Yanjiao Wang

A combined bottom–up/top–down approach to prepare a sterile injectable nanosuspension

To prepare a uniform nanosuspension of strongly hydrophobic riboflavin laurate (RFL) allowing sterile filtration, physical modification (bottom-up) was combined with high-pressure homogenization (top-down) method. Unlike other bottom-up approaches, physical modification with surfactants (TPGS and PL-100) by lyophilization controlled crystallization and compensated for the poor wettability of RFL. On one hand, crystal growth and aggregation during freezing was restricted by a stabilizer-layer adsorbed on the drug surface by hydrophobic interaction. On the other hand, subsequent crystallization of drug in the sublimation process was limited to the interstitial spaces between solvent crystals. After lyophilization, modified drug with a smaller particle size and better wettability was obtained. When adding surfactant solution, water molecules passed between the hydrophilic groups of surface active molecules and activated the polymer chains allowing them to stretch into water. The coarse suspension was crushed into a nanosuspension (MP=162 nm) by high-pressure homogenization. For long term stability, lyophilization was applied again to solidify the nanosuspension (sorbitol as cryoprotectant). A slight crystal growth to about 600 nm was obtained to allow slow release for a sustained effect after muscular administration. Moreover, no paw-licking responses and very slight muscular inflammation demonstrated the excellent biocompatibility of this long-acting RFL injection.

Decanoic acid grafted oligochitosan nanoparticles as a carrier for insulin transport in the gastrointestinal tract

The objective was to explore the potential of decanoic acid grafted oligochitosan nanoparticles (CSO-DA NPs) as a carrier for insulin. The insulin-loaded CSO-DA NPs obtained by varying the pH and concentrations of CSO and DA had a particle size of 200.6 ± 71.2 nm, with an entrapment efficiency and loading efficiency of 61.18% and 5.56%, respectively. An in vitro study of the formulation showed typical burst of insulin and pH-dependent characteristics. The NPs administered by the in situ loop method were effective in lowering the serum glucose level of rats which was based on the synergistic effect of adhesion of CSO and permeation enhancing effect of DA. In particular, the 50 IU/kg-dose of CSO-DA NPs reduced the serum glucose level by 57.18%. Histopathology investigations showed that the CSO-DA NPs had a low toxicity. Therefore, CSO-DA nanoparticles appear to be promising vehicles for insulin transport through the intestinal mucosa.

A bufadienolide-loaded submicron emulsion for oral administration: Stability, antitumor efficacy and toxicity

The purpose of this study was to develop an alternative submicron emulsion containing three bufadienolides for oral administration and evaluate its preclinical stability, efficacy, and toxicity. The bufadienolide-loaded oral submicron emulsion (BU-OE) was prepared by high-pressure homogenization. The storage stability, in vitro cytotoxicity, in vivo antitumor efficacy, acute toxicity, and long-term toxicity of BU-OE were investigated in detail to evaluate the formulation. The stability study suggested that BU-OE was stable at room temperature and could be stored for at least 18 months at 6±2 °C. The cytotoxicity test revealed that BU-OE had marked cytotoxic activities against cancer cells, but no evident inhibitory effects on normal cells. Likewise, BU-OE exhibited significant antitumor efficacy against Hep G2, HCT-8, and EC9706 cell lines and a slight inhibitory effect on BGC 803 cell line in nude mice, while comparable antitumor activity with fluorouracil injection. The LD50 of BU-OE in mice was 29.4 mg/kg (male) and 22.8 mg/kg (female), respectively. As for the long-term toxicity, BU-OE showed no apparent toxic effects except minor cardiotoxic effects which were reversible. In conclusion, submicron emulsion is a suitable delivery system for oral administration of bufadienolides, with satisfactory stability, superior antitumor efficacy and low toxicity.

Improved tumor tissue penetration and tumor cell uptake achieved by delayed charge reversal nanoparticles

The high affinity of positively charged nanoparticles to biological interfaces makes them easily taken up by tumor cells but limits their tumor permeation due to non-specific electrostatic interactions. In this study, polyion complex coated nanoparticles with different charge reversal profiles were developed to study the influence of charge reversal profile on tumor penetration. The system was constructed by polyion complex coating using micelles composed of poly (lysine)-b-polycaprolactone (PLys-b-PCL) as the cationic core and poly (glutamic acid)-g- methoxyl poly (ethylene glycol) (PGlu-g-mPEG) as the anionic coating material. Manipulation of charge reversal profile was achieved by controlling the polymer chain entanglement and electrostatic interaction in the polyion complex layer through glutaraldehyde-induced shell-crosslinking. The delayed charge reversal nanoparticles (CTCL30) could maintain negatively charged in pH 6.5 PBS for at least 2h and exhibit pH-responsive cytotoxicity and cellular uptake in an extended time scale. Compared with a faster charge reversal counterpart (CTCL70) with similar pharmacokinetic profile, CTCL30 showed deeper penetration, higher in vivo tumor cell uptake and stronger antitumor activity in vivo (tumor inhibition rate: 72.3% vs 60.2%, compared with CTCL70). These results indicate that the delayed charge reversal strategy could improve therapeutic effect via facilitating tumor penetration. STATEMENT OF SIGNIFICANCE Here, the high tumor penetration capability of PEG-coated nanoparticles and the high cellular uptake of cationic nanoparticles were combined by a delayed charge reversal drug delivery system. This drug delivery system was composed of a drug-loading cationic inner core and a polyion complex coating. Manipulation of charge reversal profile was realized by varying the crosslinking degree of the shell of the cationic inner core, through which changed the strength of the polyion complex layer. Nanoparticles with delayed charge reversal profile exhibited improved tumor penetration, in vivo tumor cell uptake and in vivo tumor growth inhibition effect although they have similar pharmacokinetic and biodistribution behaviors with their instant charge reversal counterpart.

Biocompatible riboflavin laurate long-acting injectable nanosuspensions allowing sterile filtration

Abstract The aim of this research was to prepare biocompatible riboflavin laurate (RFL) long-acting injectable nanosuspensions for intramuscular injection with a small particle size allowing sterile filtration. RFL nanosuspensions were manufactured by a precipitation-combined high-pressure homogenization method. Three kinds of mixed stabilizers-d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) as a primary stabilizer, and egg lecithin (PL-100M), Kollidon VA64, Kollidon S-630 as a secondary stabilizer, were separately applied to avoid further aggregation. In the three optimized formulations, the mean particle size of the RFL nanosuspensions was about 170 nm allowing sterilization by filtration. Results from transmission electron microscopy, differential scanning calorimeter, powder X-ray diffraction and Fourier transform infrared reflectance spectroscopy revealed that RFL existed as rod-like crystals. However, a few nano-spheres under 100 nm were found only when PL-100 was used as a secondary stabilizer, possibly due to TPGS and PL-100, which inserted into RFL during the process of crystallization and homogenization. In irritation testing, RFL long-acting injection (LAI) stabilized by TPGS and PL-100 led to mild paw-licking responses and a slight inflammatory reaction, which returned to normal by 14 d after administration. The endogenous PL-100 and nano-spheres with a small size may have contributed to the excellent biocompatibility. As a result, TPGS and PL-100 were selected as blended stabilizers to prepare the irritation-free RFL-LAI that could be sterilized by passage through a 0.22 μm millipore membrane filter.

Polyester–Solid Lipid Mixed Nanoparticles with Improved Stability in Gastro-Intestinal Tract Facilitated Oral Delivery of Larotaxel

The objective of this study was to investigate the role of core stability of nanoparticles on their performances in oral drug delivery. Solid lipids (Geleol Mono and Diglycerides Nf) were incorporated into nanoparticles composed of mPEG-b-PCL by the dialysis method. The prepared solid lipid loaded nanoparticles were found to be spherical nanoparticles with a core state and size distribution dependent on the amount of solid lipid incorporated. The critical aggregation concentrations of lipid-loaded nanoparticles were determined using pyrene fluorescence. Then, the stability of block copolymer in nanoparticles with different solid lipid contents was studied in simulated gastric fluid and simulated intestinal fluid. Solid lipids were found to stabilize nanoparticle cores by improving not only the thermodynamic stability (lowered CAC) of the nanoparticle but also the chemical stability of the block copolymer in the gastrointestinal environment. The stability of the loaded drug (larotaxel, LTX) in nanoparticles with different solid lipid contents was challenged by intestinal homogenate and rat liver microsome, and solid lipid loaded nanoparticles showed superior drug-protecting capability. Solid lipid incorporation exhibited limited influence on the cytotoxicity and cellular uptake but improved the transcytosis of nanoparticles in Caco-2 monolayers. The results of pharmacokinetic study indicated that core stabilization was helpful in promoting oral larotaxel absorption as the absolute bioavailability of LTX delivered by solid lipid loaded nanoparticles was found to be 13.17%, compared with that by the lipid-free nanoparticles (6.264%) and LTX solution (2.435%). Additionally, the results of biodistribution study indicated relatively higher particle integrity of solid lipid loaded nanoparticles, shown by slower liver and spleen accumulation rate, compared with its lipid-free counterpart. Overall, incorporation of solid lipids made the nanoparticles more suitable for oral drug delivery.

Increased dissolution of disulfiram by dry milling with silica nanoparticles

Abstract The purpose of this study was to find a suitable method to increase the dissolution of disulfiram (DSF) which is easily decomposed. The dissolution of DSF within 1 h was significantly increased from 37% to >90% by co-milling with Aerosil® 200 pharm (Aerosil) and the increased dissolution remained stable during long-term storage while there was no significant degradation of DSF. By monitoring the changes in particle size of the grinding mixture, a mosaic DSF-in-Aerosil structure was demonstrated. The core size of the mosaic DSF/Aerosil system was 3.625 µm. The particle size of DSF was reduced from 20.75 µm to ∼200 nm and the size of the mosaic DSF/Aerosil system (3.625∼7.956 µm) increased on increasing the drug-loading content. Differential scanning calorimetry and X-ray powder diffraction analysis confirmed the largely amorphous state of DSF in the mosaic drug/carrier system. Fourier transform infrared spectroscopy confirmed the presence of hydrogen bonding between DSF and Aerosil. Scanning electron microscopy and transmission electron microscopy verified the DSF-in-Aerosil relationship in the particle size determination at different size levels. The possible mechanisms of dry milling included the hypothesis that during impact and collision, DSF particles melted into the surface of Aerosil turning them into an amorphous state or they became inlayed into the interspaces of the Aerosil structure with a much smaller size.

Teniposide-loaded multilayer modified albumin nanoparticles with increased passive delivery to the lung

The nature of a particle surface has a tremendous influence on the in vitro and in vivo behavior of the particle, in addition to the particle size. In this study, multilayer modified albumin nanoparticles were developed to encapsulate teniposide, an anti-cancer agent used in the treatment of lung cancer, in order to optimize its distribution and pharmacokinetics. Multilayer nanoparticles were prepared by coating albumin particles with chitosan and subsequently with PLG–PEG. The multilayer structure was confirmed by the increase in particle size, reverse potential, surface components and morphology, suggesting a layer by layer coating mechanism, involving electrostatic interaction. According to the results of the in vitro release and cytotoxicity studies, the multilayer particles were slightly pH-sensitive to an acidic environment. More importantly, compared with the commercial injection, the modified particles showed a preference for distribution in the lung and exhibited far lower concentrations in the heart and kidney and a prolonged circulation in plasma after intravenous injection, whereas the naked albumin nanoparticles mainly accumulated in the liver and spleen. In addition, P-CS-NP with a reduced amount of PLG–PEG transiently and extensively accumulated in the lung but then rapidly migrated to the liver or spleen, suggesting that the amount of coated layer on the particles affected the targeting behavior and retention in the lung. Therefore, the structure of the albumin core and multi-coated layers are a very promising way for achieving controlled release and passively targeted delivery to the lung.

Nifedipine di-matrix depot tablets prepared by compression coating for obtaining zero-order release

Abstract Compression coating is a possible process for obtaining zero-order release. Nifedipine compression-coated (CC) di-matrix depot tablets were prepared from a single punch tablet press with low viscosity hydroxypropyl cellulose (HPC-L) as the inner polymer, and with middle viscosity hydroxypropyl cellulose (HPC-M), HPC-L and Eudragit RSPO as outer polymers. The release behavior and mechanisms in vitro of the final tablets were investigated, and gravimetric analysis was used to study the release mechanism. The fast release of the core depot and slow release of the outer depot with time formed total zero-order release. The results showed that the formulation presented ideal zero-order release at the weight ratio of nifedipine 3:5 (core: layer), the combination of HPC-L and HPC-M (56:25) in the outer depot, and with the core depot placed in the center. The CC tablets released to more than 95% in 24 h and fitted a zero-order model with the equation Mt/M∞ = 0.038t (R2 = 0.98555). In conclusion, zero-order release of nifedipine over 24 h could be achieved by applying polymer HPC-L and HPC-M with the compression coating technique.

In Vitro-In Vivo Relationship of Amorphous Insoluble API (Progesterone) in PLGA Microspheres

PurposeThe mechanism of PRG release from PLGA microspheres was studied and the correlation of in vitro and in vivo analyses was assessed.MethodsPRG-loaded microspheres were prepared by the emulsion-evaporate method. The physical state of PRG and microstructure changings during the drug release period were evaluated by powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) respectively. Pharmacokinetic studies were performed in male Sprague-Dawley rats, and the in vivo-in vitro correlation (IVIVC) was established by linear fitting of the cumulative release (%) in vitro and fraction of absorption (%) in vivo.ResultsPXRD results indicated recrystallization of PRG during release. The changes of microstructure of PRG-loaded microspheres during the release period could be observed in SEM micrographs. Pharmacokinetics results performed low burst-release followed a steady-released manner. The IVIVC assessment exhibited a good correlation between vitro and in vivo.ConclusionsThe burst release phase was caused by diffusion of amorphous PRG near the surface, while the second release stage was impacted by PRG-dissolution from crystal depots formed in microspheres. The IVIVC assessment suggests that the in vitro test method used in this study could predict the real situation in vivo and is helpful to study the release mechanism in vivo.