Structure Identification and Risk Assurance of Unknown Impurities in Pramipexole Oral Drug Formulation

Impurities compounds in any pharmaceutical product or drug substance are inevitable from a chemistry point of view. The quality and safety of a pharmaceutical product are also significantly affected by these impurities content; therefore, impurities need to be identified and characterized through the use of appropriate analytical methods. Pramipexole is a nonergot dopamine agonist used to treat various Parkinson's disease symptoms. Two unknown impurities were detected from a pramipexole dihydrochloride solid dosage form. These impurities were identified and characterized using ultra-performance liquid chromatography coupled with high-resolution mass spectroscopy (UPLC-HRMS). These impurities were found to be enriched when mannitol existed in the formulation. The structure and mechanism involved in the existence of the impurities were proposed. Furthermore, observation of the binding affinity potential risk of these impurities to the pramipexole receptor has also been demonstrated through molecular docking and molecular dynamics simulation study. The binding energy result showed that pramipexole interaction with dopamine receptors D2 and D3 was higher than pramipexole mannose adduct and pramipexole ribose adduct.

Influence of Crystal Disorder on the Forced Oxidative Degradation of Vortioxetine HBr

The present study investigates the impact of the solid-state disorder of vortioxetine hydrobromide (HBr) on oxidative degradation under accelerated conditions. A range of solid-state disorders was generated via cryogenic ball milling. The solid-state properties were evaluated by calorimetry, infrared-, and Raman spectroscopies. While salt disproportionation occurred upon milling, no chemical degradation occurred by milling. The amorphous fraction remained physically intact under ambient storage conditions. Subsequently, samples with representative disordered fractions were mixed with a solid oxidative stressor (PVP-H2O2 complex) and were compressed to compacts. The compacts were exposed to 40°C/75% RH for up to 6 h. The sample was periodically withdrawn and analyzed for the physical transformations and degradation. Two oxidative degradation products (DPs) were found to be formed, for which dissimilar relations to the degree of disorder and kinetics of formation were observed. The degradation rate of the major DP formation obtained by fitting the exponential model to the experimental data was found to increase up to a certain degree of disorder and decrease with a further increase in the disordered fraction. In contrast, the minor DP formation kinetics was found to increase monotonically with the increase in the disorder content. For the similar crystallinity level, the degradation trend (rate and extent) differed between the single-phase disorder generated by milling and physically mixed two-phase systems. Overall, the study demonstrates the importance of evaluating the physical and chemical (in)stabilities of the disordered solid state of a salt form of a drug substance, generated through mechano-activation.

Application of Formulation Principles to Stability Issues Encountered During Processing, Manufacturing, and Storage of Drug Substance and Drug Product Protein Therapeutics

The field of formulation and stabilization of protein therapeutics has become rather extensive. However, most of the focus has been on stabilization of the final drug product. Yet, proteins experience stress and degradation through the manufacturing process, starting with fermentaition. This review describes how formulation principles can be applied to stabilize biopharmaceutical proteins during bioprocessing and manufacturing, considering each unit operation involved in prepration of the drug substance. In addition, the impact of the container on stabilty is discussed as well.

A Simple Non-Linear Kinetic Model to Evaluate Stability of a Pressure Sensitive Drug

Candesartan cilexetil is challenging to formulate due to pressure induced chemical degradation. We report a statistical model based on stability data set of a marketed tablet formulation. Impurity increase over time was fitted to a reparametrized second-order kinetic model. Both kinetic model parameters have mechanistic interpretation: parameter a relates to the overall extent of pressure induced instability (the ceiling impurity level) and parameter b relates to the initial rate of degradation (how fast the ceiling is reached). A hierarchical model was then used to quantify sensitivity to tableting pressure and humidity-corrected Arrhenius equation quantified sensitivity to temperature and moisture. An overall model, based on four predictors and five estimated parameters allowed fitting of the entire stability dataset (694 stability data points) with good accuracy. Learnings allowed development of a stable formulation (soft tableting, increasing tablet size/shape and reducing moisture) and resulted in a confident stress stability test to evaluate any future product changes in a timely manner.

DSC, FT-IR and NIR with Chemometric Assessment Using PCA and HCA for Estimation of the Chemical Stability of Oral Antidiabetic Drug Linagliptin in the Presence of Pharmaceutical Excipients

Pharmaceutical excipients should not interact with active substances, however, in practice, they sometimes do it, affecting the efficacy, stability and safety of drugs. Thus, interactions between active substances and excipients are not desirable. For this reason, two component mixtures of oral antidiabetic drug linagliptin (LINA) with four excipients of different reactivity, i.e., lactose (LAC), mannitol (MAN), magnesium stearate (MGS) and polyvinylpyrrolidone (PVP), were prepared in a solid state. A high temperature and a high humidity of 60 °C and 70% RH, respectively, were applied as stressors in order to accelerate the potential interactions between LINA and excipients. Differential scanning calorimetry (DSC) as well as Fourier transform infrared (FT-IR) and near infrared (NIR) spectroscopy were used to estimate the changes due to potential interactions. In addition, chemometric computation of the data with principal component analysis (PCA) and hierarchical cluster analysis (HCA) was applied to adequately interpret the findings. Of the excipients used in the present experiment, all of them were not inert in relation to LINA. Some of the interactions were shown without any stressing, whereas others were observed under high-temperature/high-humidity conditions. Thus, it could be concluded that selection of appropriate excipients for LINA is very important question to minimize its degradation, especially when new types of formulations with LINA are being developed and manufactured.

Monitoring of the natural aging of Diclofenac tablets, NIR and MIR-ATR spectroscopy coupled with chemometrics data analysis

This study presents the analysis of the natural long-term aging of both the intact tablets and the active pharmaceutical ingredient. No forced aging conditions were applied to the samples. It is shown that the near infrared spectroscopy of the intact tablets packed in plastic blisters, supported by chemometrics, is a reliable method for detection of even slight deviations of the medicine from its regular state. Independent components analysis helps to extract source signals from spectra of the composite object "a coated tablet sealed in polyvinylchloride blister". Further analysis of the near infrared and attenuated total reflectance infrared spectra of the pure substance confirmed that the aging process detected by the analysis of the intact tablets is directly related to the degradation of the active pharmaceutical ingredient.

Drug Carriers: A Review on the Most Used Mathematical Models for Drug Release

Carriers are protective transporters of drugs to target cells, facilitating therapy under each points of view, such as fast healing, reducing infective phenomena, and curing illnesses while avoiding side effects. Over the last 60 years, several scientists have studied drug carrier properties, trying to adapt them to the release environment. Drug/Carrier interaction phenomena have been deeply studied, and the release kinetics have been modeled according to the occurring phenomena involved in the system. It is not easy to define models’ advantages and disadvantages, since each of them may fit in a specific situation, considering material interactions, diffusion and erosion phenomena, and, no less important, the behavior of receiving medium. This work represents a critical review on main mathematical models concerning their dependency on physical, chemical, empirical, or semi-empirical variables. A quantitative representation of release profiles has been shown for the most representative models. A final critical comment on the applicability of these models has been presented at the end. A mathematical approach to this topic may help students and researchers approach the wide panorama of models that exist in literature and have been optimized over time. This models list could be of practical inspiration for the development of researchers’ own new models or for the application of proper modifications, with the introduction of new variable dependency.

Oxidation of Drugs during Drug Product Development: Problems and Solutions

Oxidation is the second most common degradation pathway for pharmaceuticals, after hydrolysis. However, in contrast to hydrolysis, oxidation is mechanistically more complex and produces a wider range of degradation products; oxidation is thus harder to control. The propensity of a drug towards oxidation is established during forced degradation studies. However, a more realistic insight into degradation in the solid state can be achieved with accelerated studies of mixtures of drugs and excipients, as the excipients are the most common sources of impurities that have the potential to initiate oxidation of a solid drug product. Based on the results of these studies, critical parameters can be identified and appropriate measures can be taken to avoid the problems that oxidation poses to the quality of a drug product. This article reviews the most common types of oxidation mechanisms, possible sources of reactive oxygen species, and how to minimize the oxidation of a solid drug product based on a well-planned accelerated study.

The degradation map process - a tool for obtaining a lean stability strategy in drug development

Stability is fundamental when exploring a drug candidate's potential as a drug product. During the pharmaceutical industry drug development process information regarding stability and degradation are captured in different departments, e.g. from discovery to operations, and will be included in the overall control strategy. With a profound understanding of a drug candidate's degradation chemistry, a science and risk based approach in progressing a lean stability strategy is possible. This case study present a clear and visible concept to facilitate a lean stability strategy by the use of degradation maps and describes a process for how these can be used during drug development. The understanding of possible and/or observed degradation pathways will guide the design of the drug product and stability studies in development. A degradation map displays degradation pathways with short comments on the reaction/mechanism involved. The degradation map process starts with a theoretical degradation map. The map is updated as the drug project progresses, preferably after forced degradation experiments, after compatibility studies and finally when the late stage formulation is set. The degradation map should be used to capture information of intrinsic chemical properties of the active pharmaceutical ingredient (API) and can thereby be used to mitigate stability issues. The map is foremost a cross-functionally available tool collecting and visualizing stability information throughout the development process, and as such a valuable tool to efficiently develop a lean stability strategy.

The Identification of Quality Risk Factors for Non-biological Complex Drugs and Epilepsy Drugs Using Statistical Analysis of Formulation-Based Recalls in the USA

Pharmaceutical companies use the quality by design (QbD) approach to build high-quality drug products. A thorough understanding of risk factors is required to successfully employ QbD. In order to better understand risk factors that potentially impact drug product quality and inform future QbD approaches, we hypothesized root causes of drug product recalls based on publicly available data and a retroactive analysis of drug products recalled by the United States Food and Drug Administration (USFDA) from 2012 to 2018. We focused on two categories of drug products that pose unique regulatory challenges and an increased risk of shortage that could hinder the adequate supply of quality medicine to the patient. Knowing the significant risk factors from previous drug product recalls can help inform QbD and avoid future recalls. Quality recall reasons were studied individually to find risk factors associated with each recall category. Logistical regression statistical tests were done in R using a significance level of 0.05 to find correlations between a recalled product and its manufacturing information such as excipients and manufacturing steps. The results showed significant positive and negative correlations, such as products containing magnesium stearate are more likely to be recalled for impurities and degradation. This information could be used in the future to inform the design and manufacturing of drug products, ensuring consumers receive high-quality products with a low risk of recall.

Comprehensive Insight into Chemical Stability of Important Antidiabetic Drug Vildagliptin Using Chromatography (LC-UV and UHPLC-DAD-MS) and Spectroscopy (Mid-IR and NIR with PCA)

During forced degradation, the intrinsic stability of active pharmaceutical ingredients (APIs) could be determined and possible impurities that would occur during the shelf life of the drug substance or the drug product could be estimated. Vildagliptin belongs to relatively new oral antidiabetic drugs named gliptins, inhibiting dipeptidyl peptidase 4 (DPP-4) and prolonging the activities of the endogenous incretin hormones. At the same time, some gliptins were shown as prone to degradation under specific pH and temperature conditions, as well as in the presence of some reactive excipients. Thus, forced degradation of vildagliptin was performed at high temperature in extreme pH and oxidative conditions. Then, selective LC-UV was used for quantitative determination of non-degraded vildagliptin in the presence of its degradation products and for degradation kinetics. Finally, identification of degradation products of vildagliptin was performed using an UHPLC-DAD-MS with positive ESI. Stability of vildagliptin was also examined in the presence of pharmaceutical excipients, using mid-IR and NIR with principal component analysis (PCA). At 70 °C almost complete disintegration of vildagliptin occurred in acidic, basic, and oxidative media. What is more, high degradation of vildagliptin following the pseudo first-order kinetics was observed at room temperature with calculated k values 4.76 × 10⁻⁴ s⁻¹, 3.11 × 10⁻⁴ s⁻¹, and 1.73 × 10⁻⁴ s⁻¹ for oxidative, basic and acidic conditions, respectively. Next, new degradation products of vildagliptin were detected using UHPLC-DAD-MS and their molecular structures were proposed. Three degradants were formed under basic and acidic conditions, and were identified as [(3-hydroxytricyclo- [3.3.1.13,7]decan-1-yl)amino]acetic acid, 1-{[(3-hydroxytricyclo[3.3.1.13,7]decan-1-yl)amino]acetyl}-pyrrolidine-2-carboxylic acid and its O-methyl ester. The fourth degradant was formed in basic, acidic, and oxidative conditions, and was identified as 1-{[(3-hydroxytricyclo[3.3.1.13,7]-decan-1-yl)amino]acetyl}pyrrolidine-2-carboxamide. When stability of vildagliptin was examined in the presence of four excipients under high temperature and humidity, a visible impact of lactose, mannitol, magnesium stearate, and polyvinylpirrolidone was observed, affecting-NH- and CO groups of the drug. The obtained results (kinetic parameters, interactions with excipients) may serve pharmaceutical industry to prevent chemical changes in final pharmaceutical products containing vildagliptin. Other results (e.g., identification of new degradation products) may serve as a starting point for qualifying new degradants of vildagliptin as it is related to substances in pharmacopoeias.

Study on the Mechanism Responsible for the Incompatibility of Enalapril Maleate with Sodium Starch Glycolate

Enalapril maleate (EM) is known to suffer from incompatibilities in the solid state. This study investigates the destabilizing effect of sodium starch glycolate (SSG) on EM. This was done by varying the mixing ratio and moisture content of binary mixtures. Differential scanning calorimetry and microscopy show a loss of crystallinity of EM at the contact surface with SSG. It is shown that this is followed by decomposition of E to diketopiperazine (DKP). These phenomena are modulated by moisture. The environmental pH turned out to be crucial; when the zwitterion is formed at the appropriate pH, ring closure into DKP is promoted.

Innovations in Thermal Processing: Hot-Melt Extrusion and KinetiSol® Dispersing

Thermal processing has gained much interest in the pharmaceutical industry, particularly for the enhancement of solubility, bioavailability, and dissolution of active pharmaceutical ingredients (APIs) with poor aqueous solubility. Formulation scientists have developed various techniques which may include physical and chemical modifications to achieve solubility enhancement. One of the most commonly used methods for solubility enhancement is through the use of amorphous solid dispersions (ASDs). Examples of commercialized ASDs include Kaletra®, Kalydeco®, and Onmel®. Various technologies produce ASDs; some of the approaches, such as spray-drying, solvent evaporation, and lyophilization, involve the use of solvents, whereas thermal approaches often do not require solvents. Processes that do not require solvents are usually preferred, as some solvents may induce toxicity due to residual solvents and are often considered to be damaging to the environment. The purpose of this review is to provide an update on recent innovations reported for using hot-melt extrusion and KinetiSol® Dispersing technologies to formulate poorly water-soluble APIs in amorphous solid dispersions. We will address development challenges for poorly water-soluble APIs and how these two processes meet these challenges.

Application of Failure Mode Effect Analysis in Wurster-Based Pelletization Technology: a Technical Note

The deployment of oral multi-unit pellet formulation has gained significant attention in recent years conferring to numerous applications, especially in achieving modified release and acid resistance property. The fluidized bed coating, specifically Wurster technique is commercially utilized for pellet manufacturing, which is a complex process involving too many variables. Risk assessment tools can be employed to determine the critical variables affecting the pre-defined quality profile and screen out important parameters out of literally hundreds of variables to develop a robust product. The present review aims to describe possibly all the variables involved in Wurster coating process and application of FMEA in pellet manufacturing. A brief case study regarding applicability of FMEA to study the effects of critical factors is outlined. Risk assessment tools assist to reduce number of trials to manageable levels with aid of prior art, literature, and preliminary trials to develop an optimized product.

In-vitro cytotoxicity of various Siphonochilus aethiopicus (Schweinf.) B.L. Burtt extracts in combination with selected tableting excipients

OBJECTIVES

To investigate the cytotoxic potential of S. aethiopicus extracts in combination with chitosan and Pharmacel^® 101, on two cell lines.

METHODS

Extracts were chemically characterised utilising UPLC-Q-TOF/MS, followed by determination of cell viability and membrane integrity.

KEY FINDINGS

Ethanol (EtOH) and diethyl ether (DiEt) extracts contained significant quantities of all chosen biomarker molecules; however, only two were scarcely quantifiable in aqueous extracts. Aqueous extracts did not induce any cytotoxic effects, whereas EtOH and DiEt extracts caused concentration-dependent decreases in cell viability and membrane integrity loss in both cell lines. Ensuing exposure to EtOH extracts at 50, 100 and 150 μg/ml, HepG2 cells were considered 15.5%, 12.5% and 32.8% apoptotic, whereas DiEt extracts caused 4.5%, 13.5% and 33.9% apoptotic cells. Exposure to EtOH and DiEt extracts at 50 μg/ml ensued in 20.2% and 21.3% apoptosis in Caco-2 cells; 100 μg/ml induced apoptosis in 19.9% and 10.3% of Caco-2 cells; whereas exposure to 150 μg/ml EtOH extracts caused 12.6% apoptosis compared to 11.7% induced by the DiEt extract.

CONCLUSIONS

None of the excipients caused any significantly altered cellular effects, indicating little chance for physicochemical interactions. Aqueous extracts did not possess any cytotoxic properties. However, it is clear that organic extracts caused apoptotic and necrotic cell death.

Identification of an Adduct Impurity of an Active Pharmaceutical Ingredient and a Leachable in an Ophthalmic Drug Product Using LC-QTOF

Impurity investigations are important in pharmaceutical development to ensure drug purity and safety for the patient. The impurities typically found in drug products are degradants or reaction products of the active pharmaceutical ingredient (API) or leachable compounds from the container closure system. However, secondary reactions may also occur between API degradants, excipient impurities, residual solvents, and leachables to form adduct impurities. We hereby report an adduct-forming interaction of API (moxifloxacin) with a leachable compound (ethylene glycol monoformate) in moxifloxacin ophthalmic solution. The leachable compound originated from a low-density polyethylene bottle used in the packaging of drug products. The adduct impurity was tentatively identified as 1-cyclopropyl-6-fluoro-7-(1-(2-(formyloxy)ethyl) octahydro-6H-pyrrolo[3,4-b]pyridin-6-yl)-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (C₂₄H₂₈FN₃O₆, MW = 473.19621) using accurate mass LC-QTOF analysis. The mass accuracy error between the theoretical mass and the experimental mass of an impurity was found to be 0.2 ppm. An MS/MS analysis was utilized to provide mass spectrometry fragments to support verification of the proposed structure.

The Degradation Chemistry of GSK2879552: Salt Selection and Microenvironmental pH Modulation to Stabilize a Cyclopropyl Amine

The cyclopropyl amine moiety in GSK2879552 (1) degrades hydrolytically in high pH conditions. This degradation pathway was observed during long-term stability studies and impacted the shelf life of the drug product. This article describes the work to identify the degradation impurities, elucidate the degradation mechanism, and design a stable drug product. It was found that salt selection and control of the microenvironmental pH of the drug product formulation blend significantly improved the chemical stability of the molecule in the solid state.

Determination of chemical stability of sitagliptin by LC-UV, LC-MS and FT-IR methods

Sitagliptin was stored at high temperature/high humidity, dry hot air, UV/VIS light and different pH. Then, a selective LC-UV method was developed for determination of sitagliptin in the presence of degradation products and for estimation of degradation kinetics. Because parent drugs can react with excipients in final pharmaceutical formulations, stability of sitagliptin was also examined in the presence of excipients of different reactivity, using FT-IR and LC-UV methods. Finally, LC-MS method was used for identification of degradation products of sitagliptin. High degradation of sitagliptin, following the first order kinetics, was observed in strongly acidic, alkaline and oxidative media. The quickest degradation was found in 2 M HCl and 2 M NaOH. In addition, all excipients used in the present study, i.e. fumaric acid, lactose, mannitol and magnesium stearate showed potent interactions with sitagliptin. Some of these interactions were shown without any stress while others were accelerated by high temperature/high humidity and dry hot air, and less by UV/VIS light. Some mechanisms for the observed changes were proposed, i.e. the Michael addition in the presence of fumaric acid and the Maillard reaction in the presence of lactose. In addition, degradation of sitagliptin together with the occurrence of its impurities was stated in a broad range of stress conditions.

Excipients in parenteral formulations: selection considerations and effective utilization with small molecules and biologics

Excipients form a major component of pharmaceutical formulations and are classified as any ingredient other than the active ingredient which is included within the product formulation to improve drug product performance. Functional uses of excipients include improving solubility and stability, safety and efficacy, as bulking agents in lyophilized formulations, tonicity agents, and aiding in controlled or prolonged drug delivery. Parenteral formulations are sterile, pyrogen-free; free of particulate matter and by-pass the body's natural defense mechanisms. Excipients may demonstrate a synergistic effect when combined with an active ingredient but may also lead to unwanted reactions with the drugs and packaging components. Ideal excipients are required to be considered safe, inert and multifunctional. Contrary to the past, safety of excipients needs to be well established in order for their use in the pharmaceutical formulations. Therefore, careful consideration should be given while selecting an excipient. This review article provides an overview of the excipients used exclusively in small molecule and biological parenteral products including solutions, suspensions, and lyophilized formulations, information on the possible drug-excipient and drug-packaging interactions and the regulatory requirements for the use of pharmaceutical excipients. The readers will be able to have a comprehensive understanding of the excipients used in parenteral formulations.

A Robust Static Headspace GC-FID Method to Detect and Quantify Formaldehyde Impurity in Pharmaceutical Excipients

Formaldehyde is a highly reactive impurity that can be found in many pharmaceutical excipients. Trace levels of this impurity may affect drug product stability, safety, efficacy, and performance. A static headspace gas chromatographic method was developed and validated to determine formaldehyde in pharmaceutical excipients after an effective derivatization procedure using acidified ethanol. Diethoxymethane, the derivative of formaldehyde, was then directly analyzed by GC-FID. Despite the simplicity of the developed method, however, it is characterized by its specificity, accuracy, and precision. The limits of detection and quantification of formaldehyde in the samples were of 2.44 and 8.12 µg/g, respectively. This method is characterized by using simple and economic GC-FID technique instead of MS detection, and it is successfully used to analyze formaldehyde in commonly used pharmaceutical excipients.

DSC, FT-IR, NIR, NIR-PCA and NIR-ANOVA for determination of chemical stability of diuretic drugs: impact of excipients

It is well known that drugs can directly react with excipients. In addition, excipients can be a source of impurities that either directly react with drugs or catalyze their degradation. Thus, binary mixtures of three diuretics, torasemide, furosemide and amiloride with different excipients, i.e. citric acid anhydrous, povidone K25 (PVP), magnesium stearate (Mg stearate), lactose, D-mannitol, glycine, calcium hydrogen phosphate anhydrous (CaHPO4) and starch, were examined to detect interactions. High temperature and humidity or UV/VIS irradiation were applied as stressing conditions. Differential scanning calorimetry (DSC), FT-IR and NIR were used to adequately collect information. In addition, chemometric assessments of NIR signals with principal component analysis (PCA) and ANOVA were applied.

Between the excipients examined, lactose and starch did not show any interactions while citric acid, PVP, Mg stearate and glycine were peculiarly operative. Some of these interactions were shown without any stress, while others were caused or accelerated by high temperature and humidity, and less by UV/VIS light. Based on these results, potential mechanisms for the observed interactions were proposed Finally, we conclude that selection of appropriate excipients for torasemide, furosemide and amiloride is an important question to minimize their degradation processes, especially when new types of formulations are being manufactured.

Influence of Peroxide Impurities in Povidone on the Stability of Selected β-Blockers with the Help of HPLC

A present study was conducted to investigate compatibility of β-blocker drugs( like atenolol, labetalol hydrochloride, bisoprolol fumarate, metoprolol succinate, carvedilol and propranolol hydrochloride) with the pharmaceutical excipient povidone. To check the influence of peroxide impurity present in povidone on the stability of β-blockers, a binary mixture technique has been adopted. The binary mixtures (1:1) of β-blockers with povidone excipient were stored for the duration of 6 months at accelerated conditions (40°C and 75% RH) and analyzed with the technique of high-performance liquid chromatography (HPLC). On analysis, HPLC results shows that, the percentage of total impurity for atenolol-2.15%, bisoprolol fumarate-3.55%, carvedilol-2.19%, and labetalol hydrochloride-1.89%, with respect to povidone. To verify the interaction of H₂O₂ present in povidone as an impurity, oxidative degradation of selected active pharmaceutical ingredients were performed and degradation profile were compared with that of degradation impurities generated in drug-excipient mixture at accelerated conditions. The relative retention time (RRT) of impurities generated in accelerated stability study samples resembles the RRT of degradation products generated by oxidative degradation of pure drugs. Thus, it confirms that degradation of β-blockers with povidone was mediated by organic peroxides present as an impurity in povidone.