Effect of surfactants on the physical stability of recombinant human growth hormone

Effect of surfactants on lactate dehydrogenase aqueous solutions: A comparative study of poloxamer 188, polysorbate 20 and 80

The effect of three commonly used surfactants, poloxamer 188 (P188), polysorbate 20 and 80 (PS20 and PS80), on the stability of a model protein, lactate dehydrogenase (LDH), was compared in aqueous solutions. In the absence of a surfactant, protein solution revealed a gradual decrease in surface tension as a function of time. The addition of surfactant resulted in a rapid decrease in the surface tension. This suggested that the surface behavior was dictated by the surfactant. PS20 and PS80 were more effective than P188 in preventing LDH adsorption on the solution surface. The advantage of polysorbates over P188 was also evident from the higher LDH tetramer recovery after shaking (room temperature, 30 h), especially when the surfactants were used at concentrations ≤ 0.01% w/v. However, PS20 and PS80 accelerated protein unfolding during quiescent storage at 40 °C. Based on circular dichroism results, polysorbates perturbed the tertiary structure of LDH but not the secondary structure, while P188 did not impact the protein structure and stability. Polysorbates were more effective in stabilizing LDH against mechanical stress (shaking), but their adverse effects on protein conformational stability need to be carefully evaluated.

Factors influencing amyloid fibril formation

Protein aggregation is a complex process with several stages that lead to the formation of complex structures and shapes with a broad variability in stability and toxicity. The aggregation process is affected by various factors and environmental conditions that disrupt the protein's original state, including internal factors like mutations, expression levels, and polypeptide chain truncation, as well as external factors, such as dense molecular surroundings, post-translation modifications, and interactions with other proteins, nucleic acids, small molecules, metal ions, chaperones, and lipid membranes. During the aggregation process, the biological activity of an aggregating protein may be reduced or eliminated, whereas the resulting aggregates may have the potential to be immunogenic, or they may have other undesirable properties. Finding the cause(s) of protein aggregation and controlling it to an acceptable level is among the most crucial topics of research in academia and biopharmaceutical companies. This chapter aims to review intrinsic pathways of protein aggregation and potential extrinsic variables that influence this process.

Do Ionic Liquids Exhibit the Required Characteristics to Dissolve, Extract, Stabilize, and Purify Proteins? Past-Present-Future Assessment

Proteins are highly labile molecules, thus requiring the presence of appropriate solvents and excipients in their liquid milieu to keep their stability and biological activity. In this field, ionic liquids (ILs) have gained momentum in the past years, with a relevant number of works reporting their successful use to dissolve, stabilize, extract, and purify proteins. Different approaches in protein-IL systems have been reported, namely, proteins dissolved in (i) neat ILs, (ii) ILs as co-solvents, (iii) ILs as adjuvants, (iv) ILs as surfactants, (v) ILs as phase-forming components of aqueous biphasic systems, and (vi) IL-polymer-protein/peptide conjugates. Herein, we critically analyze the works published to date and provide a comprehensive understanding of the IL-protein interactions affecting the stability, conformational alteration, unfolding, misfolding, and refolding of proteins while providing directions for future studies in view of imminent applications. Overall, it has been found that the stability or purification of proteins by ILs is bispecific and depends on the structure of both the IL and the protein. The most promising IL-protein systems are identified, which is valuable when foreseeing market applications of ILs, e.g., in "protein packaging" and "detergent applications". Future directions and other possibilities of IL-protein systems in light-harvesting and biotechnology/biomedical applications are discussed.

Combined Effect of Shaking Orbit and Vial Orientation on the Agitation-Induced Aggregation of Proteins

Orbital shaking in a glass vial is a commonly used forced degradation test to evaluate protein propensity for agitation-induced aggregation. Vial shaking in horizontal orientation has been widely recommended to maximize the air-liquid interface area while ensuring solution contact with the stopper. We evaluated the impact of shaking orbit diameter and frequency, and glass vial orientation (horizontal versus vertical) on the aggregation of three proteins prepared in surfactant-free formulation buffers. As soon as an orbit-specific frequency threshold was reached, an increase in turbidity was observed for the three proteins in vertical orientation only when using a 3 mm agitation orbit, and in horizontal orientation only when using a 30 mm agitation orbit. Orthogonal analyses confirmed turbidity was linked to protein aggregation. The most turbid samples had a visually more homogeneous appearance in vertical than in horizontal orientation, in line with the predicted dispersion of air and liquid phases obtained from computational fluid dynamics agitation simulations. Both shaking orbits were used to assess the performance of nonionic surfactants. We show that the propensity of a protein to aggregate in a vial agitated in horizontal or vertical orientation depends on the shaking orbit, and confirm that Brij® 58 and FM1000 prevent proteins from agitation-induced aggregation at lower concentrations than polysorbate 80.

Strategies for overcoming protein and peptide instability in biodegradable drug delivery systems

The global pharmaceutical market has recently shifted its focus from small molecule drugs to peptide, protein, and nucleic acid drugs, which now comprise a majority of the top-selling pharmaceutical products on the market. Although these biologics often offer improved drug specificity, new mechanisms of action, and/or enhanced efficacy, they also present new challenges, including an increased potential for degradation and a need for frequent administration via more invasive administration routes, which can limit patient access, patient adherence, and ultimately the clinical impact of these drugs. Controlled-release systems have the potential to mitigate these challenges by offering superior control over in vivo drug levels, localizing these drugs to tissues of interest (e.g., tumors), and reducing administration frequency. Unfortunately, adapting controlled-release devices to release biologics has proven difficult due to the poor stability of biologics. In this review, we summarize the current state of controlled-release peptides and proteins, discuss existing techniques used to stabilize these drugs through encapsulation, storage, and in vivo release, and provide perspective on the most promising opportunities for the clinical translation of controlled-release peptides and proteins.

Impact of Primary Container Closure System on PS80 Oxidation and the Mechanistic Understanding

PURPOSE

Polysorbate oxidation can potentially lead to protein degradation and loss of potency, which has been a challenge for the pharmaceutical industry for decades. Many factors have been reported to impact polysorbate oxidation rate, including types of elemental impurities, peroxide content, pH, light exposure, grades of polysorbate, etc. Even though there are many publications in this field, the impact of primary container closure system on PS80 oxidation has not been systematically studied or reported. The purpose of the current study is to close this gap.

METHODS

Placebo PS80 formulations were prepared and filled into different container-closure systems (CCS), including different types of glass vials and polymer vials. Oleic acid content was monitored on stability as a surrogate value for PS80 content, which will decline upon oxidation. ICP-MS analysis and metal spiking studies were carried out to correlate the PS80 oxidation rate with metals leached from primary containers.

RESULTS

PS80 degrades via oxidation at the fastest rate in glass vials with high coefficient of expansion (COE), followed by glass vials with low coefficient of expansion, while polymer vials minimized the oxidation of PS80 in most formulation conditions explored in this paper. ICP-MS analysis demonstrated that 1) 51 COE glass has more metal leachables than 33 COE glass in this study; and 2) More metal leachables correlates with faster PS80 oxidation. Metal spiking studies confirmed the hypothesis that aluminum and iron have a synergistic catalysis effect on PS80 oxidation.

CONCLUSIONS

Primary containers of drug products play a significant role in the rate of PS80 oxidation. This study revealed a new major contributor to PS80 oxidation and potential mitigation strategy for biological drug products.

Development and Optimization of Hyaluronic Acid-Poloxamer In-Situ Gel Loaded with Voriconazole Cubosomes for Enhancement of Activity against Ocular Fungal Infection

Fungal eye infections are largely disseminated, especially in developing countries where they may leave over half a million people blind per year. The current study aims to boost the voriconazole antifungal efficiency via loading it as cubosomes (VZ-Cub) into hyaluronic acid and poloxamer-based ocular in situ gel. VZ-Cub were fabricated applying Box-Behnken design and employing phytantriol, poloxamer F127, and VZ amounts as independent variables. The produced nano vesicles were evaluated for the dependent variables of particle size (PS), entrapment efficiency (EE%), and transcorneal steady-state flux (Jss) of the VZ, and, the obtained optimal VZ-Cub was loaded into an in situ gel base to enhance its ocular residence time. The in situ gel formulation was tested for its gelation temperature, drug release behavior, transcorneal permeation effects, and antifungal activity. The optimized VZ-Cub consisted of 100 mg of phytantriol, 60 mg of poloxamer F127, and 21 mg of VZ. This formulation led to a minimum PS of 71 nm, an EE% of 66%, Jss value of 6.5 µg/(cm²·min), and stability index of 94 ± 2%. The optimized VZ-Cub-loaded in situ gel released 84% VZ after 12 h and yielded a 4.5-fold increase in drug permeation compared with the VZ aqueous dispersion. The antifungal activity, which was obtained by measuring the fungal growth inhibition zones, revealed that the VZ-Cub-loaded in situ gel formulation had a 3.89-fold increase in antifungal activity compared with the VZ dispersion. In summary, an ocular in situ gel loaded with VZ-Cub could be an effective novel nano-paradigm with enhanced transcorneal permeation and antifungal properties.

Thermoresponsive Hydrogel-Based Local Delivery of Simvastatin for the Treatment of Periodontitis

Except for routine scaling and root planing, there are few effective nonsurgical therapeutic interventions for periodontitis and associated alveolar bone loss. Simvastatin (SIM), one of the 3-hydroxy-3-methylglutaryl-cosenzyme A reductase inhibitors, which is known for its capacity as a lipid-lowering medication, has been proven to be an effective anti-inflammatory and bone anabolic agent that has shown promising benefits in mitigating periodontal bone loss. The local delivery of SIM into the periodontal pocket, however, has been challenging due to SIM's poor water solubility and its lack of osteotropicity. To overcome these issues, we report a novel SIM formulation of a thermoresponsive, osteotropic, injectable hydrogel (PF127) based on pyrophosphorolated pluronic F127 (F127-PPi). After mixing F127-PPi with F127 at a 1:1 ratio, the resulting PF127 was used to dissolve free SIM to generate the SIM-loaded formulation. The thermoresponsive hydrogel's rheologic behavior, erosion and SIM release kinetics, osteotropic property, and biocompatibility were evaluated in vitro. The therapeutic efficacy of SIM-loaded PF127 hydrogel on periodontal bone preservation and inflammation resolution was validated in a ligature-induced periodontitis rat model. Given that SIM is already an approved medication for hyperlipidemia, the data presented here support the translational potential of the SIM-loaded PF127 hydrogel for better clinical management of periodontitis and associated pathologies.

Insight into the Microcosm of the Human Growth Hormone and Its Interactions with Polymers and Copolymers: A Molecular Dynamics Perspective

Therapeutic proteins nowadays have increasingly been applied for their considerable potential in treating a wide variety of diseases. The effectiveness and potency of native therapeutic proteins are limited by various factors (e.g., stability, blood circulation time, specificity). Over the past years, a great deal of effort has been devoted to developing safe and efficient protein delivery systems. Entrapment of protein into polymeric and copolymeric matrices is common among the different types of protein-based drug formulation. However, despite the massive efforts toward developing therapeutic protein delivery in experimental studies and industrial applications, there is relatively little data on the influence of polymers and copolymers on therapeutic proteins at the atomic and molecular levels. Herein, molecular dynamics (MD) simulations are used to study the effects of biocompatible synthetic polymers including methoxy poly(ethylene glycol) (MPEG), poly(lactic acid) (PLA), and poly(lactic acid) copolymers (poly(lactic-co-glycolic acid)) PLGA and MPEG-PLA(PELA)) on the structure and dynamics of the human growth hormone (hGH), and the results are compared with previous experimental findings. Our results indicate that the hGH conformation remains stable both in pure water and in the presence of polymers, and these results are in good agreement with previous experimental data. It is shown that the MPEG chains are self-assembled and folded into a semicrystalline structure; therefore, only a small portion of the protein interacts with the polymer. The other three polymers, however, interact well with the protein and partially cover its surface. Our findings suggest that the use of these polymers for protein encapsulation has the advantage of reducing protein aggregation and thus increasing drug serum half-life. Eventually, we anticipate that the research results will expand the current knowledge about encapsulation mechanisms and the molecular interactions between hGH and the polymers.

Rosuvastatin calcium-based novel nanocubic vesicles capped with silver nanoparticles-loaded hydrogel for wound healing management: optimization employing Box-Behnken design: in vitro and in vivo assessment

Chronic wounds are a serious problem that could cause severe morbidity and even death. The ability of statins including rosuvastatin calcium (RVS) to enhance wound healing was well reported. However, RVS is poorly soluble and has low bioavailability. Thus, this study aimed to prepare and evaluate RVS-loaded nanocubics to enhance its skin performance. In addition, silver nanoparticles (AgNPs) exhibited potent antimicrobial activity, thus, the optimum RVS-loaded nanocubics was capped with AgNPs to evaluate its effect in wound management. Box-Behnken design was adopted to prepare RVS nanocubics. The design investigated the effect of lecithin, poloxamer 407 concentrations and hydration time on vesicle size, zeta potential (ZP), entrapment efficiency (EE%) and in vitro drug release%. Optimum formulation capped with AgNPs was incorporated into a gel base and examined for wound healing efficiency using different pharmacological tests in rats. Nanocubics have shown a mean diameter between 167.2 ± 7.8 and 408 ± 18.4 nm, ZP values ranging from -20.9 ± 1.9 to -53.5 ± 4 mV, EE% equivocated between 31.6 ± 1.4 and 94.4 ± 8.6 and drug release after 12 h between 17.9 ± 1.9 and 68.0 ± 4.0%. The histopathological studies and serum tumour necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β) levels confirmed the greater efficacy of RVS nanocubics capped with AgNPs gel in wound healing when compared with gentamicin ointment. RVS-loaded nanocubic vesicles and AgNPs-loaded hydrogel could be considered as a promising platform to enhance the wound healing and tissue repair processes.

Tricks and tracks in removal of emerging contaminants from the wastewater through hybrid treatment systems: A review

In recent years, many biological and physicochemical treatment technologies have been investigated for the removal of the emerging contaminants (ECs) from the wastewater matrix. However, due to the deficiency of these treatments to completely degrade the ECs in wastewater, hybrid systems were explored using the distinguishing removal potential of the different treatment processes. This review gives an insight on such hybrid systems combining several physical, chemical and biological treatments for the fast and eco-efficient removal of ECs from wastewater. Most of the hybrid systems have applied biological treatments first and then physical or chemical treatments. The hybrid system of membrane bioreactor (MBR) followed by membrane filtrations (RO/NF) effectively removed a suite of ECs such as pharmaceuticals, beta blockers, pesticides and EDCs. Some of the hybrid systems of constructed wetlands and waste stabilization ponds showed promising potential for the biosorptive removal of pharmaceuticals and some beta blockers. The hybrid systems combining activated sludge process and physical processes such as ultrafiltration (UF), reverse osmosis (RO) and gamma radiations are considered as the cost effective technologies and had better removal of trace organic pollutants. The hybrid system of MBR coupled with UV oxidation, activated carbon and ultrasound, and ozonation followed by ultrasounds, completely degraded some ECs and many pharmaceuticals. The review also synthesizes the trend followed by the hybrid system processes for the removal of various categories of ECs. The future research directions for the ECs removal utilizing hybrid nanocomposites and green sustainable technology have been suggested.

Shape Tuning and Size Prediction of Millimeter-Scale Calcium-Alginate Capsules with Aqueous Core

Controllable feature and size, good mechanical stability and intelligent release behavior is the capsule products relentless pursuit of the goal. In addition, to illustrate the quantitative relationship of structure and performance is also important for encapsulation technology development. In this study, the sphericity and size of millimeter-scale calcium sodium alginate capsules (mm-CaSA-Caps) with aqueous core were well tuned by manipulating the viscosity, surface tension, and density of CaCl₂/carboxyl methyl cellulose (CMC) drops and sodium alginate (SA) solution. The well-tuned mm-CaSA-Caps showed significant mechanical and control-releasing property effects. The results showed that the prepared mm-CaSA-Caps were highly monodispersed with average diameter from 3.8 to 4.8 mm. The viscosity of the SA solution and the viscosity and surface tension of the CaCl₂/CMC solution had significant effects on the mm-CaSA-Caps sphericity. Uniform and spherical mm-CaSA-Caps could be formed with high viscosity CaCl₂/CMC solution (between 168.5 and 917.5 mPa·s), low viscosity SA solution (between 16.2 and 72.0 mPa·s) and decreased surface tension SA solution (by adding 0.01 wt.% poloxamer 407). The diameter of the mm-CaSA-Caps could be predicted by a modified Tate’s law, which correlated well with the experimental data. The Caps with sphericity factor (SF) < 0.07 had better mechanical stability, with the crushing force 2.91–15.5 times and the surface Young’s modulus 2.1–3.99 times higher than those of the non-spherical Caps (SF > 0.07). Meanwhile, the spherical Caps had a more even permeation rate, which was helpful in producing uniform and sustained releasing applications in foodstuff, medicine, agriculture and chemical industry.

Interfacial Stress in the Development of Biologics: Fundamental Understanding, Current Practice, and Future Perspective

Biologic products encounter various types of interfacial stress during development, manufacturing, and clinical administration. When proteins come in contact with vapor-liquid, solid-liquid, and liquid-liquid surfaces, these interfaces can significantly impact the protein drug product quality attributes, including formation of visible particles, subvisible particles, or soluble aggregates, or changes in target protein concentration due to adsorption of the molecule to various interfaces. Protein aggregation at interfaces is often accompanied by changes in conformation, as proteins modify their higher order structure in response to interfacial stresses such as hydrophobicity, charge, and mechanical stress. Formation of aggregates may elicit immunogenicity concerns; therefore, it is important to minimize opportunities for aggregation by performing a systematic evaluation of interfacial stress throughout the product development cycle and to develop appropriate mitigation strategies. The purpose of this white paper is to provide an understanding of protein interfacial stability, explore methods to understand interfacial behavior of proteins, then describe current industry approaches to address interfacial stability concerns. Specifically, we will discuss interfacial stresses to which proteins are exposed from drug substance manufacture through clinical administration, as well as the analytical techniques used to evaluate the resulting impact on the stability of the protein. A high-level mechanistic understanding of the relationship between interfacial stress and aggregation will be introduced, as well as some novel techniques for measuring and better understanding the interfacial behavior of proteins. Finally, some best practices in the evaluation and minimization of interfacial stress will be recommended.

Hyaluronan-based dissolving microneedles with high antigen content for intradermal vaccination: Formulation, physicochemical characterization and immunogenicity assessment

The purpose of this study was to optimize the manufacturing of dissolving microneedles (dMNs) and to increase the antigen loading in dMNs to investigate the effect on their physicochemical properties. To achieve this, a novel single-array wells polydimethylsiloxane mold was designed, minimizing antigen wastage during fabrication and achieving homogeneous antigen distribution among the dMN arrays. Using this mold, hyaluronan (HA)-based dMNs were fabricated and tested for maximal ovalbumin (OVA) content. dMNs could be fabricated with an OVA:HA ratio as high as 1:1 (w/w), without compromising their properties such as shape and penetration into the ex vivo human skin, even after storage at high humidity and temperature. High antigen loading did not induce protein aggregation during dMN fabrication as demonstrated by complementary analytical methods. However, the dissolution rate in ex vivo human skin decreased with increasing antigen loading. About 2.7 µg OVA could be delivered in mice by using a single array with an OVA:HA ratio of 1:3 (w/w). Intradermal vaccination with dMNs induced an immune response similar as subcutaneous injection and faster than after hollow microneedle injection. In conclusion, results suggest that (i) the polydimethylsiloxane mold design has an impact on the manufacturing of dMNs, (ii) the increase in antigen loading in dMNs affects the microneedle dissolution and (iii) dMNs are a valid alternative for vaccine administration over conventional injection.

Effect of Surfactants on Mechanical, Thermal, and Photostability of a Monoclonal Antibody

The purpose of this work was to evaluate the effect of commonly used surfactants (at 0.01% w/v concentration) on mechanical, thermal, and photostability of a monoclonal antibody (MAb1) of IgG1 sub-class and to evaluate the minimum concentration of surfactant (Polysorbate 80) required in protecting MAb1 from mechanical stress. Surfactants evaluated were non-ionic surfactants, Polysorbate 80, Polysorbate 20, Pluronic F-68 (polyoxyethylene-polyoxypropylene block polymer), Brij 35 (polyoxyethylene lauryl ether), Triton X-100, and an anionic surfactant, Caprylic acid (1-Heptanecarboxylic acid). After evaluating effect of surfactants and determining stabilizing effect of Polysorbate 80 against mechanical stress without compromising thermal and photostability of MAb1, the minimum concentration of Polysorbate 80 required for mechanical stability was further examined. Polysorbate 80 concentration was varied from 0 to 0.02%. Mechanical stability was evaluated by agitation of MAb1 at 300 rotations per minute at room temperature for 72 h. Samples were analyzed for purity by SEC-HPLC, turbidity by absorbance at 350 nm, visible particles by visual inspection, and sub-visible particles by light obscuration technique on a particle analyzer. All non-ionic surfactants tested showed a similar effect in protecting against mechanical stress and did not exhibit any significant negative effect on thermal and photostability. However, Caprylic acid had a slightly negative effect on mechanical and photostability when compared to the non-ionic surfactants or sample without surfactant. This work demonstrated that polysorbate 80 is better than other surfactants tested and that a concentration of at least 0.005% (w/v) Polysorbate 80 is needed to protect MAb1 against mechanical stress.

Effect of Polysorbate 20 and Polysorbate 80 on the Higher-Order Structure of a Monoclonal Antibody and Its Fab and Fc Fragments Probed Using 2D Nuclear Magnetic Resonance Spectroscopy

We examined how polysorbate 20 (PS20; Tween 20) and polysorbate 80 (PS80; Tween 80) affect the higher-order structure of a monoclonal antibody (mAb) and its antigen-binding (Fab) and crystallizable (Fc) fragments, using near-UV circular dichroism and 2D nuclear magnetic resonance (NMR). Both polysorbates bind to the mAb with submillimolar affinity. Binding causes significant changes in the tertiary structure of mAb with no changes in its secondary structure. 2D ¹³C-¹H methyl NMR indicates that with increasing concentration of polysorbates, the Fab region showed a decrease in crosspeak volumes. In addition to volume changes, PS20 caused significant changes in the chemical shifts compared to no changes in the case of PS80. No such changes in crosspeak volumes or chemical shifts were observed in the case of Fc region, indicating that polysorbates predominantly affect the Fab region compared to the Fc region. This differential effect of polysorbates on the Fab and Fc regions was because of the lesser thermodynamic stability of the Fab compared to the Fc. These results further indicate that PS80 is the preferred polysorbate for this mAb formulation, because it offers higher protection against aggregation, causes lesser structural perturbation, and has weaker binding affinity with fewer binding sites compared to PS20.

Development of Microemulsion Delivery System of Essential Oil from Zingiber cassumunar Roxb. Rhizome for Improvement of Stability and Anti-Inflammatory Activity

The present study aims to investigate the major constituents of the essential oil from Zingiber cassumunar rhizome (EO) and to develop microemulsions with enhanced chemical stability and anti-inflammatory activity of EO. The major constituents of EO were terpinen-4-ol (40.5 ± 6.6%) and sabinene (17.4 ± 1.4%) as determined by gas chromatography-mass spectrometry. These compounds were responsible for the anti-inflammatory activities of EO. Sabinene and terpinen-4-ol significantly reduced nuclear factor-kappa B (NF-kB) expression by 47 ± 5 and 78 ± 8%, respectively (p < 0.001) and significantly reduced the interleukin-6 (IL-6) secretion levels to 64 ± 4% (p < 0.05) and 50 ± 1% (p < 0.001), respectively. EO microemulsions, developed using the system of EO/Tween 20 and propylene glycol (2:1)/water, showed the internal droplet size in the range of 211.5 ± 63.3 to 366.7 ± 77.8 nm. Both EO and EO microemulsions were shown to be safe for human use since there was no apparent toxic effect on human peripheral blood mononuclear cells. Interestingly, EO microemulsion could significantly protect sabinene from the evaporation after heating-cooling stability test, which leads to a good stability and high efficacy. Moreover, EO microemulsions significantly enhanced the anti-inflammatory effect comparing to the native EO. Therefore, microemulsions were attractive delivery system for natural anti-inflammatory compounds since they could enhance both efficacy and stability of EO.

Progress in the biological and chemical treatment technologies for emerging contaminant removal from wastewater: A critical review

This review focuses on the removal of emerging contaminants (ECs) by biological, chemical and hybrid technologies in effluents from wastewater treatment plants (WWTPs). Results showed that endocrine disruption chemicals (EDCs) were better removed by membrane bioreactor (MBR), activated sludge and aeration processes among different biological processes. Surfactants, EDCs and personal care products (PCPs) can be well removed by activated sludge process. Pesticides and pharmaceuticals showed good removal efficiencies by biological activated carbon. Microalgae treatment processes can remove almost all types of ECs to some extent. Other biological processes were found less effective in ECs removal from wastewater. Chemical oxidation processes such as ozonation/H₂O₂, UV photolysis/H₂O₂ and photo-Fenton processes can successfully remove up to 100% of pesticides, beta blockers and pharmaceuticals, while EDCs can be better removed by ozonation and UV photocatalysis. Fenton process was found less effective in the removal of any types of ECs. A hybrid system based on ozonation followed by biological activated carbon was found highly efficient in the removal of pesticides, beta blockers and pharmaceuticals. A hybrid ozonation-ultrasound system can remove up to 100% of many pharmaceuticals. Future research directions to enhance the removal of ECs have been elaborated.

Fabrication and evaluation of lipid nanoparticulates for ocular delivery of a COX-2 inhibitor

CONTEXT

The unique physiological limitations of the eye have been assigned as reason of low bioavailability by conventional drug delivery systems. There is need of such drug carriers, which ensure improved bioavailability as well as patient compliance upon instillation into the eye.

OBJECTIVE

The present investigation deals with development of solid lipid nanoparticles (SLNs) containing celecoxib (CXB) for treatment of ophthalmic inflammations.

MATERIALS AND METHODS

The SLNs were formulated by melt-emulsion sonication and low temperature-solidification process and evaluated for particle size, surface morphology, physicochemical properties, percentage drug incorporation efficiency, in vitro drug release, in vitro trans-corneal permeation, in vivo efficacy in ocular inflammation, stability study and gamma scintigraphy study to assess the residence of solid lipid nanoparticles over ocular surfaces.

RESULTS

The SLNs were spherical and the optimized formulation had particle size of 198.77 ± 7.5 nm, which is quite suitable for ocular applications. The maximum entrapment efficiency of 92.46 ± 0.07% was achieved for formulation SLN 20. The permeation across the cornea was also significantly better than aqueous suspension (8.21 ± 0.67 versus 4.61 ± 0.71) at p < 0.05.

DISCUSSION AND CONCLUSION

The SLN formulations demonstrated improved performance of entrapped CXB while mitigating the key parameters of ocular inflammation in rabbits. The particulate formulations have exhibited prolonged retention over ocular surfaces as evident from results of gamma scintigraphy using ^99mTc labeled SLNs.

Stability, biophysical properties and effect of ultracentrifugation and diafiltration on measles virus and mumps virus

Measles virus and mumps virus (MeV and MuV) are enveloped RNA viruses used for production of live attenuated vaccines for prophylaxis of measles and mumps disease, respectively. For biotechnological production of and basic research on these viruses, the preparation of highly purified and infectious viruses is a prerequisite, and to meet that aim, knowledge of their stability and biophysical properties is crucial. Our goal was to carry out a detailed investigation of the stability of MeV and MuV under various pH, temperature, shear stress, filtration and storage conditions, as well as to evaluate two commonly used purification techniques, ultracentrifugation and diafiltration, with regard to their efficiency and effect on virus properties. Virus titers were estimated by CCID50 assay, particle size and concentration were measured by Nanoparticle tracking analysis (NTA) measurements, and the host cell protein content was determined by ELISA. The results demonstrated the stability of MuV and MeV at pH <9 and above pH 4 and 5, respectively, and aggregation was observed at pH >9. Storage without stabilizer did not result in structural changes, but the reduction in infectivity after 24 hours was significant at +37 °C. Vortexing of the viruses resulted in significant particle degradation, leading to lower virus titers, whereas pipetting had much less impact on virus viability. Diafiltration resulted in higher recovery of both total and infectious virus particles than ultracentrifugation. These results provide important data for research on all upstream and downstream processes on these two viruses regarding biotechnological production and basic research.

Effect of Excipients on Liquid-Liquid Phase Separation and Aggregation in Dual Variable Domain Immunoglobulin Protein Solutions

Liquid-liquid phase separation (LLPS) and aggregation can reduce the physical stability of therapeutic protein formulations. On undergoing LLPS, the protein-rich phase can promote aggregation during storage due to high concentration of the protein. Effect of different excipients on aggregation in protein solution is well documented; however data on the effect of excipients on LLPS is scarce in the literature. In this study, the effect of four excipients (PEG 400, Tween 80, sucrose, and hydroxypropyl beta-cyclodextrin (HPβCD)) on liquid-liquid phase separation and aggregation in a dual variable domain immunoglobulin protein solution was investigated. Sucrose suppressed both LLPS and aggregation, Tween 80 had no effect on either, and PEG 400 increased LLPS and aggregation. Attractive protein-protein interactions and liquid-liquid phase separation decreased with increasing concentration of HPβCD, indicating its specific binding to the protein. However, HPβCD had no effect on the formation of soluble aggregates and fragments in this study. LLPS and aggregation are highly temperature dependent; at low temperature protein exhibits LLPS, at high temperature protein exhibits aggregation, and at an intermediate temperature both phenomena occur simultaneously depending on the solution conditions.

Protein stability in pulmonary drug delivery via nebulization

Protein inhalation is a delivery route which offers high potential for direct local lung application of proteins. Liquid formulations are usually available in early stages of biopharmaceutical development and nebulizers are the device of choice for atomization avoiding additional process steps like drying and enabling fast progression to clinical trials. While some proteins were proven to remain stable throughout aerosolization e.g. DNase, many biopharmaceuticals are more susceptible towards the stresses encountered during nebulization. The main reason for protein instability is unfolding and aggregation at the air-liquid interface, a problem which is of particular challenge in the case of ultrasound and jet nebulizers due to recirculation of much of the generated droplets. Surfactants are an important formulation component to protect the sensitive biomolecules. A second important challenge is warming of ultrasound and vibrating mesh devices, which can be overcome by overfilling, precooled solutions or cooling of the reservoir. Ultimately, formulation development has to go hand in hand with device evaluation.

Using lysine-reactive fluorescent dye for surface characterization of a mAb

The biopharmaceutical industry increasingly demands thorough characterization of protein conformation and conformational dynamics to ensure product quality and consistency. Here, we present a chromatography-based method that is able to characterize protein conformation and conformational dynamics at peptide level resolution in a high-throughput manner. The surface lysine residues of the protein were labeled with a fluorescent dye prior to enzyme digestion. The resulting peptide maps were monitored by fluorescence detection where fluorescence peak area indicates higher solvent accessibility at a specific site. The peptides of reactivity difference and the extent of the difference can be detected by HPLC with fluorescent detector alone, whereas the identity of these peptides can then be determined by mass spectrometry if desired. We first demonstrated this method is suitable for probing protein surface/conformation by studying the effect of deglycosylation on a recombinant mAb, IgG 1. We then applied our method to study the interaction of the mAb with a common excipient, polysorbate-20 (PS-20). The presence of PS-20 increased the fluorescent labeling of several lysine residues on the mAb. This result provides a first insight into PS20-mAb interaction at peptide level resolution.

Evaluation of an injectable thermosensitive hydrogel as drug delivery implant for ocular glaucoma surgery

In this study, a biodegradable thermo-sensitive hydrogel from poly(trimethylene carbonate)₁₅-F127-poly(trimethylene carbonate)₁₅ (PTMC₁₅-F127-PTMC₁₅) was designed and evaluated as an injectable implant during ocular glaucoma filtration surgery in vivo and in vitro. Mitomycin C (MMC) was loaded into this hydrogel for controlled released to prolong the efficacy and to reduce the long-term toxicity. The properties of the hydrogel were confirmed using ¹H NMR and gel permeation chromatography (GPC). Compared to the Pluronic F127 hydrogel, the PTMC₁₅-F127-PTMC₁₅ hydrogel showed a good solution-gel transition temperature at 37°C, a lower work concentration of 5% w/v and a longer mass loss time of more than 2 weeks. The in vitro study showed that the drug could be released from PTMC₁₅-F127-PTMC₁₅ (5% w/v) hydrogel for up to 16 days with only 57% of drug released in the first day. Moreover, the cell toxicity, which was tested via LDH and ANNEXIN V/PI, decreased within 72 h in human tenon's fibroblast cells (HTFs). The in vivo behavior in a rabbit glaucoma filtration surgery model indicated that this hydrogel loaded with 0.1 mg/ml MMC led to a better functional bleb with a prolonged mean bleb survival time (25.5±2.9 days). The scar tissue formation, new collagen deposition and myofibroblast generation appeared to be reduced upon histological and immunohistochemistry examinations, with no obvious side effects and inflammatory reactions. The in vitro and in vivo results demonstrated that this novel hydrogel is a safe and effective drug delivery candidate in ocular glaucoma surgery.

Utilization of a precolumn with size exclusion and reversed-phase modes for size-exclusion chromatographic analysis of polysorbate-containing protein aggregates

Size-exclusion chromatography (SEC) is a useful method for quantification of protein aggregates because of its high throughput capacity and highly quantitative performance. One of the problems in this method concerns polysorbates, which are well-known additives for protein-containing products to prevent protein aggregation, but frequently interfere with the photometric detection of protein aggregates. We developed a new SEC method that can separate polysorbates from protein sample solutions in an on-line mode with a precolumn with size exclusion and reversed-phase mixed modes. The precolumn can effectively trap polysorbates in aqueous mobile phase, and the trapped polysorbates are easily eluted with acetonitrile-containing aqueous mobile phase to clean the precolumn. Small parts of protein aggregates may be also trapped on the precolumn depending on temperature and proteins. Setting appropriate column temperature can minimize such inconvenient trapping of aggregates.

Renewal of the air-water interface as a critical system parameter of protein stability: aggregation of the human growth hormone and its prevention by surface-active compounds

Soluble proteins are often highly unstable under mixing conditions that involve dynamic contacting between the main liquid phase and a gas phase. The recombinant human growth hormone (rhGH) was recently shown to undergo aggregation into micrometer-sized solid particles composed of non-native (mis- or unfolded) protein, once its solutions were stirred or shaken to generate a continuously renewed air-water interface. To gain deepened understanding and improved quantification of the air-water interface effect on rhGH stability, we analyzed the protein's aggregation rate (r(agg)) at controlled specific air-water surface areas (a(G/L)) established by stirring or bubble aeration. We show that in spite of comparable time-averaged values for a(G/L) (≈ 100 m(2)/m(3)), aeration gave a 40-fold higher r(agg) than stirring. The enhanced r(agg) under aeration was ascribed to faster macroscopic regeneration of free a(G/L) during aeration as compared to stirring. We also show that r(agg) was independent of the rhGH concentration in the range 0.67 - 6.7 mg/mL, and that it increased linearly dependent on the available a(G/L). The nonionic surfactant Pluronic F-68, added in 1.6-fold molar excess over rhGH present, resulted in complete suppression of r(agg). Foam formation was not a factor influencing r(agg). Using analysis by circular dichroism spectroscopy and small-angle X-ray scattering, we show that in the presence of Pluronic F-68 under both stirring and aeration, the soluble protein retained its original fold, featuring native-like relative composition of secondary structural elements. We further provide evidence that the efficacy of Pluronic F-68 resulted from direct, probably hydrophobic protein-surfactant interactions that prevented rhGH from becoming attached to the air-water interface. Surface-induced aggregation of rhGH is suggested to involve desorption of non-native protein from the air-water interface as the key limiting step. Proteins or protein aggregates released back into the bulk liquid appear to be essentially insoluble.

Gelatin nanostructured lipid carriers-mediated intranasal delivery of basic fibroblast growth factor enhances functional recovery in hemiparkinsonian rats

Lipid nanoparticles with solid matrix have been given increasing attention due to their biodegradable status and ability to entrap a variety of biologically active compounds. In this study, new phospholipid-based gelatin nanoparticles encapsulating basic fibroblast growth factor (bFGF) were developed to target the brain via nasal administration. Treatment effects were assessed by quantifying rotational behavior, monoamine neurotransmitter levels and tyrosine hydroxylase expression in 6-hydroxydopamine induced hemiparkinsonian rats. The gelatin nanostructured lipid carriers (GNLs) were prepared by a water-in-water emulsion method and then freeze-dried. The GNLs possessed better profile than gelatin nanoparticles (GNs), with particle size 143±1.14nm and Zeta potential -38.2±1.2mV. The intranasal GNLs efficiently enriched exogenous bFGF in olfactory bulb and striatum without adverse impact on the integrity of nasal mucosa and showed obvious therapeutic effects on hemiparkinsonian rats. Thus, GNLs are attractive carriers for nose-to-brain drug delivery, especially for unstable macromolecular drugs such as bFGF.

FROM THE CLINICAL EDITOR

This team of authors reports the development of phospholipid-based gelatin nanoparticles encapsulating basic fibroblast growth factor to target the brain via intranasal administration. A rat model of hemiparkinsonism was applied demonstrating a good safety profile and an obvious therapeutic effect.

The effects of membrane filters used in biopharmaceutical processes on the concentration and composition of polysorbate 20

Polysorbate 20 (PS-20) is often included in the formulation for therapeutic proteins to reduce protein aggregation and surface adsorption. During the production process of therapeutic proteins, various membrane filters are used to filter product pools containing PS-20. The purpose of this study is to quantify the effects of these membrane filtration processes on the concentration and composition of PS-20. A quantitative understanding of this process provides the knowledge base for better controlling the consistency of formulation excipients in drug products. PS-20 solutions (without protein) were filtered through either 0.2 µm sterilizing filters or membrane filters with 30 kDa MWCO. The concentration of PS-20 was measured by a mixed-mode chromatography method and a nuclear magnetic resonance spectroscopy (NMR) assay. The composition of PS-20 was characterized by (1) H-NMR and a reverse-phase chromatography method. Non-specific adsorption of PS-20 on both the sterilizing filter and 30 kDa MWCO membrane filter was quantified. Composition of PS-20 was altered after 30 kDa MWCO membrane filtration, possibly because the different interactions between heterogeneous PS-20 components and the 30 kDa MWCO membrane were not uniform. As a result, the retentate after the 30 kDa MWCO membrane filtration step contains no POE sorbitan and increased amount of POE sorbitan di-esters and tri-esters.

Immunogenicity of therapeutic proteins: influence of aggregation

The elicitation of anti-drug antibodies (ADA) against biotherapeutics can have detrimental effects on drug safety, efficacy, and pharmacokinetics. The immunogenicity of biotherapeutics is, therefore, an important issue. There is evidence that protein aggregation can result in enhanced immunogenicity; however, the precise immunological and biochemical mechanisms responsible are poorly defined. In the context of biotherapeutic drug development and safety assessment, understanding the mechanisms underlying aggregate immunogenicity is of considerable interest. This review provides an overview of the phenomenon of protein aggregation, the production of unwanted aggregates during bioprocessing, and how the immune response to aggregated protein differs from that provoked by non-aggregated protein. Of particular interest is the nature of the interaction of aggregates with the immune system and how subsequent ADA responses are induced. Pathways considered here include 'classical' activation of the immune system involving antigen presenting cells and, alternatively, the breakdown of B-cell tolerance. Additionally, methods available to screen for aggregation and immunogenicity will be described. With an increased understanding of aggregation-enhanced immune responses, it may be possible to develop improved manufacturing and screening processes to avoid, or at least reduce, the problems associated with ADA.

IL-1Ra and its delivery strategies: inserting the association in perspective

Interleukin-1 receptor antagonist (IL-1Ra) is a naturally occurring anti-inflammatory antagonist of interleukin-1 family of pro-inflammatory cytokines. The broad spectrum anti-inflammatory effects of IL-1Ra have been investigated against various auto-immune diseases such as diabetes mellitus, rheumatoid arthritis. Despite of its outstanding broad spectrum anti-inflammatory effects, IL-1Ra has short biological half-life (4-6 h) and to cope with this problem, up till now, many delivery strategies have been applied either to extend the half-life and/or prolong the steady-state sustained release of IL-1Ra from its target site. Here in our present paper, we have provided an overview of all approaches attempted to prolong the duration of therapeutic effects of IL-1Ra either by fusing IL-1Ra using fusion protein technology to extend the half-life and/or development of new dosage forms using various biodegradable polymers to prolong its steady-state sustained release at the site of administration. These approaches have been characterized by their intended impact on either in vitro release characteristics and/or pharmacokinetic and pharmacodynamic parameters of IL-1Ra. We have also compared these delivery strategies with each other on the basis of bioactivity of IL-1Ra after fusion with fusion protein partner and/or encapsulation with biodegradable polymer.