Acetate Buffer pH Research Articles

A NOVEL SPECTROPHOTOMETRIC METHOD FOR THE ESTIMATION OF RANOLAZINE IN BULK DRUG AND IT’S FORMULATION

The simple, rapid, precise, accurate, robust and economical analytical method has been developed for estimation of Ranolazine in bulk and pharmaceutical dosage form. This study describes the validation of an UV Spectrophotometric method for quantitative determination of Ranolazine in pharmaceutical dosage form using acetate buffer (pH 4.4) as solvent. The maximum absorbance was found at 272 nm. The Linearity was found to be in range of 5 to 40µg/ml. The %RSD for Intraday and Interday precision studies was found to be 0.793 and 0.793 respectively. The % assay was found to be 99.6%±0.05. The average % recovery of ranoalazine was found to be in between 98.5-101.7%. LOD and LOQ was found to be 0.58 µg/ml and 1.75 µg/ml respectively. The results suggest that this method can be employed for routine analysis of Ranolazine in bulk and commercial pharmaceutical formulations. KEY WORDS: Ranolazine, UV Spectrophotometric Method, Method Development and Method Validation.

Fluorescence based methodology with greenness consideration for concurrent estimation of anti-allergic medication; application to dosage form

A green, sensitive and rapid spectrofluorimetric method for quantitative assay of an anti-allergic medication composed of montelukast and fexofenadine mixture in raw materials and dosage form was developed. The method was based on measuring the synchronous fluorimetric peak without interference, pre-separation or pre-extraction procedures. Montelukast was analyzed at 360 nm while fexofenadine was measured at 263 nm using Δλ = 20 nm for both drugs using ethanol as diluting solvent and acetate buffer of pH 4. The assay was rectilinear over the concentration range of 1.0–10.0 μg/mL for fexofenadine and 0.1–0.6 μg/mL for montelukast. The method was full validated according to ICH guidelines. The applicability of the method enables the assay of both drugs in raw materials, synthetic mixture as well as combined tablets. Moreover, the greenness of the method was assessed using different methods including; analytical eco-scale, GAPI and AGREE. All of these methods confirm that the proposed method is an eco-friendly method.

Utilizing experimental design and desirability function in optimizing RP-HPLC method for simultaneous determination of some skeletal muscle relaxants and analgesics

An experimental design and response surface methodologies using Plackett–Burman and Box-Behnken designs were applied for selecting and optimizing the most appropriate parameters which significantly affect the separation and quantitative estimation of five skeletal muscle relaxants and four analgesic drugs (baclofen, methocarbamol, dantrolene sodium, orphenadrine citrate, cyclobenzaprine hydrochloride, ketoprofen, etoricoxib, ibuprofen, and mefenamic acid) with a relatively short duration of analysis in a single run. For the separation of the nine drugs, an INERTSIL ODS-V3-5 µm C18 column (250 × 4.6 mm I.D.) was used with the optimum mobile phase conditions (45.15 mM ammonium acetate buffer pH 5.56 adjusted with acetic acid, acetonitrile, and methanol in a ratio of 30.5:29.5:40, v/v/v with a flow rate of 1.5 mL/min) and UV-detection at 220 nm. The optimized method was successfully subjected to the validation steps as described in ICH guidelines for linearity, precision, accuracy, robustness, and sensitivity. The optimized and validated method was effectively applied to determine the content of the studied drugs in their pharmaceutical preparations and to expand its applicability to the counterfeit estimation of etoricoxib in different brands of tablet dosage forms.

Optimization of HPLC Method by Using Central Composite Design for Simultaneous Estimation of Montelukast and Ebastine Dosage Form

In this work, a novel method for the simultaneous estimate of Montelukast (MONT) and Ebastine (EBAS) in bulk drugs was developed using Central Composite Design (CCD).A novel reverse-phase high-performance liquid chromatography (RP-HPLC) approach for the simultaneous measurement of Montelukast and Ebastine in bulk and formulation is what this work aims to create and test.A novel reverse-phase high-performance liquid chromatography (RP-HPLC) approach for the simultaneous measurement of Montelukast and Ebastine in bulk and formulation is what this work aims to create and test.With isocratic elution at a flow rate of 0.8 ml min-1 and a diode array detector operating at 241 nm, the separation was accomplished using methanol and 0.02M ammonium acetate buffer (pH 5.5 adjusted with diluted acetic acid) in the ratio of 80:20 v/v. Methanol composition (percent) (A), pH (B), and flow rate (C) were three independent variables that were examined.This method showed good linearity over a range of 2.5–25 μg/ml for both drugs. MONT limit of detection (LOD) and limit of quantitation (LOQ) were 0.298 and 0.905μg/ml while LOD and LOQ for EBAS were 0.594 and 1.80For both drugs, this technique demonstrated high linearity throughout a range of 2.5–25 μg/ml. Limits of detection (LOD) and quantitation (LOQ) for MONT were 0.298 and 0.905 μg/ml and 0.594 and 1.80 μg/ml for EBAS, respectively.The statistical data analysis determined that the Methanol composition and pH were the two independent variables that were most significant, with P 0.001. The suggested technique worked well and was optimised for the CCD model-based simultaneous estimate of both drugs.

Use of turbidimetry for determination of heat treatment intensity applied at pasteurization of milk

Express methods for estimating the intensity of heat treatment of milk are necessary in industry and in research work. For this reason, there are many ways to measure this parameter, which are based on different physical principles, including turbidimetric methods. The Harland & Ashworth turbidimetric method has been developed for a long time, however, due to its high reliability and ease of implementation, it is still used in practice. However, this method has a drawback: it takes a long time to perform the analysis. In this regard, the aim of the work is to develop an express method for evaluating the thermal class of milk based on the principle of measuring the concentration of soluble whey proteins. The result is achieved through the use of a turbidimetric measurement method with optimized sample preparation parameters and parameters for measuring the optical density of a suspension of protein aggregates. The method is implemented as follows. The milk sample is mixed with 0.1 N acetate buffer (pH 4.6) in a ratio that allows to obtain a concentration of soluble milk whey proteins from 0.05% to 0.1%. Recommended dilution coefficients: 1:3 for samples of ultra-pasteurized milk and pasteurized milk with high heat treatment intensity; 1:7 for samples of pasteurized milk with low heat treatment intensity and 1:14 for raw milk samples. The solution is filtered on a membrane filter with a pore size of 0.45 microns. The resulting filtrate is mixed with 24% trichloroacetic acid (TCA) in a 1:1 ratio to coagulate soluble whey proteins and form protein aggregates. After holding for 5–10 minutes, the optical density of the suspension of protein aggregates is measured at a wavelength of 650 nm. The content of water-soluble whey proteins in the sample can be calculated according to the calibration curve. The developed method allows to obtain the measurement result in less time than the Harland & Ashworth turbidimetric method.

Simultaneous assay of pyrimethamine and methylparaben in extemporaneous pediatric suspensions by an isocratic stability-indicating UPLC-DAD method

Pyrimethamine (PYM) is an antiparasitic drug used in the treatment of congenital toxoplasmosis, available only as tablets. Therefore, preparing extemporaneous formulations and their quality control is essential for safe pediatric treatment. This study aimed to develop and validate a stability-indicating method by ultra-performance liquid chromatography (UPLC) to quantify PYM and methylparaben (MP) in extemporaneous oral suspension and evaluate its applicability to the tablets assay. The analytical conditions included RP-C18 column, mobile phase composed of 0.05 M acetate buffer pH 4.5 and organic mixture (acetonitrile:methanol), at 60:40 (v/v), flow rate of 0.2 mL/min, injection volume of 2 µL and detection at 272 nm. PYM was detected at 3.9 min and MP at 4.7 min, without interference of the degradation products or other excipients. Linearity was observed in the range of 0.5 to 25 μg/mL. The method showed accuracy (mean recovery between 98.0 and 102.0%) and precision (RSD < 2%) for suspension and tablets; the method was robust regarding the variations in the analytical conditions. The developed method met the requirements of current guidelines, was indicative of stability, and was suitable for PYM determination in extemporaneous preparations and tablets.

Efficient preparation of icariin from epimedin C by recyclable biphasic enzymatic hydrolysis

Icariin is the most bioactive ingredient of Epimedium L. and a quality marker of Herba Epimedii. Conventional methods for production of Icariin are known to be inefficient, resulting in low yields and significant environmental pollution. This study aimed to develop a sustainable and effective biphasic enzymatic hydrolysis system for the efficient conversion of epimedin C to icariin. The biphasic system was created using butyl acetate and phosphate buffer (pH 4.5) at a ratio of 3:1 (V/V) along with α-L-rhamnosidase/epimedin C (2 U/1 mg) at 50 °C for 12 h. Consequently, 98.21% of epimedin C was hydrolysed to icariin, with 95.62% of the product being transferred to the organic phase. Even after four cycles of use, the conversion ratio remained high at 75.28%. Furthermore, this novel strategy was also used for the conversion of Epimedium brevicornu Maxim. extracts. The biphasic system represents a sustainable and effective method for icariin production, offering potential benefits for industrial applications.

Determination of Enantiomer in Tofacitinib Citrate Using Reversed-Phase Chiral High-Performance Liquid Chromatography

Tofacitinib citrate (RR-isomer) is a janus kinase (JAK) inhibitor approved for the treatment of rheumatoid arthritis (RA) in adults who have had an inadequate response or intolerance to methotrexate. The presence of the enantiomer of tofacitinib citrate (SS-isomer) is monitored for quality control as a possible impurity in the final product. In this study, a reversed-phase high-performance liquid chromatography (RP-HPLC) method based on a chiral recognition mechanism for the separation of tofacitinib citrate and its enantiomer was established based on the principles of green analytical chemistry. A CHIRALPAK IH column was used with a mobile phase of ammonium acetate buffer (pH 8.0) and acetonitrile in a gradient elution at a detection wavelength of 285 nm. The calibration curve exhibited excellent linearity over the range of 0.1002–20.04 μg/mL (r = 0.9999). The average recovery of the enantiomer was 98.6% with a relative standard deviation (RSD) of 0.7%. The limit of detection (LOD) and the limit of quantitation (LOQ) were 0.04 and 0.1 μg/mL, respectively. This RP-HPLC method was suitable for detecting the enantiomers of tofacitinib citrate in tablets. Furthermore, the method proved to be environmentally friendly based on the evaluation by Analytical Eco-Scale, Analytical GREEnness (AGREE) and Green Analytical Procedure Index (GAPI).

A Novel Stability-Indicating RP-HPLC Method for the Simultaneous Estimation and In Vitro and In vivo Evaluation: Curcumin and Naringin Co-amorphous System

Curcumin (CUR) is a phytochemical widely used in food industries, cosmetics, and in the treatment of various ailments. It is a polyphenol derived from turmeric and is often considered the golden spice. CUR has a low solubility of less than 1 µg/ml and poor oral bioavailability which can be improved by co-amorphization with naringin (NRG). Analytical method to simultaneously quantify CUR and NRG is not reported in literature. This study aimed to develop a stability-indicating reverse phase HPLC method in gradient mode to simultaneously quantify CUR and NRG in co-amorphous system. The co-amorphous system of CUR and NRG in molar ratios 1:1 and 1:2 was prepared by quench cooling technique. The separation was attained on a Genesis C18, (4.6 mm × 150 mm, 4 µm) column with the mobile phase comprising of methanol and a 0.1% acetate buffer pH 3.8 at a single wavelength, 289 nm. CUR and NRG eluted at 5.1 and 11.1 min, respectively. For both the molecules, the linearity range was 0.125–16 µg/ml with LOD and LOQ of 0.063 and 0.125 µg/ml. The method developed was validated as per International Conference on Harmonization (ICH) guidelines for linearity, accuracy, precision, and robustness. The method was used to estimate CUR and NRG content in co-amorphous mixture and for in vitro evaluation.Graphical

Implementing analytical quality by design in reversed phase-high performance liquid chromatography for simultaneous estimation of teriflunomide and quercetin: Applicability in dual drug loaded topical microemulsion

The current study reports the development of a novel, robust, and sensitive reversed-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous estimation of teriflunomide (TFD) and quercetin (QCN) in dual drug-loaded microemulsion. TFD and QCN have been reported to exhibit anti-inflammatory effects by targeting various inflammatory mediators involved in the pathogenesis of rheumatoid arthritis (RA). This analytical method employs a risk-based approach and follows the principles of analytical quality by design (AQbD). The study involved preliminary screening trials and systematic risk analysis to identify critical method attributes, that significantly impact the critical quality attributes (CQAs). For the optimization of method,a face centered central composite design was utilized, and 16 experimental runs were performed using design expert software version 7.0.0. Chromatographic conditions were carefully optimized using AQbD, falling within the design space and consisting of ammonium acetate buffer (pH 3.5) and acetonitrile (60:40, % v/v) with a flow rate of 1.0 mL/min. An analytical Hibar Lichospher 100 RP-18e column (250 × 4.6 mm, 5 µm) was employed, with detection wavelength of 280 nm and 367 nm for TFD and QCN, respectively. The optimized method underwent validation according to ICH guidelines and demonstrating applicability for evaluating topical microemulsion.

APPROACHES ON SURROGATE METHODS FOR IN VIVO BIOEQUIVALENCE STUDY OF FORMULATED BILAYER TABLETS OF DOMPERIDONE AND ITOPRIDE

Objective: This study aims to provide a more efficient pathway for generic drug approval while maintaining the same level of therapeutic equivalence and safety as the reference product. This was based on the equivalence of in vitro evidence other than through expensive in vivo equivalence testing. Methods: Biowaiver and IVIVC are surrogate methods for in vivo bioequivalence studies. The Biowaiver test was done according to WHO, TRS992, 2015 Annex 7, Appendix 1, the recommendation for conducting and assessing comparative dissolution. IVIVC was done by the level A Convolution method. Innovator product was used as Ganaton OD for Itopride and Motilium for Domperidone to perform the comparison testing. Results: The similarity factor (F2) between the test and innovator product of Domperidone at pH 1.2 HCl, Acetate Buffer pH 4.5, and water was 79.51, 68.00, and 58.97 and the dissimilarity factor (F1) was 7.24, 8.05 and 11.01 respectively. From the IVIVC study by level A convolution method of Cmax, AUC, Tmax of Ganaton OD and formulated Itopride were found to be 409.16ng/ml, 5652.28 ngh/ml and 4h and 252.16ng/ml, 4601.12 ngh/ml and 12 h respectively. Conclusion: The F2 limit is 50-100 and F1 is 15 mentioned as per guidelines followed for the biowaiver test, which means the formulated domperidone is deemed equivalent to (Motilium) innovator of domperidone. The predictive error on the AUC of Itopride formulated was found to be 18.59 % which was within the limit of±20 %, demonstrating the therapeutic range.

Carbon Nanotube Modified Glassy Carbon Electrodes for on‐line and off‐line in vitro Therapeutic Equivalence Assessment of Paracetamol Tablets

AbstractIn vitro bioequivalence assessment of paracetamol tablets was carried out by differential pulse voltammetry (DPV) and amperometry using a multiwalled carbon nanotube modified glassy carbon electrode (GCE/MWCNT). For the DPV developed method, samples were collected from the USP paddle apparatus, while amperometric measurements were carried out in situ. The DPV method was validated in three supporting electrolytes (per in vitro bioequivalence guidelines) by measuring the recovery from standard solutions and paracetamol tablet solutions, while precision was evaluated through the RSD (n=6). In HCl pH 1.2 solution the LOD and LOQ were 48 nM and 160 nM, respectively and the linear range was between 0.18–2.2 μM. In acetate buffer pH 4.5 the LOD and LOQ were 15 nM and 51 nM, respectively and the linear range was between 88 nM–880 nM. And in phosphate buffer pH 6.8 the LOD and LOQ were 4.6 nM and 15 nM, respectively and the linear range was between 88 nM–880 nM. Recovery values were between 95 and 105 % and precision values were less than 5 %. Results showed that both methods were effectively applied for the analysis of samples.

Combined green analytical principles and quality by design for ultraperformance liquid chromatography analytical method development, the characterization and in-silico toxicity prediction of Ixazomib degradation products using mass spectrometry

Ixazomib citrate (IC) is the first oral selective proteosome inhibitor for treating multiple myeloma. IC is prone to degradation due to its oxidative deboronation and the amide bond, affecting patient health, drug quality, and efficacy. The stability of IC is crucial during drug development as it guides the inherent stability of the molecule, its degradation pathways, packing materials, and formulation development. Following the International Conference on Harmonization (ICH) Q1A (R2) and Q1B, a stability study were performed for both solution and solid-state stress studies. Under oxidative and alkaline conditions, 3 degradation products (DPs) were identified, separated, and method-validated according to ICH Q2 (R1) guidelines. From the Design Expert statistical tool, the Central Composite Design was used to optimize the final analytical method conditions, where the p-values for the model are < 0.05%. Green analytical chemistry has significantly reduced the use of hazardous organic solvents without losing chromatographic performance. The green separation and quantification of DPs and IC on Ultra Performance Liquid Chromatography (UPLC) using an Inert-Sustain C8 (50×3.0) mm 2.0 µm column with gradient elution using 10 mM ammonium acetate buffer (pH 5.0) and ethanol at a flow rate of 0.5 mL/min and detection at 230 nm. The results of green assessment tools like GAPI, AGREE, and Analytical eco-scale found that the method is excellent for the greenness of utilizing ethanol as a solvent, shorter runtime, and lesser waste. The method was validated as per ICH Q2 guidelines, and the results found it is sensitive, precise, accurate, robust, and linear for its intended use. The method is suitable for quantifying IC and its DPs from 2.0 to 150 µg/mL with R2 values of 0.9996 with a detection limit of 1.0 µg/mL. The plausible degradation structures and pathways of DPs were outlined using tandem mass spectra employed on LC-QTOF-MS/MS in both ESI positive and negative modes. The mechanistic explanation for establishing DPs was explained in detail. The ADMET Predictor™ software predicted the physicochemical and ADMET properties. The toxicity profile reveals that DP2 and DP3 are teratogenic, while D1 and D3 show phospholipidosis.

Determination of sodium benzoate in different brands of orange juices available in Bangladesh by high-performance liquid chromatography

Sodium benzoates as a chemical preservative are common practice in modern food technology. It is permitted by international laws in food as a food additive with a restricted amount. But it is highly used in different food products like fruit juices. Therefore, an experimental study was conducted to determine the concentration of sodium benzoate in different brands of orange juices available in the market Tangail region, Bangladesh using High Performance Liquid Chromatography (HPLC). Chromatographic analysis was performed by a column (250 × 4.6 mm) with an isocratic solvent system at 40°C. The mobile phase consisted of sodium acetate and acetic acid buffer (pH was 4). The correlation of coefficient was 0.9999 from the standards curves and the variety of external standard absorptions was 0.93 to 20.05 µg/mL. Analysis of four brands of orange juice samples showed that the concentration of sodium benzoate was within the FDA standard, but two brand samples slightly exceeded the Bangladesh Standard and Testing Institute (BSTI) standard. Brand 1 and Brand 4 samples contained sodium benzoate 14.61 and 9.59 mg/100 mL respectively which were within the level BSTI standard range whereas Brand 2 and Brand 3 samples contained 16.11 and 16.33 mg/100 mL respectively which exceeded the level of BSTI standard.

Exploitation of carbon surface functionality toward additive‐free formation of gold nanocuboids suitable for sensitive assay of N‐acetylcysteine in pharmaceutical formulations

AbstractChemical additive and physical template‐free electrochemical methods to prepare carbon‐supported nanostructures of catalyst metals represent an emerging technology. Formation of the metal nano/microstructures depends not only on the electrochemical method/parameters but also on the nature of the underlying carbon material. Here, we present a comparative evolution of unevenly distributed coral‐like aggregates of nanocuboid‐shaped gold nanostructures (AuNCBs) on the oxidised form of boron, nitrogen‐doped carbon nanoonions (oxi‐B,N‐CNO) compared to evenly distributed bud‐like aggregates of cubic shaped gold nanostructures on bare glassy carbon electrode under a similar electrochemical approach. The synthesis method provided the best availability of the surface active sites, whereas the shape of the structures showed a direct influence of both outer‐sphere and inner‐sphere electron transfer reactions. The higher sensitivity of AuNCBs@oxi‐B,N‐CNO compared to individual components and bare carbon/gold electrodes toward the inner‐sphere oxidative reaction of N‐acetyl‐L‐cysteine (NAC) was exploited in order to develop an electrochemical assay method with sensitivity and linear dynamic range of (4.70 ± 0.25) × 10−4 C∙cm−2∙mM−1 and 0.2–2.5 mM, respectively in acetate buffer (pH 4.45). Furthermore, the sensor design was deployed in the quantitation of NAC in pharmaceutical preparations, resulting in 89%–106% recovery.

Simple Binding and Dissociation of a Sialoglycoprotein Using Boronic Acid-Modified Functional Interfaces on Microparticles.

An overexpression of sialic acid is an indicator of metastatic cancer, and selective detection of sialic acid shows potential for cancer diagnosis. Boronic acid is a promising candidate for this purpose because of its ability to specifically bind to sialic acid under acidic conditions. Notably, the binding strength can be easily modulated by adjusting the pH, which allows for a simple dissociation of the bound sialic acid. In this study, we developed 5-boronopicolinic acid (5-BPA)-modified magnetic particles (BMPs) to selectively capture sialic acid biomolecules. We successfully captured fetuin, a well-known sialoglycoprotein, on BMPs at >104 molecules/particle using an acetate buffer (pH 5.0). Facile dissociation then occurred when the system was changed to a pH 7.6 phosphate buffer. This capture-and-release process could be repeated at least five times. Moreover, this system could enrich fetuin by more than 20 times. In summary, BMPs are functional particles for facile purification and concentration through the selective capture of sialic acid proteins and can improve detection sensitivity compared with conventional methods. This technology shows potential for the detection of sialic acid overexpression by biological particles.

An electrochemical voltammetric response of Hg2+ and Pb2+ ions using polyaniline-benzothiazole composite modified GCE electrode: Synthesis, characterization and quantum chemical calculation

An efficient electrochemical sensor based on polyaniline-benzothiazole [(3,5-bis (benzo[d]thiazol-2-yl)-[1,1–biphenyl]-4-ol)] (PAni-BEN) composite was designed and synthesized in this study, and it was employed as an electrochemical sensor to detect Hg2+ and Pb2+ ions with good selectivity and sensitivity. Fourier transform-infrared spectroscopy, UV–Vis spectroscopy, scanning electron microscopy, and energy dispersive X-ray analysis spectroscopy were employed to examine the morphology and structure of the produced composite. The electrochemical characteristics of the electrode modifiers were evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Also, they were employed to perform both individual and simultaneous sensing studies of various metal ions using the differential pulse voltammetry technique (DPV) in a different supporting electrolyte (acetate buffer (pH 5), phosphate buffer (pH 7), and 0.1 M HCl) mediums. The PAni-BEN composite modified GCE sensor shows remarkable selectivity and sensitivity towards Hg2+ and Pb2+ ions over the other heavy metal ions in 1 to 24.84 µM, respectively. The limits of detection (S/N = 3) were 1 nM and 4.6 nM for Hg2+ and Pb2+ ions. Density Functional Theory (DFT) was used in the present study to accomplish the adsorption mechanism of the suggested sensors. The DFT calculation demonstrated that the PAni-BEN composite was formed with a lower band gap energy than BEN and DD PAni. These findings showed that the suggested sensor (PAni-BEN), which may used to detect Hg2+ and Pb2+ ions, had the lowest detection limit in the acetate buffer medium compared to the proposed electrolyte medium.

Development of chromatographic methods to determine multivitamins formulation depending on their solubility and polarity: comparative study using three greenness assessment tools

High performance liquid chromatography is one of the techniques of choice for the separation and quantitative determination of drugs in mixture form. Ipriflavone, ascorbic acid, pyridoxine, vitamin D3, and lysine are formulated together as an adjuvant combination in osteoporosis. In this work, we developed and validated two complementary high performance liquid chromatographic methods to determine the five compounds in their pharmaceutical dosage form. The first method (method A) was capable of determining ipriflavone, ascorbic acid, pyridoxine, and vitamin D3 in their bulk and combined pharmaceutical formulation. The method is based on Liquid Chromatographic separation with UV detection at 254 nm using Agilent Eclipse XDB-C18 column with a mobile phase consisting of 25 mM ammonium acetate buffer (pH 4.2): methanol in gradient mode. Due to the high polarity of lysine, it was difficult to achieve satisfactory retention on reversed phase columns. So, we separated it on a strong cation exchange column (Exsil 100 SCX) without derivatization with a mobile phase consisting of 10 mM sodium dihydrogen phosphate and 200 mM sodium chloride (pH 6) with UV detection at 210 nm (method B). Validation of the proposed methods was performed according to ICH guidelines Q2(R1). The proposed methods proved to be valid for selective analysis of the stated drugs in their bulk and combined pharmaceutical formulation. Greenness assessment of the developed methods was evaluated using three assessment tools: ESA, GAPI and the most recently developed tool AGREE, showing a satisfactory comprehensive guide of the greenness of the developed methods.

THE SIMULTANEOUS QUANTIFICATION OF RIFAMPICIN AND ISONIAZID IN PATIENTS WITH TUBERCULOSIS APPLIED TO VOLUMETRIC ABSORPTIVE MICROSAMPLING DEVICES USING HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

Objective: Rifampicin and isoniazid are the main tuberculosis treatment regimens requiring blood level measurement to optimize the treatment process. This study aims to analyze rifampicin and isoniazid quantitatively in volumetric absorptive microsampling (VAMS) prepared from a small volume of TB patients using HPLC. Methods: Analytes on the VAMS tip were extracted using 1000 ml of acetonitrile containing 10 µg/ml of cilostazol as an internal standard. Analytical separation was performed on the C-18 column at 40 ℃ with a mobile phase mixture of 50 mmol ammonium acetate buffer pH 5.0-acetonitrile-methanol (40:30:30), flow rate 0.5 ml/min. The analysis was carried out with the calibration curve over a range of 1.0–30 µg/ml for rifampicin and 0.4-20 µg/ml for isoniazid. Results: Analyte analysis in 21 patients showed that the measured value of rifampicin was 3.39–16.77 µg/ml, and isoniazid was 2.63–10.43 µg/ml at 2 h post-dose. 52.38% of patients had low blood concentrations in at least one of the drugs, 28.57% of the patients were in the therapeutic range, and 23.81% had a high blood concentration of isoniazid alone. Conclusion: The concentration of rifampicin and isoniazid in 21 tuberculosis patients varied. Dose adjustment is needed because most patients had low blood concentrations of one of the drugs, and a limited number had a high blood isoniazid concentration alone. Only some patients simultaneously had plasma concentrations within the target range of the drugs. This method was valid and reliably utilized for therapeutic drug monitoring of antituberculosis.

Investigation of pantoprazole loading and release from a magnetic-coated chitosan-modified zirconium-based metal-organic framework (MOF) as a nanocarrier in targeted drug delivery systems.

This study reports a novel magnetic and porous nanocomposite, Fe3O4@CS@UIO-66-NH2(Zr), developed by growing a zirconium-based metal-organic framework on magnetite-chitosan. It is designed for targeted and delayed pantoprazole delivery, the nanocomposite exhibits pH-sensitive behavior and functions as an efficient nanocarrier. The synthesis process involved coating magnetite nanoparticles with chitosan, followed by the growth of UIO-66-NH2(Zr) on the coated nanoparticles. The nanocomposite demonstrated high drug loading efficiency (DLE) in acetate buffer (pH 5.0) and deionized water, with loading percentages of 79% and 75%, respectively, within 48 hours. The corresponding drug loading content (DLC) was approximately 14% and 10%. The Freundlich and Langmuir models accurately described the multilayer adsorption behavior of pantoprazole on the nanocomposite's active sites. BET and EDX-map analyses confirmed that the drug was loaded into the nanocomposite's pores and uniformly adsorbed on its surface. The drug release kinetics were best described by the pseudo-second-order model. Due to its porosity, magnetic properties, and favorable drug loading characteristics, the Fe3O4@CS@UIO-66-NH2(Zr) nanocomposite shows potential as an efficient targeted drug delivery system for in vivo applications.