Stability-indicating High-performance Liquid Chromatography Method Research Articles

Development and validation of a stability-indicating HPLC method for assay of tonabersat in pharmaceutical formulations

A stability-indicating reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed to assay tonabersat and assess its stability in pharmaceutical formulations. Chromatographic separation was achieved using a Kinetex® C18 column (2.6 µm, 150 x 3 mm, 100 Å) at 50 °C, with a 20 µL injection volume. A linear gradient of acetonitrile in water (5 – 33.5 %) was applied for 1 min, followed by a gradual increase to 100 % over 26 min at a flow rate of 0.5 mL/min. Tonabersat and its degradation products were detected at 275 nm and 210 nm, respectively. The optimized method was used to evaluate the stability of tonabersat in lipid-based pharmaceutical formulations at 5 ± 3 °C, 25 ± 2°C/60 ± 5 % RH, and 40 ± 2 °C/75 ± 5 % RH over 3 months. The method was validated as per ICH guidelines and demonstrated linearity in the range of 5 – 200 µg/mL (R2 = 0.99994) with good accuracy (98.25 – 101.58 % recovery) and precision (% RSD < 2.5 %). The limits of detection and quantitation were 0.8 µg/mL and 5 µg/mL, respectively. Forced degradation studies showed significant degradation on exposure to alkaline (90.33 ± 0.80 %), acidic (70.60 ± 1.57 %), and oxidative stress (33.95 ± 0.69 %) at 70 °C, but no degradation was observed on exposure to thermal or photolytic stress. No chemical degradation was observed in either formulation on storage. Thus, the method was sensitive, specific, and suitable for stability testing of tonabersat in pharmaceutical formulations.

Analytical quality by design-based stability-indicating high performance liquid chromatography method for the estimation of evogliptin tartrate in bulk and tablet dosage form.

The present study utilized Analytical Quality by Design (AQbD) approach to develop a stability-indicating high-performance liquid chromatography (HPLC) method for estimating evogliptin tartrate using design expert software. The key parameters were methodically optimized, contours were plotted, and stability was evaluated using various forced degradation conditions. Using an Agilent HPLC system with a photo diode array (PDA) detector along with Fortis C18 column (250 × 4.6mm, 5μm) effectively separated the drug from its degradants. The mobile phase used was methanol: water (pH adjusted to 3.0, 76:24; v/v) at 0.8mL/min flow rate. Evogliptin was eluted at 2.98 min, at a detection wavelength of 267 nm. The proposed method was found to be specific, precise, linear and robust. The drug was sensitive to acidic, basic, oxidative, thermal, and photodegradation resolving six degradation products. Thus, the developed AQbD-based stability-indicating HPLC method is applicable in analyzing evogliptin in bulk, tablet dosage form and stability samples.

Development and Validation of a Novel Stability-Indicating Reverse Phase High-Performance Liquid Chromatography Method for the Quantification of Capivasertib in Bulk Drug and Pharmaceutical Dosage Form

The quantification of capivasertib has been achieved using a Waters Symmetry column with UV detection at 260 nm through a novel stability-indicating reverse-phase high-performance liquid chromatography (RP-HPLC) method that has been established and verified. The analysis can be completed in just 5 minutes. The separation and collection of capivasertib occurred at a retention time of 3.3475 minutes. The concentration range of capivasertib was shown to be linear, ranging from 50 to 300 μg/mL. The regression equations for capivasertib were determined as y = 13485.85x + 1723.04. The detection limit for capivasertib was determined to be 0.6 μg/mL, while the quantification limits were established at 2.00 and 0.5000 μg/mL, respectively.

Stability-Indicating HPLC Method for Determination of Ibuprofen and Famotidine Degradation Products.

A new stability-indicating high-performance liquid chromatographic method for the quantitative determination of ibuprofen and famotidine degradation products in combined pharmaceutical products was developed and validated. The current aim of this study is to develop a rapid, accurate and robust analytical stability indicating impurity method that can separate ibuprofen, famotidine and their related impurities by using a reversed-phase high-performance liquid chromatography. A Zorbax SB-Phenyl column (4.6 × 150mm2, 5-μm particle size) with mobile phase containing phosphate buffer solution with a pH value of 3.0 and acetonitrile was used. The flow rate was 0.8mL/min and the analytes were detected by UV detector at 265nm. The retention times of ibuprofen and famotidine were 18.43 and 5.14min, respectively. This method was validated to confirm specificity, linearity, sensitivity (limit of detection and limit of quantitation), precision, accuracy, robustness and sample stability according to the International Conference on Harmonization guidelines. Studies have been completed and reported with two active substances in the combined dosage form and seven impurities in total. There is no method in the literature that simultaneously distinguishes and quantitatively analyzes both active substances and degradation products.

LC-MS/MS characterization of stress degradation products of Gilteritinib and establishment of HPLC method for analysis of process related impurities of Gilteritinib

Background: The current investigation entails the characterization of seven degradation products (DPs) formed in different stress conditions of gilteritinib employing liquid chromatography-tandem mass spectrometry (LC-MS/MS). Methodology: This study developed a stability-indicating reversed-phase high-performance liquid chromatographic (HPLC) method for precisely determining gilteritinib in the presence of its process-related impurities in bulk drug and formulation samples. To explore the stability profile of gilteritinib, it was exposed to forced degradation experiments conducted under various conditions, including acidic, basic, oxidative, photolytic, and thermal stress. These experiments revealed the degradation of gilteritinib under basic, acidic, and photolytic conditions, forming seven distinct DPs. Result: The chromatographic resolution of gilteritinib and its impurities along with DPs was effectively achieved using a Waters Symmetry C18 (250 mm × 4.6 mm, 5 μm) column using equal volumes of solvent A and B (pH 4.5 phosphate buffer and acetonitrile in 25:75 (v/v) as solvent A, acetonitrile and methanol in 75: 25 (v/v) as solvent B) pumped isocratically at 0.7 mL/min and 230 nm wavelength. The method produces an accurate fit calibration curve in 25-175 μg/mL for gilteritinib and LOQ (0.025 μg/mL) – 0.175 μg/mL for its impurities with acceptable precision, accuracy, and recovery. Conclusion: The efficacy of this method was validated through LC-MS/MS, which allowed for the verification of the chemical structures of newly generated degradation products of gilteritinib. Hence, this method is appropriate for the resolution and evaluation of process-related impurities of gilteritinib and can also be applied for evaluating stress degradation products.

Simultaneous Determination of Fipronil, Permethrin, and Their Key Related Substances in a Topical Drug Product by a Single Stability-Indicating High-Performance Liquid Chromatography Method.

The topical veterinary drug product containing fipronil and permethrin provides an effective repellent protection and high insecticidal efficacy for dogs. The objective of this study was to develop a stability-indicating high-performance liquid chromatography (HPLC) method for simultaneous detection and quantification of fipronil, permethrin, their key degradation products, and butylated hydroxytoluene (BHT) in a topical drug product. The two active ingredients, their degradation products, and the antioxidant (BHT) were separated by a gradient elution on a Phenomenex Kinetex C18 column (150 × 3 mm, 2.6 µm particle size) maintained at 37°C with H2O acetonitrile isopropyl alcohol 85% H3PO4 (65.5 + 32.5 + 4/0.0053, v/v/v/v) as mobile phase A and acetonitrile (100%) as mobile phase B. The flow rate was 0.9 mL/min, and analytes were detected and quantified at 235 nm. The specificity of the method was demonstrated by adequate separation of fipronil, permethrin, their degradation products, and BHT in the forced degraded finished product. The linearity of the method was demonstrated in the range of 0.2% to 150% of target analytical concentration of both active ingredients and 50% to 150% for BHT. Excellent recoveries of fipronil, permethrin, and BHT in placebo spiked active ingredient solutions in the linearity range showed sufficient accuracy of the method. The LOQ and LOD of the method were determined to be 0.2% and 0.07% of the analytical concentration. A robustness study did not identify any critical parameter that adversely affected the separation and quantification. Here, we report the development and validation of a robust, stability-indicating HPLC method for identification and assay of fipronil, permethrin, and BHT, including estimation of fipronil's and permethrin's degradation products in a topical drug product for dogs. The new HPLC method permits the acquisition of data for all analytes of interest for a topical finished drug product containing fipronil, permethrin, and BHT.

Stability-indicating HPLC method optimization using quality by design with design of experiments approach for quantitative estimation of organic related impurities of Doripenem in pharmaceutical formulations

Doripenem (DM), an antibiotic used for kidney, lung, and urinary infections, underwent the development of a robust high-performance liquid chromatography (HPLC) technique using the quality-by-design approach. This method, integrating design-of-experiments, detected organic impurities in both drug substances and formulated products. Operating with a C18 analytical column in a binary gradient mode with potassium phosphate buffer (pH 6.1) and acetonitrile as mobile phases, the method ran at a flow rate of 1.20 ml/minutes, with an injection volume of 20-μl and a column temperature of 45°C. Stability testing under various conditions, including hydrolysis, oxidation, heat, humidity, and light exposure, confirmed the method’s reliability without interference. Validation studies, compliant with ICH guidelines, revealed quantitation limits of 0.006%, linearity between 0.060 and 1.800 μg/ml (R2 &gt; 0.999), and recoveries ranging from 96.8% to 99.1%. This HPLC method was effectively used for stability assessment in quality control testing, assessing doripenemic acid, doripenem assay, and organic impurities.

A quality-by-design evaluated liquid chromatography method development and validation for the separation and quantification of nitroxoline and its impurities.

A novel, isocratic, sensitive, stability-indicating high-performance liquid chromatography method was developed for the separation and quantification of related substances in nitroxoline (NTL). The chromatographic separation has been achieved on Inertsil ODS-3V, (250 × 4.6mm, 5μm) at 240nm using ethylenediamine tetraacetic acid buffer and methanol in the ratio of 60:40 v/v as mobile phase. The performance of the method has been checked as per the International Conference on Harmonization guidelines for specificity, linearity, accuracy, precision, and robustness. Regression analysis showed a correlation coefficient value greater than 0.99 for NTL and its three impurities. The detection limit of impurities was in the range of 0.01% (0.05μg/mL)-0.22% (1.1μg/mL) indicating the sensitivity of the newly developed method. The accuracy of the method was established based on the recovery obtained between 94.7% and 104.1% for all the impurities. The percentage relative standard deviation obtained for the repeatability was less than 4.0% at the specification level for all impurities. Forced degradation was performed to establish the stability-indicating nature of the method and to know about the degradation products, the quality of a drug substance changes with time under the influence of stress conditions. Thus, the proposed method was validated and found to be specific, sensitive, linear, accurate, precise, reproducible, and beneficial for routine usage.

Separation and quantitative estimation of stereo-selective enantiomers of montelukast in pharmaceutical drug substance and tablets dosage forms by using stability-indicating normal phase-HPLC method.

Montelukast sodium (MLS) is a leukotriene receptor antagonist that relieves asthma, bronchospasm, allergic rhinitis, and urticaria. A simple, robust, and stability-indicating normal phase high-performance liquid chromatography method was developed to separate and quantitatively estimate the S-enantiomer of MLS. The chiral separation was achieved using USP L51 packing material along with a mobile phase consisting of a solvent mixture (n-hexane, ethanol, and propionic acid), a flow rate of 1.0mL/min, a detection wavelength of 284 nm, a column temperature of 30°C and an injection volume of 20 μL. The enantiomers peaks were well separated from the peaks of the placebo, diluting solvent, MLS, and its known impurities with a resolution of more than 2.2 and with no interference. Accuracy and linearity were studied in a range of 0.36-3.597 μg/mL (0.03%-0.30%), with good recoveries between 92.5% and 96.8% and a linear regression coefficient above 0.996. The suggested chiral chromatography method is being considered as an alternative and equivalent method to the United States Pharmacopeia and European Pharmacopeia monographs. The developed method was effectively employed for the study of release and stability samples of MLS. This HPLC method is also capable of separating and estimating the stereo-selective isomers (R- and S-enantiomers) of sulfoxide impurity of MLS in pharmaceutical medicine.

Environmentally friendly stability-indicating HPLC method for the determination of isotretinoin in commercial products and solubility samples

In this study, an environmentally friendly “high-performance liquid chromatography (HPLC)” assay to quantify isotretinoin (ITN) in commercial products and solubility samples is designed and verified. A Nucleodur reverse-phase C18 column was used as the stationary phase to identify ITN. The ecologically friendly mobile phase was composed of ethyl acetate and ethanol (50:50 v/v), and it was delivered at a flow rate of 1.0 mL/min. ITN was measured at 354 nm in wavelength. The current HPLC method had a determination coefficient of 0.9994 and was linear in the 0.2–80 μg/g range. The current protocol for ITN measurement was also rapid (retention time = 2.78 min), accurate (%recoveries = 98.60–101.52), precise (% uncertainties = 0.71–0.98), and sensitive. According to the AGREE methodology, the current procedure received an outstanding greenness profile with an AGREE score of 0.76. By determining ITN in commercial products and solubility samples, the applicability of the current approach was proven. ITN was discovered to be present in 98.43% and 100.84%, respectively, of commercial capsule brands A and B. The ITN's solubility in numerous eco-friendly solvents was successfully measured. Under different stress conditions, the current approach was able to distinguish between its degradation products, demonstrating its stability-indicating characteristics. These findings indicated that ITN in procured capsules and solubility samples might be regularly tested by the suggested approach.

Green micellar stability-indicating high-performance liquid chromatography method for determination of rupatadine fumarate in the presence of its main impurity desloratadine: Oxidative degradation kinetics study.

A green micellar stability-indicating high-performance liquid chromatography method was developed for rupatadine fumarate determination in existence with its main impurity desloratadine. Separation was attained using Hypersil ODS column (150×4.6mm, 5μm), the micellar mobile phase consisted of 0.13M sodium dodecyl sulfate, 0.1M disodium hydrogen phosphate adjusted by phosphoric acid to pH 2.8 and 10% n-butanol. The column was maintained at 45◦ C and detection was carried out at 267nm. A linear response was achieved over the range of 2-160μg/ml for rupatadine and 0.4-8μg/ml for desloratadine. The method was applied for rupatadine determination in alergoliber tablets and alergoliber syrup without the interference of methyl paraben and propyl paraben present as main excipients. Rupatadine fumarate revealed pronounced susceptibility to oxidation; further study of oxidative degradation kinetics was carried out. Rupatadine was found to follow pseudo-first-order kinetics when exposed to 10% H2 O2 at 60 and 80°C and the activation energy was found to be 15.69Kcal/mol. At a lower temperature (40°C), degradation kinetics regression was best fitted as a polynomial quadratic relationship, thus rupatadine oxidation at a lower temperature tends to adopt a second-order kinetics rate. Oxidative degradation product structure was revealed using infrared and found to be rupatadine N-oxide at all temperature values.

A New Stability-Indicating RP-HPLC Method for Simultaneous Quantification of Diacerein and Aceclofenac in Novel Nanoemulgel Formulation and Commercial Tablet Dosage Form in the Presence of their Major Degradation Products Using DoE Approach.

The present study aimed to develop a simple, robust, sensitive and effective stability-indicating reversed-phase high-performance liquid chromatography method for simultaneous quantification of diacerein (DCN) and aceclofenac (ACE) in novel nanoemulgel formulation and commercial tablets in the presence of their main degradation product: rhein (RH) and diclofenac sodium (DLS), respectively. A fractional factorial design was used to screen the crucial independent factors, whereas a central composite design was used for the optimization of the chromatographic conditions. The separation was carried out on Phenomenex C18 column (5μm, 250 × 4.6mm), using a mobile phase consisting of phosphate buffer pH3 (0.1% v/v orthophosphoric acid) and acetonitrile (40:60v/v) at a flow rate of 1mL/min with detection at 264nm. The analytes were exposed to a variety of stress conditions, including heat, alkali, acid, oxidation, photochemical, humidity and hydrolysis. DCN, ACE, RH and DLS were found to have retention times of 4.32 ± 0.15, 5.77 ± 0.07, 8.28 ± 0.20 and 9.10 ± 0.18min, respectively. The percent recovery for all four analytes was found to be between 98 and 102, and the procedure was discovered to be linear in the range of 0.1-64μg/mL with R2 value > 0.999. The established method was validated as per ICH guidelines and successfully used to assay DCN and ACE in their combined marketed tablet dosage form and developed nanoemulgel formulation.

Stability indicating HPLC method development and validation of Fostemsavir in bulk and marketed formulations by implementing QbD approach

Background: Achieving a predictable degree of quality with intended and planned specifications is known as "quality by design." QbD (Quality-by-Design) is an alternative to conventional method development that places more attention on identifying and mitigating potential risks. Component of the Quality-by-Design methodology involves conducting a series of experiments to learn how various factors, including the dependant variables, affect the answers of interest. Here, we use a QbD (Quality-by-Design) loom to detail the creation and verification of a stability-indicating high-performance liquid chromatography (HPLC) method for Fostemsavir in both bulk and finished-goods forms.&#x0D; Results:&#x0D; In this work, we present a workable experimental design for optimising the RP-HPLC separation technique by identifying the optimum mobile phase concentration and flow rate. Below are the ideal chromatographic conditions as calculated by Design Expert version 13.0: Mobile phase: 80 parts acetonitrile to 20 parts formic acid (v/v), flow rate: 0.8 millilitres per minute, retention time: 3.24 minutes, column dimensions: GIST C18 (250 mm × 4.6 mm × 5.0 μm).&#x0D; Here we propose a practical experimental layout for determining the optimal mobile phase concentration and flow rate for the RP-HPLC separation technique. Using Design Expert version 13.0, the optimum chromatographic conditions were determined to be as follows: Shim-pack GIST C18 (250 mm 4.6 mm, 5.0 μ), mobile phase acetonitrile to 1% formic acid (80:20, v/v), flow rate 0.8 ml/min, and retention period 3.24 min.&#x0D; At a detection wavelength of 266 nm, it was discovered that the devised technique was linear over a concentration range of 50-90 μg/ml (r2 = 0.997). Test parameters for the system's appropriateness were determined to be 1.124 for the tailing factor and 9480 for the theoretical plates. Intraday RSD was found to range from 0.70 to 0.94, whereas interday RSD was found to range from 0.55 to 0.95 percent. Values for robustness were under 2%. The solution stability % RSD was calculated to be 0.83. The result of the assay was 100.05 percent. The created methodologies were used to studies of forced degradation, and the stressed materials were analysed. The parameters used to validate the procedure fell within the acceptable range recommended by ICH.&#x0D; Conclusion: Using Design Expert 13.0, we created a central composite design experiment that illustrates the relationships between mobile phase and flow rate across three levels, with retention duration, tailing factor, as well as theoretical plates as the responses of interest. By this work, we gain insight into the variables that affect chromatographic separation and strengthen our conviction that the HPLC method we've devised will serve our needs. Quantitative method development was applied to improve comprehension of multi-tiered method variables.

Development and validation of a stability-indicating RP-HPLC method for the determination of fifteen impurities in rivaroxaban

A simple and stability-indicating reverse phase high-performance liquid chromatographic (RP-HPLC) method for the determination of rivaroxaban (RIX) and its related substances was developed. Fifteen impurities of RIX, including three unreported isomers, were identified, synthesized, purified, and confirmed using MS, 1H NMR, 13C NMR, and HSQC spectral methods. This new method offered baseline separation for all monitored impurities, and was fast and reliable when compared to the European Pharmacopoeia method. Optimum separation for RIX and its related impurities was achieved on an octyldecyl silica column (YMC Core C18, 4.6 ×100 mm, 2.7 µm) by using a gradient HPLC method in 38 min. The final method was validated with respect to precision, LOD and LOQ, linearity, accuracy, and robustness. This developed method was suitable for routine quality control and drug analysis of RIX active substance.

Analytical Purity Determinations of Universal Food-Spice Curcuma longa through a QbD Validated HPLC Approach with Critical Parametric Predictors and Operable-Design’s Monte Carlo Simulations: Analysis of Extracts, Forced-Degradants, and Capsules and Tablets-Based Pharmaceutical Dosage Forms

Applications of analytical quality by design (QbD) approach for developing HPLC (High Performance Liquid Chromatography) methods for food components assays, and separations of complex natural product mixtures, are still limited. The current study developed and validated, for the first time, a stability-indicating HPLC method for simultaneous determinations of curcuminoids in Curcuma longa extracts, tablets, capsules, and curcuminoids' forced degradants under different experimental conditions. Towards separation strategy, critical method parameters (CMPs) were defined as the mobile phase solvents' percent-ratio, the pH of the mobile phase, and the stationary-phase column temperature, while the peaks resolution, retention time, and the number of theoretical plates were recognized as the critical method attributes (CMAs). Factorial experimental designs were used for method development, validation, and robustness evaluation of the procedure. The Monte Carlo simulation evaluated the developing method's operability, and that ensured the concurrent detections of curcuminoids in natural extracts, commercial-grade pharmaceutical dosage-forms, and the forced degradants of the curcuminoids in a single mixture. The optimum separations were accomplished using the mobile phase, consisting of an acetonitrile-phosphate buffer (54:46 v/v, 0.1 mM) with 1.0 mL/min flow rate, 33 °C column temperature, and 385 nm wavelength for UV (Ultra Violet) spectral detections. The method is specific, linear (R2 ≥ 0.999), precise (% RSD < 1.67%), and accurate (% recovery 98.76-99.89%), with LOD (Limit of Detection) and LOQ (Limit of Quantitation) at 0.024 and 0.075 µg/mL for the curcumin, 0.0105 µg/mL and 0.319 µg/mL for demethoxycurcumin, and 0.335 µg/mL and 1.015 µg/mL for the bisdemethoxycurcumin, respectively. The method is compatible, robust, precise, reproducible, and accurately quantifies the composition of the analyte mixture. It exemplifies the use of the QbD approach in acquiring design details for developing an improved analytical detection and quantification method.

Inclusion Complex of Clomiphene Citrate with Hydroxypropyl-β-Cyclodextrin for Intravenous Injection: Formulation and Stability Studies.

Clomiphene citrate is the first-line treatment for women with abnormal or failed ovulation. Currently, it is available as oral tablets, and the parenteral formulation does not exist. In this study, we prepared clomiphene citrate-hydroxypropyl-β-cyclodextrin inclusion complex for its use in intravenous injection. The inclusion complex was characterized in the liquid state (phase solubility) and solid state by differential scanning calorimetry, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy analyses. The sterile intravenous injection containing 0.5% clomiphene citrate was prepared and characterized for its physical properties, assay, pH, and osmolality. A stability-indicating high-performance liquid chromatography (HPLC) method for the injection was developed. The HPLC method was validated for the assay, linearity, precision and repeatability, benchtop stability, and forced degradation to elute clomiphene isomers from the degradation products. The injection was packed in sterile 10-ml glass vials with butyl rubber stoppers and stored at 40°C, room temperature, and 4°C. The samples at 0, 0.5, 1, 2, 3, and 6months were analyzed for clarity, pH, osmolality, and drug assay. The HPLC method was linear (R2 = 0.9999), precise (0.86% relative standard deviation), and stability indicating. The stability data at the accelerated (40°C) storage condition for 6months showed satisfactory results: the drug assay in the injection was between 90 and 105%, the injection remained clear, pH was between 4.0 and 4.4, and osmolality was between 270 and 350mOsm. The stability data suggests that the product is stable and meets the given analytical specifications.

Development and Validation of Stability-indicating High-Performance Liquid Chromatography Method for Estimation of Organic Impurities of Carvedilol from Bulk and its Dosage Form

Development and Validation of Stability-indicating High-Performance Liquid Chromatography Method for Estimation of Organic Impurities of Carvedilol from Bulk and its Dosage Form

Determination of Firocoxib and Its Related Substances in Bulk Drug Substance Batches of Firocoxib by a High-Speed Reversed-Phase HPLC Method With a Short Fused-Core Biphenyl Column.

Firocoxib is a nonsteroidal anti-inflammatory drug. It provides control of postoperative pain and inflammation associated with soft tissue and orthopedic surgery in dogs, and control of pain and inflammation associated with osteoarthritis in horses. A high-speed stability-indicating reversed-phase high-performance liquid chromatography method was developed to determine firocoxib and its related substances in bulk batches of firocoxib drug substance. Firocoxib was dissolved in neat acetonitrile (ACN) and analyzed on a short HALO (fused-core) biphenyl column (30 × 4.6mm i.d., 2.7-μm particle size) at flow rate of 2.5mL/min. Column temperature was maintained at 50°C. Mobile phase A is composed of 0.1% of H3PO4 in water and mobile phase B is composed of ACN. Analytes were detected with UV detection at 240nm and quantitated against an external reference standard. Firocoxib and its related compounds were adequately separated within 4min by a gradient elution. The method was validated for specificity, linearity, accuracy, precision and robustness according to method validation guidelines described in The International Conference on Harmonization. The validation data demonstrated that this method is sensitive, accurate, robust, specific and stability-indicating.

Development and Validation of Stability-Indicating High-Performance Liquid Chromatography Method for Estimation of Lacosamide in Bulk and Its Pharmaceutical Dosage Form.

A simple, specific, accurate and stability-indicating reversed-phase high-performance liquid chromatographic method was developed for the determination of lacosamide, using C18 column and a mobile phase composed of phosphate buffer (pH4.0):acetonitrile (40:60v/v). The retention time of lacosamide was found to be 2.7min. Linearity was established for lacosamide in the range of 10-50μg/mL. The percentage recovery of lacosamide was found to be in the range of 97.37-99.20%. The drug was subjected to acid, alkali, oxidation, dry heat and photolytic degradation. The degradation studies indicated condition was well resolved from the pure drug with significant differences in their retention time values. This method can be successfully employed for quantitative analysis of lacosamide in bulk drug and formulation.

Degradation pathways and impurity profiling of the anticancer drug apalutamide by HPLC and LC-MS/MS and separation of impurities using Design of Experiments.

Apalutamide, an androgen receptor inhibitor, is used to treat prostate cancer. A stability-indicating high-performance liquid chromatography method was developed for the estimation of assay and organic impurities of apalutamide in drug substance and in tablet dosages using Design of Experiments. The chromatographic separation was achieved within 30 min using Atlantis dC18 , 100 × 4.6mm, 3.0 μm and the binary gradient program (10 mm KH2 PO4 , pH3.5; acetonitrile). The detection wavelength, flow rate, column temperature and injection volume used were 270 nm, 1.0 ml/min, 45°C and 10 μl, respectively. The interaction of independent variables (pH, column temperature and flow rate) and their influences on HPLC parameters were studied using a central composite design, and then the peak separation and elution behaviors between apalutamide and its seven impurities were determined. The method validation was performed for linearity, detection limit, quantitation limit, accuracy, precision and robustness as per the International Conference on Harmonization. A high-quality recovery with good precision (91.7-106.0%) and correlations (r2 > 0.997) within a linear range of 0.12-2.24 μg/ml (0.05-0.3%, w/w) were achieved consistently for assay and organic impurities of apalutamide. The stability-indicating characteristics of the proposed method were assessed through forced degradation and mass balance studies. An effort was made to figure out the chemical structures of newly formed degradation products (DP1-DP5) using LC-MS/MS.