Practical and regulatory considerations for stability-indicating methods for the assay of bulk drugs and drug formulations

Current Applications of Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) in Pharmaceutical Analysis: Review

The present review encompasses various applications of multivariate curve resolution- alternating least squares (MCR-ALS) as a promising data handling, which is issued by analytical techniques in pharmaceutics. It involves different sections starting from a concise theory of MCR-ALS and four detailed applications in drugs analysis. Dissolution, stability, polymorphism, and quantification are the main four detailed applications. The data generated by analytical techniques associated with MCR-ALS deals accurately with different challenges compared to other chemometric tools. For each reviewed purpose, it was explained how MCR-ALS was applied and detailed information was given. Different approaches were introduced to overcome challenges that limit the use of MCR-ALS efficiently in pharmaceutical mixture were also discussed.

Expeditive Chromatographic Methods for Quantification of Solifenacin Succinate along with its Official Impurity as the Possible Acid Degradation Product

Two selective stability-indicating procedures were adopted for the quantification of Solifenacin succinate (SOL) along with its acid degradant, in its powder form or in pharmaceutical tablet. Under stress conditions, the acid degradation pathway of SOL was investigated, its official impurity (SOL imp-A) was obtained as the possible acid degradation product, also. A densitometric technique based on the separation of SOL from SOL imp-A employing HPTLC plates prelaminated with silica gel 60 F254 as the stationary phase and a developing solution containing methanol:chloroform:ammonia (8:1:1, v/v/v) and UV scanning of the developed bands at 220 nm. Linear regression analysis data for the calibration plot of SOL showed perfect linear relationships throughout the range of concentration 10-60 μg/band. A reversed phase C18 analytical column (4.6 × 250 mm, 5 μm) was also used to separate the mixture at a flow rate of 1 mL/min, using acetonitrile:0.05 M phosphate buffer (70:30, v/v) as the mobile phase and phosphoric acid to set pH = 3.5. Quantification was obtained at 220 nm using peak area and linear calibration curve across a concentration range of 10-70 μg/mL. The recommended procedures were applied to the existing dosage form, and they generated satisfactory results.

Liquid chromatographic determination of lumacaftor in the presence of ivacaftor and identification of five novel degradation products using high-performance liquid chromatography ion trap time-of-flight mass spectrometry

Lumacaftor is a transmembrane conductance regulator potentiator drug, prescribed for the treatment of cystic fibrosis in patients who are homozygous for the F508del mutation. Quantitation of lumacaftor besides its degradation products and ivacaftor was achieved on a fused-core silica particle column packed with pentafluorophenylpropyl stationary phase (Ascentis Express F5, 2.7 μm particle size 100 mm × 4.6 mm; Supelco) using gradient elution (A: 0.1% [v/v] formic acid in water, B: 0.1% [v/v] formic acid in acetonitrile [the mobile phase pH 2.5]). A constant flow rate at 1 mL/min was applied, and the detection was realized using a photodiode array detector set at 216 nm. The pseudo tablet formulation of the lumacaftor/ivacaftor fixed-dose combination preparation, namely, Orkambi®, was prepared in vitro and used for the analytical performance validation and method application studies. In addition, five novel degradation products, four of which even have no Chemical Abstracts Services registry number, were identified using high-resolution mass spectrometry instrument, and their possible mechanisms of formation were proposed. According to current literature, this paper can be regarded as the most comprehensive liquid chromatographic study on lumacaftor determination, among its counterparts.

Two Validated Chromatographic Methods for Determination of Ciprofloxacin HCl, One of its Specified Impurities and Fluocinolone Acetonide in Newly Approved Otic Solution

Two sensitive, selective and precise chromatographic methods have been established for concomitant quantification of ciprofloxacin HCl (CIP), fluocinolone acetonide (FLU) along with ciprofloxacin impurity A (CIP-imp A). The first method was thin-layer chromatography (TLC-densitometry) where separation was accomplished using TLC silica plates 60 G.F254 as a stationary phase and chloroform-methanol-33%ammonia (4.6:4.4:1, by volume) as a developing system. The obtained plates were scanned at 260 nm over concentration ranges of 1.0-40.0, 0.6-20.0 and 1.0-40.0 μg band-1 for CIP, FLU and CIP-imp A, respectively. The second method was based on high-performance liquid chromatography using a Zorbax ODS column (5 μm, 150 × 4.6 mm i.d.) where adequate separation was achieved through a mobile phase composed of phosphate buffer pH 3.6-acetonitrile (45:55, v/v) at flow rate 1.0 mL min-1 with ultraviolet detection at 254 nm. Linear regressions were obtained in the range of 1.0-40.0 μg mL-1 for CIP, 0.6-20.0 μg mL-1 for FLU and 1.0-40.0 μg mL-1 for CIP-imp A. The suggested methods were validated in compliance with the International Conference on Harmonization guidelines and were successfully applied for determination of CIP and FLU in bulk powder and newly marketed otic solution.

Mini Review on Forced Degradation Studies on Anti-Epileptic Drugs and Beyond

In this review on the forced degradation studies on anti-epileptic drugs and the development of validated stability-indicating assay methods for drug substances and products at a condition more severe than accelerated condition (i.e. 40 ± 2°C, 75 ± 5% relative humidity), the drug substance and drug product undergo degradation is known as forced or stress degradation. To know about the impurities developed during the storage of drug products in various environmental conditions. The limit of degradation allowable is 5-20%. More than 20% of degradation is abnormal and must be investigated. Any regulatory guidelines do not mention the pH conditions for acid or base hydrolysis, the temperature for thermal degradation or the concentration of the oxidation agent. Only International Conference on Harmonization (ICH) guidelines Q1B photostability stability and states that light sources must be a combination of UV and visible light. The shortcomings of mentioned techniques with appreciation to regulatory necessities are highlighted. A systematic method for the forced degradation studies on anti-epileptic drugs such as "Topiramate, Vigabatrin, Lacosamide, Tiagabine, Levetiracetam and Zonisamide" is discussed. This review helps researchers to get an idea about stability-indicating methods of development and validation for newer antiepileptic drugs and the characteristics of drug products that degrade under specific degradation conditions.

Determination of the Chemical Stability of Dapagliflozin by LC/DAD and MS/MS Methods

A simple and fast stability-indicating liquid chromatographic method with diode array detection (DAD) was developed and validated for the determination of dapagliflozin (DAPA) in bulk and tablets, in the presence of its major degradation products (DP). The drug was subjected to hydrolytic, oxidative, photolytic, thermal and humidity/thermal stress conditions, showing significant degradation under humidity/thermal with the formation of two DP, which were preliminarily identified by liquid chromatography with diode array detector coupled with electrospray ionization-tandem mass spectrometry (HPLC-DAD-ESI-MS/MS). Chromatographic separation of dapagliflozin and its DP was achieved with a core-shell RP-18 column, using acetonitrile and water as mobile phase in isocratic elution mode. The described method was linear over a range of 50-150 μg/mL. For precision, the relative standard deviation (RSD) was <1.3%, the recovery was 99.64-100.11%, and the assay demonstrated adequate selectivity. The degradation kinetics of dapagliflozin was evaluated corresponding to first-order under thermal and humidity/thermal stress conditions. Dapagliflozin was well resolved from its drug products showing the power of stability-indicating of the method. The results showed that the proposed method was found to be suitable for routine analysis, quantitative determination and the stability study of dapagliflozin in pharmaceutical samples.

Accelerated stability study of the ester prodrug remdesivir: Recently FDA-approved Covid-19 antiviral using reversed-phase-HPLC with fluorimetric and diode array detection

Remdesivir (RDV) is the first antiviral drug, approved by the Food and Drug Administration, to treat severe acute respiratory syndrome coronavirus 2. RDV is a relatively new chemical entity, 'ester prodrug', with no reported stability profile. Due to the urgency of its use and thus fast production, it is important to develop a stability-indicating method for its assay. Chromatographic separation was carried out on a C18 column (250 × 4.6 mm, 5 µm) with dual detection: diode array at 240 nm and fluorescence at λ_ex/em 245/390 nm. Isocratic elution of acetonitrile and distilled water (acidified with phosphoric acid, pH 4) in the ratio of 55:45 (v/v), respectively, was used. The linearity range using HPLC-diode array detection was 0.1-15 μg/mL, whereas that using fluorimetric detection was 0.05-15 μg/mL. As per the International Conference on Harmonization guidelines, RDV has been degraded by accelerated alkaline, acidic, neutral hydrolysis, oxidative, heat, and photolytic stress conditions. Possible degradation hypothesis of the parent molecule has been suggested and illustrated. The proposed methods have achieved selective determination of the intact drug with no peaks overlapping in all assumptions. Extensive degradation confirms threatened drug stability at thermal and basic hydrolytic stressing. The developed methods were fully validated and proved suitable for quality control routine analysis of RDV in raw material and pharmaceutical dosage forms.

Analytical Methods for Determination of Antiviral Drugs in Different Matrices: Recent Advances and Trends

Viruses are the main pathogenic substances that cause severe diseases in humans and other living things. They are among the most common microorganisms, and consequently, antiviral drugs have emerged to prevent and treat viral infections. Antiviral drugs are an essential drug group considering their prescription and consumption rates for different diseases and indications. Therefore, it is crucial to develop accurate and precise analytical methods to detect antiviral drugs in various matrices. Chromatographic techniques are used frequently for the quantification purpose since they allow simultaneous determination of antivirals. Electrochemical methods have also gained importance since the analysis can be performed quickly without the need for pretreatment. Spectrophotometric and spectrofluorimetric methods are used because they are simple, inexpensive, and less time-consuming methods. The purpose of this review is to present an overview of the analysis of currently used antiviral drugs from 2010 to 2021. Since studies on antiviral drugs are numerous, selected publications were reviewed in this article. The analysis of antiviral drugs was divided into three main groups: chromatographic, spectrometric, and electrochemical methods which were applied to different matrices, including pharmaceutical, biological, and environmental samples.

Stability Indicating Methods for Determination of Third Generation Antiepileptic Drugs and Their Related Substances

The third generation of antiepileptic drugs that have been approved by international regulatory agencies between 2007 and 2018 include rufinamide, stiripentol, eslicarbazepine acetate, lacosamide, perampanel, brivaracetam and everolimus. As part of demonstrating their safety profile, stability indicating methods are developed to monitor these drugs and their impurities. In this context, this review describe some characteristics, impurities and the stability indicating methods used for the determination of these drugs and the presence of their related substances. Through a search in official compendia and scientific articles, fifty-six analytical methodologies were identified up to October 2020. The methodologies were developed using techniques of HPLC, UPLC, HPTLC, GC and UV/Vis spectrophotometry. A majority of the methods (∼70%) employed HPLC-UV. A number of these antiepileptic drugs were found to have had a small number of studies related to their stability and for the detection of impurities. The presentation of the current level of research on third generation antiepileptic drugs highlights the need for new stability and safety studies that are necessary to develop new pharmaceutical products containing these drugs.

Stability assessment of tamsulosin and tadalafil co-formulated in capsules by two validated chromatographic methods

The advent of a new pharmaceutical formulation evokes the need for examining the chemical stability of their constituents and establishing proper stability-indicating methods. Herein, the stability of the newly co-formulated Tamsulosin and Tadalafil were examined under different stress conditions. The acidic degradation of Tamsulosin yielded its sulfonated derivative, while Tadalafil was susceptible to both acidic and basic degradation. Two stability-indicating chromatographic methods, namely; high-performance thin-layer chromatography and high-performance liquid chromatography, have been developed. Significant high-performance thin-layer chromatography-fractionation could be achieved by utilizing a stationary phase of silica gel 60 F₂₅₄ and a mobile phase composed of ethyl acetate/toluene/methanol/ammonia (4:2:4:0.6, by volumes) with densitometric recording at 280 nm over a concentration range of 0.5-25 μg/band for both drugs. The HPLC-separation could be reached on XBridge^® C₁₈ column isocraticaly by using a mobile phase having acetonitrile/phosphate buffer, pH 6.0 (45:55, v/v) pumped at a flow rate of 1.7 mL/min and applying diode array ultraviolet-detection at 210 nm over a linearity range of 3-70 μg/mL for each drug. Specificity of the two methods was additionally assured via peak purity assessment. Moreover, the methods were distinctly exploited for evaluating the drugs' stability in accelerated stability-studied samples of Tamplus^® capsules.

Capillary electrophoretic methods for quality control analyses of pharmaceuticals: A review

Capillary electrophoresis represents a promising technique in the field of pharmaceutical analysis. The presented review provides a summary of capillary electrophoretic methods suitable for routine quality control analyses of small molecule drugs published since 2015. In total, more than 80 discussed methods are sorted into three main sections according to the applied electroseparation modes (capillary zone electrophoresis, electrokinetic chromatography, and micellar, microemulsion, and liposome-electrokinetic chromatography) and further subsections according to the applied detection techniques (UV, capacitively coupled contactless conductivity detection, and mass spectrometry). Key parameters of the procedures are summarized in four concise tables. The presented applications cover analyses of active pharmaceutical ingredients and their related substances such as degradation products or enantiomeric impurities. The contribution of reported results to the current knowledge of separation science and general aspects of the practical applications of capillary electrophoretic methods are also discussed.

Comprehensive stability-indicating method development of Avanafil Phosphodiesterase type 5 inhibitor using advanced Quality-by-Design approach

Avanafil (AV) is the phosphodiesterase (PDE) type 5 inhibitor drug used in erectile dysfunction, having pyrrolidine, pyrimidine, carboxamide, and chlorine as functional groups which can easily break by environmental changes and cause toxicity. Henceforth, in detail, HPLC stability study with the Quality-by-Design (QbD) approach is presented which leads to recommended storage conditions. The stability of AV was analyzed in hydrolysis, photolysis, and thermal and oxidative conditions. The application of the QbD approach during the stability method development comprises steps as screening and optimization. Quality target product profile (QTPP) was defined, and critical quality attributes (CQAs) were assigned to meet the QTPP requirements. Primary parameters obtained from the Ishikawa diagram were studied via Placket–Burman, and four critical factors were optimized through the central composite design (CCD). The finalized method includes mobile phase [10 mM ammonium acetate, pH 4.5 adjusted by acetic acid:ACN (60:40, v/v)] at 0.9-mL/min flow rate and 239-nm wavelength. A control strategy was set up to ensure that the method repeatedly meets the acceptance criteria. Overall, 16 degradation product peaks of AV in all conditions (solid and solution state) were identified with optimized method and evaluated by HPLC-PDA study. A comprehensive systemic optimization of AV stability study is stated for the first time, which reveals that AV is prone to degrade in sunlight, moisture, and temperature. Global regulators and manufacturers should take care of the packaging, handling, and labeling of AV. A fully validated LC–MS compatible stability method can be successfully applied to monitor AV stability from its formulation which can be wisely extrapolated to assess the AV from biological samples.

Degradation studies of quetiapine fumarate by liquid chromatography-diode array detection and tandem mass spectrometry methods

Quetiapine fumarate (QUE) is an antipsychotic agent with a chemical structure that is susceptible to degradation; therefore, it is important to study its stability using appropriate analytical tools. Knowledge of the stability profile of a drug is important because chemical degradation of its active component often results in a loss of potency, affecting its efficacy and safety. This current work reports degradation studies of QUE as drug substance, under different stress conditions such as oxidation, hydrolysis, heat, humidity and photolysis, by a stability-indicating LC method. The chemical stability was evaluated using a simple HPLC/diode array detection method, with a core-shell C₁₈ column under isocratic conditions, which allows the separation of all primary degradation products (DPs) in a short run time. QUE was mainly degraded under oxidative and hydrolytic conditions, with the formation of three and two DPs, respectively, which were identified by electrospray ionization-tandem mass spectrometry. The method was properly validated in terms of linearity, accuracy, precision, selectivity, robustness and quantitation limit. Commercial tablets containing 25 mg of QUE were quantified, with results obtained within the United States Pharmacopeia limits. The proposed method is suitable to assess the stability and perform routine analysis of QUE in pharmaceutical samples.

Degradation kinetics of α-conotoxin TxID

α‐Conotoxin (CTx) TxID is a potent α3β4 nicotinic acetylcholine receptor (nAChR) antagonist that has been suggested as a potential drug candidate to treat addiction and small cell lung cancer. The function and structure of TxID have been well‐studied, but analyses of its stability have not previously been reported. The purpose of this study was to analyze the stability and forced degradation of TxID under various conditions: acid, alkali, water hydrolysis, oxidation, light, thiols, temperature, ionic strength and buffer pH. Different degradation products were formed under various conditions, and the degradation patterns of TxID showed pseudo‐first‐order kinetics. TxID degraded slowest at pH 3 within a pH range of 2–8. The major degradation products were analyzed using liquid chromatography–tandem mass spectrometry and the activity of the main product with α3β4 nAChR was analyzed using electrophysiological methods. Our analysis of TxID stability may aid the selection of appropriate conditions for peptide production, packaging and storage.

Stability of mycophenolate mofetil in polypropylene 5% dextrose infusion bags and chemical compatibility associated with the use of the Equashield® closed-system transfer device

Stability studies are necessary in healthcare settings as they facilitate fast, cost-effective and efficient work related to batch manufacturing and availability of supplies. We studied the stability of 1-10 mg/mL mycophenolate mofetil (MMF) in polypropylene 5% dextrose infusion bags prepared from Cellcept^® and with a generic brand name (Micofenolato de Mofetilo Accord) at different storage temperatures. To ensure chemical compatibility during preparation, we also tested MMF sorption to the Equashield^® closed-system drug transfer device used in this step. For this, a validated stability-indicating high-performance liquid chromatography method was developed for the quantification and identification of MMF in the infusion bags. The analytical selectivity of the assay was determined by subjecting an MMF sample to extreme values of pH, oxidative stress and heat conditions to force degradation. Protected from light, 1-10 mg/mL MMF in infusion polypropylene bags prepared from reconstituted Cellcept^® 500 mg or Accord 500 mg in 5% dextrose was stable for at least 35 days when stored at 2-8°C or between -15 and -25°C, and for 14 days when stored at 25°C. MMF loss owing to chemical sorption to the Equashield^® closed-system drug transfer device set was negligible.

Forced Degradation Studies of Ivabradine and In Silico Toxicology Predictions for Its New Designated Impurities

All activities should aim to eliminate genotoxic impurities and/or protect the API against degradation. There is a necessity to monitor impurities from all classification groups, hence ivabradine forced degradation studies were performed. Ivabradine was proved to be quite durable active substance, but still new and with insufficient stability data. Increased temperature, acid, base, oxidation reagents and light were found to cause its degradation. Degradation products were determined with the usage of HPLC equipped with Q-TOF-MS detector. Calculations of pharmacological and toxicological properties were performed for six identified degradation products. Target prediction algorithm was applied on the basis of Hyperpolarization-activated cyclic nucleotide-gated cation channels, as well as more general parameters like logP and aqueous solubility. Ames test and five cytochromes activities were calculated for toxicity assessment for selected degradation products. Pharmacological activity of photodegradation product (UV4), which is known as active metabolite, was qualified and identified. Two other degradation compounds (Ox1 and N1), which were formed during degradation process, were found to be pharmacologically active.

Forced degradation studies of biopharmaceuticals: Selection of stress conditions

Stability studies under stress conditions or forced degradation studies play an important role in different phases of development and production of biopharmaceuticals and biological products. These studies are mostly applicable to selection of suitable candidates and formulation developments, comparability studies, elucidation of possible degradation pathways and identification of degradation products, as well as, development of stability indicating methods. Despite the integral part of these studies in biopharmaceutical industry, there is no well-established protocol for the selection of stress conditions, timing of stress testing and required extent of degradation. Therefore, due to the present gap in the stability studies guidelines, it is the responsibility of researchers working in academia and biopharmaceutical industry to set up forced degradation experiments that could fulfill all the expectations from the stability studies of biopharmaceuticals under stress conditions. Concerning the importance of the function of desired stress conditions in forced degradation studies, the present review aims to provide a practical summary of the applicable stress conditions in forced degradation studies of biopharmaceuticals according to the papers published in a time period of 1992-2015 giving detailed information about the experimental conditions utilized to induce required stresses.

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.

Improvement of a stability-indicating method by Quality-by-Design versus Quality-by-Testing: a case of a learning process

The understanding of the method is a major concern when developing a stability-indicating method and even more so when dealing with impurity assays from complex matrices. In the presented case study, a Quality-by-Design approach was applied in order to optimize a routinely used method. An analytical issue occurring at the last stage of a long-term stability study involving unexpected impurities perturbing the monitoring of characterized impurities needed to be resolved. A compliant Quality-by-Design (QbD) methodology based on a Design of Experiments (DoE) approach was evaluated within the framework of a Liquid Chromatography (LC) method. This approach allows the investigation of Critical Process Parameters (CPPs), which have an impact on Critical Quality Attributes (CQAs) and, consequently, on LC selectivity. Using polynomial regression response modeling as well as Monte Carlo simulations for error propagation, Design Space (DS) was computed in order to determine robust working conditions for the developed stability-indicating method. This QbD compliant development was conducted in two phases allowing the use of the Design Space knowledge acquired during the first phase to define the experimental domain of the second phase, which constitutes a learning process. The selected working condition was then fully validated using accuracy profiles based on statistical tolerance intervals in order to evaluate the reliability of the results generated by this LC/ESI-MS stability-indicating method. A comparison was made between the traditional Quality-by-Testing (QbT) approach and the QbD strategy, highlighting the benefit of this QbD strategy in the case of an unexpected impurities issue. On this basis, the advantages of a systematic use of the QbD methodology were discussed.