Cryoprotectants for freeze drying of drug nano-suspensions: Effect of freezing rate

Freeze-drying of bupivacaine lipospheres: preparation, characterization, and evaluation of anti-microbial properties

PURPOSE

To prepare freeze-dried bupivacaine lipospheres intended for topical application in burn injuries. The aim was improving the storage stability and developing a prolonged release pattern to tackle the adverse reactions resulting from the frequent administration of bupivacaine.

METHODS

The lipospheres were prepared by hot-melt dispersion method employing bupivacaine base at 1.5 and 3%w/w, tristearin 6% w/w as the core while dipalmitoyl phosphatidylcholine (DPPC) and soy phosphatidylcholine (SPC) as the coat at 0.75, 1.5 and 3% w/w. The lotion was then freeze-dried and cryoprotected by sucrose 3% w/w. Evaluation was carried out through loading and release analysis, storage study, particle characterization including morphology, zeta potential and particle size as well as anti-microbial assessment.

RESULTS

The highest loading, (87.6 ± 0.1%), was achieved using bupivacaine 3% and SPC 0.75%. After 6 months of storage at 4 ͦC, the loading in the lotion and the freeze-dried samples were 17.4 ± 0.2 and 87.2 ± 0.3%, respectively. In vitro dissolution test demonstrated 94.5% and 95% of bupivacaine release from lotion and freeze-dried samples, after 24 h. The respective zeta potential of -1.30 and 26 mV was recorded for lotion and solid-state bupivacaine. Micromeritic evaluation of freeze-dried powder exhibited particle size of 35.23 ± 2.02 μm and highly-wrinkled-irregular morphology without detectable needle structures related to drug free crystals. The powder had rapid reconstitution property and antibacterial activity.

CONCLUSION

Freeze- drying holds a promising potential to improve the storage stability of bupivacaine lipospheres with well- preserved release pattern and particle properties for further topical application.

Kinetically Controlled Polyelectrolyte Complex Assembly of microRNA-Peptide Nanoparticles toward Treating Mesothelioma

Broad size distributions and poor long-term colloidal stability of microRNA-carrying nanoparticles, especially those formed by polyelectrolyte complexation, represent major hurdles in realizing their clinical translation. Herein, peptide design is used alongside optimized flash nanocomplexation (FNC) to produce uniform peptide-based miRNA particles of exceptional stability that display anticancer activity against mesothelioma in vitro and in vivo. Modulating the content and display of lysine-based charge from small intrinsically disordered peptides used to complex miRNA proves essential in achieving stable colloids. FNC facilitates kinetic isolation of the mechanistic steps involved in particle formation to allow the preparation of particles of discrete size in a highly reproducible, scalable, and continuous manner, facilitating pre-clinical studies. To the best of the authors knowledge, this work represents the first example of employing FNC to prepare polyelectrolyte complexes of miRNA and peptide. Encapsulation of these particles into an injectable hydrogel matrix allows for their localized in vivo delivery by syringe. A one-time injection of a gel containing particles composed of miRNA-215-5p and the peptide PKM1 limits tumor progression in a xenograft model of mesothelioma.

Impact of Additives on Drug Particles during Liquid Antisolvent Crystallization and Subsequent Freeze-Drying

The impact of single or combinations of additives on the generation of nanosuspensions of two poorly water-soluble active pharmaceutical ingredients (APIs), fenofibrate (FF) and dalcetrapib (DCP), and their isolation to the dry state via antisolvent (AS) crystallization followed by freeze-drying was explored in this work. Combinations of polymeric and surfactant additives such as poly(vinyl alcohol) or hydroxypropyl methyl cellulose and sodium docusate were required to stabilize nanoparticles (∼200-300 nm) of both APIs in suspension before isolation to dryness. For both FF and DCP, multiple additives generated the narrowest, most-stable particle size distribution, with the smallest particles in suspension, compared with using a single additive. An industrially recognized freeze-drying process was used for the isolation of these nanoparticles to dryness. When processed by the liquid AS crystallization followed by freeze-drying in the presence of multiple additives, a purer monomorphic powder for FF resulted than when processed in the absence of any additive or in the presence of a single additive. It was noted that all nanoparticles freeze-dried in the presence of additives had a flat, flaky habit resulting in large surface areas. Agglomeration occurred during freeze-drying, resulting in micron-size particles. However, after freeze-drying, powders produced with single or multiple additives showed similar dissolution profiles, irrespective of aging time before drying, thus attenuating the advantage of multiple additives in terms of size observed before the freeze-drying process.

Excipient-free lyophilization of block copolymer micelles for potential lung surfactant therapy applications

Polymer lung surfactant (PLS) is a polyethylene glycol (PEG)-brushed block copolymer micelle designed for pulmonary surfactant replacement therapy. Saccharides (e.g., sucrose and (2-hydroxypropyl)-β-cyclodextrin) and water-soluble polymers (e.g., PEG), common excipients for lyophilization, were found to severely impair the surface activity of lyophilized PLS. To investigate the feasibility of excipient-free lyophilization of PLS, we studied the effects of both PLS material parameters and lyophilization operating parameters on the redispersibility and surface availability of reconstituted PLS, all without relying on excipients. We found that the redispersibility was improved by three factors; a faster cooling rate during the freezing stage reduced freezing stress; a higher PEG grafting density enhanced dissipating effects; and the absence of hydrophobic endgroups in the PEG block further prevented micelle aggregation. Consequently, the surface availability of PLS increased, enabling the micelle monolayer at the air/water interface to achieve a surface tension below 10 mN/m, which is a key pharmaceutical function of PLS. Moreover, the lyophilized micelles in powder form could be easily dispersed on water surfaces without the need for reconstitution, which opens up the possibility of inhalation delivery, a more patient-friendly administration method compared to instillation. The successful excipient-free lyophilization unlocks the potential of PLS for addressing acute respiratory distress syndrome (ARDS) and other pulmonary dysfunctions.

Mesenchymal Stem Cell-Derived Exosomal Noncoding RNAs as Alternative Treatments for Myocardial Ischemia-Reperfusion Injury: Current Status and Future Perspectives

Ischemic cardiomyopathy is treated mainly with thrombolytic drugs, percutaneous coronary intervention, and coronary artery bypass grafting to recanalize blocked vessels. Myocardial ischemia-reperfusion injury (MIRI) is an unavoidable complication of obstructive revascularization. Compared with those of myocardial ischemic injury, few effective therapeutic options are available for MIRI treatment. The pathophysiological mechanisms of MIRI involve the inflammatory response, the immune response, oxidative stress, apoptosis, intracellular Ca2+ overload, and cardiomyocyte energy metabolism. These mechanisms exacerbate MIRI. Mesenchymal stem cell-derived exosomes (MSC-EXOs) can alleviate MIRI through these mechanisms and, to some extent, prevent the limitations caused by direct MSC administration. Therefore, using MSC-EXOs instead of MSCs to treat MIRI is a potentially beneficial cell-free treatment strategy. In this review, we describe the mechanism of action of MSC-EXO-derived noncoding RNAs in the treatment of MIRI and discuss the advantages and limitations of this strategy, as well as possible future research directions.

Biophysical characterization of siRNA-loaded lipid nanoparticles with different PEG content in an aqueous system

Although lipid nanoparticles (LNP) are potential carriers of various pharmaceutical ingredients, further investigation for maintaining their stability under various environmental stressors must be performed. This study evaluated the influence of PEGylation and stress conditions on the stability of siRNA-loaded LNPs with different concentrations of PEG (0.5 mol%; 0.5 % PEG-LNP and 1.0 mol%; 1.0 % PEG-LNP) anchored to their surface. We applied end-over-end agitation, elevated temperature, and repeated freeze and thaw (F/T) cycles as physicochemical stressors of pH and ionic strength. Dynamic light scattering (DLS), flow imaging microscopy (FIM), and ionic-exchange chromatography (IEX) were to determine the degree of aggregation and change in siRNA content. The results indicate that 0.5 % PEG-LNP resisted aggregation only at low pH levels or with salt, whereas 1.0 % PEG-LNP had increased colloidal stability except at pH 4. 0.5 % PEG-LNP withstood aggregation until 71 °C and three cycles of F/T. In contrast, 1.0 % PEG-LNP maintained colloidal stability at 90 °C and seven F/T cycles. Moreover, 1.0 % PEG-LNP had higher siRNA stability under all stress conditions. Therefore, to ensure the stability of LNP and encapsulated siRNA, the PEG concentration must be carefully controlled while considering LNPs' colloidal instability mechanisms under various stress conditions.

Formulation and Characterization of Ursodeoxycholic Acid Nanosuspension Based on Bottom-Up Technology and Box-Behnken Design Optimization

BACKGROUND

Ursodeoxycholic acid (UDCA) is a therapeutic agent used for the treatment of cholestatic hepatobiliary diseases in pediatric patients. It is a bile acid that presents high lipophilicity, and it belongs to Class II of the Biopharmaceutical Classification System (BCS), which exhibits low water solubility and high intestinal permeability, which leads to poor oral absorption. The objective of this work was to design and optimize UDCA nanosuspensions by means of the precipitation-ultrasonication method to improve the solubility, dissolution, and oral bioavailability of UDCA.

METHODS

A three-level, three-factor Box-Behnken design was used to optimize formulation variables and obtain uniform, small-particle-size UDCA nanosuspensions. The independent variables were: stabilizer percentage (X1), amplitude (X2), and sonication time (X3), and the dependent variable was the particle size (Y1). In the precipitation-ultrasonication method, UDCA was dissolved in acetone:PEG 400 (1:1 v/v) and quickly incorporated into the antisolvent (pre-cooled aqueous dispersion of HPMC E-15 0.3%), by means of intense sonication at 50 W for 5 min, controlling temperature through an ice water bath. The lyophilization efficacy was evaluated by means of a cryoprotective efficacy test, working with 10% maltose at -80 °C. The nanosuspensions were characterized by dynamic light scattering (DLS), X-ray diffraction, and scanning electron microscopy (SEM). The physicochemical stability was determined at 25 °C and 4 °C at 7, 14, 30, and 60 days, and the UDCA content was analyzed via HPLC-UV. An in vitro dissolution assay and an oral bioavailability study were performed in male Wistar rats.

RESULTS

A significant impact was achieved in the optimized nanosuspension with 0.3% (stabilizer), 50 W (amplitude), and 5 min (sonication time), with a particle size of 352.4 nm, PDI of 0.11, and zeta potential of -4.30 mV. It presented adequate physicochemical stability throughout the study and the UDCA content was between 90% and 110%. In total, 86% of UDCA was dissolved in the in vitro dissolution test. The relative oral bioavailability was similar without significant statistical differences when comparing the lyophilized nanosuspension and the commercial tablet, the latter presenting a more erratic behavior. The pharmacokinetic parameters of the nanosuspension and the commercial tablet were Tmax (1.0 ± 0.9 h vs. 2.0 ± 0.8 h, respectively), Cmax (0.558 ± 0.118 vs. 0.366 ± 0.113 µM, respectively), ΔCmax (0.309 ± 0.099 vs. 0.232 ± 0.056, respectively), AUC (4.326 ± 0.471 vs. 2.188 ± 0.353 µg/mL.h, respectively, p < 0.02), and IAUC0-24h (2.261 ± 0.187 µg/mL.h vs. 1.924 ± 0.440 µg/mL.h, respectively).

CONCLUSIONS

The developed nanosuspension presents an appropriate dosage and administration for pediatric patients. On the other hand, it exhibits an adequate absorption and UDCA oral bioavailability.

Optimization of the different phases of the freeze-drying process of solid lipid nanoparticles using experimental designs

In this work, the effect of cryoprotectant type and concentration and freeze-drying process parameters were evaluated to determine an optimal freeze-drying process for celecoxib-loaded solid lipid nanoparticles. Different cryoprotectants were tested at different weight ratios (cryoprotectant:lipid). Trehalose, maltose, and sucrose at a 1:1 wt ratio were selected for further use in optimizing the freeze-drying process through experimental designs to accurately define the freezing, primary, and secondary drying conditions of the freeze-drying process. The optimal freeze-dried solid lipid nanoparticles were subjected to a 6-month stability study at either 4 °C or 25 °C/60% RH, resulting in significant growth when the nanoparticles were stored at 25 °C/60% RH. The best results were obtained with trehalose as a cryoprotectant and storage at 4 °C. Furthermore, the in vitro release data showed a significantly different release profile before and after optimization of the freeze-drying process, suggesting that the optimization of the freeze-drying process affected the quality of the freeze-dried cake. In conclusion, a successful lyophilization process was obtained due to rational cooperation between a good formulation and optimal conditions in the freezing and drying steps. This yielded an acceptable non-collapsed freeze-dried cake with good redispersibility, minimal changes in physicochemical properties, and long-term stability at 4 °C.

Lyophilization for Formulation Optimization of Drug-Loaded Thermoresponsive Polyelectrolyte Complex Nanogels from Functionalized Hyaluronic Acid

The lyophilization of nanogels is practical not only for their long-term conservation but also for adjusting their concentration and dispersant type during reconstitution for different applications. However, lyophilization strategies must be adapted to each kind of nanoformulation in order to minimize aggregation after reconstitution. In this work, the effects of formulation aspects (i.e., charge ratio, polymer concentration, thermoresponsive grafts, polycation type, cryoprotectant type, and concentration) on particle integrity after lyophilization and reconstitution for different types of polyelectrolyte complex nanogels (PEC-NGs) from hyaluronic acid (HA) were investigated. The main objective was to find the best approach for freeze-drying thermoresponsive PEC-NGs from Jeffamine-M-2005-functionalized HA, which has recently been developed as a potential platform for drug delivery. It was found that freeze-drying PEC-NG suspensions prepared at a relatively low polymer concentration of 0.2 g.L−1 with 0.2% (m/v) trehalose as a cryoprotectant allow the homogeneous redispersion of PEC-NGs when concentrated at 1 g.L−1 upon reconstitution in PBS without important aggregation (i.e., average particle size remaining under 350 nm), which could be applied to concentrate curcumin (CUR)-loaded PEC-NGs for optimizing CUR content. The thermoresponsive release of CUR from such concentrated PEC-NGs was also reverified, which showed a minor effect of freeze-drying on the drug release profile.

Nanosuspension: A Formulation Technology for Tackling the Poor Aqueous Solubility and Bioavailability of Poorly Soluble Drugs

The poor water solubility of numerous novel drug candidates presents significant challenges, particularly in terms of oral administration. This limitation can result in various undesirable clinical implications, such as inter-patient variability, poor bioavailability, difficulties in achieving a safe therapeutic index, increased costs, and potential risks of toxicity or inefficacy. Biopharmaceutics Classification System (BCS) class II drugs face particular hurdles due to their limited solubility in the aqueous media of the gastrointestinal tract. In such cases, parenteral administration is often employed as an alternative strategy. To address these challenges, nanosuspension techniques offer a promising solution for enhancing drug solubility and overcoming oral delivery obstacles. This technique has the potential to bridge the gap between drug discovery and preclinical use by resolving problematic solubility. This literature review has delved into contemporary nanosuspension preparation technologies and the incorporation of stabilizing ingredients within the formulation. Furthermore, the manuscript explores nanosuspension strategies for both oral and parenteral/other delivery routes, and separate discussions have been presented to establish a suitable flow that addresses the challenges and strategies relevant to each administration method.

Stability and Function of Extracellular Vesicles Derived from Immortalized Human Corneal Stromal Stem Cells: A Proof of Concept Study

With significant advancement and development of extracellular vesicle (EV)-based therapies, there is a growing need to understand how their storage affects their physical and functional characteristics. EVs were isolated from the conditioned medium of a corneal stromal stem cell line (imCSSC) using Total Exosome isolation kit (TEI) and ultracentrifugation (UC) combined protocol. Purified EVs were stored at 4°C, - 80°C, room temperature (RT) after lyophilization with or without trehalose for 4 weeks. EVs stored at - 80°C and RT (lyophilization with trehalose) demonstrated a comparable morphology, while the freeze-dried samples without trehalose showed aggregation and degradation under a transmission electron microscope (TEM). Lyophilized samples without trehalose demonstrated a decreased particle concentration, recovery rate and protein concentration, which was remediated by the addition of trehalose. EVs stored at - 80℃ showed no change in the protein expression of CD9, CD63, and CD81. Regardless of the storage condition, all EV samples investigated reduced inflammation, as well as inhibited expression of fibrotic markers in vitro. Lyophilization of EVs with trehalose was a feasible storage method that retained the physical property and in vitro biological activities of EVs after 4 weeks of storage, while - 80°C offered the best retention of imCSSC-derived EV physical properties. For the first time, this data demonstrated a practical and translatable method for the storage of CSSC-derived EVs for clinical use.

Lyophilized Filovirus Glycoprotein Vaccines: Peroxides in a Vaccine Formulation with Polysorbate 80-Containing Adjuvant are Associated with Reduced Neutralizing Antibody Titers in Both Mice and Non-Human Primates

Zaire ebolavirus, Sudan ebolavirus, and Marburg marburgvirus are the filoviruses most commonly associated with human disease. Previously, we administered a three-dose regimen of trivalent vaccines comprising glycoprotein antigens from each virus in mice and non-human primates (NHPs). The vaccines, which contained a polysorbate 80-stabilized squalane-in-water emulsion adjuvant and were lyophilized from a solution containing trehalose, produced high antibody levels against all three filovirus antigens. Subsequently, single-vial formulations containing a higher concentration of adjuvant were generated for testing in NHPs, but these vaccines elicited lower neutralizing antibody titers in NHPs than previously tested formulations. In order to explain these results, in the current work we measured the size of adjuvant emulsion droplets and the peroxide levels present in the vaccines after lyophilization and reconstitution and tested the effects of these variables on the immune response in mice. Increases in squalane droplet sizes were observed when the ratio of adjuvant to trehalose was increased beyond a critical value, but antibody and neutralizing antibody titers in mice were independent of the droplet size. Higher levels of peroxides in the vaccines correlated with higher concentrations of adjuvant in the formulations, and higher peroxide levels were associated with increased levels of oxidative damage to glycoprotein antigens. Neutralizing titers in mice were inversely correlated with peroxide levels in the vaccines, but peroxide levels could be reduced by adding free methionine, resulting in retention of high neutralizing antibody titers. Overall, the results suggest that oxidation of glycoprotein antigens by peroxides in the polysorbate 80-stabilized squalane-in-water emulsion adjuvant, but not lyophilization-induced increases in adjuvant emulsion droplet size may have been responsible for the decreased neutralizing titers seen in formulations containing higher amounts of adjuvant.

Use of natural deep eutectic systems as new cryoprotectant agents in the vitrification of mammalian cells

In this work we present the potential of Natural Deep Eutectic Systems (NADES) as new vitrification media for the cryopreservation of mammalian cells. Several NADES composed of natural metabolites were prepared and tested as CPAs in two cell lines, L929 and HacaT cells. After the harvesting, cells were mixed with the eutectic systems, and frozen directly into liquid nitrogen to achieve a vitreous state. Then, the cells were thawed and it was observed that NADES were able to exert a significant cryoprotective effect in L929 cells, when compared with DMSO or in the absence of a CPA. For HacaT cells, only a eutectic system showed a slightly improvement in cell survival, while DMSO caused complete cell death. Moreover, the thermal behaviour of the best systems was studied for further understanding the protective properties of NADES as CPAs, and have shown a significant difference in terms of T_m and T_c when compared with DMSO and water. Additionally, the results obtained showed that NADES can be maintained in the growth media after the thawing step, without compromising cell viability. In summary, we have shown the great potential of NADES to be used as CPAs for the cryopreservation of different cell types, using the vitrification method.

Influence of the Dispersion Medium and Cryoprotectants on the Physico-Chemical Features of Gliadin- and Zein-Based Nanoparticles

The evaluation of the physico-chemical features of nanocarriers is fundamental because the modulation of these parameters can influence their biological and in vivo fate. This work investigated the feasibility of saline, 5% w/v glucose and phosphate-buffered saline solution, as polar media for the development of nanoparticles made up of two vegetal proteins, zein from corn and gliadin from wheat, respectively. The physico-chemical features of the various systems were evaluated using dynamic and multiple light scattering techniques, and the results demonstrate that the 5% w/v glucose solution is a feasible medium to be used for their development. Moreover, the best formulations were characterized by the aforementioned techniques following the freeze-drying procedure. The aggregation of the zein nanoparticles prepared in water or glucose solution was prevented by using various cryoprotectants. Mannose confirmed its crucial role in the cryopreservation of the gliadin nanosystems prepared in both water and glucose solution. Sucrose and glucose emerged as additional useful excipients when they were added to gliadin nanoparticles prepared in a 5% glucose solution. Specifically, their protective effect was in the following order: mannose > sucrose > glucose. The results obtained when using specific aqueous media and cryoprotectants permitted us to develop stable zein or gliadin nanoparticles as suspension or freeze-dried formulations.

Eplerenone nanocrystals engineered by controlled crystallization for enhanced oral bioavailability

Poor aqueous solubility of eplerenone (EPL) is a major obstacle to achieve sufficient bioavailability after oral administration. In this study, we aimed to develop and evaluate eplerenone nanocrystals (EPL-NCs) for solubility and dissolution enhancement. D-optimal combined mixture process using Design-Expert software was employed to generate different combinations for optimization. EPL-NCs were prepared by a bottom-up, controlled crystallization technique during freeze-drying. The optimized EPL-NCs were evaluated for their size, morphology, thermal behavior, crystalline structure, saturation solubility, dissolution profile, in vivo pharmacokinetics, and acute toxicity. The optimized EPL-NCs showed mean particle size of 46.8 nm. Scanning electron microscopy revealed the formation of elongated parallelepiped shaped NCs. DSC and PXRD analysis confirmed the crystalline structure and the absence of any polymorphic transition in EPL-NCs. Furthermore, EPL-NCs demonstrated a 17-fold prompt increase in the saturation solubility of EPL (8.96 vs. 155.85 µg/mL). The dissolution rate was also significantly higher as indicated by ∼95% dissolution from EPL-NCs in 10 min compared to only 29% from EPL powder. EPL-NCs improved the oral bioavailability as indicated by higher AUC, C_max, and lower T_max than EPL powder. Acute oral toxicity study showed that EPL-NCs do not pose any toxicity concern to the blood and vital organs. Consequently, NCs prepared by controlled crystallization technique present a promising strategy to improve solubility profile, dissolution velocity and bioavailability of poorly water-soluble drugs.

Armamentarium of Cryoprotectants in Peptide Vaccines: Mechanistic Insight, Challenges, Opportunities and Future Prospects

Vaccines are designed to leverage the immune system and produce long-lasting protection against specific diseases. Peptide vaccines are regarded as safe and effective way of circumventing problems such as mild allergic reactions associated with conventional vaccines. The biggest challenges associated with formulation of peptide vaccines are stability issues and conformational changes which lead to destruction of their activity when exposed to lyophilization process that may act as stressors. Lyophilization process is aimed at removal of water which involves freezing, primary drying and secondary drying. To safeguard the peptide molecules from such stresses, cryoprotectants are used to offer them viability and structural stability. This paper is an attempt to understand the physicochemical properties of peptide vaccines, mechanism of cryoprotection under the shed of water replacement, water substitution theory and cation-pi interaction theory of amino acids which aims at shielding the peptide from external environment by formation of hydrogen bonds, covalent bonds or cation-pi interaction between cryoprotectant and peptide followed by selection criteria of cryoprotectants and their utility in peptide vaccines development along with challenges and opportunities.

Single-vial filovirus glycoprotein vaccines: Biophysical characteristics and immunogenicity after co-lyophilization with adjuvant

Zaire ebolavirus (EBOV), Sudan ebolavirus (SUDV), and Marburg marburgvirus (MARV) are the most prevalent and pathogenic species of filovirus. Previously, we showed that glycoprotein antigens from each virus could be lyophilized to create thermostable monovalent subunit vaccines. However, cross-protection is not expected from the monovalent vaccines and therefore developing a trivalent filovirus vaccine would be desirable. Subunit protein vaccines often require the addition of an adjuvant to sufficiently boost the immunogenicity. Typically, liquid suspensions or emulsions of adjuvants and lyophilized antigens are stored in separate vials to avoid destabilizing interactions and are only mixed immediately before administration. Herein, we describe the development and characterization of monovalent and trivalent filovirus vaccines that are co-lyophilized with a squalane-in-water emulsion adjuvant. We found that the single-vial presentation retained adjuvant particle diameter and zeta potential after lyophilization and reconstitution. Furthermore, the trivalent vaccines elicited high antibody levels against all three antigens in mice and non-human primates. These results advance the prospect of developing a single-vial trivalent filovirus vaccine, which would enable easier distribution and administration of the vaccine to resource-poor areas.

Design of ultra-fine carvedilol nanococrystals: Development of a safe and stable injectable formulation

Carvedilol (CAR) is a strategic beta-blocker agent which its application has been limited by its very low water solubility. The present study describes a soluble form of drug based on nano-cocrystal (NCC) anti-solvent precipitation technique. The COSMOquick software was employed to select the optimum coformer (tartaric acid, TA) and organic solvent (acetone) relying on the enthalpy changes of cocrystallization and solubilization. Central Composite Design (CCD) considering the impact of CAR, TA, poloxamer 188 (stabilizer) concentrations, and anti-solvent/solvent ratio on CAR NCCs particle size (PS) could produce ultra-fine NCCs (about 1 nm). The lyophilization of NCCs investigating slow/fast freezing rates, various types and concentrations of cryprotectants and lyoprotectants indicated that PEG and trehalose (5 % w/vconcentration) under slow freezing rate could re-produce the initial PSs successfully. CAR NCCs indicated about 2000 fold increase in solubility compared with pure CAR. DSC and PXRD experiments proved that the formulations containing trehalose led to more crystalline and the ones comprising PEG led to more amorphous structures. Interestingly, the slow freezed PEG protected NCCs were physically stable for at least 18 months. In conclusion, the NCC technology could produce the first safe soluble form of CAR for treating hypertension urgencies easy for industrial scale-up.

A Traffic Light System to Maximize Carbohydrate Cryoprotectants' Effectivity in Nanostructured Lipid Carriers' Lyophilization

Lyophilization is often employed to transform nanoparticle suspensions to stable solid forms. This work proposed Neurofuzzy Logic (NFL) to better understand the lyophilization process of Nanostructured Lipid Carriers’ (NLCs) dispersions and the carbohydrate cryoprotectants’ (CPs) performance in these processes. NLCs were produced by hot homogenization, frozen at different speeds, and lyophilized using several CPs at variable concentrations. NLCs were characterized, and results were expressed as increase in particle size (Δ size), polydispersity (Δ PdI), and zeta potential (Δ ZP) of lyophilized powders (LP) regarding initial dispersions. CPs were classified according to their molecular weights (MW), and the osmolarities (Π) of CPs solutions were also determined. Databases obtained were finally modelled through FormRules^® (Intelligensys Ltd., Kirkwall, Scotland, UK), an NFL software. NFL models revealed that CPs’ MW determines the optimal freezing conditions and CPs’ proportions. The knowledge generated allowed the establishment of a traffic light system intended to successfully select and apply sugars for nanoparticles lyophilization.

Development of novel biopolymer-based nanoparticles loaded cream for potential treatment of topical fungal infections

OBJECTIVE

Biodegradable polymers are extensively used due to their efficient safety profiles. The aim of the current study was to fabricate, evaluate, and characterize biodegradable, biocompatible fluconazole (FLZ) loaded chitosan (CHS) chondroitin sulfate (CS) nanoparticles (NPs) for topical delivery. Polymers utilized in the formulation not only served as a carrier system but also aided in fighting with complex etiology of the disease due to their innate antifungal activities.

METHODS

NPs were prepared by the complex coacervation method, then were optimized for various parameters and subsequently loaded into a cream.

RESULTS

Scanning electron microscopic (SEM) analysis showed spherical morphology of the NPs. Prepared NPs showed an average particle size in the range of 350-450 nm and an encapsulation efficiency (EE) of 86%. The polydispersity index (PDI) was found to be 0.148 that showed a uniform distribution of NPs. Fourier transform infrared (FTIR) spectroscopy confirmed the absence of any electrostatic interaction between ingredients. In vitro drug release analyses exhibited a sustained release of the drug and higher antifungal activity than free FLZ. Ex vivo permeability and drug distribution in different skin layers ensured a site-specific delivery of the FLZ-NPs. As compared with free FLZ and other control groups, the prepared NPs also exhibited significantly higher antifungal activity against Candida albicans (p < .01).

CONCLUSION

It was concluded from the results that the FLZ-NPs laden cream could be a potential candidate for topical and site-specific delivery of the drug cargo for the potential treatment of fungal infections.

Lyophilization of Nanocapsules: Instability Sources, Formulation and Process Parameters

Polymeric nanocapsules have gained more and more interest in the medical sciences. Their core-shell structure offers numerous advantages, especially regarding their use as drug delivery systems. This review begins by presenting the different intrinsic sources of the instability of nanocapsules. The physical and chemical potential instabilities of nanocapsules reduce their shelf-life and constitute a barrier to their clinical use and to their commercialization. To overcome these issues, lyophilization is often used as a process of choice in the pharmaceutical industry especially when labile compounds are used. The state of the art of lyophilization nanocapsules is reviewed. The formulation properties and the process parameters are discussed for a complete understanding of their impact on the stability and storage of the final dried product. To assess the quality of the dried product, various characterization methods are also discussed.

Just add water: hydratable, morphologically diverse nanocarrier powders for targeted delivery

Two major obstacles that limit the widespread usage of polymeric nanocarriers include the complexity of formulation methods and their stability during storage. To address both of these issues, here we present morphologically complex nanocarriers in a hydratable powder form, which bypasses the need for expensive, harsh, and/or time-consuming nanocarrier fabrication techniques. The powders are composed of carbohydrates and self-assembling polymer amphiphiles having a low glass transition temperature. Hydration requires less than one minute and only involves the addition of aqueous media (water or saline) to rapidly obtain self-assembled micelles, worm-like micelles (i.e. filomicelles), or polymersomes from poly(ethylene glycol)-b-poly(propylene sulfide) (PEG-b-PPS) polymers. The formulated powders are highly stable, achieving hydration into monodisperse nanocarriers following >6 months of storage. Diverse drug cargoes were efficiently encapsulated during hydration, including hydrophobic small molecules for micellar morphologies, as well as individual and concurrent loading of both hydrophobic and hydrophilic molecules for vesicular morphologies. Hydrated polymersomes are shown to load hydrophilic biological macromolecules, and encapsulated enzymes retain bioactivity. Furthermore, we demonstrate that inclusion of lipid-anchored ligands in powder form permits the surface-display of targeting ligands and enhances target cell uptake, thereby extending this technology to targeted drug delivery applications. Our powder-based formulation strategy was extendable to commercially available polymer amphiphiles, including PEG-b-polystyrene and PEG-b-polycaprolactone. The formulated nanotechnologies described herein are highly modular, require minimal preparation, and remain stable in ambient long-term storage (bypassing cold chain requirements), which will enable their use in medicine (human and veterinary), research, and commercial applications from cosmetics to agriculture.

Effects of freezing rate on structural changes in L-lactate dehydrogenase during the freezing process

Freezing is a common method for improving enzyme storage stability. During the freezing process, the freezing rate is an important parameter that can affect protein stability. However, there is limited information on the denaturation mechanisms and protein conformational changes associated with the freezing rate. In this study, the effects of freezing rate on activity loss and conformational changes in a model enzyme, l-lactate dehydrogenase, were evaluated. Enzyme solutions were frozen at various rates, from 0.2 to 70.6 °C/min, and ice seeding was conducted to reduce supercooling. The results demonstrated that fast freezing results in activity loss, structural changes, and aggregation. The residual activities at freezing rates of 0.2, 12.8, and 70.6 °C/min were 77.6 ± 0.9%, 64.1 ± 0.4%, and 44.8 ± 2.0%, respectively. As the freezing rate increased, the degree of dissociation and unfolding increased significantly, as determined using blue native-polyacrylamide gel electrophoresis and fluorescence spectroscopy. Moreover, a large number of amyloid aggregates were detected in samples frozen at a fast freezing rate (70.6 °C/min). The enzyme inactivation mechanism induced by fast freezing was proposed in terms of increased dehydration at the enzyme surface and an ice/unfroze solution interface, which could be helpful to establish a common understanding of enzyme inactivation during the freezing process.

Exosomes as Naturally Occurring Vehicles for Delivery of Biopharmaceuticals: Insights from Drug Delivery to Clinical Perspectives

Exosomes as nanosized vesicles are emerging as drug delivery systems for therapeutics owing to their natural origin, their ability to mediate intercellular communication, and their potential to encapsulate various biological molecules such as proteins and nucleic acids within the lipid bilayer membrane or in the lumen. Exosomes contain endogenous components (proteins, lipids, RNA) that could be used to deliver cargoes to target cells, offering an opportunity to diagnose and treat various diseases. Owing to their ability to travel safely in extracellular fluid and to transport cargoes to target cells with high efficacy, exosomes offer enhanced delivery of cargoes in vivo. However, several challenges related to the stabilization of the exosomes, the production of sufficient amounts of exosomes with safety and efficacy, the efficient loading of drugs into exosomes, the clearance of exosomes from circulation, and the transition from the bench scale to clinical production may limit their development and clinical use. For the clinical use of exosomes, it is important to understand the molecular mechanisms behind the transport and function of exosome vesicles. This review exploits techniques related to the isolation and characterization of exosomes and their drug delivery potential to enhance the therapeutic outcome and stabilization methods. Further, routes of administration, clinical trials, and regulatory aspects of exosomes will be discussed in this review.

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.

Production and isolation of pharmaceutical drug nanoparticles

Nanosizing of pharmaceutical drug particles is one of the most important drug delivery platforms approaches for the commercial development of poorly water-soluble drug molecules. Though nanosizing of drug particles has been proven to greatly enhance drugs dissolution rate and apparent solubility, nanosized materials have presented significant challenges for their formulation as solid dosage forms (e.g. tablets, capsules). This is due to the strong Van der Waals attraction forces between dry nanoparticles leading to aggregation, cohesion, and consequently poor flowability. In this review, the broad area of nanomedicines is overviewed with the primary focus on drug nanocrystals and the top-down and bottom-up methods used in their fabrication. The review also looks at how nanosuspensions of pharmaceutical drugs are generated and stabilised, followed by subsequent strategies for isolation of the nanoparticles. A perspective on the future outlook for drug nanocrystals is also presented.

Development of polyoxyethylene (2) oleyl ether-gliadin nanoparticles: Characterization and in vitro cytotoxicity

Natural polymers have been widely investigated as materials for the delivery of active compounds as a consequence of their biocompatibility, low-cost and the opportunity they furnish to obtain micro- and nanostructures. In this investigation, commercial wheat gliadin was used as raw material with the aim of obtaining a vegetal protein-based nanoformulation to be used for various applications. The influence of non-ionic and anionic surfactants on the physico-chemical properties of gliadin nanoparticles was evaluated in order to propose a suitable candidate able to stabilize the colloidal structure. The use of Super Refined polyoxyethylene (2) oleyl ether gave the best results, promoting the formation of spherical-shaped nanosystems with a narrow size distribution. The oleyl ether-based emulsifier prevented the destabilization of the colloidal systems when pH- and temperature-dependent stress was applied. A freeze-dried formulation was obtained when mannose was used as a cryoprotectant. Polyoxyethylene (2) oleyl ether-stabilized nanosystems were shown to retain and release both hydrophilic and lipophilic model compounds in a controlled manner. The cytotoxicity of the surfactant-free and polyoxyethylene (2) oleyl ether-stabilized gliadin based nanosystems was assessed on human cells, both normal and tumoural, in order to investigate the concentrations of particles that can be used during in vitro experiments. Polyoxyethylene (2) oleyl ether-stabilized gliadin-based nanosystems are promising carriers for the delivery of several active compounds.

Development of a Nanostructured Lipid Carrier (NLC) by a Low-Energy Method, Comparison of Release Kinetics and Molecular Dynamics Simulation

Lipid nanocarriers have a great potential for improving the physicochemical characteristics and behavior of poorly water-soluble drugs, such as aqueous dispersibility and oral bioavailability. This investigation presents a novel nanostructured lipid carrier (NLC) based on a mixture of solid lipid glycerides, fatty acid esters of PEG 1500 (Gelucire^® 44/14), and an oil mix composed of capric and caprylic triglycerides (Miglyol^® 812). These NLCs were developed by a simple low-energy method based on melt emulsification to yield highly encapsulating and narrowly distributed nanoparticles (~100 nm, PdI = 0.1, and zeta potential = ~−10 mV). Rhodamine 123 was selected as a poorly water-soluble drug model and owing to its spectroscopic properties. The novel NLCs were characterized by dynamic light scattering (DLS), zeta potential, nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and colloidal stability. The drug release was determined through a dialysis bag and vertical Franzs’ cells to provide insights about the methods’ suitability, revealing similar performance regardless of their different fluid dynamics. Rhodamine 123 followed a characteristic biphasic release profile owing to the swelling of the hydrophilic polymer coating and diffusion process from the lipid core as revealed by the Korsmeyers–Peppas kinetic modeling. Moreover, to elucidate the formation and incorporation of Rhodamine 123 into the NLC core, several molecular dynamics simulations were conducted. The temperature was shown to be an important condition to improve the formation of the nanoparticles. In addition, the liquid lipid incorporation to the formulation forms nanoparticles with imperfect centers, in contrast to nanoparticles without it. Moreover, Miglyol^® 812 improves hydrophobic molecule solubility. These results suggest the potential of novel NLC as a drug delivery system for poorly water-soluble drugs.

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.

Dextran/poly-L-arginine multi-layered CaCO3-based nanosystem for vascular drug delivery

The development of heterogeneous drug delivery systems leads to innovative strategies for targeted therapy of common pathologies, such as cancer, immunological and neurological disorders. Nowadays, it is possible to choose among a great variety of nanoparticles on the basis of the needs they have to satisfy. However, a candidate for the treatment of cardiovascular pathologies is still missing. In this context, a targeted therapy implies the conceptualization of nanoparticles that take active part in the treatment of vascular pathologies. The aim of this work was to provide a method to produce multi-layered calcium carbonate (CaCO₃) nanoparticles encapsulating a model protein, bovine serum albumin, with model antibodies on their surface. CaCO₃ nanoparticles were produced by the combination of complex coacervation and mineralization and were engineered using layer-by-layer technique with a polysaccharide, dextran sulfate, and a homo-poly-amino acid, poly-L-arginine. Morphology, biocompatibility, cellular uptake, influence on cell expression of the inflammatory marker matrix metalloproteinase-9, and hemocompatibility of the nanoparticles were studied. The presence of the dextran/poly-L-arginine layers did not negatively affect the nanoparticle overall characteristics and they did not trigger proinflammatory response in vitro. Taking together all the obtained results, we consider the proposed CaCO₃ nanoparticles as a promising tool in cardiovascular field.

The potential of intranasal delivery of nanocrystals in powder form on the improvement of zaleplon performance: in-vitro, in-vivo assessment

OBJECTIVE

The present work focuses on improving zaleplon (ZAP) performance through nanosizing its insoluble particles which were then delivered intranasally in powder form.

SIGNIFICANCE

Since nanopowders have an exceptional ability to cross cell membrane, their absorption is facilitated in the solid form. Hence, delivering insoluble ZAP nanocrystals (NC) through intranasal route improves its bioavailability due to both nanosization and the escape of hepatic metabolism.

METHODS

Nanocrystals were prepared by anti-solvent precipitation followed by probe sonication in presence of Soluplus^®, Poloxamer-188 (0.25%), sodium lauryl sulfate (0.5%), and mannitol. Physicochemical evaluation of the prepared NC was done by DSC and XRPD. TGA was performed for stability detection. Ex vivo permeation study through isolated cattle nasal mucosal membrane, in addition to an in vivo bioavailability study was performed for assessment of the prepared NC.

RESULTS

Nanosization to 200 nm contributed to the enhancement in dissolution ∼100% within 30 min and reduced half-life to 1.63 min. Confirmation of adsorption of polymers over NC' surface was elucidated. TGA confirmed their thermal stability. Ex vivo permeation study showed a 2.7 enhancement ratio in favor of the prepared NC. Both the extent and rate of NC absorption through nasal mucosa of rabbits were significantly higher (p ˂ .05) than in case of oral tablets. The relative bioavailability of NC was increased 3.14 times as compared to the Sleep aid^® tablets.

CONCLUSION

The intranasal delivery of nanoscale ZAP powder proved to be a successful alternative to oral formulations that suffer poor absorption and limited bioavailability.

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.

Ternary Polypeptide Nanoparticles with Improved Encapsulation, Sustained Release, and Enhanced In Vitro Efficacy of Carfilzomib

PURPOSE

To develop a new nanoparticle formulation for a proteasome inhibitor Carfilzomib (CFZ) to improve its stability and efficacy for future in vivo applications.

METHODS

CFZ-loaded ternary polypeptide nanoparticles (CFZ/tPNPs) were prepared by using heptakis(6-amino-6-deoxy)-β-cyclodextrin(hepta-hydrochloride) (HaβCD) and azido-poly(ethylene glycol)-block-poly(L-glutamic acid sodium salt) (N₃-PEG-PLE). The process involved ternary (hydrophobic/ionic/supramolecular) interactions in three steps: 1) CFZ was entrapped in the cavity of HaβCD by hydrophobic interaction, 2) the drug-cyclodextrin inclusion complexes were mixed with N₃-PEG-PLE to form polyion complex nanoparticles, and 3) the nanoparticles were modified with fluorescent dyes (AFDye 647) for imaging and/or epithelial cell adhesion molecule (EpCAM) antibodies for cancer cell targeting. CFZ/tPNPs were characterized for particle size, surface charge, drug release, stability, intracellular uptake, proteasome inhibition, and in vitro cytotoxicity.

RESULTS

tPNPs maintained an average particle size of 50 nm after CFZ entrapment, EpCAM conjugation, and freeze drying. tPNPs achieved high aqueous solubility of CFZ (>1 mg/mL), sustained drug release (t_1/2 = 6.46 h), and EpCAM-mediated cell targeting, which resulted in increased intracellular drug accumulation, prolonged proteasome inhibition, and enhanced cytotoxicity of CFZ in drug-resistant DLD-1 colorectal cancer cells.

CONCLUSIONS

tPNPs improved stability and efficacy of CFZ in vitro, and these results potentiate effective cancer treatment using CFZ/tPNPs in future vivo studies.

Fabrication of Nanosuspensions to Improve the Oral Bioavailability of Total Flavones from Hippophae rhamnoides L. and their Comparison with an Inclusion Complex

The aim of this work was to increase the solubility and oral bioavailability of isorhamnetin, kaempferol, and quercetin in the total flavones of Hippophae rhamnoides L. (TFH) by preparing their nanosuspensions (NSs) and an inclusion complex. Based on the particle size and zeta potential, P407, Soluplus, SDS, PEG-6000, and HP-β-CD were selected as stabilizers. TFH NSs and a TFH/HP-β-CD inclusion complex were prepared, and their morphology, crystallinity, molecular interactions, and cytotoxicity were investigated. Furthermore, the saturation solubility, dissolution, and pharmacokinetics of the three flavonoids in the TFH, TFH NSs, and TFH/HP-β-CD inclusion complex were compared. The five obtained TFH NSs were physically stable, and their particle sizes were all below 200 nm. The solubility and dissolution of the three active components were obviously enhanced by the formation of the TFH NSs and TFH/HP-β-CD inclusion complex. Correspondingly, the oral bioavailability of isorhamnetin, kaempferol, and quercetin increased up to 4.11-, 3.85-, and 6.73-fold, respectively, in the TFH NSs and 2.89-, 3.71-, and 9.51-fold, respectively, in the TFH/HP-β-CD inclusion complexes compared to those in the raw TFH. In brief, both NSs and inclusion complexes can improve the oral bioavailability of the three flavonoids in TFH. Taking the drug loading and the stable ratio of the multiple components into consideration, the NSs is a more promising strategy than the inclusion complex for increasing the oral bioavailability of multiple water-insoluble components in herbal extracts. Graphical abstract.

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.

Strategies to enhance oral delivery of amphotericin B: a comparison of uncoated and enteric-coated nanostructured lipid carriers

The oral delivery of amphotericin B (AmB) has remained a challenge due to its low solubility, permeability, and instability in gastric acidic pH. To solve these issues, herein, we reported a novel approach of using nanostructured lipid carriers (NLCs) and NLCs coating with Eudragit^®L100-55 (Eu-NLCs) for the oral delivery of AmB. This study aimed to compare their ability in protecting the drug from degradation in gastrointestinal fluids and permeation enhancement in Caco-2 cells. Uncoated NLCs and Eu-NLCs possessed a mean particle size of ∼180 and ∼550 nm, with a zeta potential of ∼-30 and ∼-50 mV, respectively. Both NLCs demonstrated an AmB entrapment efficiency up to ∼75%. They possessed significantly greater AmB water solubility than the free drug by up to 10-fold. In fasted state simulated gastric fluid, Eu-NLCs provided significantly greater AmB protection from acidic degradation than uncoated NLCs. In fasted state simulated intestinal fluid, both uncoated and Eu-NLCs showed a fast release characteristic. Caco-2 cells permeation studies revealed that uncoated NLCs provided significantly higher apparent permeation coefficient (P _app) value than Eu-NLCs. Moreover, after 6 months of storage at 4 °C in the absence of light, the physicochemical stabilities of the lyophilized uncoated and Eu-NLCs could be maintained. In conclusion, the developed NLCs and Eu-NLCs could be a potential drug delivery system in improving the oral bioavailability of AmB.

Long-term storage of lipid-like nanoparticles for mRNA delivery

Lipid-like nanoparticles (LLNs) have been extensively explored for messenger RNA (mRNA) delivery in various biomedical applications. However, the long-term storage of these nanoparticles is still a challenge for their clinical translation. In this study, we investigated a series of conditions for the long-term storage of LLNs with encapsulation of mRNA. We evaluated the stability of LLNs with different concentrations of cryoprotectants (sucrose, trehalose or mannitol) under the conditions of freezing or lyophilization processes. Through in vitro and in vivo mRNA delivery studies, we identified the optimal storage condition, and found that the addition with 5% (w/v) sucrose or trehalose to LLNs could remain their mRNA delivery efficiency for at least three months in the liquid nitrogen storage condition.

How does temperature play a role in the storage of extracellular vesicles?

Extracellular vesicles (EVs) contain specific proteins, lipids, and nucleic acids that can be passed to other cells as signal molecules to alter their function. However, there are many problems and challenges in the conversion and clinical application of EVs. Storage and protection of EVs is one of the issues that need further research. To adapt to potential clinical applications, this type of problem must be solved. This review summarizes the storage practices of EVs in recent years, and explains the impact of temperature on the quality and stability of EVs during storage based on current research, and explains the potential mechanisms involved in this effect as much as possible.

Influence of Formulation Parameters on Redispersibility of Naproxen Nanoparticles from Granules Produced in a Fluidized Bed Process

The particle size reduction of active pharmaceutical ingredients is an efficient method to overcome challenges associated with a poor aqueous solubility. With respect to stability and patient's convenience, the corresponding nanosuspensions are often further processed to solid dosage forms. In this regard, the influence of several formulation parameters (i.e., type of carrier material, type and amount of additional polymeric drying excipient in the nanosuspension) on the redispersibility of naproxen nanoparticle-loaded granules produced in a fluidized bed process was investigated. The dissolution rate of the carrier material (i.e., sucrose, mannitol, or lactose) was identified as a relevant material property, with higher dissolution rates (sucrose > mannitol > lactose) resulting in better redispersibility of the products. Additionally, the redispersibility of the product granules was observed to improve with increasing amounts of polymeric drying excipient in the nanosuspension. The redispersibility was observed to qualitatively correlate with the degree of nanoparticle embedding on the surface of the corresponding granules. This embedding was assumed to be either caused by a partial dissolution and subsequent resolidification of the carrier surface dependent on the dissolution rate of the carrier material or by resolidification of the dissolved polymeric drying excipient upon drying. As the correlation between the redispersibility and the morphology of the corresponding granules was observed for all investigated formulation parameters, it may be assumed that the redispersibility of the nanoparticles is determined by their distance in the dried state.

Stability issues and approaches to stabilised nanoparticles based drug delivery system

Nanoparticles form the fundamental building blocks for many exciting applications in various scientific disciplines due to its unique features such as large surface to mass ratio, targeting potential, ability to adsorbed and carry other compound which makes them suitable for biomedical applications. However, the problem of the large-scale synthesis of nanoparticles remains challenging due to physical instability associated with nanoparticles which lead to generation of aggregates particles with high polydispersity index (PDI) indicating low particle homogeneity and eventually loss of their special nanoscale properties. The stabilisation concept can be generated by repulsive electrostatic force, which nanoparticles experience, when they are surrounded by a double layer of electric charges. Selection of proper stabiliser will govern the stability of NPs and ultimately development of optimised drug delivery system. This review summarises mechanism of physical instability issues likely to be encountered during the development of nanoformulations. It also discusses potential stabilising agents used so far and their mechanism in achieving stable nanosystems.

Poly(ethylene glycol)-poly(ε-caprolactone)-based micelles for solubilization and tumor-targeted delivery of silibinin

Introduction: Silibinin is a naturally occurring compound with known positive impacts on prevention and treatment of many types of human illnesses in general and cancer in particular. Silibinin is poorly water soluble which results in its insufficient bioavailability and lack of therapeutic efficacy in cancer. Here, we proposed to examine the potential of micelles composed of poly(ethylene glycol) (PEG) as the hydrophilic block and poly(ε-caprolactone) (PCL), poly(α-benzylcarboxylate-ε-caprolactone) (PBCL), or poly(lactide)-(PBCL) (PLA-PBCL) as hydrophobic blocks for enhancing the water solubility of silibinin and its targeted delivery to tumor.

Methods: Co-solvent evaporation method was used to incorporate silibinin into PEG-PCL based micelles. Drug release profiles were assessed using dialysis bag method. MTT assay also was used to analyze functional activity of drug delivery in B16 melanoma cells.

Results: Silibinin encapsulated micelles were shown to be less than 60 nm in size. Among different structures under study, the one with PEG-PBCL could incorporate silibinin with the highest encapsulation efficiency being 95.5%, on average. PEG-PBCL micelles could solubilize 1 mg silibinin in 1 mL water while the soluble amount of silibinin was found to be 0.092 mg/mL in the absence of polymeric micelles. PEG-PBCL micelles provided the sustained release of silibinin indicated with less than 30% release of silibinin within 24 hours. Silibinin encapsulated in PEG-PBCL micelles resulted in growth inhibitory effect in B16 cancer cells which was significantly higher than what observed with free drug.

Conclusion: Our findings showed that PEG-PBCL micellar nanocarriers can be a useful vehicle for solubilization and targeted delivery of silibinin.