Population pharmacokinetic study of caffeine citrate in Chinese premature infants with apnea.

WHAT IS KNOWN AND OBJECTIVES: Caffeine citrate is a commonly used methylxanthine for pharmacologic treatment of apnea of prematurity. The aim of this study was to develop and verify a population pharmacokinetic (PPK) model, which can provide a reference for individualized caffeine citrate treatment of apnea in Chinese premature infants. METHODS: A total of 88 serum concentration measurements from 46 preterm patients (median gestational age 29 weeks) were retrospectively collected and the relevant clinical data of patients were recorded. The PPK analysis was performed by non-linear mixed-effect modelling method using NONMEM. Allometric scaling was applied in the PPK analysis, and the final model was evaluated by graphic and statistical methods, including goodness-of-fit plots, normalized prediction distribution errors plots and bootstrap procedures. RESULTS: A one-compartment model with first-order elimination was successfully fitted to the data. The typical scaled values for the parameters clearance and volume of distribution (V) were 0.268 L/h and 109 L per 70 kg, respectively. The weight at the time of blood collection (CW) and post-natal age were identified as important predictors for pharmacokinetic parameters of caffeine. The evaluation process showed good stability and predictability of the final PPK model. WHAT IS NEW AND CONCLUSION: This is a complete PPK study of caffeine citrate in Chinese premature infants with apnea, which complements caffeine pharmacokinetic data of the premature from China. A final PPK model was developed which may serve as a beneficial tool for the use of caffeine citrate in the treatment of apnea in Chinese preterm infants.

Asiatic acid attenuates CCl4-induced liver fibrosis in rats by regulating the PI3K/AKT/mTOR and Bcl-2/Bax signaling pathways.

Liver fibrosis is a major pathological feature of chronic liver diseases, and effective therapies are limited at present. Asiatic acid (AA) is a triterpenoid isolated from Centella asiatica, which exhibits efficient anti-inflammatory and anti-oxidative activities. In this study, we attempted to evaluate the potential therapeutic effect of AA on CCl4-induced liver fibrosis in rats and to investigate the underlying molecular mechanisms. Liver fibrosis-related indexes including body weight, biochemical parameters, histological changes, the mRNA expression levels of inflammatory cytokines and biomarkers, and changes in the expression of related proteins in liver tissue were assessed. The results showed that AA treatment effectively ameliorated CCl4-induced liver injury and fibrosis. Mechanistically, AA treatment attenuated CCl4-induced oxidative stress, inflammation, and hepatocyte apoptosis and regulated the Bcl-2/Bax signaling pathway in the liver. Additionally, we demonstrated that AA also inhibited hepatic stellate cell activation and extra cellular matrix (ECM) synthesis by regulating the PI3K/AKT/mTOR signaling pathway. In conclusion, these findings suggest that AA prevents the progression of liver fibrosis through multiple mechanisms and indicate that AA might be used for the treatment of liver fibrosis in the future.

Copolymeric Micelles Loading Curcumin: Preparation, Characterization and In Vitro Evaluation.

Curcumin (Cur) has potent antitumor activity; however, its clinical use is limited due to its hydrophobicity and instability at physiological pH. In this work, Cur was incorporated into MPEG2K-P(CL-co-LLA) micelles to form the Cur-loaded micelles with drug loadings from 4.72% to 35.21% depending on the ratios of drug to MPEG2K-P(CL-co-LLA). The resulting Cur-loaded micelles were spherical with mean hydrodynamic diameters in the range of 28.8 to 58.6 nm, having excellent water-solubility and good stability at pH 7.4. The freeze-drying powders of the Cur-loaded micelles were easily rehydrated. It was found that Cur was slowly released from the micelles with a cumulative drug release percentage of 78.11% within 14 days and there was no obvious drug burst release. MTT tests showed that, the IC50 values of the Cur-loaded micelles were lower than those of free Cur against cancer cells (MDA-MB-231 cells and 4T1 cells). No matter for cancer cells (MDA-MB-231 cells and 4T1 cells) or healthy cells (L929 cells), cell viabilities were all >90% after incubating with the blank MPEG2K-P(CL-co-LLA) micelles, even at very high micelle concentration (up to 1000 µg/mL), indicating the blank micelles were of no or extremely low cytotoxicity per se. The Cur-loaded micelles were taken up mainly via endocytosis route and the cellular uptake on 4T1 cells increased with incubation time. They could induce more cell apoptosis compared to free Cur. These results suggested that curcumin-loaded MPEG2K-P(CL-co-LLA) micelles may be a potential nanoscale drug delivery system for cancer therapy.

Preparation and evaluation of pH-responsive charge-convertible ternary complex FA-PEI-CCA/PEI/DNA with low cytotoxicity and efficient gene delivery.

Because the surface of the cationic polymer gene complex is positively charged, it can result in problems such as poor blood stability and cytotoxicity. Therefore, reducing the positive charge of the cationic gene complex without affecting its transfection efficiency is crucial. To achieve this objective, a pH-responsive charge-convertible ternary complex was developed in this study. Modified plyethylenimine (PEI) with two different degrees of substitution of NH2 (plyethylenimine-1,2-cyclohexanedicarboxylic anhydride, PEI-CCA, and folic acid-plyethylenimine-1,2-cyclohexanedicarboxylic anhydride, FA-PEI-CCA) were first obtained by a chemical graft reaction. PEI-CCA and FA-PEI-CCA have significantly lower cytotoxicities and much better blood compatibilities than PEI does, and the former have an undifferentiated compression capability of DNA. The zeta potential values of the as-prepared ternary complexes (PEI-CCA/PEI/DNA and FA-PEI-CCA/PEI/DNA) were negative at pH 7.4 and positive at pH 6.5, with particle sizes of approximately 150nm. MTT assays demonstrated the significantly lower cytotoxicities of the ternary complexes compared to that of PEI/DNA. Moreover, the cytotoxicities of the ternary complexes were lower at pH 7.4 than pH 6.5. Transfection experiments in vitro revealed that the mean fluorescence intensities and transfection efficiencies of the ternary complexes were lower than for PEI/DNA at pH 7.4 but were almost the same at pH 6.5. The ternary complex with a FA group had significantly higher mean fluorescence intensity and transfection efficiency than did the ternary complex without it. In addition, the transfection experiment in 293T cells preliminarily validated the targeting function of the FA group of the ternary complex.

Evaluation of antibacterial activity of N-phosphonium chitosan as a novel polymeric antibacterial agent.

N-phosphonium chitosans (NPCSs) with different degrees of substitution (3%, 13% and 21%) were synthesized and evaluated as novel polymeric antibacterial agents. Their antibacterial activities compared with hydroxypropyltrimethyl ammonium chloride chitosan (HACC), parent chitosan and (5-carboxypentyl) triphenylphosphonium bromide (CTPB) were tested against Escherichia coli and two strains of drug-resistance Staphylococcus aureus by minimal inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and biofilm prevention assays. The results show that the NPCS with 3% or 13% substitution has lower MIC and MBC values and stronger ability to inhibit biofilm formation of all the three bacteria than HACC, chitosan and CTPB. In addition, the antibacterial activity of NPCSs increases with their substitution decreasing from 21% to 3%. Overall, the antibacterial activity of NPCS with 3% or 13% substitution is better than that of NPCS with 21% substitution, HACC with 22% substitution, chitosan and CTPB. It can be considered that NPCS with appropriate degree of substitution has favorable antibacterial activity and is a potential polymeric antibacterial agent.

Enhancing curcumin anticancer efficacy through di-block copolymer micelle encapsulation.

We report herein the development of a novel aqueous formulation and improved antitumor activity for curcumin by encapsulating it into a biocompatible and biodegradable poly(L-lactic acid) based poly(anhydride-ester)-b-poly(ethylene glycol) (PAE-b-PEG) micelle. The resulting curcumin loaded micelles were completely water-dispersible, overcoming the problem of poor water solubility that limited its efficacy and bioavailability. In vitro cellular studies revealed that the curcumin-loaded micelles were taken up mainly via endocytosis route and exhibited higher cytotoxicities toward model cancer cell lines (HeLa and EMT6) than free curcumin. An in vivo biodistribution study revealed that the curcumin-loaded micelles displayed significantly enhanced accumulation inside the tumor of EMT6 breast tumor-bearing mice. More impressively, the curcumin-loaded micelles showed stronger antitumor activity, higher anti-angiogenesis effects and induced apoptosis on the EMT6 breast tumor model bearing mice than free curcumin. Furthermore, the curcumin-loaded micelles showed no significant toxicity towards hemotological system, major organs or tissues in mice. Combined with a high antitumor activity and low toxic side-effects, the curcumin-loaded micelles developed here thus appear to be a highly attractive nanomedicine for effective, targeted cancer therapy.

Selective tissue distribution and long circulation endowed by paclitaxel loaded PEGylated poly(ε-caprolactone-co-L-lactide) micelles leading to improved anti-tumor effects and low systematic toxicity.

High tumor targeting and sustained drug concentration are key points for successful anti-tumor therapy, however, it is a challenging task. In this work, a novel micelle formulation of paclitaxel (PTX) has been prepared for the purpose of prolonging the blood circulation time as well as improving the accumulation of the drug within the tumor tissue. PEGylated P(CL-co-LLA) (poly(ε-caprolactone-co-L-lactide)) micelles containing PTX were prepared by solid dispersion-sonication method with a higher drug-loading efficiency and encapsulation ratio (28.4% and 94.7%, respectively). Pharmacokinetic study revealed that the drug-loading micelles exhibited a higher AUC values and a prolonged residence time of drug in the blood circulation than those of PTX injection. As demonstrated by tissue distribution and anti-tumor study in S180 tumor-bearing mice, the PEG-P(CL-co-LLA)/PTX micelles displayed modified tissue distribution of PTX and increased accumulation of PTX in tumor, therefore, resulted in anti-tumor effects enhancement and drug concentration in the normal tissues reduction. Furthermore, the preliminary safety tests were performed by measuring the body weight, histopathology, blood cell counts and clinical chemistry parameters, and the results showed no subacute toxicity to hematological system, major organs or tissues in mice. Taken together, our valuation shows that PEG-P(CL-co-LLA) micelles is a potential drug delivery system of PTX for the effective treatment of the tumor and systematic toxicity reduction, thus, the micellar formulation can provide a useful alternative dosage form for i.v. administration of PTX.

Synthesis, in vitro and in vivo evaluation of new norcantharidin-conjugated hydroxypropyltrimethyl ammonium chloride chitosan derivatives as polymer therapeutics.

New norcantharidin-conjugated hydroxypropyltrimethyl ammonium chloride chitosan derivatives (NCTD-HACCs) were synthesized and characterized by (1)H NMR, Fourier-transform infrared spectroscopy (FT-IR), and wide-angle X-ray diffraction (WAXD). Two NCTD-HACCs with different degrees of substitution (DS) (12.2% and 24.8%) were obtained, which had good water solubility. NCTD was released from the NCTD-HACCs via hydrolysis, faster in pH 5.0 than pH 7.4 and presenting one biphasic drug release pattern with rapid release at the initial stage and slow release later. Fluorescence microscope and flow cytometry analysis demonstrated that the NCTD-HACC was endocytosized into MGC80-3 cells and the uptaken amount increased as incubation time. Compared with free NCTD, the NCTD-HACCs showed lower in vitro anti-tumor activity against human gastric cancer MGC80-3 cells, but higher in vivo tumor growth inhibition in S180 tumor-bearing mice. The in vivo near-infrared (NIR) fluorescence real-time imaging result showed the fluorescence intensity in tumor was much higher than that in heart, liver, spleen and lung (except kidney) after i.v. injection of the FITC-labeled NCTD-HACC2, indicating specific accumulation of the NCTD-HACC in tumor.