Chlorin e6-loaded sonosensitive magnetic nanoliposomes conjugated with the magnetic field for enhancing anti-tumor effect of sonodynamic therapy.

In sonodynamic therapy (SDT), when Chlorin e6 (Ce6) accumulates in tumor tissues, its anti-tumor effect can be achieved by ultrasound activation. To increase the local drug concentration of Ce6 in tumor cells, we had established a novel drug delivery system, Ce6-loaded sonosensitive magnetic nanoliposome (Ce6/SML), which realized the targeting delivery by the external magnetic field. It was worth mentioning that the targeting release of Ce6/SML and the activation on Ce6 could be achieved simultaneously by ultrasound of SDT. In our study, after Ce6 was loaded into the sonosensitive magnetic nanoliposome (SML), the values of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in vitro and in vivo were determined, indicating the activation on Ce6 of ultrasound. The delivery system also displayed the tumor-targeting ability and anti-tumor activity, which associated with the determined tumor growth and expression levels of angiogenin (ANG), vascular endothelial growth factor (VEGF) and tumor necrosis factor-alpha (TNF-α). In conclusion, the Ce6/SML-SDT-Targeted delivery system could effectively enhance the anti-tumor activity of SDT and had a great potential application for the treatment of malignant tumors located in deep tissues.

Hydroxycamptothecin liposomes based on thermal and magnetic dual-responsive system: preparation, in vitro and in vivo antitumor activity, microdialysis-based tumor pharmacokinetics.

Due to the absence of lactone form of hydroxycamptothecin, the commercially available hydroxycamptothecin injection exhibits inefficient therapeutic effects. In this study, we constructed a novel delivery system (thermosensitive magnetic liposomes) that protects lactone form of hydroxycamptothecin from blood or water. After hydroxycamptothecin was loaded into the thermosensitive magnetic liposome (HCPT/TML), its in vitro and in vivo antitumor activity and microdialysis-based tumour pharmacokinetics were determined. The results demonstrated that HCPT/TMLs possessed favourable physicochemical features and significant cytotoxicity against the Huh-7 cells in vitro. In the in vivo antitumor study and tumour pharmacokinetics, HCPT/TMLs displayed effective targeting delivery and antitumor effects, which corresponded to the determined hydroxycamptothecin concentration in tumour tissue. In conclusion, this thermal and magnetic dual-responsive system can efficiently deliver hydroxycamptothecin to tumour tissue and has great potential application in cancer treatment.

An LC/MS quantitative and microdialysis method for cyclovirobuxine D pharmacokinetics in rat plasma and brain: The pharmacokinetic comparison of three different drug delivery routes.

To explore the brain-targeting of cyclovirobuxine D(CVB-D) after administered intranasally, the pharmacokinetics of CVB-D via three different drug delivery routes: intragastric (i.g.), intranasal (i.n.), and intravenous (i.v.) in rat brain and blood was compared. Firstly, an in vivo microdialysis method for sampling CVB-D in both plasma and brain of the rat was established. Secondly, a liquid chromatography-tandem mass spectrometry method has been developed and validated for determination of CVB-D in microdialysis samples. For plasma and brain microdialysis samples, liquid-liquid extraction was used and donepezil was chosen as internal standard. Both were followed by HPLC separation and positive electrospray ionization tandem mass spectrometry detection (ESI-MS/MS). Chromatographic separation was achieved on a agilent C18 column with a mobile phase of methanol-water (50:50, v/v) (pH 3.2) containing 0.1% formic acid and 5mM ammonium acetate. Mass spectrometric detection in the positive ion mode was carried out by selected reaction monitoring (MRM) of the transitions at m/z 403.4→372.3 for CVB-D and m/z 380.2→243.1 for donepezil (IS). Good linearities were obtained in the range of 10-4000ng/mL in rat microdialysates for CVB-D. The lowest limit of quantitation was 5ng/mL, with an extraction recovery >75%, and no significant matrix effects. Intra- and inter-day precisions were all <15% with accuracies of 97.26-116.20%. All of which proved that the established method was successfully applied to the pharmacokinetic study of CVB-D. Simultaneously, brain uptake and pharmacokinetic studies were performed by determination of CVB-D concentration in blood and brain respectively for CVB-D i.g., i.n. and i.v.. Results showed that the intranasal CVB-D could improve brain targeting and had advantages for direct nose to brain transport of CVB-D when compared with injection and oral delivery routes, which indicates that intranasal administration of CVB-D could be a promising approach for the treatment of cerebrovascular disease.

[Study of pharmacokinetics of nicotine in local brain by using microdialysis and stable labeled isotope].

The paper is to report the study of pharmacokinetics of transdermal administered nicotine in the brain of freely moving rat by using microdialysis with stable labeled isotope as internal standard. The pharmacokinetic behavior of nicotine in Sprague Dawley rat brain was investigated after intranasal administration (3.75 mg). Brain fluid samples were collected by intracerebral microdialysis with DL-nicotine as internal standard. Concentrations of nicotine and DL-nicotine in the sample were measured by HPLC-MS/MS. Main pharmacokinetic parameters were calculated and analyzed by Das 2.0 pharmacokinetic software. The recovery of nicotine and the delivery of DL-nicotine were the same. The fate of absorption and distribution was two compartment model and the values of t1/2alpha was 170.31 min, t1/2beta was 263.30 min and the AUC(0-infinity) was 2.75 x 10(5) microg x L(-1) min separately. DL-nicotine can be used to calibrate the recovery of nicotine, and the new method of stable isotope microdialysis can be used to study the pharmacokinetics of freely moving rat. It will make sense for the treatment of addiction of tobacco and provide a new thought for the research of pharmacokinetics-pharmacodynamic combination.

[Internal standard method to determine the recovery of nicotine in microdialysis].

The paper reports the evaluation of the feasibility of using internal standard method for the determination of nicotine recovery in microdialysis in vitro. This in vitro experiment included two conditions. Nicotine and codeine phosphate were dissolved in Ringer's solution. Nicotine, codeine phosphate and the mixture of them were perfused through the CMA30 linear probe separately to calculate the proportion of the recovery (or delivery) of nicotine to that of codeine phosphate. And then codeine was perfused through the probe which was immersed in nicotine solution with different concentrations to calculate the proportion, too. In another condition nicotine was dissolved in rat plasma. The rat plasma protein binding rate was determined by using retrodialysis and internal standard method in vitro. The results are as follows: the proportion of the recovery (or delivery) of nicotine to that of codeine phosphate was fairly stable. The delivery of codeine was independent of nicotine concentration in the external medium. Protein binding rate determined by retrodialysis was almost the same as that determined by internal standard method. It suggests that the internal standard method is an effective way in the determination of nicotine recovery and codeine phosphate can be used as the internal standard.

[Dynamic determination of sinomenine in skin by microdialysis].

OBJECTIVE: To explore the feasibility and advantages of using microdialysis as sampling method for dynamic determination of sinomenine in topical skin. METHODS: In this study, sinomenine was administered to the rats by transdermal drug delivery system and celiac injection. With microdialysis technique for sampling, the concentration of sinomenine in dialysate was determined by high performance liquid chromatography (HPLC). RESULTS: Under existing determination condition, topical drug concentration in the skin of rats was hard to be detected after sinomenine administered to the skin, but it could be detected after celiac injection. CONCLUSION: Microdialysis sampling method can be used to determine topical drug concentration in the skin dynamically, and this method is better than traditional methods obviously.

[Bioequivalence study of sinomenine patch by microdialysis].

OBJECTIVE: To study bioequivalence of Sinomenine patch made by different preparation process, and to testify feasibility and superiority of microdialysis as a new method in topical bioequivalence study. METHOD: Normal gel patch and liposome gel patch of sinomenine were prepared by different preparation, nude mouse served as the experimental subjects sampling method of drug in the skin was tissue homogenization microdialysis, and drug concentration in dialysate was determined by HPLC. RESULT: Results of tissue homogenization showed that liposome gel patch leads more remainder drug in the skin of nude mouse than normal gel patch, and results of microdialysis showed that liposome gel patch led higher instantaneous drug concentration than normal gel patch. Concentration-time curve of sinomenine in the skin accorded with the results of most dermal delivery systems studies over the world. CONCLUSION: Topical bioequivalence of liposome gel patch of sinomenine is higher than that of normal gel patch of sinomenine. Microdialysis can be used to study bioavailability and bioequivalence of different preparation.

[Study on determination of entrapment efficiency of sinomenine liposomes].

OBJECTIVE: To establish an HPLC method for the determination of entrapment efficiency of sinomenine liposomes. METHOD: The liposomes and dissociated drugs were separated by sephadex filtration, mini-column centrifugation and dialysis. The methodology study and the optimization of determining condition were carried out at the same time. RESULT: Sephadex filtration could effectively separate the sinomenine liposomes from dissociated sinomenine. The column recovery was 98.8%, the average entrapment efficiency of three tests was64.9%, RSD 2.67%. CONCLUSION: The method was simple, exact, and had a good reappearance. It can be used to examine the entrapment efficiency of sinomenine liposomes.