Investigation of Fragment Antibody Stability and Its Release Mechanism from Poly(Lactide-co-Glycolide)-Triacetin Depots for Sustained-Release Applications

Metronidazole-Loaded Camphor-Based In Situ Forming Matrix for Periodontitis Treatment

Periodontitis is a widespread oral health problem caused by bacterial infections that lead to tooth loss and other systemic diseases. The aim of this study was to provide an alternative treatment for periodontitis by developing a metronidazole-loaded in situ forming matrix (ISM) using camphor as its matrix former. Five-percent w/w metronidazole dissolved in N-methyl pyrrolidone (NMP) with varying concentrations of camphor (30-50% w/w) and triacetin (0-25% w/w) were used. The physicochemical properties and antimicrobial activities of formulations were evaluated. Results showed that as the percentage of camphor increased, viscosity, density, contact angle, surface tension, and force of injection increased, while water tolerance decreased. The same trend was observed when increasing the triacetin concentration. The optimal metronidazole-loaded ISM was obtained at 40% w/w camphor and 5% w/w triacetin, which prolonged the release of metronidazole up to 6 days with Fickian diffusion release profile. The higher concentration of triacetin slowed down the phase inversion that led to an incomplete formation of the matrix and resulted in an inefficiently prolonged release of the metronidazole. Antimicrobial activities demonstrated that the developed formulation efficiently inhibited periodontitis-induced microorganisms including Porphyromonas gingivalis, Staphylococcus aureus, Escherichia coli, and Candida albicans. The metronidazole-loaded camphor-based ISM has potential as a new drug delivery system for periodontitis treatment.

Phase Inversion-Based Doxycycline Hyclate-Incorporated Borneol In Situ Gel for Periodontitis Treatment

Borneol has been successfully employed as a gelling agent for in situ forming gel (ISG). While 40% borneol can regulate drug release, there is interest in novel approaches to achieve extended drug release, particularly through the incorporation of hydrophobic substances. Herein, triacetin was selected as a hydrophobic additive solvent for doxycycline hyclate (Dox)-loaded 40% borneol-based ISGs in N-methyl-2-pyrrolidone (NMP) or dimethyl sulfoxide (DMSO), which were subsequently evaluated in terms of their physicochemical properties, gel formation morphology, water sensitivity, drug release, and antimicrobial activities. ISG density and viscosity gradually decreased with the triacetin proportion to a viscosity of <12 cPs and slightly influenced the surface tension (33.14-44.33 mN/m). The low expelled force values (1.59-2.39 N) indicated the convenience of injection. All of the prepared ISGs exhibited favorable wettability and plastic deformation. Higher gel firmness from ISG prepared using NMP as a solvent contributed to the ability of more efficient controlled drug release. High triacetin (25%)-loaded ISG retarded solvent diffusion and gel formation, but diminished gel firmness and water sensitivity. ISG containing 5% triacetin efficiently prolonged Dox release up to 10 days with Fickian diffusion and presented effective antimicrobial activities against periodontitis pathogens such as Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans. Therefore, the Dox-loaded 40% borneol-based ISG with 5% triacetin is a potential effective local ISG for periodontitis treatment.

Long-acting injectable formulation technologies: Challenges and opportunities for the delivery of fragile molecules

INTRODUCTION

The development of long acting injectables (LAIs) for protein and peptide therapeutics has been a key challenge over the last 20 years. If these molecules offer advantages due to their high specificity and selectivity, their controlled release may confer several additional benefits in terms of extended half-life, local delivery, and patient compliance.

AREA COVERED

This manuscript aims to give an overview of peptide and protein based LAIs from an industrial perspective, describing both approved and promising technologies (with exceptions of protein engineering strategies and devices), their advantages and potential improvements to aid their access to the market.

EXPERT OPINION

Many LAIs have been developed for peptides, with formulations on the market for several decades. On the contrary, LAIs for proteins are still far from the market and issues related to manufacturing and sterilization of these products still need to be overcome. In situ forming depots (ISFDs), whose simple manufacturing conditions and easy administration procedures (without reconstitution) are strong advantages, appear as one of the most promising technologies for the delivery of these molecules. In this regard, the approval of ELIGARD® in the early 2000's (which still requires a complex reconstitution process), paved the way for the development of second-generation, ready-to-use ISFD technologies like BEPO® and FluidCrystal®.

How neutron scattering techniques benefit investigating structures and dynamics of monoclonal antibody

Over the past several decades, great progresses have been made for the pharmaceutical industry of monoclonal antibody (mAb). More and more mAb products were approved for human therapeutics. This review describes the state of art of utilizing neutron scattering to investigate mAbs, in the aspects of structures, dynamics, physicochemical stability, functionality, etc. Firstly, brief histories of mAbs and neutron scattering, as well as some basic knowledges and principles of neutron scattering were introduced. Then specific examples were demonstrated. For the structure and structural evolution investigation of in dilute and concentrated mAbs solution, in situ small angle neutron scattering (SANS) was frequently utilized. Neutron reflectometry (NR) is powerful to probe the absorption behaviors of mAbs on various surfaces and interfaces. While for dynamic investigation, quasi-elastic scattering techniques such as neutron spin echo (NSE) demonstrate the capabilities. With this review, how to utilize and take advantages of neutron scattering on investigating structures and dynamics of mAbs were demonstrated and discussed.

Intra-articular delivery of full-length antibodies through the use of an in situ forming depot

Monoclonal antibodies (mAbs) are large size molecules that have demonstrated high therapeutic potential for the treatment of cancer or autoimmune diseases. Despite some excellent results, their intravenous administration results in high plasma concentration. This triggers off-target effects and sometimes poor targeted tissue distribution. To circumvent this issue, we investigated a local controlled-delivery approach using an in situ forming depot technology. Two clinically relevant mAbs, rituximab (RTX) and daratumumab (DARA), were formulated using an injectable technology based on biodegradable PEG-PLA copolymers. The stability and controlled release features of the formulations were investigated. HPLC and mass spectrometry revealed the preservation of the protein structure. In vitro binding of formulated antibodies to their target antigens and to their cellular FcγRIIIa natural killer cell receptor was fully maintained. Furthermore, encapsulated RTX was as efficient as classical intravenous RTX treatment to inhibit the in vivo tumor growth of malignant human B cells in immunodeficient NSG mice. Finally, the intra-articular administration of the formulated mAbs yielded a sustained local release associated with a lower plasma concentration compared to the intra-articular delivery of non-encapsulated mAbs. Our results demonstrate that the utilization of this polymeric technology is a reliable alternative for the local delivery of fully functional clinically relevant mAbs.

Microstructure, Quality, and Release Performance Characterization of long-Acting Polymer Implant Formulations with X-Ray Microscopy and Quantitative AI Analytics

Long-acting implants are typically formulated using carrier(s) with specific physical and chemical properties, along with the active pharmaceutical ingredient (API), to achieve the desired daily exposure for the target duration of action. In characterizing such formulations, real-time in-vitro and in-vivo experiments that are typically used to characterize implants are lengthy, costly, and labor intensive as these implants are designed to be long acting. A novel characterization technique, combining high resolution three-dimensional X-Ray microscopy imaging, image-based quantification, and transport simulation, has been employed to provide a mechanistic understanding of formulation and process impact on the microstructures and performance of a polymer-based implant. Artificial intelligence-based image segmentation and image data analytics were used to convert morphological features visualized at high resolution into numerical microstructure models. These digital models were then used to calculate key physical parameters governing drug transport in a polymer matrix, including API uniformity, API domain size, and permeability. This powerful new tool has the potential to advance the mechanistic understanding of the interplay between drug-microstructure and performance and accelerate the therapeutic development long-acting implants.

Ectoine and Hydroxyectoine Stabilize Antibodies in Spray-Dried Formulations at Elevated Temperature and during a Freeze/Thaw Process

Maintenance of protein stability during manufacture, storage, and delivery is necessary for the successful development of a drug product. Herein, the utility of two compatible solutes-ectoine and hydroxyectoine-in stabilizing a model protein labeled Fab2 has been investigated. Specifically, the performance of ectoine and hydroxyectoine in stabilizing Fab2 in a spray-dried formulation at elevated temperature and after multiple freeze/thaw cycles has been compared with the performance of a formulation containing trehalose and a formulation containing no excipient as controls. In the solid state at 90 and 37 °C and in freeze concentrate systems, ectoine and hydroxyectoine suppress protein aggregation. Like trehalose, hydroxyectoine also limits N-terminal pyroglutamate formation in Fab2 in the solid state. The extent of protein stabilization is dependent on the excipient concentration in the formulation, but at a 1:1 excipient to protein mass ratio, hydroxyectoine is better than trehalose in stabilizing Fab2. The results presented here suggest that ectoine and hydroxyectoine are effective excipients for stabilizing therapeutic antibodies.

Improvement in mechanical properties and biodegradability of PLA using poly(ethylene glycol) and triacetin for antibacterial wound dressing applications

Wound is among the most common injuries. A suitable wound dressing has a significant effect on the healing process. In this study, a porous wound dressing was prepared using poly (lactic acid) (PLA) and two plasticizers, polyethylene glycol (PEG) and triacetin (TA), through solvent casting method. For antibacterial activities, metronidazole was incorporated in the structure. The morphology was investigated by scanning electron microscopy (SEM). In addition, the effect of plasticizers ratio on porosity growth was evaluated. It was also observed that each had a unique effect on the structure's porosity. The mechanical properties confirmed the effect of both plasticizers on increasing polymer softness and flexibility, and the most similar formulations to human skin in terms of mechanical properties were introduced. According to the results, TA had stronger effect on mechanical properties. The differential scanning calorimetry (DSC) showed the effect of increasing plasticizer concentration on crystalline structure and Tm reduction of PLA. The water contact angle measurement showed that both plasticizers enhanced hydrophilic characteristics of PLA, and this effect was weaker in PEG-containing formulations. The in vitro degradation study showed biodegradability, as a desirable property in wound dressing. Results suggested that higher degradation can be obtained by both plasticizers at the same time. The results also showed that PEG was more effective in enhancing water absorbency. In vitro drug release study indicated an explosive release and the highest amount was 85% over 186 h. The antibacterial activity test confirmed the effectiveness of the drug in preventing bacterial growth in the drug-containing formulations, while it showed the antibacterial property of TA. MTT assay was performed and the cellular toxicity of the formulations was checked and those that revealed the least toxicity were introduced.

Extended Hildebrand Solubility Approach: Prediction and Correlation of the Solubility of Itraconazole in Triacetin: Water Mixtures at 298.15°K

Objectives

The aim of the study is to explore the suitability of an empirical approach for the extended Hildebrand solubility approach (EHSA) to predict and correlate the solubility of the crystalline drug itraconazole (ITRA) in triacetin: water mixtures.

Materials and Methods

The physicochemical properties of ITRA like fusion enthalpy, solubility parameter, and ideal mole fraction solubility were estimated. The solubilities of ITRA in mixed solvent blends comprising triacetin: water were determined at 298.15°K. Theoretical solubilities were back calculated using a polynomial regression equation of the interaction energy parameter W as a function of the solubility parameter (δ₁) of the solvent mixture. Similarly, the solubilities were predicted by direct method based on the use of logarithmic experimental solubilities (logX₂ ) against the solubility parameter (δ₁) of the solvent mixture. The predictive capabilities of both EHSA and the direct method were compared using mean percent deviations.

Results

The solubility of ITRA was increased in all the triacetin: water blends and was highest in the blend in which the solubility parameter of ITRA equaled that of the solvent mixture. The prediction capacities of the direct method (mean % deviation was -1.89%) were better than those of EHSA (mean % deviation was 9.76%) in the fifth order polynomial.

Conclusion

The results indicated that the solubility of any crystalline solute can be adequately predicted and correlated with the mere knowledge of physicochemical properties and EHSA. The information could be of help in process and formulation development.

Data-Driven Development of Predictive Models for Sustained Drug Release

Mathematical modeling of drug release can aid in the design and development of sustained delivery systems, but the parameter estimation of such models is challenging owing to the nonlinear mathematical structure and complexity and interdependency of the physical processes considered. Highly parameterized models often lead to overfitting, strong parameter correlations, and as a consequence, inaccurate model predictions for systems not explicitly part of the fitting database. Here, we show that an efficient stochastic optimization algorithm can be used not only to find robust estimates of global minima to such complex problems but also to generate metadata that allow quantitative evaluation of parameter sensitivity and correlation, which can be used for further model refinement and development. A practical methodology is described through the analysis of a predictive drug release model on published experimental data sets. The model is then used to design a zeroth-order release profile in an experimental system consisting of an antibody fragment in a poly(lactic-co-glycolic acid) solvent depot, which is validated experimentally. This approach allows rational decision-making when developing new models, selecting models for a specific application, or designing formulations for experimental trials.

In Situ Characterization of the Microstructural Evolution of Biopharmaceutical Solid-State Formulations with Implications for Protein Stability

Lyophilized and spray-dried biopharmaceutical formulations are used to provide long-term stability for storage and transport, but questions remain about the molecular structure in these solid formulations and how this structure may be responsible for protein stability. Small-angle neutron scattering with a humidity control environment is used to characterize protein-scale microstructural changes in such solid-state formulations as they are humidified and dried in situ. The findings indicate that irreversible protein aggregates of stressed formulations do not form within the solid-state but do emerge upon reconstitution of the formulation. After plasticization of the solid-state matrix by exposure to humidity, the formation of reversibly self-associating aggregates can be detected in situ. The characterization of the protein-scale microstructure in these solid-state formulations facilitates further efforts to understand the underlying mechanisms that promote long-term protein stability.

Strategies for modifying drug residence time and ocular bioavailability to decrease treatment frequency for back of the eye diseases

INTRODUCTION

Treating posterior eye diseases has become a major area of focus for pharmaceutical and biotechnology companies. Current standard of care for treating posterior eye diseases relies on administration via intravitreal injection. Although effective, this is not without complications and there is great incentive to develop longer-acting therapeutics and/or sustained release delivery systems. Here, we present an overview of emerging technologies for delivery of biologics to the back of the eye.

AREAS COVERED

Posterior eye diseases, intravitreal injection, age-related macular degeneration, anti-VEGF, ocular pharmacokinetics, novel technologies to extend half-life, in vivo models, translation to the clinic, and hurdles to effective patient care.

EXPERT OPINION

Posterior eye diseases are a worldwide public health issue. Although anti-VEGF molecules represent a major advance for treating diseases involving choroidal neovascularization, frequent injection can be burdensome for patients and clinicians. There is a need for effective and patient-friendly treatments for posterior eye diseases. Many technologies that enable long-acting delivery to the back of the eye are being evaluated. However, successful development of novel therapies and delivery technologies is hampered by a multitude of factors, including patient education, translatability of in vitro/in vivo preclinical data to the clinic, and regulatory challenges associated with novel technologies.

One-step solid-oil-water emulsion for sustained bioactive ranibizumab release

BACKGROUND

The advent of therapeutic proteins highlights the need for delivery systems that protect and extend the duration of its action. Ranibizumab-VEGF is one such drug used for treating wet AMD. This paper describes a facile method to sustain bioactive ranibizumab release from PLGA-based particles.

METHODS

Two emulsion techniques were explored namely: water-in-oil-in-water (WOW) and solid-in-oil-in-water (SOW) emulsion. The bioactivity of ranibizumab was evaluated by comparing its binding capability to VEGF, measured with ELISA to total protein measured by microBCA.

RESULTS

During the emulsion process, contact of ranibizumab with the water-oil interface is the main destabilizing factor and this can be prevented with the use of amphiphilic PVA and solid-state protein in WOW and SOW emulsion respectively. In vitro release of the ranibizumab-loaded particles indicated that a 15-day release could be achieved with SOW particles while the WOW particles generally suffered from a burst release. Released ranibizumab was capable of inhibiting endothelial cell growth indicating its retention of bioactivity. The suppression of burst release from the SOW particles was attributed to the relatively smooth surface morphology of the SOW microparticles.

CONCLUSIONS

The use of SOW encapsulation in modulating ranibizumab release while maintaining their bioactivity has been highlighted.