pH-activatable oxidative stress amplifying dissolving microneedles for combined chemo-photodynamic therapy of melanoma.

Photodynamic therapy (PDT)-mediated oxidation treatment is extremely attractive for skin melanoma ablation, but the strong hydrophobicity and poor tumor selectivity of photosensitizers, as well as the oxygen-consuming properties of PDT, leading to unsatisfactory therapeutic outcomes. Herein, a tumor acidic microenvironment activatable dissolving microneedle (DHA@HPFe-MN) was developed to realize controlled drug release and excellent chemo-photodynamic therapy of melanoma via oxidative stress amplification. The versatile DHA@HPFe-MN was fabricated by crosslinking a self-synthesized protoporphyrin (PpIX)-ADH-hyaluronic acid (HA) conjugate HA-ADH-PpIX with "iron reservoir" PA-Fe3+ complex in the needle tip via acylhydrazone bond formation, and dihydroartemisinin (DHA) was concurrently loaded in the hydrogel network. HA-ADH-PpIX with improved water solubility averted undesired aggregation of PpIX to ensure enhanced PDT effect. DHA@HPFe-MN with sharp needle tip, efficient drug loading and excellent mechanical strength could efficiently inserted into skin and reach the melanoma sites, where the acidic pH triggered the degradation of microneedles, enabling Fe-activated and DHA-mediated oxidation treatment, as evidenced by abundant reactive oxygen species (ROS) generation. Moreover, under light irradiation, a combined chemo-photodynamic therapeutic effect was achieved with amplified ROS generation. Importantly, the Fe-catalyzed ROS production of DHA was oxygen-independent, which work in synergy with the oxygen-dependent PDT to effectively destroy tumor cells. This versatile microneedles with excellent biosafety and biodegradability can be customized as a promising localized drug delivery system for combined chemo-photodynamic therapy of melanoma.

Tumor-targeted hyaluronic acid-based oxidative stress nanoamplifier with ROS generation and GSH depletion for antitumor therapy.

Tumor cells with innate oxidative stress are more susceptible to exogenous ROS-mediated oxidative damage than normal cells. However, the generated ROS could be scavenged by the overexpressed GSH in cancer cells, thus causing greatly restricted efficiency of ROS-mediated antitumor therapy. Herein, using cinnamaldehyde (CA) as a ROS generator while ß-phenethyl isothiocyanate (PEITC) as a GSH scavenger, we designed a tumor-targeted oxidative stress nanoamplifier to elevate intracellular ROS level and synchronously suppress antioxidant systems, for thorough redox imbalance and effective tumor cells killing. First, an amphiphilic acid-sensitive cinnamaldehyde-modified hyaluronic acid conjugates (HA-CA) were synthesized, which could self-assemble into nano-assembly in aqueous media via strong hydrophobic interaction and π-π stacking. Then, aromatic PEITC was appropriately encapsulated into HA-CA nano-assembly to obtain HA-CA/PEITC nanoparticles. Through enhanced permeability retention (EPR) effect and specific CD44 receptor-mediated endocytosis, HA-CA/PEITC nanoparticles could accumulate in tumor tissues and successfully release CA and PEITC under acidic lysosomal environment. Both in vitro and in vivo results showed that the nanoparticles could efficiently boost oxidative stress of tumor cells via generating ROS and depleting GSH, and finally achieve superior antitumor efficacy. This nanoamplifier with good biosafety provides a potential strategy to augment ROS generation and suppress GSH for enhanced oxidation therapy.

pH-responsive hyaluronic acid-based nanoparticles for targeted curcumin delivery and enhanced cancer therapy.

Curcumin (CUR) display promising antitumor effects, however, the poor water solubility severely limited its clinical application. To overcome this problem, polymeric nanocarriers have been adopted for targeted CUR delivery and enhanced cancer therapy. In this paper, utilizing an acid-labile hydrazone linkage, hydrophobic CUR was conjugated with hydrophilic hyaluronic acid (HA) to form amphiphilic HA-ADH-CUR conjugates, which could subsequently self-assemble to form nanoparticles (HA@CUR NPs) in aqueous. The in vitro drug release experiments showed that HA@CUR NPs exhibited a pH-responsive CUR release behavior, and the release rate of CUR was 73.5 % in pH 5.0. Further, in vitro cell experiments showed HA@CUR NPs could be efficiently internalized by 4T1 and MCF-7 cancer cells through CD44 receptor mediated endocytosis and successfully release CUR in acidic lysosome environment for chemotherapy. In vivo antitumor experiments showed that, compared to free CUR, HA@CUR NPs could efficiently cumulate in tumor site via EPR effect and CD44 mediated endocytosis, achieve superior therapeutic effect for tumor growth suppression. Therefore, HA@CUR NPs were a highly promising nanocarrier for hydrophobic CUR to realize enhanced cancer therapy with good biosafety.

Calcium phosphate nanoparticles functionalized with alendronate-conjugated polyethylene glycol (PEG) for the treatment of bone metastasis.

Because of the peculiarity of the bone microstructure, the uptake of chemotherapeutics often happens at non-targeted sites, which induces side effects. In order to solve this problem, we designed a bone-targeting drug delivery system that can release drug exclusively in the nidus of the bone. Alendronate (ALN), which has a high ability to target to hydroxyapatite, was used to fabricate double ALN-conjugated poly (ethylene glycol) 2000 material (ALN-PEG2k-ALN). The ALN-PEG2k-ALN was characterized using 1H NMR and 31P NMR and FTIR. ALN-PEG2k-ALN-modified calcium phosphate nanoparticles (APA-CPNPs) with an ALN targeting moiety and hydrophilic poly (ethylene glycol) arms tiled on the surface was prepared for bone-targeted drug delivery. The distribution of ALN-PEG2k-ALN was tested by X-ray photoelectron spectroscopy. Isothermal titration calorimetry data indicated that similar to free ALN, both ALN-PEG2k-ALN and APA-CPNPs can bind to calcium ions. The bone-binding ability of APA-CPNPs was verified via ex vivo imaging of bone fragments. An in vitro release experiment demonstrated that APA-CPNPs can release drug faster in an acid environment than a neutral environment. Cell viability experiments indicated that blank APA-CPNPs possessed excellent biocompatibility with normal cells. Methotrexate (MTX) loaded APA-CPNPs have the same ability to inhibit cancer cells as free drug at high concentrations, while they are slightly weaker at low concentrations. All of these experiments verified the prospective application of APA-CPNPs as a bone-targeting drug delivery system.

Novel Galactosylated Poly(ethylene glycol)-Cholesterol for Liposomes as a Drug Carrier for Hepatocyte-Targeting.

In this study, three types of galactosylated cholesterol (i.e., gal-PEG194-chol, gal-PEG1000-chol and gal-PEG2000-chol) were synthesized with one terminal of polyethylene glycol of various chain lengths conjugated to the galactoside moiety, and the other terminal conjugated to the cholesterol. The galactose-modified liposomes were prepared by thin film-hydration method and doxorubicin (DOX) was loaded to the liposomes by using a ammonium sulfate gradient procedure. The liposomal formulations with galactosylated cholesterol were characterized. Flow cytometry and laser confocal scanning microscopy analyses showed that the galactose-modified liposomes facilitated the intracellular uptake of liposomes into HepG2 via asialoglycoprotein receptor (ASGP-R) mediated endocytosis. Cytotoxicity assay showed that the cell proliferation inhibition effect of galactose-modified liposomes was higher than that of the unmodified liposomes. Additionally, the study on frozen section of liver showed that the galactose-modified liposomes enhanced the intracellular uptake of liposomes into hepatocytes. Taken together, these results suggested that liposomes containing such galactosylated cholesterol (i.e., gal-PEG-chol), had a great potential as drug delivery carriers for hepatocyte-selective targeting.

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.

[Determination of vitexin in plasma by HPLC-MS/MS method and its pharmacokinetics in rats].

OBJECTIVE: To establish a HPLC-MS/MS method for the determination of vitexin in rat plasma and its pharmacokinetics. METHODS: The HPLC-MS/MS method used Capcell Pak C18 column (50 mm x 2.0 mm I. D., 5 microm). The mobile phase was methanol and water (95:5, V/V, containing 0.1% formic acid) at a flow rate of 0.2 mL/min. Electrospray ionization (ESI) in negative ion mode and multiple reaction monitoring (MRM) was used for the quantification of vitexin with a monitored transitions m/z 431-->311 for vitexin and m/z 269-->225 for internal standard (I. S., emodin). RESULTS: Linear calibration curves were obtained over the concentration range of 0.5-2000 ng/mL (r = 0.9960) with the lowest limit of quantification (LLOQ) of 0.5 ng/mL. The recovery was in the range of 76.1%-89.0%. The relative standard deviations for the intra-day and inter-day validation were less than 11%. CONCLUSION: The method is simple, accurate, fast, sensitive and suitable for the pharmacokinetic study of vitexin in rats.

[Effect of verapamil on pharmacokinetics of puerarin in rats].

OBJECTIVE: To investigate the effect of verapamil on the pharmacokinetics of puerarin in rats. METHOD: Puerarin with or without verapamil was administered intravenously or orally to rats. The concentration of puerarin in serum was determined by HPLC. RESULT: No significant difference was found between the control and 0.5 microg x g(-1) verapamil combined groups for intravenous administration, and there was significant difference between the control and 2. 5 microg x g(-1) verapamil combined groups (P < 0.05). When puerarin was administered orally with verapamil, significant difference was found between the control and combined groups (P < 0.05). CONCLUSION: Verapamil inhibited puerarin metabolism when puerarin was coadministered with verapamil, so it is necessary to change the therapeutic dose of puerarin.

[Preparation of self-microemulsifying soft capsule and investigation of dissolution for Duyiwei].

OBJECTIVE: To prepare the self-microemulsifying soft capsule (SMESC) of Duyiwei and investigate its dissolution property. METHODS: Through solubility experiment, self-microemulsification in vitro, drawing phase diagram and investigating the stability of solution, the optimum formulation was determined for Duyiwei. The dissolution of SMESC was measured, taking the commercial capsule as reference. RESULTS: In the optimum formulation, Labrasol, Transcutol P and ethyl oleate were screened as emulsifier, co-emulsifier and oil phase, respectively. The optimized proportion was 60: 25: 15. The dissolution of SMESC in water was more than 85% in 10 minutes, while that of the commercial capsule was less than 50% in 60 minutes. CONCLUSION: In comparison with the commercial capsule, the dissolution of SMESC is sufficiently improved in water.

[Assessment of Pueraria lobata isoflavone with self-microemulsifying drug delivery systems in vitro and in vivo].

OBJECTIVE: To evaluate the self-microemulsifying ability and dissolution behavior of pueraria lobata isoflavone in vitro and the pharmacokinetic behavior in rats. METHODS: The self-microemulsifying rate was evaluated by the self-microemulsifying time and the self-microemulsifying efficiency was evaluated by the particle size of resultant microemulsions. The plasma concentrations were evaluated by HPLC and dissolution and pharmacokinetic behavior of self-microemulsifying drug delivery systems were evaluated by comparison with commercial tablets. RESULTS: The system was self-microemulsified in 2 min and the particle size was less than 50 nm. The dis- solution of SMESC in distilled water was more than 90% at 10 min, while those of the commercial tablet were less than 50% at 120 min. 82% increase in the relative bioavailability was observed for the self microemulsifying drug delivery systems compared with Yufengningxin tablets. Tmax was smaller in the self-microemulsifying drug delivery systems compared with Yufengningxin tablets. CONCLUSION: The self-microemulsifying drug delivery systems can increase drug dissolution in vitro and absorption in vivo significantly.

Pharmacokinetic behaviors and oral bioavailability of oridonin in rat plasma.

AIM: To study the intravenous and oral pharmacokinetic behavior of oridonin and its extent of absolute oral bioavailability in rats. METHODS: Oridonin was administered to rats via iv (5, 10 and 15 mg/kg), po (20, 40 and 80 mg/kg) or ip administration (10 mg/kg). The concentrations of oridonin in rat plasma were determined by a high performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC/ESI-MS) method and the pharmacokinetic parameters were determined by non-compartmental analysis. RESULTS: The plasma concentration of oridonin after intravenous administration decreased polyexponentially, and the pharmacokinetic parameters of oridonin were dose-independent within the examined range. Oridonin was absorbed rapidly after oral gavage with a t(max) of less than 15 min; the extent of absolute bioavailability of oridonin following oral administration was 4.32%, 4.58% and 10.8%. The extent of absolute bioavailability of oridonin following intraperitoneal administration was 12.6%. CONCLUSION: First order rate pharmacokinetics were observed for oridonin within the range of iv doses, while the extent of absolute oral bioavailability was rather low and dose- dependent. The low and dose-dependent extent of oral bioavailability may be due to the saturation of first-pass effects.

Quantitative structure-retention relationship studies using immobilized artificial membrane chromatography I: amended linear solvation energy relationships with the introduction of a molecular electronic factor.

Linear solvation energy relationships (LSERs) amended by the introduction of a molecular electronic factor were employed to establish quantitative structure-retention relationships using immobilized artificial membrane (IAM) chromatography, in particular ionizable solutes. The chromatographic indices, log k(IAM), were determined by HPLC on an IAM.PC.DD2 column for 53 structurally diverse compounds, including neutral, acidic and basic compounds. Unlike neutral compounds, the IAM chromatographic retention of ionizable compounds was affected by their molecular charge state. When the mean net charge per molecule (delta) was introduced into the amended LSER as the sixth variable, the LSER regression coefficient was significantly improved for the test set including ionizable solutes. The delta coefficients of acidic and basic compounds were quite different indicating that the molecular electronic factor had a markedly different impact on the retention of acidic and basic compounds on IAM column. Ionization of acidic compounds containing a carboxylic group tended to impair their retention on IAM, while the ionization of basic compounds did not have such a marked effect. In addition, the extra-interaction with the polar head of phospholipids might cause a certain change in the retention of basic compounds. A comparison of calculated and experimental retention indices suggested that the semi-empirical LSER amended by the addition of a molecular electronic factor was able to reproduce adequately the experimental retention factors of the structurally diverse solutes investigated.

Self-microemulsifying drug delivery systems (SMEDDS) for improving in vitro dissolution and oral absorption of Pueraria lobata isoflavone.

The aim of our investigation was to develop and characterize self-microemulsifying drug delivery systems (SMEDDS) of Pueraria lobata isoflavone to improve its in vitro dissolution and oral absorption in beagle dogs. SMEDDS consisted of oil (ethyl oleate), a surfactant (Tween 80), and a cosurfactant (Transcutol P). In all the SMEDDS, the level of Pueraria lobata isoflavone was fixed at 20% w/w of the vehicle. The in vitro self-microemulsification properties and droplet size analysis of SMEDDS were studied following their addition to water under mild agitation. A pseudoternary phase diagram was constructed identifying the efficient self-microemulsification region. From these investigations, an optimized formulation was selected and its dissolution and bioavailability were compared with a tablet formulation in beagle dogs. The in vitro dissolution rate of puerarin from SMEDDS was more than threefold faster than that from Yufengningxin tablets (Pueraria lobata isoflavone tablets). A 2.5-fold increase in the relative bioavailability was observed for the SMEDDS compared with Yufengningxin tablets. The absolute bioavailability of the SMEDDS was 82.32 +/- 15.51%, which was significantly improved compared with that of Yufengningxin tablets. These results demonstrate the potential of SMEDDS as an efficient way of improving the oral absorption of Pueraria lobata isoflavone.

Study on the bioavailability of puerarin from Pueraria lobata isoflavone self-microemulsifying drug-delivery systems and tablets in rabbits by liquid chromatography-mass spectrometry.

To evaluate the bioavailability of puerarin from Pueraria lobata isoflavone self-microemulsifying drug delivery systems (SMEDDS) and Yufengningxin tablets, a rapid and specific liquid chromatography--mass spectrometric method was developed and validated to determine puerarin in rabbit serum. The analyte was extracted from serum samples by precipitating the serum proteins, separated on a Diamonsil C(18) column and detected by mass spectrometry with an electrospray ionization interface. 4-Hydroxybenzaldehyde was used as the internal standard. The method has a limit of quantitation of 10 ng/mL using 200 microL serum. The intra-day relative standard deviations (RSDs) ranged from 3.7 to 6.9% and inter-day RSDs were within 6.5%. After administration of SMEDDS and tablets to rabbits, a significant difference was observed in main pharmacokinetic parameters of t(max), C(max) and AUC(0--infinity) between SMEDDS and tablets, and a 2.2-fold increase in the relative bioavailability of puerarin was observed with the SMEDDS compared with Yufengningxin tablets. It was concluded that the absorption of puerarin from Pueraria lobata isoflavone SMEDDS was enhanced.

Determination of 3-n-butylphthalide in rabbit plasma by HPLC with fluorescence detection and its application in pharmacokinetic study.

A rapid, sensitive and specific reversed-phase high-performance liquid chromatographic method was developed for the determination of 3-n-butylphthalide, a drug currently being developed for treatment of stroke, in rabbit plasma. Fluorescence detection at an excitation wavelength of 280 nm and an emission wavelength of 304 nm was used for quantification of 3-n-butylphthalide. Ibuprofen was used as internal standard. Plasma samples were extracted with diethyl ether under acidic conditions. After evaporation of the organic phase, the extract was dissolved in mobile phase and injected into the chromatograph with C(18) column and a mobile phase of 0.05 mol/L sodium acetate buffer (pH 4.5)-acetonitrile (400:600). The peak area ratio vs concentration in plasma was linear over the range of 0.0212-4.24 microg/mL (correlation coefficient r = 0.9984) and the limit of quantification was 0.0212 microg/mL. Mean recovery was determined as 101.0% by analysis of plasma standard samples containing 0.0424, 0.424, 2.12 and 4.24 microg/mL of 3-n-butylphthalide. The intra-day relative standard deviations (RSDs) ranged from 3.6 to 8.9% and inter-day RSDs were within 8.0%. Pharmacokinetics of a single intravenous dose of 3-n-butylphthalide to the rabbits was presented to illustrate the applicability of this method. 3-n-Butylphthalide exhibited linear pharmacokinetics after intravenous administration to rabbits over the dose range 1-10 mg/kg.