Fatty acid composition analysis in polysorbate 80 with high performance liquid chromatography coupled to charged aerosol detection

Monitoring polysorbate 80 degradation in protein solutions using Total Holographic Characterization

The degradation of polysorbate surfactants can limit the shelf life of biologic pharmaceutical products. Polysorbate is susceptible to degradation via either oxidation or hydrolysis pathways which releases free fatty acids (FFA) and other complex polymers. Degradants from Polysorbate 80 (PS80) can form particles and impact drug product quality. PS80 degradation products appear at low concentrations, and their refractive indexes are similar to that of the buffer, making them very challenging to detect. Furthermore, aggregates of FFA are similar in size and refractive index to protein aggregates adding complexity to characterizing these particles in protein solutions. Total Holographic Characterization (THC) is used in this work to characterize FFA particles of oleic acid and linoleic acid, the two most common degradation products of PS80. We demonstrate that the characteristic THC profile of the FFA oleic acid emulsion droplets can be used to monitor the degradation of PS80. THC can detect oleic acid at a concentration down to less than 100 ng/mL. Using the characteristic THC signal of oleic acid as a marker, the degradation of PS80 in protein solutions can be monitored quantitatively even in the presence of other contaminants of the same size, including silicone oil emulsion droplets and protein aggregates.

Oxidation of polysorbates - An underestimated degradation pathway?

To ensure the stability of biologicals over their entire shelf-life, non-ionic surface-active compounds (surfactants) are added to protect biologics from denaturation and particle formation. In this context, polysorbate 20 and 80 are the most used detergents. Despite their benefits of low toxicity and high biocompatibility, specific factors are influencing the intrinsic stability of polysorbates, leading to degradation, loss in efficacy, or even particle formation. Polysorbate degradation can be categorized into chemical or enzymatic hydrolysis and oxidation. Under pharmaceutical relevant conditions, hydrolysis is commonly originated from host cell proteins, whereas oxidative degradation may be caused by multiple factors such as light, presence of residual metal traces, peroxides, or temperature, which can be introduced upon manufacturing or could be already present in the raw materials. In this review, we provide an overview of the current knowledge on polysorbates with a focus on oxidative degradation. Subsequently, degradation products and key characteristics of oxidative-mediated polysorbate degradation in respect of different types and grades are summarized, followed by an extensive comparison between polysorbate 20 and 80. A better understanding of the radical-induced oxidative PS degradation pathway could support specific mitigation strategies. Finally, buffer conditions, various stressors, as well as appropriate mitigation strategies, reagents, and alternative stabilizers are discussed. Prior manufacturing, careful consideration and a meticulous risk-benefit analysis are highly recommended in terms of polysorbate qualities, buffers, storage conditions, as well as mitigation strategies.

Development of UPLC-UV-ELSD Method for Fatty Acid Profiling in Polysorbate 80 and Confirmation of the Presence of Conjugated Fatty Acids by Mass Spectrometry, UV Absorbance and Proton Nuclear Magnetic Resonance Spectroscopy

Polysorbate 80 (PS80), a chemical substance composed of sorbitol, ethylene glycol, and fatty acids, is commonly used in pharmaceutical drug products to stabilize formulations. However, recent studies have demonstrated that PS80 may hydrolyze over time and the released free fatty acids (FFAs) may lead to particle formation. Naming conventions of fatty acids in current pharmacopeia and in products' certificates of analysis (CoA) of PS80 do not typically distinguish between isomeric species of fatty acids in PS80. Thus, methods to fully characterize the fatty acid species present in PS80 raw materials are needed to enhance quality control strategies of pharmaceuticals using PS80. Here, extended effort is taken to characterize fatty acids in hydrolyzed PS80 raw materials and elucidate the identities of isomeric fatty acid species. In this work, a method was developed and optimized for separation and detection of fatty acids in alkaline hydrolyzed PS80 raw materials using ultra performance liquid chromatography (UPLC) with ultra-violet (UV) detection and evaporative light scattering detection (ELSD). Fatty acids not specified in the current pharmacopeias were detected in PS80 raw material by the developed LC-UV-ELSD method including conjugated forms of linoleic and linolenic fatty acid species. Their identities were orthogonally confirmed by retention time agreement with analytical standards, accurate mass by high resolution mass spectrometry, UV absorbance, and proton nuclear magnetic resonance spectroscopy. The detected conjugated fatty acids are theoretically more hydrophobic and less soluble than their unconjugated counterparts and may increase the propensity of PS80 to form particles upon hydrolysis. This work highlights the need for better quality control of PS80 raw material, as it may eventually play a critical role in product quality of therapeutic proteins.

Analytical Quality by Design: Achieving Robustness of an LC-CAD Method for the Analysis of Non-Volatile Fatty Acids

An alternative to the time-consuming and error-prone pharmacopoeial gas chromatography method for the analysis of fatty acids (FAs) is urgently needed. The objective was therefore to propose a robust liquid chromatography method with charged aerosol detection for the analysis of polysorbate 80 (PS80) and magnesium stearate. FAs with different numbers of carbon atoms in the chain necessitated the use of a gradient method with a Hypersil Gold C₁₈ column and acetonitrile as organic modifier. The risk-based Analytical Quality by Design approach was applied to define the Method Operable Design Region (MODR). Formic acid concentration, initial and final percentages of acetonitrile, gradient elution time, column temperature, and mobile phase flow rate were identified as critical method parameters (CMPs). The initial and final percentages of acetonitrile were fixed while the remaining CMPs were fine-tuned using response surface methodology. Critical method attributes included the baseline separation of adjacent peaks (α-linolenic and myristic acid, and oleic and petroselinic acid) and the retention factor of the last compound eluted, stearic acid. The MODR was calculated by Monte Carlo simulations with a probability equal or greater than 90%. Finally, the column temperature was set at 33 °C, the flow rate was 0.575 mL/min, and acetonitrile linearly increased from 70 to 80% (v/v) within 14.2 min.

Fabrication and Characterization of Clozapine Nanoemulsion Sol-Gel for Intranasal Administration

Clozapine is the most effective antipsychotic for treatment-resistant schizophrenia. However, it causes many adverse drug reactions (ADRs), which lead to poor treatment outcomes. Nose-to-brain (N2B) drug delivery offers a promising approach to reduce peripheral ADRs by minimizing systemic drug exposure. The aim of the present study was to develop and characterize clozapine-loaded nanoemulsion sol-gel (CLZ-NESG) for intranasal administration using high energy sonication method. A range of oils, surfactants, and cosurfactants were screened with the highest clozapine solubility selected for the development of nanoemulsion. Pseudoternary phase diagrams were constructed using a low-energy (spontaneous) method to identify the microemulsion regions (i.e., where mixtures were transparent). The final formulation, CLZ-NESG (pH 5.5 ± 0.2), comprising 1% w/w clozapine, 1% w/w oleic acid, 10% w/w polysorbate 80/propylene glycol (3:1), and 20% w/w poloxamer 407 (P407) solution, had an average globule size of ≤30 nm with PDI 0.2 and zeta potential of -39.7 ± 1.5 mV. The in vitro cumulative drug release of clozapine from the nanoemulsion gel at 34 °C (temperature of nasal cavity) after 72 h was 38.9 ± 4.6% compared to 84.2 ± 3.9% with the control solution. The permeation study using sheep nasal mucosa as diffusion barriers confirmed a sustained release of clozapine with 56.2 ± 2.3% cumulative drug permeated after 8 h. Additionally, the histopathological examination found no severe nasal ciliotoxicity on the mucosal tissues. The thermodynamic stability studies showed that the gel strength and viscosity of CLZ-NESG decreased after temperature cycling but was still seen to be in "gel" form at nasal temperature. However, the accelerated storage stability study showed a decrease in drug concentration after 3 months, which can be expected at elevated stress conditions. The formulation developed in this study showed desirable physicochemical properties for intranasal administration, highlighting the potential value of a nanoemulsion gel for improving drug bioavailability of clozapine for N2B delivery.

Polysorbate 80 and histidine quantitative analysis by NMR in the presence of virus‐like particles

Polysorbate‐80 (PS80) and histidine are common excipients in vaccine and therapeutic protein formulation. A simple quantitative NMR method to measure both PS80 and histidine in human papillomavirus (HPV) virus‐like particle (VLP) vaccine for aqueous and alum‐containing samples is described. The new NMR method is compared to current colorimetric methods for PS80 and RP HPLC for histidine. The new NMR method is comparable to current assays with an advantage of a simpler sample treatment for PS80. The efficiency is also increased because one method can now provide two assay results instead of two separate methods. Furthermore, the NMR method can detect PS80 stability due to hydrolysis and oxidation when PS80 is stored in a stainless steel container by observing a change of its NMR line shape profile.

Intra-micellar and extra-micellar oxidation in phosphate and histidine buffers containing polysorbate 80

Polysorbate is a key excipient included in formulations of therapeutic proteins to help prevent aggregation and surface adsorption. The stability of both polysorbate and therapeutic proteins can be compromised by oxidative degradation. In general, polysorbate is added to formulations at concentrations above the critical micelle concentration (cmc). To date, however, few experiments have quantitatively addressed the extent of extra- and intra-micellar oxidation of polysorbate in pharmaceutically relevant buffers. This study utilizes 2,2'-azobis(2-methylpropionamidine)dihydrochloride (AAPH), a peroxyl radical-generating initiator, C11-BODIPY(581/591), a lipid peroxidation probe, and fluorescence spectroscopy to reveal that both intra- and extra-micellar oxidation proceed in pharmaceutically relevant phosphate and histidine buffers. It is further demonstrated that the relative extent of oxidation observed in the intra- and extra-micellar compartments is similar irrespective of the buffer system.

Antibiotic-loaded lipid-based nanocarrier: a promising strategy to overcome bacterial infection

According to the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC), bacterial infections are one of the greatest threats to global health, food production, and life expectancy. In this sense, the development of innovative formulations aiming at greater therapeutic efficacy, safety, and shorter treatment duration compared to conventional products is urgently needed. Lipid-based nanocarriers (LBNs) have demonstrated the potential to enhance the effectiveness of available antibiotics. Among them, liposome, nanoemulsion, solid lipid nanoparticle (SLN), and nanostructured lipid carrier (NLC) are the most promising due to their solid technical background for laboratory and industrial production. This review describes recent advances in developing antibiotic-loaded LBNs against susceptible and resistant bacterial strains and biofilm. LBNs revealed to be a promising alternative to deliver antibiotics due to their superior characteristics compared to conventional preparations, including their modified drug release, improved bioavailability, drug protection against chemical or enzymatic degradation, greater drug loading capacity, and biocompatibility. Antibiotic-loaded LBNs can improve current clinical drug therapy, bring innovative products and rescue discarded antibiotics. Thus, antibiotic-loaded LBNs have potential to open a window of opportunities to continue saving millions of lives and prevent the devastating impact of bacterial infection.

Industry perspective on the use and characterization of polysorbates for biopharmaceutical products Part 1: Survey report on current state and common practices for handling and control of polysorbates

Polysorbates (PS) are widely used as a stabilizer in biopharmaceutical products. Industry practices on various aspects of PS are presented in this part 1 survey report based on a confidential survey and following discussions by 16 globally acting major biotechnology companies. The current practice and use of PS during manufacture across their global manufacturing sites are covered in addition to aspects like current understanding of the (in)stability of PS, the routine QC testing and control of PS, and selected regulatory aspects of PS. The results of the survey and extensive cross-company discussions are put into relation with currently available scientific literature. Part 2 of the survey report (upcoming) will focus on understanding, monitoring, prediction, and mitigation of PS degradation pathways to develop an effective control strategy.

Predicting Leachables Solubilization in Polysorbate 80 Solutions by a Linear Solvation Energy Relationship (LSER)

PURPOSE

A linear solvation energy relationship (LSER) was developed to predict the partitioning of neutral chemicals from polysorbate 80 (PS 80) micelles to water. Predicted partition coefficients were converted to a concentration dependent solubilization strength of aqueous PS 80 solutions. This solubilization strength represents a key parameter to project equilibrium levels of leaching from pharmaceutical plastic materials.

METHODS

To construct the LSER model equation, partition coefficients between PS 80 micelles and water were measured via a reference phase method or collected from the literature. Multiple linear regression of partition coefficients against five publicly available solute parameters was used to obtain the LSER system parameters.

RESULTS

112 chemically diverse compounds were incorporated for LSER model regression. The model equation shows a very good fit (R² = 0.969, SD = 0.219) for the entire dataset. The accuracy of the multi-parameter LSER model was proven to be substantially better in comparison to a single-parameter log-linear model based on the octanol-water partition coefficient.

CONCLUSION

PS 80 solubilization strength in water can expediently and accurately be calculated for neutral organic compounds with the proposed LSER model. LSER system parameters provide insightful chemical information with respect to solubilization in aqueous solutions of PS 80.

Identification and direct determination of fatty acids profile in oleic acid by HPLC-CAD and MS-IT-TOF

Oleic acid is a pharmaceutical excipient and has been widely used in many dosage forms. It remains unclear in terms of the fatty acids (FAs) profile. In this study, a sensitive and direct method based on high-performance liquid chromatography coupled with charged aerosol detector (HPLC-CAD) was developed to study the compositions of oleic acid. The chromatographic conditions were optimized to achieve good separation and high sensitivity. The components of oleic acid were identified by ion trap/time of flight mass spectrometry (MS-IT-TOF). Twenty-seven FAs were identified based on the exact mass-to-charge ratio and fragments, among which 13 FAs were confirmed with the reference standards. Nine FAs in the oleic acid samples including oleic acid, linolenic acid, myristic acid, palmitoleic acid, linoleic acid, palmitic acid, stearic acid, arachidic acid and behenic acid were simultaneously determined by the developed HPLC-CAD, which showed good linearity with r²>0.999. The limit of detection (LOD) and limit of quantification (LOQ) of 9 FAs were 0.006-0.1 μg mL^-1 and 0.032-0.22 μg mL^-1, respectively. The components with concentration level not less than 0.03 % (referring to the sample concentration of 1.0 mg mL^-1) can be quantified. The mean recovery values of 9 FAs ranged from 96.5%-103.6% at three concentration levels of 80 %, 100 % and 120 %. The repeatability and intermediate precision were less than 5.0 % for oleic acid and components with concentration levels more than 0.05 %. In contrast to the conventional pre-column derivatization gas chromatography (GC), HPLC-CAD could unbiasedly and directly detect more components, especially the FAs with long carbon chains. Overall, the developed novel HPLC-CAD method can ameliorate the deficiency of the indirect GC method recorded in current pharmacopeias, thus having great potential for the comprehensive understanding and quality control of oleic acid.

Corona charged aerosol detector non-uniform response factors of purified alcohol ethoxylated homologues using liquid chromatography

Surfactants are used in various applications: cosmetics, pharmaceuticals, petrochemicals, environmental, etc. Many of these compounds are polydisperse, and because of this intrinsic polydispersity, it is essential to have a universal detector with a uniform response to quantify them in a simple way. Indeed, Charged Aerosol Detector (CAD) was presented as a universal detector with a uniform response. Thus, in the present study, the CAD response, in a High-Performance Liquid Chromatography - CAD configuration (HPLCCAD), was evaluated using purified alcohol ethoxylated surfactants. A semi-preparative liquid chromatography step using a Hydrophilic interaction chromatography (HILIC) bare silica column (150 mm, 4.6 mm, 2.6 µm) was implemented to prepare eleven homologues of BrijC10, a nonionic surfactant. These homologues differed only by the number of ethylene oxide units. BrijC10 homologues were analyzed by HPLCCAD, using a HILIC bare silica column (150 mm, 2.1 mm, 2.6 µm) to determine the HPLCCAD response factors of purified homologues. From the calibration curves (from 100 to 500 mg.kg^-1), their response factors were estimated: differences in response factors were observed and a maximum difference in response factors of 3.6 was obtained. Thus, it could be concluded that CAD hyphenated to HILIC separation did not present a uniform response for this homologue's distribution.

Degradation of polysorbates 20 and 80 catalysed by histidine chloride buffer

Polysorbates are amphiphilic, non-ionic surfactants, and they represent one of the key components of biopharmaceuticals. They serve as stabilisers, and their degradation can cause particle formation, which has been an industry-wide issue over the past decade. To determine the influence of the buffers most frequently used in biopharmaceuticals on polysorbate degradation, an accelerated stability study was carried out using placebo formulations containing 0.02% polysorbates and 20 mM buffers (pH 5.5, 6.5). These included histidine chloride, sodium citrate, sodium succinate and sodium phosphate buffers. The rate of polysorbate degradation was highest in histidine chloride buffer, and therefore we further focused on the mechanism here. The predominant degradation pathway of polysorbates in this buffer was ester hydrolysis, catalysed by the imidazole moiety of the histidine. Interestingly, the presence of therapeutic proteins in the formulations slowed histidine-catalysed degradation of polysorbates in 50% of cases, with negligible degradation seen otherwise. This emphasises the complex nature of the interactions between the components of biopharmaceutical drug products. Nonetheless, there are disadvantages of using histidine chloride buffers in biopharmaceuticals that contain polysorbates. Careful consideration should be given to selection of excipients used in parenteral formulations, whereby compatibility between buffer and surfactant is of key importance.

Screening of Polysorbate-80 Composition by High Resolution Mass Spectrometry with Rapid H/D Exchange

Polysorbate (PS) is a widely used polymeric excipient in biotherapeutic formulations to stabilize and protect protein drugs. Commercial PS is a highly heterogeneous mixture of structurally related components. PS composition can impact the stabilizer performance of PS in formulated protein drugs. Characterization of PS heterogeneity is, however, analytically challenging. In this work, a high-throughput screening protocol is presented for the profiling of the PS-80 polysorbate form using high resolution mass spectrometry (HRMS) coupled with a rapid hydrogen/deuterium (H/D) exchange in deuterated methanol. The protocol takes advantage of accurate mass measurements from HRMS analysis and utilizes H/D exchange-induced mass shifts that are characteristic to structures (particularly the number of terminal hydroxyl groups) of PS molecules to definitively identify species. In particular, mass shifts caused by deuterium uptake were used (1) to confirm molecular identities assigned by accurate mass measurements (which adds an extra level of identification confidence) and (2) to differentiate isomers that have an identical mass (thus, undistinguishable by high mass accuracy), but differ in the number of terminal hydroxyls. These data were input to an automated searching algorithm against a molecular mass database covering over 17000 potential PS-80 molecular species. The identified species were then visualized with Kendrick Mass Defect plots. The analysis protocol identified and profiled over 180 species from PS-80 samples in a high-throughput fashion without requiring chromatographic separation to reduce complexity of mixtures or tandem mass spectrometric analysis to conduct structural elucidation.

Monitoring polysorbate hydrolysis in biopharmaceuticals using a QC-ready free fatty acid quantification method

Hydrolysis of the non-ionic surfactant polysorbate upon long-term storage poses significant challenges to development of biopharmaceutical liquid formulations. Low concentrations of intact surfactant may compromise its protective properties and thus affect protein stability. In addition, accumulation of polysorbate hydrolysis products is increasingly put into context with the formation of visible and subvisible particulates based on the low solubility of the main degradation products. Despite of this potential negative impact on product quality, quantification of the released free fatty acids is performed commonly in an indirect and consequently insensitive manner by determining the remaining PS content or by cumbersome methods, which are unsuitable for routine testing in quality control laboratories. For this purpose, this study describes the development and qualification of a label-free, reliable liquid-chromatography single quad mass detector (LC-QDa)-based method capable of resolving slight changes in the free fatty acid profile which can be readily integrated into quality control facilities. The practical utility of the herein described method is outlined by a case study on the real-time storage stability of a formulated monoclonal antibody.

A Newly Identified Impurity in Polysorbate 80, the Long-Chain Ketone 12-Tricosanone, Forms Visible Particles in a Biopharmaceutical Drug Product

Visible particles linked to polysorbates (PSs) used in biopharmaceutical drug products (DPs) have been observed repeatedly in recent years as an industry-wide issue, with PS degradation and insoluble degradation products, especially fatty acids and fatty acid esters, being suspected as root cause. We have shown that the visible particles observed in a monoclonal antibody DP solution in vials after 18 months of long-term storage at 5 ± 3°C were neither linked to reduction in PS (PS80) concentration nor to any known PS degradation product, but consist of 12-tricosanone, an impurity present in the raw material PS80, not a degradation product. The occurrence of visible 12-tricosanone particles in DP correlated with the usage of specific PS80 raw material lots, where 12-tricosanone was found as impurity at elevated levels. The quantities detected in these PS80 lots directly translate into the amount found in the respective monoclonal antibody DP batches. This is the first time that a clear correlation between the occurrence of the impurity 12-tricosanone in PS80 and the occurrence of visible particles in DP batches is reported. The observation and techniques described enable the control of this ketone in PS raw materials, providing means to prevent respective visible particle formation in DP.

Optimization of Ultrasonic-assisted Extraction of Fatty Acids in Seeds of Brucea Javanica (L.) Merr. from Different Sources and Simultaneous Analysis Using High-Performance Liquid Chromatography with Charged Aerosol Detection

Our research aimed to optimize the oil extraction process and determine the fatty acids in Brucea javanica (L.) Merr. seeds. The extraction technology was optimized using response surface methodology. A Box-Behnken design was employed to investigate the effects of three independent variables on an ultrasonic-assisted extraction technique, namely, sonication time (X₁: 20–40 min), liquid–solid ratio (X₂: 16:1 mL/g–24:1 mL/g), and ethanol concentration (X₃: 90%–100%). The optimum conditions of sonication time, liquid–solid ratio, and ethanol concentration were 40 min, 24:1 mL/g, and 100%, respectively. The content of fatty acids and the oil yield were 14.64 mg/g and 16.87%, respectively, which match well with the predicted models. The optimum number of extraction times was eventually identified as two. A new rapid method for the qualitative and quantitative analysis of the fatty acids of B. javanica (L.) Merr. seed oil using HPLC with a charged aerosol detector was described. The fatty acid contents of 14 batches of B. javanica (L.) Merr. seed oil were determined, and the relevance and difference were analyzed by fingerprint analysis. The fingerprint has five common peaks, and the similarity was greater than 0.991. HPLC analysis represents a specialized and rational approach for the quality identification and comprehensive evaluation of B. javanica (L.) Merr. seed oils.

Lipid-associated oral delivery: Mechanisms and analysis of oral absorption enhancement

The majority of newly discovered oral drugs are poorly water soluble, and co-administration with lipids has proven effective in significantly enhancing bioavailability of some compounds with low aqueous solubility. Yet, lipid-based delivery technologies have not been widely employed in commercial oral products. Lipids can impact drug transport and fate in the gastrointestinal (GI) tract through multiple mechanisms including enhancement of solubility and dissolution kinetics, enhancement of permeation through the intestinal mucosa, and triggering drug precipitation upon lipid emulsion depletion (e.g., by digestion). The effect of lipids on drug absorption is currently not quantitatively predictable, in part due to the multiple complex dynamic processes that can be impacted by lipids. Quantitative mechanistic analysis of the processes significant to lipid system function and overall impact on drug absorption can aid in the understanding of drug-lipid interactions in the GI tract and exploitation of such interactions to achieve optimal lipid-based drug delivery. In this review, we discuss the impact of co-delivered lipids and lipid digestion on drug dissolution, partitioning, and absorption in the context of the experimental tools and associated kinetic expressions used to study and model these processes. The potential benefit of a systems-based consideration of the concurrent multiple dynamic processes occurring upon co-dosing lipids and drugs to predict the impact of lipids on drug absorption and enable rational design of lipid-based delivery systems is presented.