An Overview of Degradation Strategies for Amitriptyline

Antidepressant drugs play a crucial role in the treatment of mental health disorders, but their efficacy and safety can be compromised by drug degradation. Recent reports point to several drugs found in concentrations ranging from the limit of detection (LOD) to hundreds of ng/L in wastewater plants around the globe; hence, antidepressants can be considered emerging pollutants with potential consequences for human health and wellbeing. Understanding and implementing effective degradation strategies are essential not only to ensure the stability and potency of these medications but also for their safe disposal in line with current environment remediation goals. This review provides an overview of degradation pathways for amitriptyline, a typical tricyclic antidepressant drug, by exploring chemical routes such as oxidation, hydrolysis, and photodegradation. Connex issues such as stability-enhancing approaches through formulation and packaging considerations, regulatory guidelines, and quality control measures are also briefly noted. Specific case studies of amitriptyline degradation pathways forecast the future perspectives and challenges in this field, helping researchers and pharmaceutical manufacturers to provide guidelines for the most effective degradation pathways employed for minimal environmental impact.

The CombE-IDMS Alternate Potency Method for H5N1 and H5N8 Cell-Based Vaccines

Assaying the potency of inactivated viral influenza vaccines is performed using single radial immunodiffusion, which is the globally accepted release method for potency. Under conditions of a rapidly emerging pandemic, such as the 2009 H1N1 influenza pandemic, a recognized obstacle in the delivery of vaccines to the public is the time needed for the distribution of calibrated SRID reagents (antisera and antigen standards) to vaccine manufacturers. Previously, we first described a novel streamlined MS-based assay, CombE-IDMS, which does not rely on antisera/antibodies or reference antigens, as a potential rapidly deployable alternate potency method through a comparison with SRID on adjuvanted seasonal quadrivalent vaccine cell-based (aQIVc) materials. In this report, we further demonstrate that the CombE-IDMS method can also be applied to measure the potency of pre-pandemic H5N1 and H5N8 monovalent vaccine materials, each subtype both unadjuvanted and adjuvanted, through a forced degradation study. Overall, CombE-IDMS results align with those of the gold standard SRID method on both H5N1 and H5N8 materials under conditions of thermal, pH, oxidative and freeze/thaw stress, lending further evidence for the CombE-IDMS method's suitability as an alternate assay for potency of both seasonal and pandemic influenza vaccines.

Quantitation of native and forced degraded collagens by capillary zone electrophoresis: Method development and validation

A new capillary zone electrophoresis method for collagen quantitation was developed and validated according to the International Council for Harmonization guideline Q2 (R1). The Sircol collagen assay and ultraviolet spectrometry were employed as reference methods. Capillary zone electrophoresis enables specific, simple, and fast determination within 9 min. It is less user-dependent and more automated than the Sircol collagen assay. With a limit of detection of 18.0 μg/mL, the new method is less sensitive than the Sircol collagen assay, which has a limit of detection of 6.5 μg/mL. Nonetheless, capillary zone electrophoresis covers a wider linearity range (50-400 μg/mL) compared to the Sircol collagen assay (5-80 μg/mL), with similar precision. Additional advantages of capillary zone electrophoresis are the ability to gain information on collagen integrity and to simultaneously determine native and denatured collagens. This approach represents a modern and legitimate alternative to the Sircol collagen assay. The developed method has been successfully applied to the study of three collagen products and samples from forced degradation.

Validation of stability-indicating LC method, degradation study, and impact on antioxidant and antifungal activities of Eugenia uniflora leaves extract

The aim of this study is to demonstrate the stability-indicating capacity of an analytical method for Eugenia uniflora, enhance understanding of the stability of myricitrin, and assess the effect of degradation of spray-dried extract (SDE) on antioxidant and antifungal activities. Validation of the stability-indicating method was carried out through a forced degradation study of SDE and standard myricitrin. The antioxidant and antifungal activities of SDE were evaluated both before and after degradation. The quantification method described was found to be both accurate and precise in measuring myricitrin levels in SDE from E. uniflora, with excellent selectivity that confirmed its stability-indicating capability. The forced degradation study revealed that the marker myricitrin is sensitive to hydrolysis, but generally stable under other stress conditions. By contrast, the standard myricitrin displayed greater susceptibility to degradation under forced degradation conditions. Analysis of the antioxidant activity of SDE before and after degradation showed a negative impact in this activity due to degradation, while no significant effect was observed on antifungal activity. The method described can be a valuable tool in the quality control of E. uniflora, and the findings can assist in determining the optimal conditions and storage of products derived from this species.

Biological Assay to Determine Gonadotropin Potency: From In Vivo to In Vitro Sustainable Method

Various preparations of follicle-stimulating hormone (FSH) are commercially available; however, they differ in glycoforms composition and purity owing to their respective sources. Additional chemical/physical changes can also be introduced during manufacturing and can impact their biological activity (biopotency), which is routinely assessed using an in vivo bioassay (Steelman-Pohley). This study aimed to determine whether an in vitro bioassay could assess biopotency by distinguishing between r-hFSH chemical/physical variants with similar ability to the in vivo bioassay. The specific activity (units of biological activity per mg of product) of variants of r-hFSH generated through enrichment (acidic/basic), stress (oxidative/acidic pH) and enzymatic treatment (desialylation and desialylation/degalactosylation) was compared using the in vivo and in vitro bioassays. The in vitro bioassay reliably detected potential chemical/physical modifications in r-hFSH variants that may impact biopotency. Overall, the methods demonstrated a comparable ability to detect changes in specific activities due to chemical/physical differences in r-hFSH variants. These data indicate that the in vitro bioassay is suitable to replace the in vivo bioassay.

Quality by Design (QbD)-Steered Development and Validation of Analytical and Bioanalytical Methods for Raloxifene: Application of Monte Carlo Simulations and Variance Inflation Factor

A sensitive, rapid, reproducible and economical high-performance liquid chromatographic (HPLC) method is reported for the quantification of raloxifene hydrochloride employing QbD principles. Factor screening studies, employing Taguchi design, indicated buffer volume percentage and isocratic flow rate as the critical method parameters (CMPs), which significantly influence the chosen critical analytical attributes, i.e., tailing factor and theoretical plate number. Method conditions were subsequently optimized using face-centered cubic design with magnitude of variance inflation factor for assessing multicollinearity among CMPs. Method operable design region (MODR) was earmarked and liquid chromatographic separation optimized using 0.05 M citrate buffer, acetonitrile, and methanol (57:40:3 v/v/v) as mobile phase at 0.9 mL.min^-1 flow rate, λ_max of 280 nm and column temperature of 40°C. Validation of developed analytical method was accomplished as per ICH guidelines confirming high levels of linearity, precision, accuracy, robustness, and sensitivity. Application of Monte Carlo simulations enabled the attainment of best plausible chromatographic resolution and corroboration of the MODR, thus demarcated. Establishment and validation of the bioanalytical method using rat plasma samples, along with forced degradation and stability studies, corroborated the aptness of developed HPLC methods for drug quantification in the biological fluids, as well as in bulk and marketed dosage forms.

Development, stability-Indicating assessment, and evaluation of influential method conditions using a full factorial design for the determination of Nintedanib Esylate related impurities

The design of an appropriate analytical method for assessing the quality of pharmaceuticals requires a deep understanding of science, and risk evaluation approaches are appreciated. The current study discusses how a related substance method was developed for Nintedanib esylate. The best possible separation between the critical peak pairs was achieved using an X-Select CSH Phenyl Hexyl (150 × 4.6) mm, 3.5 μm column. A mixture of water, acetonitrile, and methanol in mobile phase-A (70:20:10) and mobile phase-B (20:70:10), with 0.1% trifluoroacetic acid and 0.05% formic acid in both eluents. The set flow rate, wavelength, and injection volumes were 1.0 mL/min, 285 nm, and 5 μL, respectively, with gradient elution. The method conditions were validated as per regulatory requirements and United States Pharmacopeia general chapter <1225>. The correlation coefficient for all impurities from the linearity experiment was found to be >0.999. The % relative standard deviation from the precision experiments ranged from 0.4 to 3.6. The mean % recovery from the accuracy study ranged from 92.5 to 106.5. Demonstrated the power of the stability-indicating method through degradation studies; the active drug component is more vulnerable to oxidation than other conditions. Final method conditions were further evaluated using a full-factorial design. The robust method conditions were identified using the graphical optimization from the design space. This article is protected by copyright. All rights reserved.

Development of stability-indicating method for separation and characterization of benidipine forced degradation products using LC-MS/MS

The present study describes forced degradation of benidipine (BEN) as per  Q1A (R2) and Q1B guidelines of the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. BEN degraded under hydrolysis (neutral, acidic, and alkaline), hydrogen peroxide induced oxidation, and UV light mediated photolytic degradation. A total of 14 degradation products (DPs) were found in all degradation studies, comprising 4 hydrolytic DPs, 8 oxidative DPs, and 4 photolytic DPs. A selective stability-indicating method was developed using an XBridge BEH C18 column with gradient elution program consisting of ammonium acetate (10 mM, 4.8 pH, acetic acid) and acetonitrile. The flow rate was maintained at 1 ml min^-1 . All DPs were separated well using the developed HPLC method and were characterized using LC-MS/MS data. As this method is effective in identifying and separating BEN and its DPs with sufficient resolution, it can be used in laboratories for quality control of drugs in daily routine analysis and stability studies.

Structural elucidation of two novel degradants of lurasidone and their formation mechanisms under free radical-mediated oxidative and photolytic conditions via liquid chromatography-photodiode array/ultraviolet-tandem mass spectrometry and one-dimensional/two-dimensional nuclear magnetic resonance spectroscopy

Lurasidone is an antipsychotic drug clinically used for the treatment of schizophrenia and bipolar disorder. During a mechanism-based forced degradation study of lurasidone, two novel degradation products were observed under free radical-mediated oxidative (via AIBN) and solution photolytic conditions. The structures of the two novel degradants were identified through an approach combining HPLC, LC-MSⁿ (n = 1, 2), preparative HPLC purification and NMR spectroscopy. The degradant formed under the free radical-mediated condition is an oxidative degradant with half of the piperazine ring cleaved to form two formamides; a mechanism is proposed for the formation of the novel N,N'-diformyl degradant, which should be readily applicable to other drugs that contain a piperazine moiety that is widely present in drug molecules. The degradant observed under the solution photolytic condition is identified as the photo-induced isomer of lurasidone with the benzisothiazole ring altered into a benzothiazole ring.

The Characterization of Polysorbate

Polysorbates (PSs), including PS20 and PS80, are non-ionic surfactants widely used in the pharmaceutical industry to enhance drug solubility and stability. Despite their wide application, PSs are prone to degradation by either hydrolysis or oxidation in drug formulations during storage; therefore, a PS characterization method assessing protein products is needed for stability testing and for understanding the degradation pathway. In this article, we detail our protocol for sample preparation for forced degradation study and our instrumentation setup for PS profiling and quantitation in protein samples. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Sample preparation for forced degradation of polysorbate in protein samples Basic Protocol 2: Two-dimensional liquid chromatography coupled with charged aerosol detector or mass spectrometry to analyze polysorbate degradation.

Recent Progresses in Analytical Perspectives of Degradation Studies and Impurity Profiling in Pharmaceutical Developments: An Updated Review

Forced degradation studies have been used to simplify analytical methodology development and achieve a deeper knowledge about the inherent stability of active pharmaceutical ingredients (API) and drug products. This provides insight into degradation species and pathways. Identification of impurities in pharmaceutical products is closely related to the selection of the most appropriate analytical methods like HPLC-UV, LC-MS/MS, LC-NMR, GC-MS, and capillary electrophoresis. Herein, recent trends in analytical perspectives during 2018-April 14, 2021, are discussed based on forced and impurity degradation profiling of pharmaceuticals. Literature review showed that several methods have been used for experimental design and analysis conditions such as matrix type, column type, mobile phase, elution modes, detection wavelengths, and therapeutic category. Thus, since these factors influence the separation and identification of the impurities and degradation products, we attempted to perform a statistical analysis for the developed methods according to the abovementioned factors.

The impact of forced degradation conditions on mAb dimer formation and subsequent influence on aggregation propensity

Monoclonal antibody (mAb) aggregation can present major challenges for the development of biotherapeutics. An understanding of the molecular mechanisms of mAb aggregation is highly desirable both because it allows the performance of informed risk assessments regarding the criticality of mAb aggregates and because it may facilitate rational stabilization of aggregation prone regions. Here, we report the generation and isolation of dimer species of an IgG4 mAb (mAb1) that were present in stressed material under differing levels of temperature stress. We demonstrate the power of combining established higher order techniques with non-routine analysis, such as small-angle X-ray scattering, hydrogen/deuterium exchange mass spectrometry (HDX-MS), and protein conformational array enzyme-linked immunosorbent assay (PCA ELISA), and show that dimer species formed under temperature stress are structurally distinct from those present in unstressed mAb1. Specifically, stress-induced dimers are shown to adopt a more elongated conformation with a greater degree of unfolding when compared to native dimers. Analysis by HDX-MS and PCA ELISA, supported by in silico shape and charge molecular docking, enabled the identification of residues in both the variable and constant domains that appear to play a significant role in the dimerization of mAb1. Furthermore, we show that dimers formed under temperature stress are significantly more long-lived than those present in unstressed mAb1. We also present evidence that mAb1 dimers can behave as aggregation nuclei, and that dimers produced under high-temperature stress do so to a greater extent. This work presents an advancement in our understanding of the molecular mechanisms of mAb aggregation and highlights the importance of structural characterization of dimer species during the development of mAb biotherapeutics.Abbreviations: 2DSA: 2-Dimensional Spectrum Analysis; CD: Circular Dichroism; CDR: Complementarity-Determining Region; CQA: Critical Quality Attribute; DSC: Differential Scanning Calorimetry; FTIR: Fourier Transform Infrared spectroscopy; HDX-MS: Hydrogen/Deuterium Exchange Mass Spectrometry; HIC: Hydrophobic interaction chromatography; HMWS: High Molecular Weight Species; HOS: Higher Order Structure; mAb: Monoclonal Antibody; MD: Molecular Dynamics PCA; ELISA: Protein Conformational Array Enzyme-Linked Immunosorbent Assay; Rg: Radius of Gyration; SAXS: Small Angle X-ray Scattering; SE-HPLC: Size Exclusion High Performance Liquid Chromatography; SV-AUC: Sedimentation Velocity-Analytical Ultracentrifugation.

Design of experiments applied to stress testing of pharmaceutical products: A case study of Albendazole

Forced degradation tests are studies used to assess the stability of active pharmaceutical ingredients (APIs) and their formulations. These tests are performed submitting the API under extreme conditions in order to know the main degradation products in a short period of time. The results of these studies are used to assess the degradation susceptibility of APIs and to validate chromatographic analytical methods. However, most of degradation studies are performed using one-factor-at-the-time (OFAT) which does not consider the interactions between degradation variables. This work proposes the use of Design of Experiment (DoE) approach in forced degradation of albendazole (ABZ). It was used a central composite design (CCD) to evaluate the forced degradation in a multivariate way. Experiments were performed taking into account the variables pH, temperature, oxidizing agent (H₂O₂) and UV radiation. It was verified the influence of the variables and their interactions on the ABZ degradation. The ABZ oxidation showed to be the main degradation route for ABZ, which is strongly influenced by the temperature. The hydrolysis was relevant at alkaline medium and high temperature. LC-IT-MSⁿ was used to identify the degradation products. It was found three known degradation products (albendazole-2-amino, albendazole sulfoxide and albendazole sulfone) and a new derivate of albendazole molecule (albendazole sulfoxide with a chlorine). This last one was isolated and characterized by UPLC-QToF-MS and NMR analyses.

Development of an Accelerated Stability Model to Estimate Purple Corn Cob Extract Powder (Moradyn) Shelf-Life

Moradyn is an Italian purple corn variety whose cobs represent a rich source of polyphenols. At the industrial level, they are used to produce a dried extract (MCE) by the addition of 20% Arabic gum. In order to evaluate the extract solid-state stability, an innovative accelerated stress protocol was developed following the isoconversion approach. The degradation kinetics of cyanidin-3-O-glucoside (C3G), the most suitable marker to monitor the overall MCE degradation status, was monitored under five temperature–humidity (RH) combinations. These data were used to build a mathematical model, able to estimate the C3G stability at 25 °C and 30% RH, whose predictiveness was further assessed by comparing the predicted vs. experimental C3G isoconversion time. Finally, by applying this model, the expiry date of the extract was calculated to be within 26–33 days, confirming that the addition of 20% Arabic gum is insufficient to stabilize MCE and highlighting the need of a new formula in order to prolong MCE shelf-life.

Development and greenness assessment of a stability-indicating HPLC-DAD method for simultaneous determination of allopurinol and benzbromarone

The growing interest in Green Analytical Chemistry (GAC) principles through the replacement of polluting analytical procedures with greener ones, has encouraged us to develop an eco-friendly stability-indicating HPLC with diode array detection method (HPLC-DAD) for simultaneous determination of allopurinol (ALP) and benzbromarone (BNZ). Effective separation was accomplished using Durashell C18 column (4.6 × 250 mm, 5 µm particle size) with gradient elution of the mobile phase composed of 0.02 M ammonium acetate (pH 5.0) and methanol. Quantification of ALP and BNZ was based on measuring their peak areas at 251 nm. ALP and BNZ peaks eluted at retention times 4.85 and 10.30 min respectively. The proposed HPLC procedure was carefully validated in terms of system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection, and quantification limits. The linearity range for both ALP and BNZ was 5-100 µg/mL with correlation coefficients >0.9999. Forced degradation conditions of neutral, acidic, and alkaline hydrolysis, oxidation, and thermal degradation were applied on both drugs. Good resolution of the drugs from their forced degradation products proved that the proposed method is stability-indicating. In addition, the resolution of both drugs from about 10 pharmacologically or chemically related pharmaceutical compounds of different medicinal categories showed the high specificity of the proposed method. The validated HPLC method was successfully applied to the simultaneous determination of both drugs in their tablet dosage forms. Furthermore, greenness assessment and comparison with previously published methods were carried out using two different GAC metrics, namely, the national environmental method index (NEMI) and the analytical Eco-Scale.

Validated Stability-Indicating GC-MS Method for Characterization of Forced Degradation Products of Trans-Caffeic Acid and Trans-Ferulic Acid

When dealing with simple phenols such as caffeic acid (CA) and ferulic acid (FA), found in a variety of plants, it is very important to have control over the most important factors that accelerate their degradation reactions. This is the first report in which the stabilities of these two compounds have been systematically tested by exposure to various different factors. Forced degradation studies were performed on pure standards (trans-CA and trans-FA), dissolved in different solvents and exposed to different oxidative, photolytic and thermal stress conditions. Additionally, a rapid, sensitive, and selective stability-indicating gas chromatographic-mass spectrometric method was developed and validated for determination of trans-CA and trans-FA in the presence of their degradation products. Cis-CA and cis-FA were confirmed as the only degradation products in all the experiments performed. All the compounds were perfectly separated by gas chromatography (GC) and identified using mass spectrometry (MS), a method that additionally elucidated their structures. In general, more protic solvents, higher temperatures, UV radiation and longer storage times led to more significant degradation (isomerization) of both trans-isomers. The most progressive isomerization of both compounds (up to 43%) was observed when the polar solutions were exposed to daylight at room temperature for 1 month. The method was validated for linearity, precision as repeatability, limit of detection (LOD) and limit of quantitation (LOQ). The method was confirmed as linear over tested concentration ranges from 1−100 mg L⁻¹ (r²s were above 0.999). The LOD and LOQ for trans-FA were 0.15 mg L⁻¹ and 0.50 mg L⁻¹, respectively. The LOD and LOQ for trans-CA were 0.23 mg L⁻¹ and 0.77 mg L⁻¹, respectively.

Establishment of validated stability indicating purity method based on the stress degradation behavior of gonadotropin-releasing hormone antagonist (ganirelix) in an injectable formulation using HPLC and LC-MS-QTOF

Stress study of a drug substance or pharmaceutical drug product provides a vision into degradation pathways and degradation products of the active pharmaceutical ingredient and helps in interpretation of the chemical structure of the degradation impurities. In the current study, Ganirelix active ingredient presented in the Orgalutran® was stressed with acidic and alkali hydrolysis, photolysis, thermal and oxidation conditions as per the guidelines of International Conference on Harmonization (ICH) Q1A (R2). Ganirelix was found to be labile under thermal and alkali hydrolytic stress conditions, while it was stable to acid hydrolytic, oxidative and photolytic stress. All degradation products were separated with a resolution > 1.5 on a C18 column (2.6 µm, 25 cm×4.6 mm) using a hydrophilic ion pair such as sodium perchlorate, at a concentration <0.04 M. In total, four major degradant impurities were found during stress study. These impurities were fractionated and desalted by flash chromatography for identification of chemical structures. LC-MS-QTOF analysis revealed that two degradation products are diastereomers of Ganirelix, one degradation product is a deamination compound and other degradation product result from the insertion of a new amino acid residue in the Ganirelix peptide sequence. The developed method is sensitive enough to quantify the related substances of Ganirelix at the 0.04% level with that of Ganirelix test concentration.

Stability-indicating method for the novel antifungal compound RI76: Characterization and in vitro antifungal activity of its active degradation product

RI76 is a novel 2-thiazolylhydrazone compound with reported antifungal activity. In preclinical drug development, it is fundamental to know the impurity profile and to understand degradation mechanisms of the molecule. In our study, RI76 was subjected to forced degradation conditions, and a stability-indicating HPLC-DAD method was developed and validated. Separation was carried out on a C18 column (150 × 4.6 mm i.d., 5 μm) maintained at 40°C using a 1 mL/min flow rate of 2 mM ammonium acetate with 0.1% formic acid (pH 3.0) and acetonitrile in gradient mode. The method was linear in the range of 0.7-91 μg/mL for RI76 and 0.7-25 μg/mL for its degradation product PD76. The formation of a major degradation product was quickly observed when RI76 was in aqueous solution. The chemical structure of this product, named PD76, was proposed based on LC-UV-MS experiments, synthesized in-house, and confirmed by NMR spectroscopy and chromatographic analysis. In vitro antifungal activity assays demonstrated that this resultant product shows a promising activity against clinically important Candida and Cryptococcus strains, matching or surpassing the activity of its precursor and of well-established antifungal drugs.

A multivariate quantification of Box-Behnken design assisted method development and validation of dextromethorphan hydrobromide and desloratadine simultaneously by reverse-phase HPLC in in-house syrup formulation

An innovative high-performance liquid chromatography assay method was developed and validated for quantification of dextromethorphan hydrobromide and desloratadine simultaneously in monophasic liquid formulation by preparing syrup containing 30 mg/5 mL of dextromethorphan hydrobromide and 1.2 mg/mL of desloratadine. The chromatographic severance was executed by gradient solution A and B. The composition of buffer solution A contained 0.05 M monobasic potassium, then 1 mL triethylamine was added to it and the pH was adjusted to 2.3 with orthophosphoric acid. Methanol was used as solution B. The gradient elution was executed with Kromasil C8 (250 mm × 4.6 mm) column having 1.5 mL/min flow rate and 20 µL injection volume with UV-estimation at 254 nm for dextromethorphan hydrobromide and DES. The present research was planned according to Box-Behnken design by utilizing design expert software, using four factors such as column temperature (A), flow rate (B), mobile phase-organic phase (C), and pH (D); correspondingly the selected response variables were resolution between A and B, that is, desloratadine and methyl paraben (Y1), tailing of dextromethorphan hydrobromide (Y2), and tailing of desloratadine (Y3). The parameters such as system suitability, linearity, accuracy, precision, robustness, limit of detection, limit of quantitation, and ruggedness were analyzed to validate the developed method in accordance with current regulatory guidelines.

Intrinsic Stability Study and Forced Degradation Profiling of Olopatadine Hydrochloride by RP-HPLC-DAD-HRMS Method

Objectives

Forced degradation determines the intrinsic stability of a molecule by establishing degradation pathways in order to identify the likely degradation products (DPs). The objective of the present research was to establish intrinsic stability and forced degradation profiling of olopatadine hydrochloride.

Materials and Methods

The intrinsic stability of olopatadine hydrochloride was evaluated by RP-HPLC, where a mixture of 0.1% formic acid and organic phase (methanol:acetonitrile; 50:50 % v/v) was used as mobile phase at 1.0 mL/min in gradient mode. Different stress conditions were employed to explore the intrinsic stability of olopatadine hydrochloride.

Results

In acidic condition, five DPs, i.e. OLO1, OLO2, OLO3, OLO4, and OLO5, were observed. OLO5 was the major DP that increased with time and the peak area of OLO was decreased. In addition to OLO3 and OLO5, two more DPs were observed in alkaline condition, i.e. OLO6 and OLO7. OLO5 and OLO6 were two major DPs; OLO5 increased with time while OLO6 had a zigzag pattern of peak area with time. All DPs of neutral condition were also found in acidic condition while OLO3 and OLO5 were common in all three types of hydrolytic degradation.

Conclusion

Thus, OLO has similar pattern of degradation profiling in all hydrolytic conditions (acidic, alkaline, and neutral). No degradation was found in thermal, ultraviolet light, or oxidative conditions over 10 days. OLO-Imp was recognized as an analogue structure of OLO and proposed as 11-[(3-dimethylamino)-propylidene]-6,11-dihydro-dibenz[b,e]oxepin-2-propanoic acid in standard drug. OLO1 was identified as (2-(4-(dimethylamino) butyl) phenyl)methanol, which may be formed by cleavage of the tricyclic ring in neutral condition.

Degradation Pathway of a Taxane Derivative DS80100717 Drug Substance and Drug Product

The degradation pathway of a taxane derivative and anticancer agent, DS80100717, was investigated. Several degradants were generated under acidic, basic, and oxidative stress conditions in solution. The chemical structures of eight degradants of DS80100717 were elucidated using MS and NMR. The major degradant of the DS80100717 drug substance derived by heating in solid-state was the N-oxide form via oxidation and C2'-epimer of the side chain via acid hydrolysis. We proposed previously unreported degradation pathways of DS80100717 with taxane derivatives such as paclitaxel, docetaxel, and cabazitaxel.

Stability-indicating HPLC method for acyclovir and lidocaine in topical formulations

A simple, rapid and accurate stability-indicating HPLC assay was developed for the determination of acyclovir and lidocaine in topical formulations. Chromatographic separation of acyclovir and lidocaine was achieved using a reversed-phase C₁₈ column and a gradient mobile phase (20 mm ammonium acetate pH 3.5 in water and acetonitrile). The degradation products of acyclovir and lidocaine in the samples were analyzed by ultra performance liquid chromatography-time of flight mass spectrometry. The HPLC method successfully resolved the analytes from the impurities and degradation products in the topical formulation. Furthermore, the method detected the analytes from the human skin leachables following the extraction of the analytes in the skin homogenate samples. The method showed linearity over wide ranges of 5-500 and 10-200 μg/ml for acyclovir and lidocaine in the topical product, respectively, with a correlation coefficient (r² ) >0.9995. The relative standard deviations for precision, repeatability, and robustness of the method validation assays were <2%. The skin extraction efficiency for acyclovir and lidocaine was 92.8 ± 0.7% and 91.3 ± 3.2%, respectively, with no interference from the skin leachables. Thus, simultaneous quantification of acyclovir and lidocaine in the topical formulations was achieved.

Chemometrics Approaches in Forced Degradation Studies of Pharmaceutical Drugs

Chemometrics is the chemistry field responsible for planning and extracting the maximum of information of experiments from chemical data using mathematical tools (linear algebra, statistics, and so on). Active pharmaceutical ingredients (APIs) can form impurities when exposed to excipients or environmental variables such as light, high temperatures, acidic or basic conditions, humidity, and oxidative environment. By considering that these impurities can affect the safety and efficacy of the drug product, it is necessary to know how these impurities are yielded and to establish the pathway of their formation. In this context, forced degradation studies of pharmaceutical drugs have been used for the characterization of physicochemical stability of APIs. These studies are also essential in the validation of analytical methodologies, in order to prove the selectivity of methods for the API and its impurities and to create strategies to avoid the formation of degradation products. This review aims to demonstrate how forced degradation studies have been actually performed and the applications of chemometric tools in related studies. Some papers are going to be discussed to exemplify the chemometric applications in forced degradation studies.

Forced degradation of tacrolimus and the development of a UHPLC method for impurities determination

An ultra-high performance liquid chromatography method for simultaneous determination of tacrolimus impurities in pharmaceutical dosage forms has been developed. Appropriate chromatographic separation was achieved on a BEH C18 column using gradient elution with a total run time of 14 min. The method was applied to analyses of commercial samples and was validated in terms of linearity, precision, accuracy, sensitivity and specificity. It was found to be linear, precise and accurate in the range of 0.05 to 0.6 % of the impurities level in pharmaceutical dosage forms. Stability indicating power of the method was demonstrated by the results of forced degradation studies. The forced degradation study in solution revealed tacrolimus instability under stress alkaline, thermal, light and photolytic conditions and in the presence of a radical initiator or metal ions. The drug was stable at pH 3-5. Solid-state degradation studies conducted on amorphous tacrolimus demonstrated its sensitivity to light, elevated temperature, humidity and oxidation.

Degradation Kinetics, In Vitro Dissolution Studies, and Quantification of Praziquantel, Anchored in Emission Intensity by Spectrofluorimetry

OBJECTIVES

A simple, rapid, specific, and highly sensitive ecofriendly spectrofluorimetric method has been developed for the quantification of praziquantel.

MATERIALS AND METHODS

A linear relationship was found between fluorescence intensity and praziquantel concentration in the range of 1-20 μg/mL in water at emission wavelength of 286 nm after excitation wavelength at 263 nm with a good correlation coefficient (0.999).

RESULTS

The proposed method was validated according to International Conference on Harmonization guidelines and statistical analysis of the results revealed high accuracy and good precision with the percentage relative standard deviation values less than 2. The detection and quantification limits were 0.27 and 0.81 μg/mL, respectively. The proposed method was extended to investigate the stability of the drug and its degradation kinetics in the presence of acidic, alkaline, and oxidative conditions.

CONCLUSION

The method was utilized for in vitro dissolution studies of praziquantel tablet formulation. The suggested procedures could be used for the assessment of praziquantel in drug substance and drug products as well as in the presence of its degradation products.

Deamidation and isomerization liability analysis of 131 clinical-stage antibodies

Contemporary in vivo and in vitro discovery platform technologies greatly increase the odds of identifying high-affinity monoclonal antibodies (mAbs) towards essentially any desired biologically relevant epitope. Lagging discovery throughput is the ability to select for highly developable mAbs with drug-like properties early in the process. Upstream consideration of developability metrics should reduce the frequency of failures in later development stages. As the field moves towards incorporating biophysical screening assays in parallel to discovery processes, similar approaches should also be used to ensure robust chemical stability. Optimization of chemical stability in the early stages of discovery has the potential to reduce complications in formulation development and improve the potential for successful liquid formulations. However, at present, our knowledge of the chemical stability characteristics of clinical-stage therapeutic mAbs is fragmented and lacks comprehensive comparative assessment. To address this knowledge gap, we produced 131 mAbs with amino acid sequences corresponding to the variable regions of clinical-stage mAbs, subjected these to low and high pH stresses and identified the resulting modifications at amino acid-level resolution via tryptic peptide mapping. Among this large set of mAbs, relatively high frequencies of asparagine deamidation events were observed in CDRs H2 and L1, while CDRs H3, H2 and L1 contained relatively high frequencies of instances of aspartate isomerization.

Reverse-Phase Chromatographic Determination and Intrinsic Stability Behavior of 5-[(4-Chlorophenoxy)Methyl]-1,3,4-Oxadiazole-2-Thiol

The study describes the development and preliminary validation of a simple reverse-phase chromatographic method for determination of a novel drug candidate, 5-[(4-chlorophenoxy) methyl]-1,3,4-oxadiazole-2-thiol (OXCPM), in bulk and stressed solution, in order to find out the intrinsic stability behavior of the compound. Isocratic elution was carried out at a flow rate of 1.0 mL min-1 through a Promosil C18 column maintained at 25 °C, using the mobile phase comprising acetonitrile and aqueous o-H3PO4 (pH 2.67) (1:1, V/V). Detection was performed at 258 nm. The response of the detector was linear in a concentration range of 1.25-50.00 μg mL-1 with the correlation coefficient of 0.9996 ± 0.0001. Cumulative intra-day, inter-day and inter-instrument accuracy (99.5 ± 1.0, 100.2 ± 1.0 and 100.3 ± 0.4 %, resp.) with RSD less than 5 % indicated that the method was accurate and precise. The resolution and selectivity factor (>2 and >1, resp.), particularly in copper metal- and dry-heat-stress solutions, depicted the selectivity of the method. OXCPM remained stable under hydrolytic (acidic and neutral pH, ≤ 37 °C), photolytic and moist heat stress conditions. Under alkaline conditions (hydrolytic and photolytic), polar products were formed that eluted very fast through the column (tR < 3.75 min). At room temperature, the compound was susceptible to oxidation by hydrogen peroxide and transition metals. The ionogram of most of the stress solutions indicated the presence of a product having m/z 256, which might be a result of N- or Smethylation or -SH oxidation. The results of the study indicate that the method is selective, sensitive and suitable to be used for determination of OXCPM in bulk and under stress conditions.

Liquid chromatographic and spectrofluorimetric assays of empagliflozin: Applied to degradation kinetic study and content uniformity testing

Stability-indicating high-performance liquid chromatography (HPLC) and spectrofluorimetric methods were developed for determination of empagliflozin (EGF). EGF was subjected to oxidation, wet heat, photo-degradation, acid hydrolysis and alkali hydrolysis. The alkaline degradation pathway was subjected to a kinetics study as the major product obtained after stress conditions. Arrhenius plots were constructed and the activation energies of the degradation process were calculated. HPLC was used for the kinetic study as it enabled simultaneous determination of EGF and the degradation product while the spectrofluorimetric assay was applied to content uniformity testing due to its higher sensitivity and lower limit of detection (LOD). Isocratic chromatographic elution was attained for HPLC on a Intersil® C₁₈ column (150 mm × 4 mm, 5 μm), using a mobile phase of acetonitrile-potassium dihydrogen phosphate buffer pH 4, (50:50, v/v) at a flow rate of 1 ml/min with ultraviolet (UV) detection at 225 nm. The relative fluorescence intensity was recorded by spectrofluorimeter applying synchronous mode using ∆λ = 70 nm at 297.6 nm. Linearity ranges were found to be 5-50 μg/ml and 50-1000 ng/ml for HPLC and spectrofluorimetric methods, respectively.

Quantification of Newly Discovered Anti-Cancer Drug Enzalutamide in Bulk and Synthetic Mixture by Stability Indicating TLC Method

OBJECTIVE

An impressionable, discriminatory and precise stability indicating high performance thin layer chromatographic method has been developed and validated for the estimation of Enzalutamide in bulk and synthetic mixture.

METHOD

The method engaged HPTLC aluminium plates pre-coated with silica gel 60F-254 as the stationary phase while the solvent system was ethyl acetate: toluene (4.5:5.5, v/v). The Rf value of enzalutamide was detected to be 0. 39 ± 0. 005 and the densitometric analysis was carried out in absorbance mode at 246 nm. The linear regression analysis data for the calibration plots presented a virtuous linear relationship for enzalutamide over a concentration range of 20 - 1000ng/band.

RESULTS

The limit of detection and limit of quantification for enzalutamide was found to be 9.05 and 27.43 ng/band. Enzalutamide was imperilled to acid and alkali hydrolysis, chemical oxidation, dry heat degradation and photolytic degradation. The degraded product peaks were well resolved from the pure drug peak with substantial difference in their Rf values.

CONCLUSION

Stressed samples were assayed using developed TLC technique. Suggested method was validated with respect to linearity, accuracy, precision and robustness. The method was successfully applied to the estimation of enzalutamide in synthetic mixture.

The Use of a 2,2'-Azobis (2-Amidinopropane) Dihydrochloride Stress Model as an Indicator of Oxidation Susceptibility for Monoclonal Antibodies

Protein oxidation is a major pathway for degradation of biologic drug products. Past literature reports have suggested that 2,2-azobis (2-amidinopropane) dihydrochloride (AAPH), a free radical generator that produces alkoxyl and alkyl peroxyl radicals, is a useful model reagent stress for assessing the oxidative susceptibility of proteins. Here, we expand the applications of the AAPH model by pairing it with a rapid peptide map method to enable site-specific studies of oxidative susceptibility of monoclonal antibodies and their derivatives for comparison between formats, the evaluation of formulation components, and comparisons across the stress models. Comparing the free radical-induced oxidation model by AAPH with a light-induced oxidation model suggests that light-sensitive residues represent a subset of AAPH-sensitive residues and therefore AAPH can be used as a preliminary screen to highlight molecules that need further assessment by light models. In sum, these studies demonstrate that AAPH stress can be used in multiple ways to evaluate labile residues and oxidation sensitivity as it pertains to developability and manufacturability.

Force degradation behavior of glucocorticoid deflazacort by UPLC: isolation, identification and characterization of degradant by FTIR, NMR and mass analysis

In this investigation, sensitive and reproducible methods are described for quantitative determination of deflazacort in the presence of its degradation product. The method was based on high performance liquid chromatography of the drug from its degradation product on reverse phase using Acquity UPLC BEH C18 columns (1.7 µm, 2.1 mm × 150 mm) using acetonitrile and water (40:60 V/V) at a flow rate of 0.2 mL/minute in UPLC. UV detection was performed at 240.1 nm. Deflazacort was subjected to oxidative, acid, base, hydrolytic, thermal and photolytic degradation. The drug was found to be stable in water and thermal stress, as well as under neutral stress conditions. However, forced-degradation study performed on deflazacort showed that the drug degraded under alkaline, acid and photolytic stress. The degradation products were well resolved from the main peak, which proved the stability-indicating power of the method. The developed method was validated as per ICH guidelines with respect to accuracy, linearity, limit of detection, limit of quantification, accuracy, precision and robustness, selectivity and specificity. Apart from the aforementioned, the results of the present study also emphasize the importance of isolation characterization and identification of degradant. Hence, an attempt was made to identify the degradants in deflazacort. One of the degradation products of deflazacort was isolated and identified by the FTIR, NMR and LC-MS study.

Rapid assessment of oxidation via middle-down LCMS correlates with methionine side-chain solvent-accessible surface area for 121 clinical stage monoclonal antibodies

Susceptibility of methionine to oxidation is an important concern for chemical stability during the development of a monoclonal antibody (mAb) therapeutic. To minimize downstream risks, leading candidates are usually screened under forced oxidation conditions to identify oxidation-labile molecules. Here we report results of forced oxidation on a large set of in-house expressed and purified mAbs with variable region sequences corresponding to 121 clinical stage mAbs. These mAb samples were treated with 0.1% H₂O₂ for 24 hours before enzymatic cleavage below the hinge, followed by reduction of inter-chain disulfide bonds for the detection of the light chain, Fab portion of heavy chain (Fd) and Fc by liquid chromatography-mass spectrometry. This high-throughput, middle-down approach allows detection of oxidation site(s) at the resolution of 3 distinct segments. The experimental oxidation data correlates well with theoretical predictions based on the solvent-accessible surface area of the methionine side-chains within these segments. These results validate the use of upstream computational modeling to predict mAb oxidation susceptibility at the sequence level.

Development and Validation of Miglitol and Its Impurities by RP-HPLC and Characterization Using Mass Spectrometry Techniques

Alpha glucoside inhibitors used to treat type-2 diabetes mellitus (DM) are likely to be safe and effective. These agents are most effective for postprandial hyperglycemia. Miglitol is a type of drug used to treat type-2 DM. A simple, selective, linear, precise and accurate reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for a related substance of miglitol and its identification, and characterization was done by different mass spectrometry techniques. The gradient method at a flow rate of 1.0 mL/min was employed on a prevail carbohydrate ES column (250 × 4.6 mm, 5 μm particle size) at a temperature of 35 °C. Mobile phase A consisted of 10 mM dipotassium hydrogen orthophosphate adjusted to pH 8.0 using concentrated phosphoric acid and mobile phase B consisted of acetonitrile. The ultraviolet detection wavelength was 210 nm and 20 μL of the sample were injected. The retention time for miglitol was about 24.0 min. Forced degradation of the miglitol sample was conducted in accordance with the International Conference on Harmonisation (ICH) guidelines. Acidic, basic, neutral, and oxidative hydrolysis, thermal stress, and photolytic degradation were used to assess the stability-indicating the power of the method. Substantial degradation was observed during oxidative hydrolysis. No degradation was observed under the other stress conditions. The method was optimized using samples generated by forced degradation and sample solutions spiked with impurities and epimers. Good resolution of the analyte peak from peaks, corresponding to process-related impurities, epimers and degradation products, was achieved and the method was validated as per the ICH guidelines. The method can successfully be applied for routine analysis of miglitol.

Stability-Indicating High-Performance Liquid Chromatography Assay for the Determination of Sulthiame in Pharmaceutical Dosage Forms

A stability-indicating assay by reversed-phase high performance liquid chromatography method was developed and validated for the determination of sulthiame (STM). The chromatographic separation was achieved on a reversed-phase NovaPack C18 column and an isocratic mobile phase consisting of deionized water:methanol (70:30, v/v). The flow rate was 1.0 mL/min (ultraviolet detection at 210 nm). The STM was separated within 2.83 min. The linearity of the method was demonstrated in the range of 20.0–200.0 μg/mL and a coefficient of determination of r² = 0.9999. The limits of detection and quantification were 4.2 and 9.5 μg/mL, respectively. The intraday and interday precisions were less than 1%. Accuracy of the method ranged from 98.3% to 101.7%, with a relative standard deviation of <1%. STM was degraded by accelerated breakdown in alkaline, acidic, or oxidative stress conditions. This method allows accurate and reliable determination of STM for drug stability assay in pharmaceutical studies.

Forced Degradation Studies of Aloe Emodin and Emodin by HPTLC

Anthraquinones are natural phenolic compounds, which are reported to act as anti-aging, anti-inflammatory, antioxidant, anti-cancer, laxative and antitumor agents. They are abudant in plants like candle bush, aloes, cascara bark and rhubarb. The present work was to observe the effect of different forced degradation conditions by high-performance thin layer chromatography on potential markers i.e. aloe emodin and emodin. Both aloe emodin and emodin were subjected to various forced degradation studies such as oxidation, acid and alkaline hydrolysis, photolysis, hydrolytic and thermal degradation. Aloe emodin, was more susceptible to acid hydrolysis and degradation was found to a lesser extent under thermal degradation whereas significant degradation was observed under acid hydrolysis, lesser extent was observed under alkali hydrolysis for emodin. Forced degradation studies on aloe emodin and emodin gives information about its storage and intrinsic stability conditions considering the advanced pharmaceutical aspects of formulation.

Structural elucidation of gemifloxacin mesylate degradation product

Gemifloxacin mesylate (GFM), chemically (R,S)-7-[(4Z)-3-(aminomethyl)-4-(methoxyimino)-1-pyrrolidinyl]-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid methanesulfonate, is a synthetic broad-spectrum antibacterial agent. Although many papers have been published in the literature describing the stability of fluorquinolones, little is known about the degradation products of GFM. Forced degradation studies of GFM were performed using radiation (UV-A), acid (1 mol L(-1) HCl) and alkaline conditions (0.2 mol L(-1) NaOH). The main degradation product, formed under alkaline conditions, was isolated using semi-preparative LC and structurally elucidated by nuclear magnetic resonance (proton - (1) H; carbon - (13) C; correlate spectroscopy - COSY; heteronuclear single quantum coherence - HSQC; heteronuclear multiple-bond correlation - HMBC; spectroscopy - infrared, atomic emission and mass spectrometry techniques). The degradation product isolated was characterized as sodium 7-amino-1-pyrrolidinyl-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylate, which was formed by loss of the 3-(aminomethyl)-4-(methoxyimino)-1-pyrrolidinyl ring and formation of the sodium carboxylate. The structural characterization of the degradation product was very important to understand the degradation mechanism of the GFM under alkaline conditions. In addition, the results highlight the importance of appropriate protection against hydrolysis and UV radiation during the drug-development process, storage, handling and quality control.

Characterization of forced degradation products of pazopanib hydrochloride by UHPLC-Q-TOF/MS and in silico toxicity prediction

Pazopanib (PZ), an anti-cancer drug, was subjected to forced degradation under hydrolytic (acid, base and neutral), oxidative, photolytic and thermal stress conditions as per International Conference on Harmonization guidelines. A selective stability indicating validated method was developed using a Waters Acquity UPLC HSS T3 (100 × 2.1 mm, 1.7 µm) column in gradient mode with ammonium acetate buffer (10 mM, pH 5.0) and acetonitrile. PZ was found to degrade only in photolytic conditions to produce six transformation products (TPs). All the TPs were identified and characterized by liquid chromatography/atmospheric pressure chemical ionization-quadrupole-time of flight mass spectrometry experiments in combination with accurate mass measurements. Plausible mechanisms have been proposed for the formation of TPs. In silico toxicity was predicted using TOPKAT and DEREK softwares for all the TPs. The TP, N4-(2,3-dimethyl-2H-indazol-6-yl)-N4-methylpyrimidine-2,4-diamine, was found to be genotoxic, whereas all other TPs with sulfonamide moiety were hepatotoxic. The data reported here are expected to be of significance as this study foresees the formation of one potential genotoxic and five hepatotoxic degradation/transformation products.

Characterization of degradation products of ivabradine by LC-HR-MS/MS: a typical case of exhibition of different degradation behaviour in HCl and H2SO4 acid hydrolysis

A validated stability-indicating HPLC method was established, and comprehensive stress testing of ivabradine, a cardiotonic drug, was carried out as per ICH guidelines. Ivabradine was subjected to acidic, basic and neutral hydrolysis, oxidation, photolysis and thermal stress conditions, and the resulting degradation products were investigated by LC-PDA and LC-HR-MS/MS. The drug was found to degrade in acid and base hydrolysis. An efficient and selective stability assay method was developed on Phenomenex Luna C18 (250 × 4.6 mm, 5.0 µm) column using ammonium formate (10 mM, pH 3.0) and acetonitrile as mobile phase at 30 °C in gradient elution mode. The flow rate was 0.7 ml/min and detection wavelength was 286 nm. A total of five degradation products (I-1 to I-5) were identified and characterized by LC-HR-MS/MS in combination with accurate mass measurements. The drug exhibited different degradation behaviour in HCl and H2SO4 hydrolysis conditions. It is a unique example where two of the five degradation products in HCl hydrolysis were absent in H2SO4 acid hydrolysis. The present study provides guidance to revise the stress test for the determination of inherent stability of drugs containing lactam moiety under hydrolytic conditions. Most probable mechanisms for the formation of degradation products have been proposed on the basis of a comparison of the fragmentation pattern of the drug and its degradation products. In silico toxicity revealed that the degradation products (I-2 to I-5) were found to be severe irritants in case of ocular irritancy. The analytical assay method was validated with respect to specificity, linearity, range, precision, accuracy and robustness.

Stability indicating studies on NMITLI 118RT+ (standardized extract of withania somnifera dunal)

Background:

Withania somnifera Dunal (Ashwagandha) is an Indian medicinal plant of great medicinal value; used in many clinically proven conditions. NMITLI-118RT+ is a candidate drug under a Council of Scientific and Industrial Research (CSIR) networking project. It is a chemotype of W. somnifera's root extract, which has been used for the present study.

Objectives:

The present investigation aims to develop and validate a simple isocratic reverse phase-high performance liquid chromatography (RP-HPLC) system for the detection and estimation of Withanolide A (marker compound) and its analytical application for stability indicating studies on NMITLI-118RT+.

Material and Methods:

A validated RP-HPLC method for Withanolide A was established on a Waters HPLC system and the same was used on NMITLI-118RT+ for quantification and fingerprinting purposes, and for establishing forced degradation, isothermal stress tests, and drug-excipient testing protocols as per International Conference on Harmonization (ICH) guidelines.

Results:

A validated method was established, which could detect the marker at a retention time of around 6.3 minutes, with a linearity range of 2-100 μg/mL, by varying the amounts of the said marker, which were estimated in four different batches of NMITLI-118RT+. Photostability as per ICH guidelines suggested a slight loss of the active constituent and maximum degradation was afforded with alkali followed by acid, and then peroxide, in the forced degradation studies. In the drug-excipient studies, the maximum amount of active constituent could be detected in the samples with ethyl cellulose and the least with hydroxy propyl cellulose.

Conclusion:

The method developed here was simple and rapid. The various stability indicating studies carried out in the present investigation would be useful for formulation development and were suggestive of deciding the recommended storage conditions for NMITLI-118RT+.

Evaluation of degradation kinetics and physicochemical stability of tenofovir

Tenofovir (TFV) has been proven to prevent the transmission of the Human Immunodeficiency Virus (HIV) through the vagina. But, there is little information available about its stability under various storage and stress conditions. Hence, this study aimed to investigate the degradation behavior and physicochemical stability of TFV using liquid chromatography coupled mass spectrometry (LC-MS) and solid state X-ray diffraction (XRD) analyses. The LC-MS analysis was performed on a QTrap mass spectrometer with an enhanced mass spectrum (EMS) scan in positive mode. A reversed phase C18 column was used as the stationary phase. TFV exhibited degradation under acidic and alkaline hydrolytic conditions. The degradation products with m/z 289.2 and 170 amu have been proposed as 6-Hydroxy adenine derivative of TFV, and (2-hydroxypropan-2-yloxy) methylphosphonic acid, respectively. A pseudo-first-order degradation kinetic allowed for estimating the shelf-life, half-life, and time required for 90% degradation of 3.84, 25.34, and 84.22 h in acidic conditions, and 58.26, 384.49, and 1277.75 h in alkaline conditions, respectively. No significant degradation was observed at pH 4.5 (normal cervicovaginal pH) and oxidative stress conditions of 3% and 30% v/v hydrogen peroxide solutions. The shelf life of TFV powder at room temperature was 23 months as calculated by using an Arrhenius plot. The XRD pattern showed that the drug was stable and maintained its original crystallinity under the accelerated and thermal stress conditions applied. Stability analyses revealed that the TFV was stable in various stress conditions; however, formulation strategies should be implemented to protect it in strong acidic and alkaline environments.

Characterization of forced degradation products of ketorolac tromethamine using LC/ESI/Q/TOF/MS/MS and in silico toxicity prediction

Ketorolac, a nonsteroidal anti-inflammatory drug, was subjected to forced degradation studies as per International Conference on Harmonization guidelines. A simple, rapid, precise, and accurate high-performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (LC/ESI/Q/TOF/MS/MS) method has been developed for the identification and structural characterization of stressed degradation products of ketorolac. The drug was found to degrade in hydrolytic (acidic, basic, and neutral), photolytic (acidic, basic, and neutral solution), and thermal conditions, whereas the solid form of the drug was found to be stable under photolytic conditions. The method has shown adequate separation of ketorolac tromethamine and its degradation products on a Grace Smart C-18 (250 mm × 4.6 mm i.d., 5 µm) column using 20 mM ammonium formate (pH = 3.2): acetonitrile as a mobile phase in gradient elution mode at a flow rate of 1.0 ml/min. A total of nine degradation products were identified and characterized by LC/ESI/MS/MS. The most probable mechanisms for the formation of degradation products have been proposed on the basis of a comparison of the fragmentation of the [M + H](+) ions of ketorolac and its degradation products. In silico toxicity of the drug and degradation products was investigated by using topkat and derek softwares. The method was validated in terms of specificity, linearity, accuracy, precision, and robustness as per International Conference on Harmonization guidelines.

Development and validation of a stability-indicating high performance liquid chromatographic (HPLC) method for the determination of related substances of micafungin sodium in drug substances

An isocratic, sensitive and stability-indicating high performance liquid chromatographic (HPLC) method for separation and determination of the related substances of micafungin sodium was developed. The chromatographic separation was achieved on Agilent Zorbax SB-C18 column (250 × 4.6 mm, 5 μm). Forced degradation study confirmed that the newly developed method was specific and selective to the degradation products. The performance of the method was validated according to the present ICH guidelines for specificity, linearity, accuracy, precision and robustness. Regression analysis showed correlation coefficient value greater than 0.999 for micafungin sodium and its six impurities. Limit of detection of impurities was in the range of 0.006%-0.013% indicating the high sensitivity of the newly developed method. Accuracy of the method was established based on the recovery obtained between 98.2% and 102.0% for all impurities. RSD obtained for the repeatability and intermediate precision experiments, was less than 1.0%. The method was successfully applied to quantify related substances of micafungin sodium in bulk drugs.

Stability-indicating Method for the Estimation of Riluzole in Tablets

A stability-indicating reverse-phase high-pressure liquid chromatography method with photodiode array detector was developed and validated for estimation of riluzole in the bulk and tablet dosage forms. Riluzole was subjected to stress conditions (light, heat, humidity, acid/base hydrolysis and oxidation) and the stressed samples were analyzed by developed method. Degradation was observed in acidic, basic, oxidative and thermal conditions. The degradation products were well resolved from riluzole peak. An inertsil-ods column (250×4.6 mm, 5 μ) with a mobile phase comprising 0.02% v/v formic acid:acetonitrile(35:65 v/v) at a flow rate of 1.0 ml/min was used and eluents were monitored at 260 nm. The retention time of riluzole was 5.7 min. Complete validation for the method was carried out according to Internation Conference on Harmonization guidelines. Linearity was achieved in the range 10-50 μg/ml with a correlation coefficient (r) 0.9998. The percent assay was 100.92 and mean percentage recovery was found to be 101.10.

Developability studies before initiation of process development: improving manufacturability of monoclonal antibodies

Monoclonal antibodies constitute a robust class of therapeutic proteins. Their stability, resistance to stress conditions and high solubility have allowed the successful development and commercialization of over 40 antibody-based drugs. Although mAbs enjoy a relatively high probability of success compared with other therapeutic proteins, examples of projects that are suspended due to the instability of the molecule are not uncommon. Developability assessment studies have therefore been devised to identify early during process development problems associated with stability, solubility that is insufficient to meet expected dosing or sensitivity to stress. This set of experiments includes short-term stability studies at 2-8 þC, 25 þC and 40 þC, freeze-thaw studies, limited forced degradation studies and determination of the viscosity of high concentration samples. We present here three case studies reflecting three typical outcomes: (1) no major or unexpected degradation is found and the study results are used to inform early identification of degradation pathways and potential critical quality attributes within the Quality by Design framework defined by US Food and Drug Administration guidance documents; (2) identification of specific degradation pathway(s) that do not affect potency of the molecule, with subsequent definition of proper process control and formulation strategies; and (3) identification of degradation that affects potency, resulting in program termination and reallocation of resources.

A Rapid Stability-Indicating RP-HPLC Method for the Determination of Betaxolol Hydrochloride in Pharmaceutical Tablets

A stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method was developed for the determination of betaxolol hydrochloride, a drug used in the treatment of hypertension and glaucoma. The desired chromatographic separation was achieved on a Nucleosil C18, 4 μm (150 × 4.6 mm) column, using isocratic elution at a 220 nm detector wavelength. The optimized mobile phase consisted of a 0.02 M potassium dihydrogen phosphate: methanol (40:60, v/v, pH 3.0 adjusted with o- phosphoric acid) as solvent. The flow rate was 1.6 mL/min and the retention time of betaxolol hydrochloride was 1.72 min. The linearity for betaxolol hydrochloride was in the range of 25 to 200 μg/mL. Recovery for betaxolol hydrochloride was calculated as 100.01%–101.35%. The stability-indicating capability was established by forced degradation experiments and the separation of unknown degradation products. The developed RP-HPLC method was validated according to the International Conference on Harmonization (ICH) guidelines. This validated method was applied for the estimation of betaxolol hydrochloride in commercially available tablets.

Development and Validation of Stability-indicating HPLC Method for Betamethoasone Dipropionate and Related Substances in Topical Formulation

A gradient reversed phase HPLC method was developed and validated for analysis of betamethasone dipropionate, its related substances and degradation products, using Altima C(18) column (250×4.6 mm, 5 μm) with a flow rate of 1.0 ml/min and detection wavelength of 240 nm. The mobile phase A is a mixture of water, tetrahydrofuran and acetonitrile in the ratio of 90:4:6 (v/v/v) while mobile phase B is a mixture of acetonitrile, tetrahydrofuran, water and methanol in the ratio of 74:2:4:20 (v/v/v/v). The samples were analyzed using 20 μl injection volume and the column temperature was maintained at 50°. The limit of detection and limit of quantitation were found to be 0.02 μg/ml and 0.07 μg/ml, respectively. The stability-indicating capability of method was established by forced degradation studies and method demonstrated successful separation of drug, its related substances and degradation products. The method was validated as per the International Conference on Harmonization guidelines. The developed method is linear in the range of 0.07 to 200% of specification limits established for all the known related substances; betamethasone17-propionate, betamethasone 21-propionate, betamethasone 17-propionate-21-acetate (RSD <5, 2, 1%, respectively, r(2)=09991-0.9999 for sample concentration of 100 μg/ml). The method is sensitive, specific, linear, accurate, precise and stability indicating for the quantitation of drug, its related substances and other degradation compounds.

Stability-indicating Simultaneous HPTLC Method for Olanzapine and Fluoxetine in Combined Tablet Dosage Form

A rapid, selective and stability-indicating high performance thin layer chromatographic method was developed and validated for the simultaneous estimation of olanzapine and fluoxetine in combined tablet dosage form. Olanzapine and fluoxetine were chromatographed on silica gel 60 F₂₅₄ TLC plate using methanol:toluene (4:2 v/v) as the mobile phase and spectrodensitometric scanning-integration was performed at a wavelength of 233 nm using a Camag TLC Scanner III. This system was found to give compact spots for both olanzapine (R_f value of 0.63±0.01) and fluoxetine (R_f value of 0.31±0.01). The polynomial regression data for the calibration plots showed good linear relationship with r²=0.9995 in the concentration range of 100-800 ng/spot for olanzapine and 1000-8000 ng/spot for fluoxetine with r²=0.9991. The method was validated in terms of linearity, accuracy, precision, recovery and specificity. The limit of detection and the limit of quantification for the olanzapine were found to be 30 and 100 ng/spot, respectively and for fluoxetine 300 and 1000 ng/spot, respectively. Olanzapine and fluoxetine were degraded under acidic, basic and oxidation degradation conditions which showed all the peaks of degraded product were well resolved from the active pharmaceutical ingredient. Both drugs were not further degraded after thermal and photochemical degradation. The method was found to be reproducible and selective for the simultaneous estimation of olanzapine and fluoxetine. As the method could effectively separate the drugs from their degradation products, it can be employed as a stability-indicating method.

Identification of Forced Degradation Products of Itopride by LC-PDA and LC-MS

Degradation products of itopride formed under different forced conditions have been identified using LC-PDA and LC-MS techniques. Itopride was subjected to forced degradation under the conditions of hydrolysis, photolysis, oxidation, dry and wet heat, in accordance with the International Conference on Harmonization. The stress solutions were chromatographed on reversed phase C18 (250×4.6 mm, 5 μm) column with a mobile phase methanol:water (55:45, v/v) at a detection wavelength of 215 nm. Itopride degraded in acid, alkali and oxidative stress conditions. The stability indicating method was developed and validated. The degradation pathway of the drug to products II-VIII is proposed.

Development and validation of a RP-HPLC method for stability-indicating assay of gemifloxacin mesylate including identification of related substances by LC-ESI-MS/MS, 1H and 13C NMR spectroscopy

A validated stability indicating RP-HPLC assay of gemifloxacin mesylate was developed by separating its related substances on an Inertsil-ODS3V-C18 (4.6 × 250 mm; 5 μm) column using 0.1% trifluoroaceticacid (pH 2.5) and methanol as a mobile phase in a gradient elution mode at a flow rate of 1.0 mL/min at 27°C. The column effluents were monitored by a photodiode array detector set at 287 nm. The method was validated in terms of accuracy, precision and linearity as per ICH guidelines. Forced degradation of gemifloxacin (GFX) was carried out under acidic, basic, thermal, photolysis and peroxide conditions and the degradation products were separated and characterized by ESI-MS/MS, (1) H and (13) C NMR spectroscopy. The method was successfully applied to the analysis of bulk drugs and the recoveries of gemifloxacin and impurities were in the range of 97.60-102.90 and 96.99-102.10%, respectively. No previous reports were found in the literature on identification of degradation products of gemifloxacin.

Stability indicating high-performance liquid chromatography method for the estimation of artemether in capsule dosage forms

A new simple, sensitive, precise, and accurate high-performance liquid chromatography (HPLC) method of analysis for artemether both as a bulk drug and in capsule formulations was developed and validated. The method employed mobile phase acetonitrile (ACN) and buffer in the ratio 65:35 of pH 6.5 adjusted with tryethylamine. The linear regression analysis data for the calibration plots showed good linear relationship with r² = 0.9996 in the concentration range 250-750 μg/ml. The mean value slope and intercept were 9355.5 and −93.5, respectively. The method was validated for precision, accuracy, and recovery studies. Limit of detection (LOD) and Limit of quantitation (LOQ) for artemether were found to be 21.83-750 μg/ml, respectively. The method has been successfully applied in the analysis of marketed capsule formulations. The presented method was found to be reliable to separate all the degradents from all the stress conditions with resolution of more than 1.5 showing that it is a stability indicating method.