Tumor immune checkpoint therapy and the drug delivery strategies / 药学学报

Tumor immune checkpoint therapy is a clinical treatment strategy developed based on the new principle of the inhibition of negative immune regulation. In this article, the tumor immune checkpoint therapy and the drug delivery strategies were reviewed, mainly including immunity and tumor therapy, tumor immune checkpoint therapy and its mechanism of action, clinical application of tumor immune checkpoint therapy and therapeutic drugs, immune resistance of programmed cell death protein 1 (PD1)/programmed cell death ligand 1 (PDL1) treatment and countermeasures, drug delivery strategies for tumor immune checkpoint therapeutic agents, etc. As a revolutionary new immunotherapy strategy, tumor immune checkpoint therapy has shown obvious superior therapeutic efficacy in a variety types of tumor. However, tumor immune checkpoint therapy is also faced with a big challenge, namely, immunotherapy resistance. With the discovery of new mechanism, the continuous development of new therapeutic drugs and delivery strategies, tumor immune checkpoint therapy is expected to further improve the clinical efficacy of tumor.

Spectrometric analyses of larotaxel and larotaxel liposomes quantification by high performance liquid chromatography / 北京大学学报(医学版)

OBJECTIVE@#Larotaxel is a new chemical structure drug, which has not been marketed worldwide. Accordingly, the standard identification and quantification methods for larotaxel remain unclear. The spectrometric analyses were performed for verifying weight molecular formula, molecular weight and chemical structure of larotaxel. Besides, a quantification method was developed for measuring larotaxel in the liposomes.@*METHODS@#The molecular formula, molecular weight and chemical structure of larotaxel were studied by using mass spectrometry (MS), infra-red (IR), nuclear magnetic resonance (NMR) and ultraviolet-visible (UV-vis) spectrometric techniques. The absorption wavelength of larotaxel was investigated by UV-vis spectrophotometry full-wavelength scanning. Besides, a quantification method was developed by high performance liquid chromatography (HPLC), and then validated by measuring the encapsulation efficacy of larotaxel liposomes.@*RESULTS@#The four spectral characteristics of larotaxel were revealed and the corresponding standard spectra were defined. It was confirmed that larotaxel had the structure of tricyclic diterpenoids, with the molecular formula of C45H53NO14, the molecular weight of 831.900 1, and the maximum absorption wavelength of 230 nm. The quantitative method of larotaxel was established by using HPLC with a reversed phase C18 column (5 μm, 250 mm×4.6 mm), a mobile phase of acetonitrile-water (75:25, volume/volume), and a detection wavelength of 230 nm. The validation study exhibited that the established HPLC method was stable, and had a high recovery and precision in the quantitative measurement of larotaxel in liposomes. In addition, a new kind of larotaxel liposomes was also successfully prepared. The particle size of the liposomes was about 105 nm, with an even size distribution. And the encapsulation efficiency of larotaxel in the liposomes was above 80%.@*CONCLUSION@#The present study offers reference standard spectra of larotaxel, including MS, IR, NMR, and UV-vis, and confirms the molecular formula, molecular weight and chemical structure of larotaxel. Besides, the study develops a rapid HPLC method for quality control of larotaxel liposomes.

Pharmacokinetics of epirubicin hydrochloride long-circulating thermosensitive liposomes in rat plasma / 药学学报

To develop and validate a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of epirubicin hydrochloride (EPI) in rat plasma, daunorubicin hydrochloride was used as internal standard. The plasma samples were deproteinated with methanol, and separation was performed on a reversed-phase CAPCELL PAK C18 column (3.0 mm x 50 mm, 3 microm). The mobile phase contained methanol-0.1% formic acid (80:20). Detection was carried out by multiple reaction monitoring on a HP1200-6410 QQQ LC/MS system. Different preparations of EPI solution, EPI-LIP (EPI-liposome) and EPI-LTSL (EPI-thermosensitive liposome) was administered in rats by i.v with the same dosage (12 mg kg(-1)). The pharmacokinetic model and parameters were fitted and calculated by the DAS ver2.0 software. The calibration curve was linear in the range of 0.01-50 microg mL(-1). The limit of quantification was 0.01 microg mL(-1). RSDs of intra- and interbatch precisions were all less than 11.9%. The average extract recovery was 89.3% and 92.1%, respectively. The pharmacokinetics of EPI in rats with all preparations were fitted to three compartments, which all fast distributed and slowly eliminated. The t1/2 alpha, t1/2 beta, t1/2 gamma, AUC(0-infinity), and MRT(0-infinity) of EPI-LTSL group were 7.5, 1.3, 12.6, 12.9, 3.7 times those of EPI solution group; and 1.6, 1.4, 12.3, 2.9, 2.6 times those of EPI-LIP group. Moreover, the CL of the latter two groups was about 13.4 times of the former EPI-LTSL group. EPI-LTSL can significantly improve AUC and prolong the circulation time of EPI in rat plasma.

Recent advances in liposomes and nanoparticles as drug carriers for drug delivery / 中国医学科学院学报

Liposomes and nanoparticles have been used as drug carriers to increase solubility, prolong drug duration in vivo, target drug delivery, reduce toxicity and combat multi-drug resistance. With major advances in the preparation techniques, preparation material, and surface modifiers in recent years, liposomes and nanoparticles delivery systems have achieved success in fields including cancer therapy, overcoming biological barriers, and biological drugs and vaccine carriage.

The in vitro cytotoxicity and in vivo toxicity of doxorubicin antiresistant stealth liposomes / 药学学报

<p><b>AIM</b>Multidrug resistance ( MDR) as a major obstacle to successful clinical cancer chemotherapy, searching a novel effective antiresistant drug would be necessary.</p><p><b>METHODS</b>A novel doxorubicin anti-resistant stealth liposomes (DARSLs) was prepared by co-encapsulating doxorubicin (DOX) and verapamil (VER) into stealth liposomes with ammonium sulfate gradient remote loading approach. In vitro cytotoxity of various DOX formulations and in vivo toxicity of DARSLs were evaluated using DOX-resistant rat prostate cancer cell line (MLLB2), human uterus sarcoma cell line (MES-SA/DX5) and normal SD rats, separately.</p><p><b>RESULTS</b>The DARSLs liposome suspensions mainly consisted of homogeneous large unilamellar vesicles (LUV) with average particle size of (118.1 +/- 22.3) nm. Encapsulation efficiencies of DOX and VER in DARSLs were more than 90% and about 70%, respectively, when the ratio of DOX/VER/Lipid was 1: 0.11 :10 (w/w/w). In vitro cytotoxicity tests of the DARSLs using rat prostate cancer cell line (MLLB2) and human uterus sarcoma cell line (MES-SA/DX5) showed that 5 micromol x L(-1) VER significantly reversed DOX-resistance of these 2 cell lines and DARSLs was the most effective on inhibition of DOX-resistant cell growth. Besides, compared to FDFV, much slower DOX distribution (confocal microscopy) to nuclei and cytoplasm in MLLB2 cells for DARSLs suggested that it might possess distinct mechanism of cytotoxicity. Systemic and cardiac toxicity evaluations in normal SD rats suggested that liposomal encapsulation could significantly improve the severe cardiotoxicity arising from simultanous administration of DOX and VER.</p><p><b>CONCLUSION</b>DARSLs is a novel anticancer liposome formulation with lower cardiotoxicity, effective drug-resistance reversal and intravenous injection.</p>

In vitro transdermal permeation of lidocaine-dodecanol binary eutectic system / 药学学报

<p><b>AIM</b>To study the effect of lidocaine-dodecanol binary eutectic system on the transdermal permeation of lidocaine.</p><p><b>METHODS</b>Binary eutectic mixture of different proportions of lidocaine and dodecanol were prepared and the patch containing the binary eutectic mixture was developed. The solubilities of pure lidocaine and lidocaine from the binary eutectic system were determined in pH 7.9 phosphate buffer. The transdermal flux of lidocaine from the patches containing the binary eutectic system and pure lidocaine were measured using Franz-type single diffusion cell.</p><p><b>RESULTS</b>The melting point of the lidocaine-dodecanol binary eutectic system was markedly lower than that of pure lidocaine. The steady state transdermal flux of lidocaine from the patch of the binary eutectic system was six times as much as that of pure lidocaine patch.</p><p><b>CONCLUSION</b>The lidocaine-dodecanol binary eutectic system could produce high thermodynamic activity of the drug and the high driving force for transdermal permeation of lidocaine.</p>

Preparation of doxorubicin-loaded stealth liposomes modified with RGD mimetic and cellular association in vitro / 药学学报

<p><b>AIM</b>To investigate the possibility of using stealth liposomes modified with arginine-glycine-aspartic acid (RGD) mimetic as the targeted carriers to achieve increased accumulation in tumor and enhanced intracellular delivery for the encapsulated anticancer drugs.</p><p><b>METHODS</b>RGD mimetic (RGDm) as a ligand for integrins was synthesized and covalently conjugated to the active PEGylated phospholipids (DSPE-PEG-BTC) to form RGDm conjugate (DSPE-PEG-RGDm). Then RGDm-modified SL (RGDm-SL) containing DOX (RGDm-SL-DOX) and SL containing DOX (SL-DOX) were prepared by film dispersion followed by ammonium sulfate gradient method. The pH-sensitive probe, BCECF-AM, was used to study the binding of melanoma cells to DSPE-PEG-RGDm. Flow cytometry and confocal microscopy were performed to evaluate the cellular association or DOX uptake for RGDm-SL-DOX or SL-DOX in vitro.</p><p><b>RESULTS</b>The melanoma cells A375 and B16 showed enhanced binding to the immobilized DSPE-PEG-RGDm. The cells treated with RGDm-SL-DOX showed remarkable increase in cellular association or DOX uptake compared with SL-DOX.</p><p><b>CONCLUSION</b>The RGDm-modified SL could be as the targeted carriers to facilitate the delivery of the encapsulated anti-cancer drugs into tumor cells by receptor-mediated way.</p>

Preparation of cyclosporine A pH sensitive nanoparticles and oral pharmacokinetics in rats / 药学学报

<p><b>AIM</b>To study the preparation conditions and its oral pharmacokinetic characteristics of cyclosporine A (CyA) pH sensitive nanoparticles.</p><p><b>METHODS</b>The CyA pH sensitive nanoparticles were prepared by the quasi-emulsion solvent diffusion technique (QESD). Male Sprague-Dawley (SD) rats weighing (250 +/- 20) g were selected and randomly divided into five groups. The bioavailability of CyA from nanoparticles and Neoral microemulsion were assessed at a dose of 15 mg x kg(-1) by gavage. The concentration of CyA in whole blood samples was detected by HPLC to evaluate the relative bioavailability of CyA pH sensitive nanoparticles.</p><p><b>RESULTS</b>The blood concentration profiles of CyA pH sensitive nanoparticles in rats fitted to two compartment models using 3P87 pharmacokinetic calculation program. Compared with the Neoral microemulsion, the relative bioavailability of CyA was 94.8%, 115.2%, 113.6% and 132.5% for CyA-E100, CyA-L100, CyA-L100-55 and CyA-S100 nanoparticles respectively.</p><p><b>CONCLUSION</b>CyA-S100 nanoparticles was shown to significantly improve the oral bioavailability of CyA compared with Neoral microemulsion (P < 0.05). While there were no significant differences between Neoral microemulsion and other CyA pH sensitive nanoparticles. With these results, the potential of pH-sensitive nanoparticles for the oral delivery of CyA was confirmed. Furthermore, this formulation approach can be used to improve the oral bioavailability of other poorly soluble and poorly absorbable drugs.</p>