Chunshun Zhao

Self-nanoemulsifying drug delivery system of persimmon leaf extract: Optimization and bioavailability studies.

In current study, a self-nanoemulsifying drug delivery system (SNEDDS) of persimmon (Diospyros kaki) leaf extract (PLE) was developed and characterized to compare its in vitro dissolution and relative bioavailability with commercially available tablets (Naoxinqing tablets). Pseudo-ternary phase diagrams were constructed by phase diagram by micro plate dilution (PDMPD) method, of which the evaluation method was improved to use Multiskan Ascent for identifying turbidity. The formulation of PLE-loaded SNEDDS was optimized by an extreme vertices experimental design. The optimized nanoemulsion formulation, loading with 44.48 mg/g PLE total flavonoids, consisted of Cremophor EL, Transcutol P, Labrafil M 1944 CS (56:34:10, w/w), and it remained stable after storing at 40°C, 25°C, 4°C for at least 6 months. When diluted with water, the SNEDDS droplet size was 34.85 nm and the zeta potential was -6.18 mV. Compared with the commercial tablets, the AUC of both quercetin and kaempferol, which are representative active flavonoids of PLE, was increased by 1.5-fold and 1.6-fold respectively following oral administration of PLE-loaded SNEDDS in fasting beagle dogs. These results indicate that SNEDDS is a promising drug delivery system for increasing the oral bioavailability of PLE.

Inclusion complexes of HP-β-cyclodextrin with agomelatine: Preparation, characterization, mechanism study and in vivo evaluation

Agomelatine (AGM), is efficacious in both the acute phase and the continuation phase of depression. However, its poor water-solubility, low bioavailability and polymorphism limit its pharmacological effects. To address these problems, agomelatine-hydroxypropyl-β-cyclodextrin inclusion complex (AGM/HPβ-CD) was prepared successfully by freeze-drying. The products was evaluated by structural characterization, solubilization test, in-situ absorption of rat intestinal tract and pharmacokinetic study. In addition, thermodynamic studies were performed, the results indicated that the inclusion process was enthalpy-determined and exothermic nature of complexation, signifying the role of steric interactions in complex formation. Molecular docking of AGM with HPβ-CD has been conducted as well to verify the experimental findings and predict the stable molecular structure of the inclusion complex. The in vivo data showed that, AGM was mainly absorbed in duodenum and jejunum by passive diffusion. AGM/HPβ-CD inclusion complex displayed earlier Tmax and higher Cmax, and the AUC0-12h was approximately twice larger than its physical mixture. These results suggested that AGM/HPβ-CD inclusion complex was established with 1:1 stoichiometry through the naphthalene group of AGM and it was deeply inserted into the cavity of HPβ-CD, and the inclusion complex could significantly enhance the oral bioavailability of AGM.

Improvement of pharmacokinetic and antitumor activity of layered double hydroxide nanoparticles by coating with PEGylated phospholipid membrane

Layered double hydroxide (LDH) has attracted considerable attention as a drug carrier. However, because of its poor in vivo behavior, polyethylene glycolylated (PEGylated) phospholipid must be used as a coformer to produce self-assembled core–shell nanoparticles. In the present study, we prepared a PEGylated phospholipid-coated LDH (PLDH) (PEG-PLDH) delivery system. The PEG-PLDH nanoparticles had an average size of 133.2 nm. Their core–shell structure was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy. In vitro liposome-cell-association and cytotoxicity experiments demonstrated its ability to be internalized by cells. In vivo studies showed that PEGylated phospholipid membranes greatly reduced the blood clearance rate of LDH nanoparticles. PEG-PLDH nanoparticles demonstrated a good control of tumor growth and increased the survival rate of mice. These results suggest that PEG-PLDH nanoparticles can be a useful drug delivery system for cancer therapy.

Synthesis of novel tetravalent galactosylated DTPA-DSPE and study on hepatocyte-targeting efficiency in vitro and in vivo.

For the purposes of obtaining a hepatocyte-selective drug delivery system, a novel tetravalent galactosylated diethylenetriaminepentaacetic acid-distearoyl phosphatidylethanolamine (4Gal-DTPA-DSPE) was synthesized. The chemical structure of 4Gal-DTPA-DSPE was confirmed by proton nuclear magnetic resonance and mass spectrometry. The four galactose-modified liposomes (4Gal-liposomes) were prepared by thin-film hydration method, then doxorubicin (DOX) was encapsulated into liposomes using an ammonium sulfate gradient loading method. The liposomal formulations with 4Gal-DTPA-DSPE were characterized by laser confocal scanning microscopy and flow cytometry analysis, and the results demonstrated that the 4Gal-liposomes facilitated the intracellular uptake of DOX into HepG2 cells via asialoglycoprotein receptor-mediated endocytosis. Cytotoxicity assay showed that the cell proliferation inhibition effect of 4Gal-liposomes was higher than that of the conventional liposomes without the galactose. Additionally, pharmacokinetic experiments in rats revealed that the 4Gal-liposomes displayed slower clearance from the systemic circulation compared with conventional liposomes. The organ distributions in mice and the study on frozen sections of liver implied that the 4Gal-liposomes enhanced the intracellular uptake of DOX into hepatocytes and prolonged the circulation. Taken together, these results indicate that liposomes containing 4Gal-DTPA-DSPE have great potential as drug delivery carriers for hepatocyte-selective targeting.

Application of a continuous intrinsic dissolution-permeation system for relative bioavailability estimation of polymorphic drugs.

A new continuous dissolution-permeation system, consisting of an intrinsic dissolution apparatus and an Ussing chamber, was developed for screening and identification of high-bioavailability polymorphisms at pre-formulation stages. Three different solid forms of two model drugs (agomelatine and carbamazepine) were used to confirm the systems predictive ability. Ranks for cumulative permeation of the three solids were: Form III>Form I>Form II for agomelatine, and Form III>Form I>the dihydrate form for carbamazepine. Regression analysis of these parameters and published pharmacokinetics confirmed linear IVIVCs (most correlation coefficients >0.9). To confirm dissolution-absorption relationships, permeability coefficients were calculated. Relatively constant values among various polymorphisms for each drug supported a linear dependency between polymorphism-increased dissolution and polymorphism-enhanced permeation. A combined analysis of intrinsic dissolution rates and permeability coefficients revealed that both drugs are of the BCS II class and have dissolution-limited absorption. In conclusion, our new system was valuable not only for high-bioavailability polymorphism screening, but also for drug classification within the BCS system.

Near infrared light triggered reactive oxygen species responsive nanoparticles for chemo-photodynamic combined therapy

Currently, the strategy of combining photodynamic therapy (PDT) and chemotherapy for enhancing cancer therapeutic efficiency has aroused extensive interest. Nonetheless, weaknesses such as low local concentration, uncontrollable release of the drug, a non-suitable treatment light source, and a low response to the tumor site of PDT lead to the combined treatment effect not being ideal. Herein, we proposed simple and intelligent ROS-responsive zinc phthalocyanine sensitized TiO2 nanoparticles which conjugated with chlorambucil (CBL) (mTiO2-BCBL@ZnPC NPs) in an attempt to solve these issues. Not only were the nanoparticles triggered in near infrared radiation (NIR) for PDT with various reactive oxygen species (ROS) being generated, but the nanoparticles also realized the controllable release of CBL by H2O2, a major kind of ROS, through cleavage of the phenylboronic ester between CBL and the nanoparticle. Impressively, the controllable release of CBL under NIR irradiation showed an on-off characteristic and time dependency. In addition, the well-defined mTiO2-BCBL@ZnPC NPs with a 30 nm average diameter showed good stability and biocompatibility. The in vitro cytotoxicity studies demonstrated that the mTiO2-BCBL@ZnPC NPs were more cytotoxic under NIR irradiation than the mTiO2@ZnPC NPs and CBL, while the mTiO2-BCBL@ZnPC NPs were less cytotoxic under dark conditions. The above results implied that photo-controlled drug release is a promising choice for cancer therapy due to its high selectivity, good safety and low side-effects, and would be expected to be used in chemo-photodynamic combined therapy for improving the therapeutic efficiency.

Discovery of 3-n-butyl-2,3-dihydro-1H-isoindol-1-one as a potential anti-ischemic stroke agent

To develop novel anti-ischemic stroke agents with better therapeutic efficacy and bioavailability, we designed and synthesized a series of 3-alkyl-2,3-dihydro-1H-isoindol-1-ones compounds (3a–i) derivatives, one of which (3d) exhibited the strongest inhibitory activity for the adenosine diphosphate-induced and arachidonic acid-induced platelet aggregation. This activity is superior to that of 3-n-butylphthalide and comparable with aspirin and edaravone. Meanwhile, 3d not only exhibited a potent activity in scavenging free radicals and improving the survival of HT22 cells against the reactive oxygen species-mediated cytotoxicity in vitro but also significantly attenuated the ischemia/reperfusion-induced oxidative stress in ischemic rat brains. Results from transient middle cerebral artery occlusion and permanent middle cerebral artery occlusion model, indicated that 3d could significantly reduce infarct size, improve neurobehavioral deficits, and prominently decrease attenuation of cerebral damage. Most importantly, 3d possessed a very high absolute bioavailability and was rapidly distributed in brain tissue to keep high plasma drug concentration for the treatment of ischemic strokes. In conclusion, our findings suggest that 3-alkyl-2,3-dihydro-1H-isoindol-1-ones, a novel series of compounds, might be candidate drugs for the treatment of acute ischemic strokes, and 3d may be a promising therapeutic agent for the primary and secondary prevention of ischemic stroke.

Systemic toxicity induced by aggregated layered double hydroxide nanoparticles

Layered double hydroxide (LDH) nanoparticles are emerging as one of the promising nanomaterials for biomedical applications, but their systemic toxicity in vivo has received little attention. In the present study, the effects of inorganic nanoparticle aggregation on their systemic toxicity were examined. Remarkably, aggregation was observed after the mixing of naked LDH nanoparticles with saline or erythrocytes. Significant accumulation of the naked LDH nanoparticles in the lungs of mice was detected 1 h after intravenous administration, and the survival rate of mice was 0% after 6 repeated injections. Furthermore, flocculent precipitates in the alveoli and congestion in the lung interstitium were observed in the dead mice. However, lipid membrane-coated LDH nanoparticles would not form aggregates and could be injected intravenously >6 times without causing death. These findings suggested that repeated injections of LDH were lethal even at low dose (30 mg/kg), and lipid membrane coating can be considered as an approach for reducing this risk.