Critical freezing rate in freeze drying nanocrystal dispersions

Exploring the Dissolution, Solid-state Properties, and Long-term Storage Stability of Cryoprotectant-free Fenbendazole Nanoparticles

Fenbendazole is an antiparasitic drug widely used in veterinary medicine to treat parasitic infections caused in animals like cattle, horses, sheep, and dogs. Recently, it has been repositioned as a potential alternative for cancer treatment. However, it is a highly hydrophobic molecule (0.9 ug/mL), which can compromise its dissolution rate and absorption. Thus, this work aimed to apply a nanotechnological approach to improve drug solubility and dissolution performance. Fenbendazole nanoparticles stabilized by different poloxamers were obtained by lyophilization without cryoprotectants. The behavior of the drug in the solid state was analyzed by X-ray diffractometry, differential scanning calorimetry, and infrared spectroscopy. The nanosystems were also evaluated for solubility and dissolution rate. A long-term stability evaluation was performed for three years at room temperature. The yields of the lyophilization ranged between 75 and 81% for each lot. The nanoparticles showed a submicron size (< 340 nm) and a low polydispersity depending on the stabilizer. The physicochemical properties of the prepared systems indicated a remarkable amorphization of the drug, which influenced its solubility and dissolution performance. The drug dissolution from both the fresh and aged nanosystems was significantly higher than that of the raw drug. In particular, nanoparticles prepared with poloxamer 407 showed no significant modifications in their particle size in three years of storage. Physical stability studies indicated that the obtained systems prepared with P188, P237, and P407 suffered certain recrystallization during long storage at 25 °C. These findings confirm that selected poloxamers exhibited an important effect in formulating fenbendazole nanosystems with improved dissolution.

Nanoparticle-based oral formulation can surprise you with inferior in vivo absorption in humans

Particle size reduction leads to an increase in the drug dissolution rate, which in turn can lead to a substantial increase in the bioavailability of a poorly soluble compound. To improve bioavailability, a practically insoluble investigational drug, ODM-106, was nanomilled and capsule formulations with three different drug amounts were prepared for the first-in-man study. Fast in vitro dissolution was achieved from all the capsules containing different amounts of drug nanoparticles but in the clinical study, surprisingly, low bioavailability was observed from the highest capsule strength (100 mg) in comparison to a lower strength (10 mg). In order to study further the discrepant in vitro-in vivo correlation (IVIVC), a discriminative dissolution method was developed. It was noticed that the degree of supersaturation increased significantly as the stabilizers' concentration within the dried nanoformulations was increased. Hypromellose provided a physical barrier between nanoparticles to prevent aggregation during drying. SLS on the other hand improved wettability and provided supersaturation. The drug load, nanoparticle/polymer/surfactant/filler ratios and selected drying step were discovered to be critical to the nanoformulations' performance. Aggregation of nanoparticles, in the absence of optimal stabilizer concentration, compromised dissolution due to decreased surface area. In conclusion, the early development of a discriminative dissolution method and cautious selection of the nanoparticle/polymer ratio before manufacturing clinical batches is recommended.

Alginate-amphotericin B nanocomplexes covered by nanocrystals from bacterial cellulose: physico-chemical characterization and in vitro toxicity

Nanocomplexes systems made up natural poylymers have pharmacotechnical advantages such as increase of water solubility and a decrease of drugs toxicity. Amphotericin B (AmB) is a drug apply as anti-leishmanial and anti-fungal, however it has low water solubility and high toxicity, limiting its therapeutic application. With this in mind, the present study aimed to produce nanocomplexes composed by alginate (Alg), a natural polymer, with AmB covered by nanocrystals from bacterial cellulose (CNC). For this reason, the nanocomplexes were produced utilizing sodium alginate, amphotericin B in a borate buffer (pH 11.0). The CNC was obtained by enzymatic hydrolysis of the bacterial cellulose. To CNC cover the nanocomplexes 1 ml of the nanocomplexes was added into 1 ml of 0.01% CNC suspension. The results showed an ionic adsorption of the CNC into the Alg-AmB nanocomplexes surface. This phenomena was confirmed by an increase in the particle size and PDI decrease. Besides, nanocomplexes samples covered by CNC showed uniformity. The amorphous inclusion of AmB complex into the polysaccharide chain network in both formulations. AmB in the nanocomplexes was in supper-aggregated form and showed good biocompatibility, being significantly less cytotoxic in vitro against kidney cells and significantly less hemolytic compared to the free-drug. The in vitro toxicity results indicated the Alg-AmB nanocomplexes can be considered a non-toxic alternative to improve the AmB therapeutic effect. All process to obtain nanocomplexes and it coat was conduce without organic solvents, can be considered a green process, and allowed to obtain water soluble particles. Furthermore, CNC covering the nanocomplexes brought additional protection to the system can contribut advancement in the pharmaceutical.

Freeze-drying of nanoparticles: How to overcome colloidal instability by formulation and process optimization

Lyophilization of nanoparticle (NP) suspensions is a promising technology to improve stability, especially during long-term storage, and offers new routes of administration in solid state. Although considered as a gentle drying process, freeze-drying is also known to cause several stresses leading to physical instability, e.g. aggregation, fusion, or content leakage. NPs are heterogeneous regarding their physico-chemical properties which renders them different in their sensitivity to lyophilization stress and upon storage. But still basic concepts can be deducted. We summarize basic colloidal stabilization mechanisms of NPs in the liquid and the dried state. Furthermore, we give information about stresses occurring during the freezing and the drying step of lyophilization. Subsequently, we review the most commonly investigated NP types including lipophilic, polymeric, or vesicular NPs regarding their particle properties, stabilization mechanisms in the liquid state, and important freeze-drying process, formulation and storage strategies. Finally, practical advice is provided to facilitate purposeful formulation and process development to achieve NP lyophilizates with high colloidal stability.

Efficacy and Safety of Azelaic Acid Nanocrystal-Loaded In Situ Hydrogel in the Treatment of Acne Vulgaris

Acne vulgaris is a common, multifactorial, inflammatory skin disease affecting the pilosebaceous unit. Topical therapy is the first choice in the treatment of mild to moderate acne, and azelaic acid (AZA) is one of the most commonly used drugs. The aim of this study was to evaluate the safety and efficacy of a low-dose azelaic acid nanocrystal (AZA-NC) hydrogel in the treatment of mild to moderate facial acne. The study was designed as a double-blind, randomized controlled trial. Patients were randomized to treatment with AZA-NC hydrogel, 10%, or AZA cream, 20%, administered in quantities of approximately 1 g twice daily for 8 weeks. Efficacy of therapy was measured by the number of lesions and safety by the frequency and severity of adverse events. At week 8, the success rate of treatment with AZA-NC hydrogel, 10%, was 36.51% (p < 0.001) versus 30.37% (p < 0.001) with AZA cream. At week 8, treatment with AZA-NC hydrogel, 10%, resulted in a significant reduction in total inflammatory lesions from baseline of 39.15% (p < 0.001) versus 33.76% (p < 0.001) with AZA cream, and a reduction in non-inflammatory lesions from baseline of 34.58% (p < 0.001) versus 27.96% (p < 0.001) with AZA cream, respectively. The adverse event rate was low and mostly mild.

Ultracentrifugation Techniques for the Ordering of Nanoparticles

A centrifugal field can provide an external force for the ordering of nanoparticles. Especially with the knowledge from in-situ characterization by analytical (ultra)centrifugation, nanoparticle ordering can be rationally realized in preparative (ultra)centrifugation. This review summarizes the work back to the 1990s, where intuitive use of centrifugation was achieved for the fabrication of colloidal crystals to the very recent work where analytical (ultra)centrifugation is employed to tailor-make concentration gradients for advanced materials. This review is divided into three main parts. In the introduction part, the history of ordering microbeads in gravity is discussed and with the size of particles reduced to nanometers, a centrifugal field is necessary. In the next part, the research on the ordering of nanoparticles in analytical and preparative centrifugation in recent decades is described. In the last part, the applications of the functional materials, fabricated from centrifugation-induced nanoparticle superstructures are briefly discussed.

Freeze-Dried Clopidogrel Loaded Lyotropic Liquid Crystal: Box-Behnken Optimization, In-Vitro and In-Vivo Evaluation

BACKGROUND

Clopidogrel (CLP) suffers from extensive first pass metabolism results in a negative impact on its oral systemic bioavailability. Cubosomes are Lyotropic Liquid Crystalline (LLC) nano-systems comprising monoolein, a steric stabilizer and an aqueous system, it considered a promising carrier for different pharmaceutical compounds. Box-Behnken Design (BBD) is an efficient tool for process analysis and optimization skipping forceful treatment combinations.

OBJECTIVE

The study was designed to develop freeze-dried clopidogrel loaded LLC (cubosomes) for enhancement of its oral bioavailability.

METHODS

A 3³ BBD was adopted, the studied independent factors were glyceryl monooleate (GMO lipid phase), Pluronic F127 (PL F127steric stabilizer) and polyvinyl alcohol powder (stabilizer). Particle Size (PS), Polydispersity Index (PDI) and Zeta Potential (ZP) were set as independent response variables. Seventeen formulae were prepared in accordance with the bottom up approach and in-vitro evaluated regarding PS, PDI and ZP. Statistical analysis and optimization were achieved using design expert software®, then the optimum suggested formula was prepared, in-vitro revaluated, freeze-dried with 3% mannitol (cryoprotectant), solid state characterized and finally packed in hard gelatin capsule for comparative in-vitro release and in-vivo evaluation to Plavix®.

RESULTS

Results of statistical analysis of each individual response revealed a quadratic model for PS and PDI where a linear model for ZP. The optimum suggested formula with desirability factor equal 0.990 consisting of (200 mg GMO, 78.15 mg PL F127 and 2% PVA). LC/MS/MS study confirmed significant higher C_max, AUC_0-24h and AUC_0-∞ than that of Plavix®.

CONCLUSION

The results confirm the capability of developed carrier to overcome the low oral bioavailability.

Freeze-Drying of Pharmaceutical and Nutraceutical Nanoparticles: The Effects of Formulation and Technique Parameters on Nanoparticles Characteristics

Nanoparticles (NPs) are of the most interesting novel vehicles for effective drug delivery to humans. Freeze drying is known as an engaging process to improve the long lasting stability of NPs formulations. This study aims to elucidate the importance of various parameters involving in freeze-drying of the most common pharmaceutical/nutraceutical NPs including nanosuspensions, nanocrystals (NCs), cocrystals/nanococrystals, nanoemulsions (NEs), nanocapsules (NCPs) and nanospheres (NSPs). Regarding this, the therapeutic goals of NPs and specifications of drug must be considered. According to our survey, the most influential factors for achieving optimum results include type and concentration of cryoprotectant/lyoprotectant, stabilizer structure and concentration, the NPs concentration in solution, freezing, annealing, and drying rate, the interaction between protectants and stabilizer, solvent type and antisolvent to solvent ratio. The study shows that for each class of NPs, specific variables are of highest significance and should be optimized. For instance, about NCs, freezing rate and antisolvent/solvent ratio should be particularly considered and for emulsified NPs, the best results have been obtained by 5-20% of saccharides as cryoprotectants. These findings suggest that to obtain a product with the lowest aggregation and particle size (PS), optimization of the effective factors in formulation and lyophilization process are essential.

Formulation of Ketoconazole Nanocrystal-Based Cryopellets

Commercial development of nanosuspensions for oral drug delivery generally involves a drying step which aims to generate a stable product that rapidly releases the nanocrystals once rehydrated and can be easily processed into a final dosage form (e.g., filled into hard capsule). Cryopelletisation is a freeze drying technique allowing the production of lyophilised micrometric spheres with good flowability. In the current work, the possibility to formulate redispersible ketoconazole nanocrystal-based cryopellets able to withstand intensive handling was investigated. Cryopellets were generated by first freezing regular droplets of nanosuspension using liquid nitrogen followed by water removal by sublimation in a standard freeze dryer. Low-friable cryopellets (< 1%) were produced by embedding the nanocrystals in a stabilizing hydroxypropyl cellulose SSL grade matrix, thus proving that these structures can withstand intensive handling. A threshold quantity of hydroxypropyl cellulose SSL grade (5/20 hydroxypropyl cellulose SSL grade-to-drug mass ratio) was required in combination with D-α-tocopherol polyethylene glycol 1000 succinate (vitamin E TPGS) to successfully recover the nanocrystals over storage. A further addition of micronised crospovidone has shown a positive effect on the dissolution performance of cryopellets. Altogether, this study demonstrated that the design of cryopellets combining the strengths of freeze-dried powders (porous internal structure, low residual humidity) and pellets (free-flowing units, mechanical resistance during handling) can potentially improve the nanocrystal's redispersibility compared with other drying techniques while facilitating the downstream processing.

Transformation of Meloxicam Containing Nanosuspension into Surfactant-Free Solid Compositions to Increase the Product Stability and Drug Bioavailability for Rapid Analgesia

Purpose

The aim of this work was to study the influence of solidification of meloxicam (Mel) containing nanosuspension (nanoMel) on the physical stability and drug bioavailability of the products. The nanoMel sample had poly(vinyl alcohol) (PVA) as a protective polymer, but no surfactant as a further stabilizing agent because the final aim was to produce surfactant-free solid phase products as well.

Methods

The solidified samples produced by fluidization and lyophilization (fluidMel, lyoMel) were examined for particle size, crystallinity, and in vitro release of Mel compared to similar parameters of nanoMel. The products were subjected to an animal experiment using per oral administration to verify their bioavailability.

Results

Mel containing (1%) nanoMel sample was produced by wet milling process using an optimized amount of PVA (0.5%) which resulted in 130 nm as mean particle size and a significant reduction in the degree of crystallinity (13.43%) of Mel. The fluidization technique using microcrystalline cellulose (MCC) as carrier resulted in a quick conversion and no significant change in the critical product parameters. The process of lyophilization required a longer operation time, which resulted in the amorphization of the crystalline carrier (trehalose) and the recrystallization of Mel increased its particle size and crystallinity. The fluidMel and lyoMel samples had nearly five-fold higher relative bioavailability than nanoMel application by oral administration. The correlation between in vitro and in vivo studies showed that the fixed Mel nanoparticles on the surface of solid carriers (MCC, trehalose) in both the artificial gastric juice and the stomach of the animals rapidly reached saturation concentration leading to faster dissolution and rapid absorption.

Conclusion

The solidification of the nanosuspension not only increased the stability of the Mel nanoparticles but also allowed the preparation of surfactant-free compositions with excellent bioavailability which may be an important consideration for certain groups of patients to achieve rapid analgesia.

A two-dimensional assembly of ultrafine cobalt oxide nanocrystallites anchored on single-layer Ti3C2Tx nanosheets with enhanced lithium storage for Li-ion batteries

Recently, Ti-based MXenes were expected to compete with graphene and other carbonaceous materials towards Li-ion batteries (LIBs) due to their two-dimensional (2D) open structure, cost efficiency, superior conductivity and low Li⁺ diffusion barrier. However, the relatively moderate capacity and aggregation tendency hamper their practical applications in next-generation LIBs. Herein, we explore for the first time a scalable bottom-up approach to fabricate a series of Co₃O₄@single-layer Ti₃C₂T_x (s-Ti₃C₂T_x) hybrids, where numerous homogeneous Co₃O₄ nanocrystallites (NCs), serving both as a spacer and electroactive phase, are anchored uniformly on the surface of s-Ti₃C₂T_x nanosheets (NSs) through the Co-O-Ti interfacial bonds. Furthermore, detailed experimental analyses clearly shed light upon the formation mechanism of the hybrid Co₃O₄@s-Ti₃C₂T_x NSs. Thanks to the structural and compositional merits, the 2D Co₃O₄@s-Ti₃C₂T_x NSs even exhibit a remarkable high-rate capacity of ∼223 mA h g^-1 at an ultra-high current density of 10 A g^-1, and a long-span cycle life with a high reversible capacity of 550 mA h g^-1 at 1 A g^-1 after 700 consecutive cycles. Corresponding density functional theory calculation further confirms that the Co-O-Ti interfacial function leads to an even higher pseudocapacitive contribution and faster lithium storage behavior due to the enhanced interfacial electron transfer.

The relationship between microstructure and photocatalytic behavior in lanthanum-modified 2D TiO2 nanosheets upon annealing of a freeze-cast precursor

Titanium dioxide modified with 3 wt% La was prepared via a green freeze-casting method, and its photocatalytic activity was tested in terms of its ability to degrade 4-chlorophenol (4-CP) and remove total organic carbon (TOC). Under annealing conditions, the freeze-cast precursor was transformed into an La-modified anatase with a well-defined 2D TiO₂ nanosheet morphology. Rietveld refinement of the X-ray diffraction patterns confirmed the substitutional nature of the La cation that induced local structural variations and involved subtle ion displacement in the TiO₂ lattice due to the ionic size effect. Despite nearly identical tetragonal structures, replacement of Ti with La alters the photocatalytic activity through a reduction in band gap energies and an increase in charge carrier mobility. Material annealed at 650 °C exhibited the highest photocatalytic performance and achieved efficient TOC removal. Upon annealing at 800 °C, nanoscale lanthanum-enriched regions were generated due to the diffusive migration of La cations and phase transition from anatase to rutile. The La³⁺ cation, acting as a structural promoter, supported 2D TiO₂ growth with well controlled crystallite size, surface area and porosity. La³⁺ could be regarded as a potential electronic promoter that can reduce the band gap of 2D TiO₂ nanosheets and can provide a signature of the electron transfer and carrier charge separation. Both methods, kinetics of degradation of 4-CP and TOC, provided similar results, revealing that the photocatalytic activity under UV light irradiation increased in the order 950C < 500 °C < 800 °C < 650 °C < TiO₂-P25.

In Situ Incorporation of Pores and Nanoparticles into Polymer Surfaces Using Melt Crystallization

Engineering the surface properties of a material without affecting its bulk properties is desirable for many applications, but it is often not readily achievable because it requires a complex series of processing steps. This study presents for the first time a simple and straightforward method that can convert regular flat polymer surfaces into various porous composite surfaces. The controlled dissolution of the polymer surface by a dispersion and subsequent melt crystallization allows for the successful embedding of dispersed inorganic or organic particles in the pore walls. The porous surface morphology is not significantly affected by the type of dispersed particle, but the contact and sliding angles and surface wettability are. Both superhydrophobic and oil/water separation surfaces can be conveniently fabricated from flat polymer surfaces. This novel and versatile technique could provide engineering freedom for the future development of various functional materials.

Binder-free dry particulate coating process using a mild vibration field: Effects of glass-transition temperature and powdering method of polymeric coating agents on coating performance

We employed a new dry coating process with mild-intensity vibration to prepare a 100-µm-sized microparticle capable of prolonged release of a drug. To accomplish this without using a binder, a series of laboratory-made acrylic latexes with different glass transition temperatures (Tg) ranging from 30 °C to 80 °C were employed as coating agents, and the effects of Tg and powdering method of the coating agents on coating performance were investigated. The laboratory-made acrylic latexes were powdered by spray-drying (SD) or freeze-drying (FD). Diclofenac sodium (DS)-loaded ion-exchange-resin with particle size ∼100 µm was used as a core particle. The process utilized vibrations with amplitude of 0.5 mm and frequency of 90 Hz to form an ordered mixture composed of the core particles with the loosely-layered coating agents. Subsequently, the coating agents were fixed mechanically on the core particle by impaction of zirconia beads. The coating agents powdered by FD showed higher coating efficiencies than those powdered by SD, irrespective of the differences in Tg values. Among the coating agents powdered by FD, the particles coated at Tg = 60 °C exhibited the most prolonged drug-release, although the coating efficiency was not the highest. In our proposed process utilizing mild vibration, we demonstrated that adjusting the Tg of the coating agents is crucial to the formation of binder-free multiple coating layers for prolonged drug release.

Nanocrystals: A perspective on translational research and clinical studies

Poorly soluble small molecules typically pose translational hurdles owing to their low solubility, low bioavailability, and formulation challenges. Nanocrystallization is a versatile method for salvaging poorly soluble drugs with the added benefit of a carrier-free delivery system. In this review, we provide a comprehensive analysis of nanocrystals with emphasis on their clinical translation. Additionally, the review sheds light on clinically approved nanocrystal drug products as well as those in development.

Chitin nano-whiskers (CNWs) as a bio-based bio-degradable reinforcement for epoxy: evaluation of the impact of CNWs on the morphological, fracture, mechanical, dynamic mechanical, and thermal characteristics of DGEBA epoxy resin

Chitin nano-whiskers (CNWs) reinforcement for producing optically transparent epoxy nanocomposites with enhanced fracture, mechanical and thermal characteristics.

Electrospun amorphous solid dispersions of poorly water-soluble drugs: A review

The development of oral dosage forms for poorly water-soluble active pharmaceutical ingredients (APIs) is a persistent challenge. A range of methods has been explored to address this issue, and amorphous solid dispersions (ASDs) have received increasing attention. ASDs are typically prepared by starting with a liquid precursor (a solution or melt) and applying energy for solidification. Many techniques can be used, with the emergence of electrospinning as a potent option in recent years. This method uses electrical energy to induce changes from liquid to solid. Through the direct applications of electrical energy, electrospinning can generate nanofiber-based ASDs from drug-loaded solutions, melts and melt-solutions. The technique can also be combined with other approaches using the application of mechanical, thermal or other energy sources. Electrospinning has numerous advantages over other approaches to produce ASDs. These advantages include extremely rapid drying speeds, ease of implentation, compatibility with a wide range of active ingredients (including those which are thermally labile), and the generation of products with large surface areas and high porosity. Furthermore, this technique exhibits the potential to create so-called 'fifth-generation' ASDs with nanostructured architectures, such as core/shell or Janus systems and their combinations. These advanced systems can improve dissolution behaviour and provide programmable drug release profiles. Additionally, the fiber components and their spatial distributions can be precisely controlled. Electrospun fiber-based ASDs can maintain an incorporated active ingredient in the amorphous physical form for prolonged periods of time because of their homogeneous drug distribution within the polymer matrix (typically they comprise solid solutions), and ability to inhibit molecular motion. These ASDs can be utilised to generate oral dosage forms for poorly water-soluble drugs, resulting in linear or multiple-phase release of one or more APIs. Electrospun ASDs can also be exploited as templates for manipulating molecular self-assembly, offering a bridge between ASDs and other types of dosage forms. This review addresses the development, advantages and pharmaceutical applications of electrospinning for producing polymeric ASDs. Material preparation and analysis procedures are considered. The mechanisms through which performance has been improved are also discussed.

Quality-by-Design approach to the fluid-bed coating of ginkgo lactone nanosuspensions

The Quality-by-Design (QbD) approach was employed to investigate the fluid-bed coating process for the conversion of ginkgo lactone (GL) liquid nanosuspensions into dried nanosuspensions. The effects of critical process variables including inlet air temperature, inlet air capacity and atomizing air pressure were investigated. The particle size and percent yield were optimized using a full factorial design. A Box-Behnken design (BBD) was employed to generate the response surface and optimize process conditions. Multi-linear regression and one-way ANOVA were used to analyze the relationship between critical variables and responses. The results showed that all three selected variables were significant factors (p < 0.05) affecting the particle size. Higher inlet temperature, inlet air capacity or atomizing air pressure will cause an increase of particle size. In addition, the percent yield primarily depended on the inlet air temperature and inlet air capacity (p < 0.05). A higher percent yield was obtained at a higher inlet air temperature or inlet air capacity. The optimal conditions for BBD, including inlet air temperature, inlet air capacity and atomizing air pressure, were set at 40 °C, 11.6 Nm³ and 0.7 bar, respectively. Compared with the raw GLs, the optimized products presented an amorphous state and possessed much faster dissolution. The particle size, percent yield, PDI, zeta-potential and redispersibility index of the optimized products were 254.3 ± 9.8 nm, 82.36 ± 1.87%, 0.155 ± 0.02, −32.9 ± 3.8 mV and 113 ± 4.4% (n = 3), respectively. These results indicate that fluid-bed coating technology based on a QbD approach was sufficient for the solidification of nanosuspensions.

The Quality-by-Design (QbD) approach was employed to investigate the fluid-bed coating process for the conversion of ginkgo lactone (GL) liquid nanosuspensions into dried nanosuspensions.

Preparation Nanocrystals of Poorly Soluble Plant Compounds Using an Ultra-Small-Scale Approach

The usage of downscaling technology for producing nanosuspensions/nanocrystals can be beneficial for formulation development, which has attracted increased attention recently. An ultra-small bead milling method (5 mg compound per batch, smallest scale to date) was tested to produce nanocrystals of four poorly soluble plant compounds, i.e., quercetin, rutin, resveratrol, and hesperidin. A particle size of ranged from 200 to 500 nm was obtained for nanosuspensions of four compounds and the stabilizer selection could be achieved within 2 h by using this ultra-small bead milling method. Six months stability was observed for selected samples. In addition, the scalability of the ultra-small lab-scale milling was confirmed when it was conducted under optimal conditions. A simple and fast ultra-small-scale approach for nanosuspension production was established. Freeze-drying was applied to convert nanosuspensions into solid forms. Finally, freeze-dried intermediates with good redispersity and physical stability were obtained, which could be used for further application.

High drug-loading nanomedicines: progress, current status, and prospects

Drug molecules transformed into nanoparticles or endowed with nanostructures with or without the aid of carrier materials are referred to as "nanomedicines" and can overcome some inherent drawbacks of free drugs, such as poor water solubility, high drug dosage, and short drug half-life in vivo. However, most of the existing nanomedicines possess the drawback of low drug-loading (generally less than 10%) associated with more carrier materials. For intravenous administration, the extensive use of carrier materials might cause systemic toxicity and impose an extra burden of degradation, metabolism, and excretion of the materials for patients. Therefore, on the premise of guaranteeing therapeutic effect and function, reducing or avoiding the use of carrier materials is a promising alternative approach to solve these problems. Recently, high drug-loading nanomedicines, which have a drug-loading content higher than 10%, are attracting increasing interest. According to the fabrication strategies of nanomedicines, high drug-loading nanomedicines are divided into four main classes: nanomedicines with inert porous material as carrier, nanomedicines with drug as part of carrier, carrier-free nanomedicines, and nanomedicines following niche and complex strategies. To date, most of the existing high drug-loading nanomedicines belong to the first class, and few research studies have focused on other classes. In this review, we investigate the research status of high drug-loading nanomedicines and discuss the features of their fabrication strategies and optimum proposal in detail. We also point out deficiencies and developing direction of high drug-loading nanomedicines. We envision that high drug-loading nanomedicines will occupy an important position in the field of drug-delivery systems, and hope that novel perspectives will be proposed for the development of high drug-loading nanomedicines.

Controlling Agglomeration of Protein Aggregates for Structure Formation in Liquid Oil: A Sticky Business

Proteins are known to be effective building blocks when it comes to structure formation in aqueous environments. Recently, we have shown that submicron colloidal protein particles can also be used to provide structure to liquid oil and form so-called oleogels ( de Vries , A. J. Colloid Interface Sci. 2017 , 486 , 75 - 83 ) . To prevent particle agglomeration, a solvent exchange procedure was used to transfer the aggregates from water to the oil phase. The aim of the current paper was to elucidate on the enhanced stability against agglomeration of heat-set whey protein isolate (WPI) aggregates to develop an alternative for the solvent exchange procedure. Protein aggregates were transferred from water to several solvents differing in polarity to investigate the effect on agglomeration and changes in protein composition. We show that after drying protein aggregates by evaporation from solvents with a low polarity (e.g., hexane), the protein powder shows good dispersibility in liquid oil compared to powders dried from solvents with a high polarity. This difference in dispersibility could not be related to changes in protein composition or conformation but was instead related to the reduction of attractive capillary forces between the protein aggregates during drying. Following another route, agglomeration was also prevented by applying high freezing rates prior to freeze-drying. The rheological properties of the oleogels prepared with such freeze-dried protein aggregates were shown to be similar to that of oleogels prepared using a solvent exchange procedure. This Research Article provides valuable insights in how to tune the drying process to control protein agglomeration to allow for subsequent structure formation of proteins in liquid oil.

The Roles of Vitrification of Stabilizers/Matrix Formers for the Redispersibility of Drug Nanocrystals After Solidification: a Case Study

To elucidate the roles of vitrification of stabilizers/matrix formers for the redispersibility of drug nanocrystal powder after solidification at storage stress, the influence of different drying methods and storage stresses on stability of drug nanocrystals was systemically investigated. A poorly soluble drug, baicalin, used as model drug was converted into baicalin nanocrystals (BCN-NC). The residual moisture contents of BCN-NC were applied at two different stress conditions defined as "conservative" (<1%) and "aggressive" (>1%), respectively. The influence of different stabilizers, matrix formers, and storage stresses on the redispersibility of BCN-NC powder was systemically investigated, respectively. The results showed that storage stresses had significantly influence the redispersibility of BCN-NC. Aggressive storage temperature and residual moisture could be unfavorable factors for stability of drug nanocrystals, due to the exacerbation of aggregation of BCN-NC induced by vitrification. It was demonstrated that vitrification of spray-dried BCN-NC was dependent on temperature and time. The polymeric stabilizers hydroxypropylmethylcellulose (HPMC) and sodium carboxymethyl starch (CMS-Na) with high glass transition temperature (T _g) played more important role in protecting the BCN-NC from breakage during storage, compared to the surfactants Tween 80, D-α-tocopherol acid polyethylene glycol 1000 succinate (TPGS), or RH 40. Besides, the polyvinylpyrrolidone K30 (PVP K30) and lactose with high T _g were effective matrix formers for preserving the redispersibility of BCN-NC. It was concluded that the vitrification transition of stabilizers/matrix formers could be responsible for aggregation of drug nanocrystals during storage, which was a time-dependent process. The suitable residual moisture contents (RMC) and T _g were very important for preserving the stability of drug nanocrystals during storage.

Nanoformulation and encapsulation approaches for poorly water-soluble drug nanoparticles

During the last few decades the nanomedicine sector has emerged as a feasible and effective solution to the problems faced by the high percentage of poorly water-soluble drugs. Decreasing the size of such drug compounds to the nanoscale can significantly change their physical properties, which lays the foundation for the use of nanomedicine for pharmaceutical applications. Various techniques have been developed to produce poorly water-soluble drug nanoparticles, mainly to address the poor water-soluble issues but also for the efficient and targeted delivery of such drugs. These techniques can be generally categorized into top-down, bottom-up and encapsulation approaches. Among them, the top-down approaches have been the main choice for industrial preparation of drug nanoparticles while other methods are actively investigated by researchers. In this review, we aim to give a comprehensive overview and latest progress of the top-down, bottom-up, and encapsulation methods for the preparation of poorly water-soluble drug nanoparticles and how solvents and additives can be selected for these methods. In addition to the more industrially applied top-down approaches, the review is focused more on bottom-up and encapsulation methods, particularly covering supercritical fluid-related methods, cryogenic techniques, and encapsulation with dendrimers and responsive block copolymers. Some of the approved and mostly used nanodrug formulations on the market are also covered to demonstrate the applications of poorly water-soluble drug nanoparticles. This review is complete with perspectives on the development and challenges of fabrication techniques for more effective nanomedicine.

Solidification drug nanosuspensions into nanocrystals by freeze-drying: a case study with ursodeoxycholic acid

To elucidate the effect of solidification processes on the redispersibility of drug nanocrystals (NC) during freeze-drying, ursodeoxycholic acid (UDCA) nanosuspensions were transformed into UDCA-NC via different solidification process included freezing and lyophilization. The effect of different concentrations of stabilizers and cryoprotectants on redispersibility of UDCA-NC was investigated, respectively. The results showed that the redispersibility of UDCA-NC was RDI-20 °C < RDI-80 °C < RDI-196 °C during freezing, which indicated the redispersibility of UDCA-NC at the conventional temperature was better more than those at moderate and rigorous condition. Compared to the drying strengthen, the employed amount and type of stabilizers more dramatically affected the redispersibility of UDCA-NC during lyophilization. The hydroxypropylmethylcellulose and PVPK30 were effective to protect UDCA-NC from damage during lyophilization, which could homogeneously adsorb into the surface of NC to prevent from agglomerates. The sucrose and glucose achieved excellent performance that protected UDCA-NC from crystal growth during lyophilization, respectively. It was concluded that UDCA-NC was subjected to agglomeration during solidification transformation, and the degree of agglomeration suffered varied with the type and the amounts of stabilizers used, as well as different solidification conditions. The PVPK30-sucrose system was more effective to protect UDCA-NC from the damage during solidification process.

A brief literature and patent review of nanosuspensions to a final drug product

Particle size reduction can be used for enhancing the dissolution of poorly water-soluble drugs in order to enhance bioavailability. In nanosuspensions, the particle size of the drug is reduced to nanometer size. Nanosuspensions after downstream processing into drug products have successfully shown its impact on formulation design, the augmentation of product life cycle, patent life, and therapeutic efficacy. Formulation considerations for the nanosuspension formulation, its processing into a solid form, and aspects of material characterization are discussed. Technology assessments and feasibility of upstream processes for nanoparticle creation, and subsequently transformation into a drug product via the downstream processes have been reviewed. This paper aims to bridge formulation and process considerations along with patent reviews and may provide further insight into understanding the science and the white space. An analysis of current patent outlook and future trends is described to fully understand the limitations and opportunities in intellectual property generation.

Stability of nanosuspensions in drug delivery

Nanosuspensions are nanosized colloidal dispersion systems that are stabilized by surfactants and/or polymers. Because nanosizing results in the creation of new interfaces and in a positive Gibbs free energy change, nanosuspensions are thermodynamically unstable systems with a tendency toward agglomeration or crystal growth. Despite extensive research on nanosuspension technology, stability remains a limitation for pharmaceutical or industrial applications of nanosuspensions. Furthermore, the empirical relationship between stabilizer efficacy and nanosuspension stability has not been well characterized. This review focuses on the issue of nanosuspension stability in drug delivery to present the state of the art of nanosuspensions. Therefore, this review will discuss unstable suspensions, methods and guidelines for selecting and optimizing stabilizers, approaches for enhancing stability, and other factors that influence nanosuspension stability. This review could serve as a reference for the educated selection of a stabilizer for a specific drug candidate and the optimization of the operational parameters for nanosuspension formulation, rather than the currently practiced trial-and-error approach.

Application of the combinative particle size reduction technology H 42 to produce fast dissolving glibenclamide tablets

Standard particle size reduction techniques such as high pressure homogenization or wet bead milling are frequently used in the production of nanosuspensions. The need for micronized starting material and long process times are their evident disadvantages. Combinative particle size reduction technologies have been developed to overcome the drawbacks of the standard techniques. The H 42 combinative technology consists of a drug pre-treatment by means of spray-drying followed by standard high pressure homogenization. In the present paper, spray-drying process parameters influencing the diminution effectiveness, such as drug and surfactant concentration, were systematically analyzed. Subsequently, the untreated and pre-treated drug powders were homogenized for 20 cycles at 1500 bar. For untreated, micronized glibenclamide, the particle size analysis revealed a mean particle size of 772 nm and volume-based size distribution values of 2.686 μm (d50%) and 14.423 μm (d90%). The use of pre-treated material (10:1 glibenclamide/docusate sodium salt ratio spray-dried as ethanolic solution) resulted in a mean particle size of 236 nm and volume-based size distribution values of 0.131 μm (d50%) and 0.285 μm (d90%). These results were markedly improved compared to the standard process. The nanosuspensions were further transferred into tablet formulations. Wet granulation, freeze-drying and spray-drying were investigated as downstream methods to produce dry intermediates. Regarding the dissolution rate, the rank order of the downstream processes was as follows: Spray-drying>freeze-drying>wet granulation. The best drug release (90% within 10 min) was obtained for tablets produced with spray-dried nanosuspension containing 2% mannitol as matrix former. In comparison, the tablets processed with micronized glibenclamide showed a drug release of only 26% after 10 min. The H 42 combinative technology could be successfully applied in the production of small drug nanocrystals. A nanosuspension transfer to tablets that maintained the fast dissolution properties of the drug nanocrystals was successfully achieved.

D-Alpha-tocopherol acid polyethylene glycol 1000 succinate, an effective stabilizer during solidification transformation of baicalin nanosuspensions

Baicalin nanosuspensions, stabilized with 10% TPGS (relative to the weight of baicalin), were transformed into nanosuspensions powders by solidification process. Solidification methods for this transformation included freeze-drying, spray drying or vacuum drying. High pressure homogenization was applied for production of baicalin nanosuspensions used TPGS, SDS, P188, HPMC and MC as stabilizer, respectively. The influence of the different solidification transformation methods on the redispersibility of solid drug nanosuspensions was systemically investigated, such as freeze-drying, spray drying and vacuum drying. Each method was applied with three grades of process stresses called as "conservative", "moderate" and "aggressive" conditions, and the redispersibility index (RDI) of nanosuspensions stabilized by stabilizers (such as TPGS, SDS, P188, HPMC and MC) during those process was investigated. The results showed that there was significant difference in RDI of nanosuspensions after solidification process. The RDI(a) (1.09, 1.01, 1.05, 0.99), RDI(b) (1.03, 0.99, 1.06, 1.02) and RDI(c) (1.01, 1.01, 1.09, 1.08) of nanosuspensions stabilized by TPGS were more small during different solidification process, compared with those of nanosuspensions stabilized by other stabilizer. It was concluded that the baicalin nanosuspensions were subjected to agglomeration or crystal growth during solidification transformation, especially at high aggressive stress conditions. Meanwhile, compared to other stabilizer, the TPGS was more effective for stability of baicalin nanosuspensions, which could exhibit higher affinity to the drug crystal and stronger surface adsorption at different solidification stresses.