Studying the morphology of lyophilized protein solids using X-ray micro-CT: effect of post-freeze annealing and controlled nucleation

Wurster Technology-Assisted Step-by-Step Engineering of Multi-layered Pellets (Sprinkles): Microscopy, Micro-CT, and e-Tongue-Based Analysis

The advancement in the formulation and characterization techniques have paved the path for development of new as well as modification of existing dosage forms. The present work explores the role of micro-computed tomography (micro-CT) as advanced characterization technique for multi-layered-coated pellets to ascertain the quality of coated pellets. The work further explored in-house e-tongue technique for understanding palatability of formulation in early stages of development thus by reducing clinical taste evaluation time. The developed multi-layered-coated pellets were characterized using microscopy (optical and electron microscopy). The obtained results demonstrated formation of spherical-shaped pellets with uniform coating. The uniform coating was further confirmed by results obtained from scanning electron microscopy (SEM) and cross-sectional SEM analysis, which showed visible difference in pellet surface before and after multi-layered coating. The micro-CT results confirmed the visible demarcation of layers (drug and polymer, i.e., hydroxypropyl methylcellulose (HPMC) and eudragit (EPO)) along with uniform thickness of various layering. The dissolution study of developed pellets suggested the role of layering EPO on drug release from pellets. The e-tongue analysis proved to be an excellent tool for early prediction of taste masking of drug via multi-layered pellets and can serve as potential platform for taste masking with high specificity. The overall results suggest the suitability of developed multi-layered platform as efficient dosage form (sprinkle) in pediatric/geriatric product development.

Rational Design, Synthesis, and Characterization of a Solid Δ9-Tetrahydrocannabinol Nanoformulation Suitable for "Microdosing" Applications

Background: This article highlights the formulation of a solid Δ9-tetrahydrocannabinol (THC)-loaded ingestible prepared from pure THC distillate. Methods: A THC-containing ethanol-assisted cannabinoid nanoemulsion (EACNE) was created using a solvent displacement technique. Subsequently, the EACNE was converted to a solid powdery material while still retaining its THC potency, a format uniquely suited for "microdosing" applications. Results: EACNE had an average lipid droplet size of ∼190 nm, with a polydispersity index of 0.15, and an average droplet ζ potential of -49±10 mV. The nanoemulsion (NE) was colloidally stable for at least 6 weeks, with no meaningful change in cannabinoid potency over the experimental period, as determined by high-performance liquid chromatography analysis. The EACNE remained stable when subjected to physical stresses such as heat, freeze/thaw cycles, carbonation, dilution to beverage concentrations, high sucrose concentrations, and a pH range between 5 and 8. The microencapsulated EACNE demonstrated limited free-flowing behavior but was freely redispersible in water without any visible phase separation. Conclusions: We report the design, creation, and characterization of a THC NE generated without the use of specialized equipment, such as a microfluidizer or a high-pressure homogenizer. This emulsion could readily be converted to a water-redispersible powder. This embodiment is particularly suited for THC "microdosing," a practice that might decouple the health benefits of THC from its psychotropic effects.

Freezing process influences cake appearance of a lyophilized amorphous protein formulation with low solid content and high fill configuration

Low solid content and high fill drug product configuration pose special challenges for achieving elegant cake appearance after lyophilization. In this study, such a configuration for a protein formulation required lyophilization within a narrow primary drying operating space to obtain elegant cakes. Freezing process optimization was explored as a solution. A Design of Experiment (DoE) approach was used to evaluate the effect of shelf cooling rate, annealing temperature, and their interaction on cake appearance. The slope of product resistance (R_p) vs. dried layer thickness (L_dry) was used as the quantitative response because elegant cake appearance correlated with a lower initial R_p and positive slope. As the R_p vs. L_dry slope can be experimentally established within the first 1/6th of the total primary drying duration, partial lyophilization runs were executed, allowing for rapid screening. The DoE model revealed that a slow cooling rate (≤0.3 °C/min) and high annealing temperature (≥-10 °C) resulted in a better cake appearance. Furthermore, X-ray micro-computed tomography showed that elegant cakes exhibited uniform porous structure and larger pores, while inelegant cakes showed dense top layers with smaller pores. With the optimized freezing process, the primary drying operating space was broadened with improved cake appearance and batch homogeneity.

Skin drug delivery using lipid vesicles: A starting guideline for their development

Lipid vesicles can provide a cost-effective enhancement of skin drug absorption when vesicle production process is optimised. It is an important challenge to design the ideal vesicle, since their properties and features are related, as changes in one affect the others. Here, we review the main components, preparation and characterization methods commonly used, and the key properties that lead to highly efficient vesicles for transdermal drug delivery purposes. We stand by size, deformability degree and drug loading, as the most important vesicle features that determine the further transdermal drug absorption. The interest in this technology is increasing, as demonstrated by the exponential growth of publications on the topic. Although long-term preservation and scalability issues have limited the commercialization of lipid vesicle products, freeze-drying and modern escalation methods overcome these difficulties, thus predicting a higher use of these technologies in the market and clinical practice.

Understanding the Impact of Microstructures on Reconstitution and Drying Kinetics of Lyophilized Cake Using X-ray Microscopy and Image-Based Simulation

The drying time of lyophilization and resultant cake microstructure are dependent on each other as water and solvent leave a lyophilized cake. The drying rate affects the size, distribution, and tortuosity of the pores as these macropores evolve during the primary drying phase, which in return impact the further removal of water and solvent from the cake throughout the drying period. This interplay results in a microstructure that determines the reconstitution time for a given formulation. The current study employs advanced X-ray Microscopy (XRM) coupled with mathematical models to correlate the microstructure with the drying kinetics and the reconstitution time. The normalized diffusion coefficients, derived from the reconstructed 3D microstructure of the cake, correlate with the solid content of the pre-lyophilization solution and agree with the mass transfer coefficients from a semi-empirical drying model built with lyophilization process data. Specifically, a solution with less solid content leads to a lyophilized cake with larger pores, thinner walls, and a greater pore volume compared to a solution with more solid content. Consequently, models from the microstructure and drying experiments reveals faster mass transfer independently. While the mass transfer models from the cake structure and the lyophilization process data accurately represents the drying kinetics, both models are inadequate to describe the reconstitution process due to the significant impact from formulation ingredients that alter the mass transfer mechanism via solubility and wettability. In summary, X-ray microscopy imaging and mathematical models are powerful tools that provide insights into the lyophilization process from a new angle.

Impact of Excipients on Stability of Polymer Microparticles for Autoimmune Therapy

Therapies for autoimmune diseases such as multiple sclerosis and diabetes are not curative and cause significant challenges for patients. These include frequent, continued treatments required throughout the lifetime of the patient, as well as increased vulnerability to infection due to the non-specific action of therapies. Biomaterials have enabled progress in antigen-specific immunotherapies as carriers and delivery vehicles for immunomodulatory cargo. However, most of this work is in the preclinical stage, where small dosing requirements allow for on-demand preparation of immunotherapies. For clinical translation of these potential immunotherapies, manufacturing, preservation, storage, and stability are critical parameters that require greater attention. Here, we tested the stabilizing effects of excipients on the lyophilization of polymeric microparticles (MPs) designed for autoimmune therapy; these MPs are loaded with peptide self-antigen and a small molecule immunomodulator. We synthesized and lyophilized particles with three clinically relevant excipients: mannitol, trehalose, and sucrose. The biophysical properties of the formulations were assessed as a function of excipient formulation and stage of addition, then formulations were evaluated in primary immune cell culture. From a manufacturing perspective, excipients improved caking of lyophilized product, enabled more complete resuspension, increased product recovery, and led to smaller changes in MP size and size distribution over time. Cocultures of antigen-presenting cells and self-reactive T cells revealed that MPs lyophilized with excipients maintained tolerance-inducing function, even after significant storage times without refrigeration. These data demonstrate that excipients can be selected to drive favorable manufacturing properties without impacting the immunologic properties of the tolerogenic MPs.

Comparative Evaluation of Pellet Cushioning Agents by Various Imaging Techniques and Dissolution Studies

Most of the commercially available pharmaceutical products for oral administration route are marketed in the tablet dosage forms. However, compression of multiparticulate systems is a challenge for the pharmaceutical research and industry, especially if the individual unit is a coated particle, as the release of the active ingredient depends on the integrity of the coating. In the present study, polymer-coated pellets tableted with different types of excipients (powder, granules, pellets) then were investigated by various tablet-destructive (microscopic) and tablet non-destructive (microfocus X-ray; microCT) imaging methods. The information obtained from the independent evaluation of the in vitro drug release profiles model is confirmed by the results obtained by image analysis, regardless of whether X-ray or stereomicroscopic images of the coated, tableted pellets were used for image analysis. The results of this study show that the novel easy-to-use, fast, and non-destructive MFX method is a good alternative to the already used microscopic image analysis methods regarding the characterization of particulates, compressed into tablets.

Dynamical in-situ observation of the lyophilization and vacuum-drying processes of a model biopharmaceutical system by an environmental scanning electron microscope

The paper discusses the real-time monitoring of the changing sample morphology during the entire lyophilization (freeze-drying) and vacuum-drying processes of model biopharmaceutical solutions by using an environmental scanning electron microscope (ESEM); the device's micromanipulators were used to study the interior of the samples in-situ without exposing the samples to atmospheric water vapor. The individual collapse temperatures (T_c) of the formulations, pure bovine serum albumin (BSA) and BSA/sucrose mixtures, ranged from -5 to -29 °C. We evaluated the impact of the freezing method (spontaneous freezing, controlled ice nucleation, and spray freezing) on the morphologies of the lyophiles at the constant drying temperature of -20 °C. The formulations with T_c above -20 °C resulted in the lyophiles' morphologies significantly dependent on the freezing method. We interpret the observations as an interplay of the freezing rates and directionalities, both of which markedly influence the morphologies of the frozen formulations, and, subsequently, the drying process and the mechanical stability of the freeze-dried cake. The formulation with T_c below -20 °C yielded a collapsed cake with features independent of the freezing method. The vacuum-drying produced a material with a smooth and pore-free surface, where deep cracks developed at the end of the process.

In-Situ X-ray Imaging Of Sublimating Spin-Frozen Solutions

Spin-freeze-drying is a promising technique to enable long-term storage of pharmaceutical unit doses of aqueous drug solutions. To investigate the sublimation of the ice during the primary phase of freeze-drying, X-ray imaging can yield crucial temporally resolved information on the local dynamics. In this paper, we describe a methodology to investigate the sublimation front during single unit-dose freeze-drying using 4D in-situ X-ray imaging. Three spin-frozen samples of different solutions were imaged using this methodology and the process characteristics were analysed and reduced to two-dimensional feature maps.

Morphological Analysis of Spherical Adsorptive Carbon Granules Using Three-Dimensional X-Ray Micro-computed Tomography

The purpose of this study was to clarify applicability of three-dimensional X-ray micro-computed tomography (3D X-ray micro-CT) to elucidate interior morphology of spherical adsorptive carbon fine granules. Scanning of small single spherical granule hold on the rotating sample stage provided the structural information without particular preparation (e.g., slicing) that can affect the definite morphology. The three model formulations with similar appearance showed different internal structure in the 3D images, including large hollow in one of them. Other formulations showed some small empty or higher density area in the filled granules, suggesting uneven distribution of carbon. The results indicated relevance of the X-ray micro-CT analysis on the physical characterization of the spherical adsorptive carbon granule formulations.