Combination of NMR Methods To Reveal the Interfacial Structure of a Pharmaceutical Nanocrystal and Nanococrystal in the Suspended State

Nanocrystal technologies in biomedical science: From the bench to the clinic

The pharmaceutical industry is grappling with a pressing crisis in drug development characterized by soaring R&D costs, setbacks in blockbuster drug development due to poor aqueous solubility, and patent-related limitations on newly approved molecules. To combat these challenges, diverse strategies have emerged to enhance the solubility and dissolution rates of Biopharmaceutics Classification System (BCS) II and IV drug molecules. Enter drug nanocrystals, a revolutionary nanotechnology-driven, carrier-free colloidal drug delivery system. This review provides a comprehensive insight into nanocrystal strategies, stabilizer selection criteria, preparation methods, advanced characterization techniques, the evolving nanocrystal technological landscape, current market options, and exciting clinical prospects for reshaping the future of pharmaceuticals.

Pharma 4.0-Artificially Intelligent Digital Twins for Solidified Nanosuspensions

Digital twins capacitate the industry 4.0 paradigm by predicting and optimizing the performance of physical assets of interest, mirroring a realistic in-silico representation of their functional behaviour. Although advanced digital twins set forth disrupting opportunities by delineating the in-service product and the related process dynamic performance, they have yet to be adopted by the pharma sector. The latter, currently struggles more than ever before to improve solubility of BCS II i.e., hard-to-dissolve active pharmaceutical ingredients by micronization and subsequent stabilization. Herein we construct and functionally validate the first artificially intelligent digital twin thread, capable of describing the course of manufacturing of such solidified nanosuspensions given a defined lifecycle starting point and predict and optimize the relevant process outcomes. To this end, we referenced experimental data as the sampling source, which we then augmented via pattern recognition utilizing neural network propagations. The zeta-dynamic potential metrics of the nanosuspensions were correlated to the interfacial Gibbs energy, while the density and heat capacity of the material system was calculated via the Saft-γ-Mie statistical fluid theory. The curated data was then fused to physical and empirical laws to choose the appropriate theory and numeric description, respectively, before being polished by tuning the critical parameters to achieve the best fit with reality.

Drug Nanocrystals for Active Tumor-Targeted Drug Delivery

Drug nanocrystals, which are comprised of active pharmaceutical ingredients and only a small amount of essential stabilizers, have the ability to improve the solubility, dissolution and bioavailability of poorly water-soluble drugs; in turn, drug nanocrystal technology can be utilized to develop novel formulations of chemotherapeutic drugs. Compared with passive targeting strategy, active tumor-targeted drug delivery, typically enabled by specific targeting ligands or molecules modified onto the surface of nanomedicines, circumvents the weak and heterogeneous enhanced permeability and retention (EPR) effect in human tumors and overcomes the disadvantages of nonspecific drug distribution, high administration dosage and undesired side effects, thereby contributing to improving the efficacy and safety of conventional nanomedicines for chemotherapy. Continuous efforts have been made in the development of active tumor-targeted drug nanocrystals delivery systems in recent years, most of which are encouraging and also enlightening for further investigation and clinical translation.

Exploring the influence factors and improvement strategies of drug polymorphic transformation combined kinetic and thermodynamic perspectives during the formation of nanosuspensions

Nanosuspensions can effectively increase saturation solubility and improve the bioavailability of poorly water-soluble drugs attributed to high loading and surface-to-volume ratio. Wet media milling has been regarded as a scalable method to prepare nanosuspensions because of its simple operation and easy scale-up. In recent years, besides particle aggregation and Ostwald ripening, polymorphic transformation induced by processing has become a critical factor leading to the instability of nanosuspensions. Therefore, this review aims to discuss the influence factors comprehensively and put forward the corresponding improvement strategies of polymorphic transformation during the formation of nanosuspensions. In addition, this review also demonstrates the implication of molecular simulation in polymorphic transformation. The competition between shear-induced amorphization and thermally activated crystallization is the global mechanism of polymorphic transformation during media milling. The factors affecting the polymorphic transformation and corresponding improvement strategies are summarized from formulation and process parameters perspectives during the formation of nanosuspensions. The development of analytical techniques has promoted the qualitative and quantitative characterization of polymorphic transformation, and some techniques can in-situ monitor dynamic transformation. The microhydrodynamic model can be referenced to study the stress intensities by analyzing formulation and process parameters during wet media milling. Molecular simulation can be used to explore the possible polymorphic transformation based on the crystal structure and energy. This review is helpful to improve the stability of nanosuspensions by regulating polymorphic transformation, providing quality assurance for nanosuspension-based products.

Pharmaceutical nanococrystal synthesis: a novel grinding approach

Nanococrystals – a new green in situ surfactant-assisted mechanochemical synthesis.

Antibacterial activities of physiologically stable, self-assembled peptide nanoparticles

In this study, we report that host defense protein-derived ten amino acid long disulfide-linked peptides self-assemble in the form of β-sheets and β-turns, and exhibit concentration-dependent self-assembly in the form of nanospheres, termed as disulfide linked nanospheres (DSNs). As expected, bare DSNs are prone to aggregation in ionic solutions and in the presence of serum proteins. To yield physiologically stable self-assembled peptide-based materials, DSNs are stabilized in the form of supramolecular assemblies using β-cyclodextrins (β-CD) and fucoidan, as delivery carriers. The inclusion complexes of DSNs with β-CD (β-CD-DSN) and electrostatic complexation of fucoidan with DSNs (FC-DSN) stabilizes the secondary structure of DSNs. Comparison of β-CD-DSNs with FC-DSNs reveals that inclusion complexes of DSNs formed in the presence of β-CD are highly stable under physiological conditions, show high cellular uptake, exhibit bacterial flocculation, and enhance antibacterial efficacies of DSNs in a range of Gram-positive and Gram-negative bacteria.

Integrating Elastic Tensor and PC-SAFT Modeling with Systems-Based Pharma 4.0 Simulation, to Predict Process Operations and Product Specifications of Ternary Nanocrystalline Suspensions

Comminution of BCS II APIs below the 1 μm threshold followed by solidification of the obtained nanosuspensions improves their dissolution properties. The breakage process reveals new crystal faces, thus creating altered crystal habits of improved wettability, facilitated by the adsorption of stabilizing polymers. However, process-induced transformations remain unpredictable, mirroring the current limitations of our atomistic level of understanding. Moreover, conventional equations of estimating dissolution, such as Noyes–Whitney and Nernst–Brunner, are not suitable to quantify the solubility enhancement due to the nanoparticle formation; hence, neither the complex stabilizer contribution nor the adsorption influence on the interfacial tension occurring between the water and APIs is accounted for. For such ternary mixtures, no numeric method exists to correlate the mechanical properties with the interfacial energy, capable of informing the key process parameters and the thermodynamic stability assessment of nanosuspensions. In this work, an elastic tensor analysis was performed to quantify the API stability during process implementation. Moreover, a novel thermodynamic model, described by the stabilizer-coated nanoparticle Gibbs energy anisotropic minimization, was structured to predict the material’s system solubility quantified by the application of PC-SAFT modeling. Comprehensively merging elastic tensor and PC-SAFT analysis into the systems-based Pharma 4.0 algorithm provided a validated, multi-level, built-in method capable of predicting the critical material quality attributes and corresponding key process parameters.

Nondestructive Investigation of the Agglomeration Process for Nanosuspensions via NMR Relaxation of Water Molecules

This study investigated an agglomeration of nanoparticles in a suspension using nuclear magnetic resonance (NMR) relaxation. The nanosuspension was prepared by wet bead milling using indomethacin and polyvinylpyrrolidone as an active pharmaceutical ingredient (API) and stabilizer, respectively. Transmission profiles using a dispersion analyzer based on multilight scattering technology confirmed that agglomeration occurred at 25 °C immediately after wet bead milling. In this study, we focused on the water molecules, not nanoparticles, and obtained the T₂ relaxation time (T₂) of the water molecules using the time-domain NMR (TD-NMR) technique. During the storage period, the T₂ value rapidly increased at the beginning of the storage. In a suspension system, because the T₂ value of water molecules is known to reflect the surface area of the particle, the observed rapid increase in T₂ value indicated an agglomeration of nanoparticles. Therefore, it was shown that the measurement of T₂ relaxation of a nanosuspension could evaluate the agglomeration process. This technique directly observes water molecules as opposed to nanoparticles. Thus, we believe that TD-NMR is a general-purpose technique that is independent of the type of API or polymer.

Recent applications of electrical, centrifugal, and pressurised emerging technologies for fibrous structure engineering in drug delivery, regenerative medicine and theranostics

Advancements in technology and material development in recent years has led to significant breakthroughs in the remit of fiber engineering. Conventional methods such as wet spinning, melt spinning, phase separation and template synthesis have been reported to develop fibrous structures for an array of applications. However, these methods have limitations with respect to processing conditions (e.g. high processing temperatures, shear stresses) and production (e.g. non-continuous fibers). The materials that can be processed using these methods are also limited, deterring their use in practical applications. Producing fibrous structures on a nanometer scale, in sync with the advancements in nanotechnology is another challenge met by these conventional methods. In this review we aim to present a brief overview of conventional methods of fiber fabrication and focus on the emerging fiber engineering techniques namely electrospinning, centrifugal spinning and pressurised gyration. This review will discuss the fundamental principles and factors governing each fabrication method and converge on the applications of the resulting spun fibers; specifically, in the drug delivery remit and in regenerative medicine.

Characterizing and Exploring the Differences in Dissolution and Stability Between Crystalline Solid Dispersion and Amorphous Solid Dispersion

Solid dispersion is one of the most effective ways to improve the dissolution of insoluble drugs. When the carrier can highly disperse the drug, it will increase the wettability of the drug and reduce the surface tension, thus improving the solubility, dissolution, and bioavailability. However, amorphous solid dispersions usually have low drug loading and poor stability. Therefore, the goal of this work is to study the increased dissolution and high stability of high drug-loading crystalline solid dispersion (CSD), and the difference in dissolution and stability of high-loading and low-loading amorphous solid dispersion (ASD). A CSD of nimodipine with a drug loading of 90% was prepared by wet milling, with hydroxypropyl cellulose (model: HPC-SL) and sodium dodecyl sulfate as stabilizers and spray drying. At the same time, the gradient drug-loaded ASD was prepared by hot melt extrusion with HPC-SL as the carrier. Each preparation was characterized by DSC, PXRD, FT-IR, SEM, and in vitro dissolution testing. The results indicated that the drug in CSD existed in a crystalline state. The amorphous drug molecules in the low drug-loading ASD were uniformly dispersed in the carrier, while the drug state in the high drug-loading ASD was aggregates of the amorphous drug. At the end of the dissolution assay, the 90% drug-loading CSD increased cumulative dissolution to 60%, and the 10% drug-loading ASD achieved a cumulative dissolution rate of 90%.

Degrees of order: A comparison of nanocrystal and amorphous solids for poorly soluble drugs

Poor aqueous solubility is currently a prevalent issue in the development of small molecule pharmaceuticals. Several methods are possible for improving the solubility, dissolution rate and bioavailability of Biopharmaceutics Classification System (BCS) class II and class IV drugs. Two solid state approaches, which rely on reductions in order, and can theoretically be applied to all molecules without any specific chemical prerequisites (compared with e.g. ionizable or co-former groups, or sufficient lipophilicity), are the use of the amorphous form and nanocrystals. Research involving these two approaches is relatively extensive and commercial products are now available based on these technologies. Nevertheless, their formulation remains more challenging than with conventional dosage forms. This article describes these two technologies from both theoretical and practical perspectives by briefly discussing the physicochemical backgrounds behind these approaches, as well as the resulting practical implications, both positive and negative. Case studies demonstrating the benefits and challenges of these two techniques are presented.

Study on the stabilization mechanisms of wet-milled cepharanthine nanosuspensions using systematical characterization

Objectives: Stability issues are inevitable problems that are encountered in nanosuspension (NS) technology developments and in the industrial application of pharmaceuticals. This study aims to assess the stability of wet-milled cepharanthine NSs and elucidate the stabilization mechanisms of different stabilizers.Methods: The aggregation state was examined via scanning electron microscopy, laser diffraction, and rheometry. The zeta potential, stabilizer adsorption, surface tension, and drug-stabilizer interactions were employed to elucidate the stabilization mechanisms.Results: The results suggest that croscarmellose sodium (CCS), D-α-tocopherol polyethylene glycol 1000 succinate (TPGS), or polyvinyl pyrrolidone VA64 (PVP VA64) alone was able to prevent nanoparticle aggregation for at least 30 days. Attempts to evaluate the stability mechanisms of different stabilization systems revealed that CCS improved the steric-kinetic stabilization of the NSs, attributed to its high viscosity, swelling capacity, and physical barrier effects. In contrast, the excellent physical stability of TPGS systems was mainly due to the reduced surface tension and higher crystallinity. PVP VA64 can adsorb onto the surfaces of nanoparticles and stabilize the NS via steric forces.Conclusion: This study demonstrated the complex effects of CCS, TPGS, and PVP VA64 on cepharanthine NS stability and presented an approach for the rational design of stable NSs.

Enhanced the Bioavailability of Sterile 20(S)-Protopanaxadiol Nanocrystalline Suspension Coated by Bovine Serum Albumin for Intramuscular Injection: In Vitro and In Vivo Evaluation

The aim of this study was to prepare a 20(S)-protopanaxadiol nanocrystalline suspension and enhance the bioavailability of 20(S)-protopanaxadiol by intramuscular injection. 20(S)-Protopanaxadiol nanocrystalline suspension was prepared using an anti-solvent combined with ultrasonic approach, in which meglumine and bovine serum albumin were screened as the optimized stabilizer and the coating agent during spray drying process, respectively. The optimal nanocrystallines were nearly spherical with a uniform particle size distribution, the mean particle size, polydispersity index, and drug loading of which were 151.20 ± 2.54 nm, 0.11 ± 0.01, and 47.15% (w/w), respectively. Sterile 20(S)-protopanaxadiol nanocrystalline suspension was obtained by passing through a 0.22-μm membrane, and the average filtration efficiency (FE%) was 99.96%. The cumulative release percentage of 20(S)-protopanaxadiol nanocrystalline suspension was 92.36% 20(S)-protopanaxadiol within 60 min in vitro, which was relatively rapid compared with that of the physical mixture for 12.51% and the 20(S)-protopanaxadiol bulk powder for 9.71% during the same time interval. The sterile 20(S)-protopanaxadiol nanocrystalline suspension caused minimal irritation responses by histological examination, indicating a good biocompatibility between the 20(S)-protopanaxadiol nanocrystalline suspension and muscle tissues. In pharmacokinetic study, the absolute bioavailability of 20(S)-protopanaxadiol nanocrystalline suspension for intramuscular injection and for oral gavage was 5.99 and 0.03, respectively. In summary, the 20(S)-protopanaxadiol nanocrystalline via intramuscular injection is an efficient drug delivery system to improve its bioavailability.