exhibit high stability and don't cause the negative effect on cells. Additionally, the chrysophanol release and kinetic model of chrysophanol release from the XPC composites in different pH buffer solutions were investigated and evaluated. Using drug carriers such as xanthan gum and polycaprolactone can enhance the release of chrysophanol in both pH 2.0 and pH 7.4 buffer solutions. In the presence of biopolymers, the distribution ability of chrysophanol in aqueous solutions such as pH 2.0 buffer, pH 7.4 buffer solutions, and 0.9 % NaCl solution was enhanced significantly. This will be favorable for an increase in the absorption of chrysophanol in the human body.

Selective Determination of Acetaminophen in Presence of Ascorbic Acid at Poly (p-Methoxyphenol) Electrode

In the present work, we discuss the modification of a gold electrode with p-methoxyphenol and its application as a sensor for acetaminophen (ACP) in a phosphate buffer solution (pH = 7.4). The modified electrode was subsequently employed to determine acetaminophen in the presence of ascorbic acid (AA) using differential pulse voltammetry (DPV). The peak positions and relative sensitivity of ACP/AA were influenced by the potential window used during polymerization. For polymerization between 0 and 1.0 V, the peak potentials recorded in the phosphate buffer solution (pH = 7.4) were 488 mV for ACP and 280 mV vs. Ag/AgCl for AA. Furthermore, the effects of pH and electrolyte type on the linearity range and detection limit were investigated. The high selectivity and sensitivity for ACP were attributed to charge discrimination and analyte accumulation. The detection limit for the 3σ-test was determined to be 0.2 nM. This study highlights the potential of the modified gold electrode for selective and sensitive detection of acetaminophen, even in the presence of interfering substances such as ascorbic acid. The optimization of polymerization conditions and the comprehensive analysis of pH and electrolyte effects contribute to the electrode's superior performance.

Simple, rapid and enzyme-free assay for potentiometric determination of L-cysteine based on meso-2,3-dimercaptosuccinic acid self-assembled gold electrode

As a sulfur containing α-amino acid in nature, L-cysteine plays a crucial role in a variety of metabolic pathways with many important physiological functions. However, it is still a great challenge to construct a simple and rapid approach for L-cysteine up to now. In this paper, a simple, rapid and enzyme-free method was developed for potentiometric determination of L-cysteine by using meso-2,3-dimercaptosuccinic acid self-assembled monolayer on gold electrode. The surface morphology and property of self-assembled membrane with and without L-cysteine combined were characterized by means of scanning electron microscopy, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry, respectively. The recognition mechanism may be attributed to formation of hydrogen bonds between meso-2,3-dimercaptosuccinic acid and the target molecule of L-cysteine, producing a double electric layer at the sensing interface, that the membrane potential decreases with increasing concentration of L-cysteine. The assay results showed that good linear potential response to L-cysteine in Tris-HCl buffer solution (pH=7.0) was obtained in a range of 1.0 × 10-8 to 1.0 × 10-3 mol/L, with a slope of −57.00 ± 0.63 mV/-pc (25 °C) and a detection limit of 7.9 × 10-9 mol/L. The electrode possessed fast response time (45 s), good reproducibility, and strong anti-interference performance. Moreover, the electrode can be well applied to the detection of L-cysteine in pig serums with a recovery rate of 94.3 ∼ 106.3%, indicating a promising application prospect.

Freshwater snail flesh (Pomacea paludosa) incubated with bromelain enzyme levels in feed on the carcass quality of Alabio male ducks (Anas plathyrhyncos Borneo)

This study aimed to determine Freshwater snail flesh (Pomacea paludosa) incubated with bromelain enzyme levels in feed on the carcass quality of alabio male ducks. The treatment as ; P0 basal diet + 100% fish meal, P1 basal diet + 75% fish meal + 25% freswater snail flesh incubated bromelain enzym, P2 basal diet + 50% fish meal + 50% freswater snail flesh incubated bromelain enzym, P3 : basal diet + 25 % fish meal + 75% freswater snail flesh incubated bromelain enzym, P4 : basal diet + 100% freswater snail flesh . In each treatment, two male Alabio ducks were taken randomly and then slaughtered. The crude protein, crude fat, moisture, pH, and texture, by taking as many samples as 20 g of sample then mashed for 2 minutes and added 40 ml aquadest. pH measurement is done with pH meter, which was previously calibrated with buffer solution of pH 7.0 and 4.0. Meat tenderness is measured by using the shear warner bratzler tool Instron, , protein,fat and moiture using proximate analysis The result showed that level freshwater snail flesh incubated with bromelain enzym in feed up to 7.5-10% on Alabio male duck diets improved crude protein meat (21.51±0.19 to 23.90±0.40) but decreased meat moisture ( 69.46±0.79 to 62.79±0.27) and decreased crude fat meat (9.55±0.44 to 4.18±0.53). Meanwhile, the tenderness of the meat increased from 3.55% on the control feed to 26.77% on the feed using 7.5-10%.

Application of &lt;i&gt;in vitro&lt;/i&gt; studies to predict the pharmacokinetics of rivaroxaban tablets

Introduction. The most important stage of pharmaceutical development of a generic drug is a clinical trial involving humans – a bioequivalence study. Considering the importance of finding rivaroxaban drugs in the list of vital and essential drugs, as part of ensuring technological sovereignty, the use of scientific robust and effective methods for determining the quality of the dosage form is required.Aim. Conduct a study of rivaroxaban tablets on a physiologically relevant tester to predict pharmacokinetic profiles.Materials and methods. The objects of the study are "Xarelto®, film-coated tablets, 10 mg" (series BXJS871, with an expiration date of October 31, 2024, Bayer AG, Germany), "Xarelto®, film-coated tablets, 20 mg" (series BXKDF32, with an expiration date of May 17, 2026, Bayer AG, Germany) and "Rivaroxaban, film-coated tablets, 10 mg" and "Rivaroxaban, film-coated tablets, 20 mg", domestically produced, with valid expiration dates. During the study, reagents were used to prepare dissolution media and perform quantitative determination. The physiologically relevant test was performed on the SC PRT-6 device (LLC "Scientific Compliance", Russia). The quantitative content of released rivaroxaban within the comparative dissolution kinetics test in a medium of 0.1 in a medium of 0.1 % sodium lauryl sulfate solution in a phosphate buffer solution pH 6.5 was carried out on a SF-2000 spectrophotometer (LLC "OKB Spektr", Russia). The quantitative content of released rivaroxaban within the comparative dissolution kinetics test in biorelevant dissolution media and physiological relevance test was assessed on a high-performance liquid chromatograph "Chromatec-Crystal HPLC 2014" (CJSC "Chromatec", Russia). Pharmacokinetic profiles were modeled in the PK-Sim® (Systems Biology Software Suite 11.2, Bayer Technology Services GmbH, Germany) program based on the data obtained within the physiologically relevant test. The clinical study of rivaroxaban tablets was a prospective, open-label, randomized, crossover, two-stage comparative study in two groups of volunteers with a single dose of drugs on the fast condition. The study randomized 30 healthy male volunteers aged 18–45 years.Results and discussion. A complex of in vitro tests was conducted, profiles were obtained that allow us to evaluate the dynamics and degree of release of the studied drugs in various parts of the human gastrointestinal tract. A comparison of the sequential and hybrid schemes for conducting the physiological relevance test was carried out. Within the framework of the set of tests, qualitative and quantitative correlation with the clinical trials data was observed only for the hybrid physiological relevance test scheme. Based on the results of physiological relevance test using different schemes, pharmacokinetic profiles for a pair of drugs were predicted and the prediction error was assessed.Conclusion. A set of scientific in vitro tests was conducted for the drugs "Xarelto®, film-coated tablets, 10 mg and 20 mg", "Rivaroxaban, film-coated tablets, 10 mg and 20 mg". Based on the physiological relevance test results, pharmacokinetic profiles for a pair of drugs were predicted with low error and high reliability. As part of the comparison of data obtained during clinical trial and modeling, the smallest prediction error was noted when performing physiological relevance test using a hybrid scheme.

Solubility Reinforcement using Binary Solvent Mixtures and its use in Development and Validation of UV-Spectrophotometric Method for Posaconazole

Objectives: To develop a method that meets the requirements as per ICH guidelines for validation and can be used as simple, specific, economical, and repeatable for routine quality control analysis of formulations containing Posaconazole. Materials and Methods: The maximum absorbance of Posaconazole was successfully recorded using a precise 1:1 ratio of binary solvent system Methanol: Buffersolution pH 7.4 at 262nm. Results: After a preliminary physicochemical investigation the precipitation of the Posaconazole issue was resolved using a precise 1:1 ratio of binary solvent system Methanol: Buffersolution pH 7.4. Development and validation of the analytical method was done using the same binary solvent system. The maximum absorbance with this solvent system was found at 262nm, while the calibration curve shows a Regression coefficient (R2) of about 0.9984 for its linearity in the concentration range of 2.5 to 15µ/ml. The developed method was validated and meets the requirements as per ICH (International Conference for Harmonization) guidelines where the Limit of Detection (LOD) as well as Limit of Quantification (LOQ) were noted as 0.74µ/ml and 2.25µ/ml. Percentage recovery was within the permissible range (with a % relative standard deviation of less than 2.0). Conclusion: The results from validation parameters specifically accuracy or % recovery and robustness study reveal that the developed method meets the requirements and can be used as simple, specific, economical, and repeatable for routine quality control analysis of formulations containing Posaconazole.

Systematic Method Development and Validation of Paclitaxel and Tamoxifen by RP-HPLC for Simultaneous Estimation in Nanoformulations

Background: Paclitaxel (PTX) is well known anticancer drug used for treatment of a wide range of cancers. Tamoxifen (TMX) is a gold-standard drug for the treatment of breast cancer. They show synergistic action against breast cancer. Quantitative analytical methods are still not available for simultaneous quantification of these drugs. So for the first time, we developed and validated a new systematic analytical technique for simultaneous estimation of PTX and TMX in nanoformulations. Objective: Systematic method development and validation of Paclitaxel and Tamoxifen by RP-HPLC for simultaneous estimation in nanoformulations. Methods: PTX and TMX were successfully separated and quantified using RP-HPLC. The detection was done based on the isobastic point of both drugs. Thermo Scientific Company's C18 column, measuring 2.5 cm × 4.5 cm x 5 µm, was utilized for separation. A 50:50 (vol/vol) ratio of ACN: Phosphate buffer solution (pH 3.0) was employed as the mobile phase, with a flow rate of 1 mL/minute. The detection was done at 235nm. The method was developed and validated as per the criteria. The developed method was then evaluated for applicability by detecting both analytes in prepared SLN and LPHNPs. Results: The well-resolved separate peaks of both analytes were found and distinct RT for PTX and TMX. The linear relationship of both the analytes against concentration was found over the concentration range of 0.25-9 µg/mL. The PTX RT was 10.358 minutes and that of TMX was 12.57 minutes. Every criterion for method validation fell within the acceptable range. The method is precise with inter-day and intra-day precision and shows a %RSD of &lt; 2%.

Preparation and application of boron and fluorine co-doped rGO electrochemical sensor

N, NF, and NS-doped reduced graphene oxide(rGO) are used for the detection of dopamine (DA), however, the sensitivity and linear detection range still need to be improved. In this paper, BF-doped reduced graphene oxide (BFrGO) synthesized by hydrothermal method using fluoroboric acid as boron and fluorine sources used for the efficient detection of DA. The electrochemical detection results under the optimal buffer solution pH = 3.4 showed that the sensitivity of its detection of DA is as high as 0.804 μA/μM, the linear detection range is in the range of 5–100 μM, and the detection limit is 0.98 μM. XPS showed the formation of BC3, BC2O, BCO2, C–F half-ionic and C–F ionic bonds. DFT calculations show that B doping of rGO provides active sites and enhances its electrical conductivity. and F doping of rGO introduces new electrically active sites and improves the charge transfer ability. The synergistic effect of BF provides more active sites and enhances the charge transfer ability and adsorption energy. The BFrGO as an electrochemical sensor will provide new research directions.