Acetate Buffer pH Research Articles

DEVELOPMENT AND VALIDATION OF AN RP-HPLC METHOD FOR THE DETERMINATION OF ULIPRISTAL ACETATE IN BULK AND PHARMACEUTICAL DOSAGE FORM

Objective: This work makes an attempt to establish a sensitive and accurate method for the development and validation of an analytical method for estimation of ulipristal acetate (UPA) in bulk and pharmaceutical dosage form.
 Methods: A mixture of 20 mM acetate buffer pH 3.7 and methanol in the ratio of 70:30 (v/v %) was used as the mobile phase. An xBridge™ C18 column (250 mm × 4.6 mm, 5μ) was used for the analysis at a flow rate of 1 ml/min, injection volume of 20 μl, run time of 15 min, and detection wavelength of 309 nm. The repeatability (within-day in triplicates) and intermediate precision (for 2 days) were carried out by six injections and the obtained results within and between the days of trials were expressed as percent relative standard deviation (% RSD). The linearity of the method was determined by the analysis of analyte concentration across a range of 10 μg/ml–60 μg/ml.
 Results: The % RSD values of precision studies were found to be below the accepted limit of 2%. The method was found to be linear with a correlation coefficient (R2) of 0.98. The method was also found to be accurate and robust with suitable values. Limit of detection (LOD) and limit of quantification (LOQ) of the method were found to be 0.371 μg/ml and 1.23 μg/ml, respectively.
 Conclusion: The results of analysis prove that this method can be used for the routine determination of UPA in bulk drug and in pharmaceutical dosage forms.

Solvent‐Promoted Oxidation of Aromatic Alcohols/Aldehydes to Carboxylic Acids by a Laccase‐TEMPO System: Efficient Access to 2,5‐Furandicarboxylic Acid and 5‐Methyl‐2‐Pyrazinecarboxylic Acid

AbstractLaccase coupled with 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy (TEMPO) is a well‐known catalytic system for the oxidation of alcohols to the carbonyl compounds. In this work, a simple yet effective solvent engineering strategy is developed to enable aromatic alcohols/aldehydes to be efficiently oxidized to carboxylic acids by a laccase‐TEMPO system. Citrate buffer (100–300 mm, pH 6) rather than the widely used acetate buffer (pH 4–5) proves to be optimal for this purpose. The roles of citrate are discussed in laccase‐TEMPO‐catalyzed synthesis of carboxylic acids. 5‐Hydroxymethylfurfural (HMF) of 200 mm is oxidized to 2,5‐furandicarboxylic acid (FDCA), a top‐value biobased chemical in the polymer industry, in 28 h with a yield of up to 97%. Of the 18 substrates examined, 11 alcohols are converted to target carboxylic acids with >90% yields by this method, with 2 alcohols giving >60% yields of carboxylic acids. Gram‐scale preparation of FDCA and 5‐methyl‐2‐pyrazinecarboxylic acid, an important drug intermediate, is demonstrated with total turnover numbers up to 110 000 for laccase and space‐time yields up to 1.0 g/(L•h). This chemoenzymatic approach may be a promising alternative to traditional chemical oxidations for the synthesis of carboxylic acids.

A Simultaneous, Validated RP-HPLC Method for Determination of Eight Cephalosporins in Pharmaceutical Formulations.

A reversed phase high performance liquid chromatographic method with isocratic solvent system has been developed and validated for the simultaneous determination of eight of cephalosporins antibiotics (Cefepime Hydrochloride, Ceftazidime, Ceftiofur Sodium, Cefotaxime Sodium, Ceftriaxone Sodium, Cefoperazone Sodium, Cephradine and Cefazolin Sodium) in pharmaceutical formulations with run time of 35 min. The best separation was obtained by using a 250 mm × 4.6 mm i.d, 5.0 μm particle size C8 reversed phase Agilent column and 0.1 M ammonium acetate buffer (pH 5.6): Acetonitril, 95:5 (v/v) as mobile phase at a flow rate of 0.8 mL/min. UV detection was conducted at 250 nm and column temperature at 30° C. The method linearity achieved over the concentration range of 0.5-50 μg/ mL with correlation coefficient (r2= 0.9999) for each studied cephalosporins. The developed method achieved lower limits of detection (0.018 µg/mL: 0.03 µg/mL) and lower limits of quantification (0.056 µg/mL: 0.09 µg/mL). The suggested method is highly sensitive, accurate, precise, and could be used for quality control assay and routine analysis for this group of cephalosporins in pharmaceutical formulations.

Zwitterionic Ion Chromatography Coupled with Ultra-violet Detection for the Quantification of 2-Deoxyguanosine in Human Serum

A simple ZIC-HILIC-UV technique was developed and applied for the determination of 2-deoxyguanosine in the human serum. The separa-tion took place in the ZIC1 and ZIC5 self-designed stationary phases, in gradient elution mode with a buffer for acetonitrile acetate and 254 nm UV detection. The 2-deoxyguanosine conduct with varying acetate buffer, ACN and pH values has been tested and the results have established the hydrophilicity of 2-deoxyguanosine. The mechanism of separation is based on the hydrophilic and ion exchange partitioning of the2-deoxyguanosine. We have defined and mentioned the current effect of both ZIC1 and ZIC5 stationary stationary phenomena on chromatographic conditions (sodium acetate buffer concentration, ACN and pH). All existing methods are a useful alternative to the current 2-deoxyguanosine separation methods.

Biochemical Characterization of Two Polygalacturonases Purified from the Digestive Juice of the Snail Limicolaria flammea

Polygalacturonases constitute the major part of pectinase preparations for many bioprocess purposes. Investigation on the digestive juice of snail Limicolaria flammea led to purification of two polygalacturonases named PG1 and PG2. Properties of these enzymes were examined to explore their potential in biotechnology applications. A three steps procedure including size exclusion, anion and cation exchange and hydrophobic interaction chromatography were used for purification. The enzymes PG1 and PG2 had native molecular weights of approximately 46 and 86 kDa, respectively and functioned both as monomeric structures. The purified polygalacturonases PG1 and PG2 showed optimum hydrolysis activities at 50°C in sodium acetate buffer pH 5.6. The common inhibitor of the two purified polygalacturonases activity were Mn2+, Ca2+, Zn2+, EDTA, SDS and L-cystein. NH3+ stimulate the polygalacturonase PG1 while Ba2+ was an activator for polygalacturonase PG2. Substrate specificity indicated that these enzymes hydrolyse a broad range of pectin from different sources. The highest activity of PG1 was observed with apple pectin and lemon pectin while PG2 showed its highest activity with orange pectin. The catalytic efficiency of PG1 was highest for lemon pectin (0.125 µmol/min/mL) and orange pectin (0.124 µmol/min/mL). PG2 displayed highest catalytic efficiency (0.325 µmol/min/mL) towards orange pectin. These results suggest that orange and lemon pectin would be the potential physiological substrates of the two purified enzymes.

Development of a validated hydrophilic interaction chromatography method for the determination of cefotaxime in pharmaceutical preparations

Cefotaxime is considered as one of the semi-synthetic, 3rd generation, cephalosporin antibiotics that have been utilized for treating a lot of infections resulting from different organisms. The technique of hydrophilic chromatography interaction (HILIC) has increased the accuracy and sensitivity concerning other methods, particularly spectrophotometer. The objective of this article was to introduce a simple method for the estimation of cefotaxime in pure and pharmaceutical injection forms and study the separation mechanism of cefotaxime. HILIC mode achieved excellent separation under chromatographic conditions on a HALO ® HILIC 2.7 column (100 mm x 2.1 mm I.D.) at 35 ° C with the following conditions: 10:90% acetate buffer (pH 5.5-40 mM): acetonitrile as eluent and wavelength of detection 254 nm. The proposed HILIC method exhibited high precision (RSD% < 0.5%), concentration ranges of 100-5500 ppb, and the lowest detection limit was 6.8167 ppb with a coefficient of determination of 0.9998 for cefotaxime. The findings of the method were used statistical tests compared to the British Pharmacopoeia protocol, which did not show any difference in accuracy among the methods

Structural Polymorphism of Sorafenib Tosylate as a Key Factor in Its Solubility Differentiation

The presence of active pharmaceutical ingredients (APIs) in the forms of different polymorphic states can induce differences in their physicochemical properties. In the case of poorly soluble APIs, like the oncological drug sorafenib tosylate, small variations in solubility may result in large bioavailability differences. The control of its therapeutic dose is crucial from the effective pharmacotherapy point of view and the reduction of side effects. Therefore, this study aimed to assess the influence of sorafenib tosylate polymorphic forms on its solubility and, consequently, permeability, based on passive diffusion through membranes simulating the gastrointestinal tract (GIT) conditions. In the first part of the work, two crystalline forms of sorafenib tosylate were identified using the X-ray powder diffraction, FT-IR, and Raman spectroscopy. Subsequently, solubility studies were carried out. Both forms of sorafenib tosylate were insoluble in 0.1 N hydrochloric acid (HCl), in acetate buffer (pH 4.5), and in phosphate buffer (pH 6.8). Solubility (mg/mL) of form I and III of sorafenib tosylate in 0.1 N HCl + 1.0% SDS was 0.314 ± 0.006 and 1.103 ± 0.014, respectively, in acetate buffer pH 4.5 + 1.0% SDS it was 2.404 ± 0.012 and 2.355 ± 0.009, respectively, and in phosphate buffer pH 6.8 + 1.0% SDS it was 0.051 ± 0.005 and 1.805 ± 0.023, respectively. The permeability study was assessed using the parallel artificial membrane permeability assay (PAMPA) model. The apparent permeability coefficient (Papp—cm s−1) of form I and III in pH 1.2 was 3.01 × 10−5 ± 4.14 × 10−7 and 3.15 × 10−5 ± 1.89 × 10−6, respectively, while in pH 6.8 it was 2.72 × 10−5 ± 1.56 × 10−6 and 2.81 × 10−5 ± 9.0 × 10−7, respectively. Changes in sorafenib tosylate concentrations were determined by chromatography using the high-performance liquid chromatography (HPLC)–DAD technique. As a result of the research on the structural polymorphism of sorafenib tosylate, its full spectral characteristics and the possibility of using FT-IR and Raman spectroscopy for the study of polymorphic varieties were determined for the first time, and the HPLC method was developed, which is appropriate for the assessment of sorafenib solubility in various media. The consequences of various physicochemical properties resulting from differences in the solubility of sorafenib tosylate polymorphs are important for pre-formulation and formulation studies conducted with its participation and for the safety of oncological sorafenib therapy.

Development of Stability Indicating HPLC-UV Method for Determination of Process Impurities and Degradation Products in Sofosbuvir and Velpatasvir Tablets

A simple and sensitive stability indicating HPLC-UV method was developed for the analysis of process impurities and degradation products in Sofosbuvir and Velpatasvir pharmaceutical formulations. Analysis was performed on C18 analytical column (250 mm × 4.6 mm, 5 μm), using a mobile phase of 0.05M ammonium acetate buffer (pH 6.5) with acetonitrile at 45 : 55 (v/v) ratio and a flow rate of 1.0 mL/min. The detection wavelength for simultaneous determination of both ingredients using UV detector was 268 nm. The method was validated for accuracy, precision, linearity, and specificity using reference standards of process impurities and degradation products. The calibration curve was linear and the limits of detection and quantification were determined using 3δ/slope and 10δ/slope expressions, respectively. Forced degradation studies for Sofosbuvir and Velpatasvir drug substances and products were designed under different environmental stress conditions. The effect of alkaline, acidic, oxidative, and thermal stress conditions on Sofosbuvir and Velpatasvir substances and dosage forms was studied. The influence of heat and humidity was studied at 80 ± 5°C and 75 ± 5% RH. Similarly, the photolytic studies were performed on visible light at 200 Wh/m2 UV and 1.2 million lux h/m2 in a climatic chamber. The proposed method is stability-indicating and has been successfully applied to the analysis of process impurities and degradation products in Sofosbuvir and Velpatasvir pharmaceutical formulations. The degradation products were characterized by MS, NMR and IR spectroscopy analysis for identification of degradation products and determination of mechanisms.

A rime ice-inspired bismuth-based flexible sensor for zinc ion detection in human perspiration.

A nature-inspired special structure of bismuth is newly presented as Zn ion sensing layer for high-performance electrochemical heavy metal detection sensor applications. The rime ice-like bismuth (RIBi) has beensynthesized using an easy ex situ electrodeposition method on the surface of a flexible graphene-based electrode. The flexible graphene-based electrode was fabricated via simple laser-writing and substrate-transfer techniques. The Zn ion sensing performance of the proposed heavy metal sensor was evaluated by square wave anodic stripping voltammetry after investigating the effects of several parameters, such as preconcentration potential, preconcentration time, and pH of acetate buffer. The proposed RIBi-based heavy metal sensor demonstrated a good linear relationship between concentration and current in the range 100-1600ppb Zn ions with an acceptable sensitivity of 106nA/ppb·cm2. The result met the requirements in terms of common human perspiration levels (the average Zn ion concentration in perspiration is 800ppb). In addition, the heavy metal sensor response to Zn ions was successfully performed in human perspiration samples as well, and the results were consistent with those measured by atomic absorption spectroscopy. Besides, the fabricated Zn ion sensor exhibited excellent selectivity, repeatability, and flexibility. Finally, a PANI-LIG-based pH sensor (measurement range: pH4-7) was also integrated with the Zn ion sensor to form a single chip hybrid sensor. These results may provide a great possibility for the use of the proposed flexible sensor to realize wearable perspiration-based healthcare systems. Graphical abstract.

A high-performance voltammetric methodology for the ultra-sensitive detection of riboflavin in food matrices based on graphene oxide-covered hollow MnO2 spheres

A high-performance voltammetric methodology was developed to achieve ultra-sensitive detection of riboflavin, employing an electrode modified by graphene oxide-covered hollow MnO2 spheres nanocomposite with high catalytic activity, large surface area, and hierarchical layered structure. Under the optimal conditions, the current responses of the oxidation peak located at −0.39 V showed a good linear relationship versus the concentration of riboflavin in the range of 1.0 nM–4.0 μM in acetate buffer (pH 5.4). The limit of detection was determined as 0.26 nM. Moreover, the proposed electrode exhibited high reproducibility (relative standard deviation of 1.7%, n = 10) and excellent stability (97.6% sensitivity within two months), which has been successfully applied to the quantification of riboflavin in complicated food matrices, with results in good accordance with those obtained by chromatography as a reference method, indicating it is an effective sensing platform for ultra-sensitive determination of riboflavin in practical applications.

Tailored gentamicin release from silica nanocarriers coated with polyelectrolyte multilayers

Controlling antibiotic release kinetics is essential for effective treatment and for many biomedical applications. Herein, silica nanoparticles were prepared and loaded with gentamicin through various routes (Layer-by-layer (LbL), entrapment, adsorption). LbL coatings involved the polyelectrolytes poly(styrene sulfonate) (PSS) and Poly(allylamine hydrochloride) (PAH), where the nanoparticles coated with quadruple layers (QL) of [PSS/gentamicin/PSS/PAH]. The nanoparticles were characterized by zeta potential, transmission electron microscope (TEM) and thermogravimetric analysis (TGA). Moreover, nanoparticles' gentamicin release was tested in different release media (acetate buffer pH 5 and PBS pH 7.4). The gentamicin LbL-coated nanoparticles were successful to sustain drug release over 2 weeks. Although the entrapment method was similarly able to sustain drug release over two weeks, it showed lower drug loading when compared to the LbL-coated nanoparticles. In contrast, simple adsorption on bare silica surface resulted in significantly lower drug loading and 90 % release on day 1. The release of gentamicin showed pH-responsive behavior, with higher release at pH 5. This work demonstrates that gentamicin release from silica nanocarriers can be controlled by the different approaches for loading gentamicin. This will give different release profiles tailored for many biomedical applications such as antibiotic-loaded bone cement or implant coatings.

Development and validation of a fast HPLC method for methyldopa enantiomers using superficially porous particle based macrocyclic glycopeptide stationary phase

Methyldopa is a centrally acting antihypertensive agent, whose pharmacological activity is attributed to the S-α-methyldopa enantiomer. The assessment of enantiomeric purity is an essential quality control test for chiral drugs, as the presence of certain impurities in a drug can interfere with the desired pharmacological effect. The present study was undertaken to evaluate different chiral stationary phases composed of macrocyclic glycopeptides (vancomycin, teicoplanin and aglycone teicoplanin) and the use of superficially porous particles for the efficient separation of methyldopa enantiomers. The reversed-phase and polar ionic elution modes were evaluated, with different proportions of solvents and additives. The influence of the flow rate and temperature on the analysis were also evaluated. Different stationary phases in different elution modes exhibited suitable selectivity and fast analysis. Total separation of the enantiomers were obtained with the teicoplanin and teicoplanin aglycone stationary phases. The teicoplanin aglycone column produced excellent resolution values and very fast separation analyzes. The use of the teicoplanin aglycone chiral stationary phase for the analysis of MDopa enantiomers is innovative and has not yet been explored in the literature. The best method was obtained and validated with teicoplanin aglycone in the reversed-phase mode using 20 mM ammonium acetate buffer pH 4.0/MeOH (20:80), column temperature of 45 °C and flow rate of 1.0 mL/min, which presented a total run time less than 5 min, a resolution of 5.05 and good peak symmetry. The method can be used in pharmaceutical quality control laboratories and support the stereospecific synthesis of the drug.

COMPARATIVE DISSOLUTION STUDIES OF WARFARIN SODIUM TABLETS: INFLUENCE OF AGITATION RATE, DISSOLUTION MEDIUM, AND USP APPARATUS

Objective: The aim of this study was to carry out comparative dissolution studies with warfarin sodium reference tablets under the hydrodynamic environments generated by the USP basket and paddle apparatus and flow-through cell using different agitation rates and dissolution media.&#x0D; Methods: Dissolution profiles were obtained with the USP basket and paddle apparatus at 50, 75, and 100 rpm and 900 ml of water as dissolution medium. After this, dissolution profiles of warfarin sodium were obtained with the USP paddle apparatus and flow-through cell method using 0.1 N hydrochloric acid, acetate buffer pH 4.5, phosphate buffer pH 6.8, and water. Spectrophotometric determination at 308 nm was carried out during 30 min. Dissolution profiles were compared with model-independent and model-dependent approaches.&#x0D; Results: Significant differences were found with mean dissolution time and dissolution efficiency at 50 and 75 rpm (*P&lt;0.05). Makoid-Banakar was the best-fit model used to describe the in vitro release performance of warfarin sodium with 50-100 rpm and the USP basket and paddle apparatuses. Significant differences in all calculated parameters were found (*P&lt;0.05) excepting percent dissolved at 30 min with 0.1 N hydrochloric acid and phosphate buffer pH 6.8.&#x0D; Conclusion: More research is necessary to identify the in vitro release performance of poorly soluble drugs under available USP apparatuses considering factors as agitation rate and kind of dissolution media. The knowledge of the in vitro release performance of reference drug products is important for the design of better generic formulations

Antioxidant and organic acid evaluation of Geaster saccatum mushroom by chemical and electrochemical assay at carbon nanotube paste electrode

The study was aimed to investigate the antioxidant and organic acid composition of Geaster saccatum mushroom by chemical and electrochemical assay. The antioxidant activity was done by using DPPH and ABTS reagents while the cyclovoltametry (CV) and differential pulse voltamery (DPV) were used to determine its electrochemical behavior at single walled carbon nano tube paste electrode in 0.02 M acetate buffer (pH 5.0), to explore the adsorptive character of its antioxidant compounds at working electrode as a function of pH, scan rate and potential. The organic acid analysis of this mushroom was carried out by High performance liquid chromatography. In DPPH, the scavenging rate was 56.4 ± 0.78%, at 20 µg/ml, reached to 93.4 ± 0.93% at 100 µg/ml, with 61.01 μg/ml as its IC50. Similarly, in ABTS, at same concentrations, scavenging rates were 38.14 ± 0.54% and 95.16 ± 0.43%, with 58.03 μg/ml as its IC50, respectively. HPLC quantified eight organic acids with gallic acid at highest concentration (193.34 mg/kg dry wt) followed by ketoglutaric acid (181.16 mg/kg dry wt.) and oxallic acid (69.54 mg/kg dry wt.). The CV produced a clear irreversible anodic peak at Epa = 0.69 ± 0.01 V, while, ascorbic acid produced a single anodic peak at Epa = 0.29 ± 0.01 V and gallic acid produced two anodic peaks at Epa = 0.41 ± 0.01 V and second at Epa = 0.69 ± 0.01 V. However, only one anodic peak of mushroom was found in DPV at 0.56 ± 0.01 V, which increased proportionally at each increasing concentration of mushroom extract. The results declared this mushroom as one of the best source of organic acids which characterized it as a better antioxidant food as well as medicine.

QbD-Based Development and Validation of an Efficient RPHPLC Method for Estimation of Abiraterone Acetate in Bulk, Tablet, and In-House-Developed Nano-Formulation

The present study focused on the development of a simple, reliable, cost-effective, precise, and stable quality by design (QbD) RP-HPLC method for estimation of Abiraterone Acetate in bulk, pharmaceutical dosage form, and in-house-developed nano-formulation. The essential analytical target profile (ATP), and critical analytical attributes (CAAs) were described. Plackett-Burman Design and Box-Behnken Design were used for screening and optimization of critical method parameters (CMPs). The chromatographic method with reverse-phase isocratic mode, C-18 column, 69: 31 (% v/v) acetonitrile, and ammonium acetate buffer (pH 3.5) as a mobile phase with a flow rate of 0.75 ml/min and 235 nm detection wavelength was developed. The method was validated as per International Conference on Harmonization guideline and found to be linear between 10 to 180 μg/ml with R2 0.997, detection limit of 3.64 μg/ml, and quantitation limit of 11.05 μg/ml. Precision was demonstrated using a relative standard deviation of 1.55 % and 1.59 % for inter and intraday studies respectively. The developed method was also used for the analysis of ABT in bulk, tablet dosage form, and in-house-developed nanosponges prepared using different cross-linking agents, devoid of any interference of formulation excipients. The method effectively established the utility of QbD for optimizing chromatographic conditions used for the estimation of Abiraterone acetate.

Adenine Adsorption in Different pH Acetate Buffer

The research results facilitate the description of adenine adsorption on the mercury electrode with reference to the pH of the supporting electrolyte which was the acetate buffer with pH of 3, 4, 5 and 6. The thermodynamic analysis indicates that the curves of the differential volume of the studied systems with adenine do not overlap with the curves for the supporting electrolyte – the acetate buffer. This indicates the occurrence of adsorption of the studied compound on the mercury electrode within the whole range of applied concentrations in the case of every tested pH value of the acetate buffer. Adsorption energy and interaction constants were determined using the Frumkin isotherm and the viral isotherm. It was demonstrated that a adenine molecule is adsorbed on the mercury electrode in a buffer with pH 4, 5 and 6 through the negative pole, whereas in a buffer with pH 3 through the positive pole. Physical adsorption was observed in the studied systems. This is indicated by the occurrence of a typical maximum on the curve of the relation the relative surface excess amounts and the potential of the electrode; crossed curves of the following relation surface charge of the electrode from its potential (surface charge of the electrode from its potential σ = f(E)) at one point and, thus, the possibility of determining electrical parameters characterizing maximum adsorption as well as the absence of linearity of the function free energy of adsorption as a function of electrode potential ∆G0 = f(E).

Change in hydrolytic enzyme efficiency over time

Change in hydrolytic enzyme efficiency over time. The purpose of this study was to determine the action of hydrolytic enzymes (by Dyadic Cellulase CP CONC, and the Dyadic Xylanase 2 XP CONC) over time. Chromatographic analysis of holocellulose samples subjected to enzymatic hydrolysis was performed. The following hydrolysis parameters were used: time 48h, temperature 45 ⁰C, acetate buffer pH 5.4, commercial enzymes Dyadic. Holocellulose extracted by the sodium chlorite method from white poplar wood (Populus alba L.) was used. The final yield of enzymatic hydrolysis was determined. The results of hydrolysis performed at intervals were compared. The results obtained show that the hydrolysis yield of holocellulose after five months decreased by 40 p.p. for glucose yield and by 25 p.p. for xylose yield. The yield for glucose after two and a half years decreases by 68 p.p. and 62 p.p. for xylose compared to the initial yield.

Solubility enhancement of nimodipine using mixed hydrotropic solid dispersion technique

Background and objective: Low aqueous solubility of active pharmaceutical ingredients has an effect on both formulation development and bioavailability. Nimodipine is an antihypertensive agent with low oral bioavailability, which might be attributed to the extremely poor water solubility. This study aimed to increase the solubility of nimodipine in water using hydrotropes and solid dispersion technology to increase dissolution rate compared to the marketed drug product. Methods: Solubility of nimodipine was determined separately in sodium acetate, sodium citrate, sodium benzoate, and niacinamide solutions at a concentration of 10, 20, 30, and 40% w/v using distilled water as a solvent. The highest solubility was obtained in 40% sodium benzoate solution. Mixed concentrations of hydrotropic agents were used in ratio 1:3 (niacinamide: sodium benzoate). Fourier-transform infrared spectroscopy was used to exclude any drug-hydrotropes interaction. The dissolution rate of nimodipine from solid dispersion and physical mixture were studied using USP type II dissolution test apparatus in acetate buffer (pH 4.5) as a dissolution media. Results: Hydrotropic solid dispersion of nimodipine with a blend (30% sodium benzoate and 10% niacinamide) increased the dissolution rate of the drug by 1.5 folds compared to the marketed conventional nimodipine tablet. Fourier-transform infrared analysis did not show any physicochemical interaction between drug and carriers in solid dispersion formulation. Conclusion: The hydrotrop is a novel and safe compound. It is a successful way to enhance the solubility of poorly aqueous soluble drugs. Immediate dissolution of practically insoluble drug nimodipine in dissolution media indicates that it has a great potential to solubilize the drug in biological fluids. Thus, a considerable improvement in bioavailability and onset of action of the drug can be predictable. Adding of a hydrotropic agent with nimodipine in solid dispersion increased the dissolution rate of the drug compared to the marketed conventional nimodipine tablet Keywords: Hydrotropes; Nimodipine; Solubility enhancement; Solid dispersion.

Development and Validation of a Ultra Flow Liquid Chromatography Method for the Assay of Boceprevir Using a Quality-by-Design Approach

Quality by design guided. The assay method of Boceprevir is developed in accordance with ICH Q8(R2) guideline with due validation. .In this process, the Target analytical profile (TAP) of the drug was set and critical method parameters (CMP) were investigated by systematic risk assessment experimentation to control critical Quality Attributes (CQA). In this, A Cause Effect Risk Assessment Matrix with Control-Noise-Experiment (CNX) is used for identifying the high-risk variables i.e Percentage of Organic Modifier (% methanol), pH of the Buffer and flow rate of the mobile phase. The surface response methodology was applied to optimize the critical method parameters (CMP) as well as Critical Quality Attributes (CQA) to find out the Design space of the method. The Optimum assay method condition was mobile phase Acetate Buffer (50mM) pH 5.4: Methanol (11:89), Flow rate: 0.9 ml/min, Lambda Max: 207. The separation was achieved in the Eclip Plus C-18 column (250 × 4.6 mm, 5μm) at ambient temperature. The retention time of Boceprevir was found to be 4.2 min. The method evaluation was performed according to the (Q2R1) ICH guideline.

Development of Ion pair Chromatography Method for Assay of Telaprevir by Response Surface Methodology

Response surface methodology approach has been utilized for the assay of Telaprevir in pure and formulation using ion-pair chromatography. In this, A risk assessment approach (Control-Noise-Experiment) has been used for identifying the risk factors, i.e. Percentage of Organic Modifier (% Acetonitrile), Buffer’s pH and flow rate of the method. The Central Composite design was applied to optimize the critical method parameters (CMPs) and to find out the Design space (DS) of the method. The coefficient of correlation (R2),%CV and Lack of fit are utilized for the evaluation of method responses (Retention time and Asymmetric factor Evaluation of model is justified by two diagnostic plots (normal probability plot of residuals and plot of residuals vs predicted values). The mobile phase is Acetate Buffer (20mM) pH 4.4: Acetonitrile (35:65) with 0.9 ml/min of Flow rate. The separation has taken placed in the Eclip Plus C-18 column (250 × 4.6 mm, 5μm) at 268 nm. The retention time of Boceprevir was found to be 4.6 min. The validation of the optimized method has performed according to ICH guideline. The method has been successfully used for routine analysis of the Telaprevir throughout the life cycle of the product.