Preparation of propranolol hydrochloride cubosomes by pH gradient method / 药学实践杂志

Objective To prepare propranolol hydrochloride loaded cubosomes (PPL-Cubs) with high entrapment efficiency. Methods PPL-Cubs was prepared by pH gradient method. Pressure and cycles of high pressure homogenization, dosage of glyceryl monooleate and poloxamer 407 were optimized to prepare blank cubosomes with particle size and polydispersity index as the indexes. The influences of various factors, including exterior pH values, internal pH values, the ratio of carrier to drug, particle size and polydispersity index of blank cubosomes, incubation temperature and time, and drug concentration on the entrapment efficiency were investigated. Results The blank cubosomes with small particle size and polydispersity index was prepared under homogenization conditions of 900 bar for 7 cycles, glyceryl monooleate dosage of 25%, and poloxamer 407 dosage of 5%. PPL-Cubs showed high entrapment efficiency with exterior pH value of 8.5, internal pH value of 3.0, ratio of carrier to drug of 6∶1, incubation temperature of 20 ℃, and incubation time of 15 min, and drug concentration of 1%. The particle size and polydispersity index of blank cubosomes showed no influence on entrapment efficiency. Conclusion PPL-Cubs with high entrapment efficiency could be prepared under the pH gradient method.

The reversed intra- and extracellular pH in tumors as a unified strategy to chemotherapeutic delivery using targeted nanocarriers

Solid tumors are complex entities, comprising a wide variety of malignancies with very different molecular alterations. Despite this, they share a set of characteristics known as "hallmarks of cancer" that can be used as common therapeutic targets. Thus, every tumor needs to change its metabolism in order to obtain the energy levels required for its high proliferative rates, and these adaptations lead to alterations in extra- and intracellular pH. These changes in pH are common to all solid tumors, and can be used either as therapeutic targets, blocking the cell proton transporters and reversing the pH changes, or as means to specifically deliver anticancer drugs. In this review we will describe how proton transport inhibitors in association with nanocarriers have been designed to block the pH changes that are needed for cancer cells to survive after their metabolic adaptations. We will also describe studies aiming to decrease intracellular pH in cancer using nanoparticles as molecular cages for protons which will be released upon UV or IR light exposure. Finally, we will comment on several studies that have used the extracellular pH in cancer for an enhanced cell internalization and tumor penetration of nanocarriers and a controlled drug delivery, describing how nanocarriers are being used to increase drug stability and specificity.

Preparation of dl-tetrahydropalmatine ethosomes and their ex vivo transdermal permeation properties / 中草药

Objective To prepare dl-tetrahydropalmatine (dl-THP) ethosomes (ETS) and elucidate their transdermal absorption properties. Methods Dl-tetrahydropalmatine ethosomes (dl-THP ETS) were prepared by ethanol injection combined with pH-gradient active drug-loading method. Their physicochemical properties including elasticity, vesicle size, morphology and entrapment efficiency were characterized. Franz diffusion cells were used to investigate the ex vivo skin permeation characteristics of the formulation with liposomes (LPS) and tinctures being used as reference preparations. Results According to a preferred formulation of dl-THP ETS [dl-THP 100 mg, vitamin E 1.3 mg, soybean lecithin 1 200 mg, cholesterol 120 mg, absolute ethanol 9 mL and citrate buffered saline (pH 3.0) 21 mL, 0.1 mol/L NaOH solution suitable quantity (to adjust the pH value to 5.5) ], the obtained dl-THP ETS had an elasticity index of (20.1 ± 1.1) mL, an average size of (85.8 ± 0.9) nm with a polydispersity index of (0.082 ± 0.003) and an entrapment efficiency of (81.7 ± 3.2)%. The cumulative permeated drug quantity per unit area (Qn) of dl-THP ETS in 24 h was (2 306.4 ± 592.3) μg/cm2 with no significant difference compared with the Qn of the LPS [(2 434.2 ± 564.4) μg/cm2] (P > 0.05) and about 4 times of that of the tincture [(633.1 ± 218.0) μg/cm2] (P < 0.05). And the averages of RSD of the Qn at each time point were (28.37 ± 10.9)% and (62.83 ± 44.1)% for the ETS and LPS, respectively, indicating that the Qn fluctuation among samples of the ETS was smaller than that of the LPS (P < 0.05). Average correlation coefficients of (0.968 ± 0.033) and (0.882 ± 0.078) (P < 0.05) were obtained for the ETS and LPS respectively when their 24 h permeation curves were fitted to linear relationship, indicating the permeation of the former was closer to zero-order kinetics than that of the latter. Conclusion The dl-THP ETS have a high elasticity, a suitable size, a high entrapment efficiency, and enhanced and stable percutaneous absorption in line with zero-order kinetics.

Preparation and evaluation of novel purine derivative F7 thermosensitive liposome / 国际药学研究杂志

Objective To prepare F7 thermosensitive liposome and evaluate its physicochemical properties, then investigate its cytotoxicity against tumor cells in vitro. Methods The F7 thermosensitive liposome was prepared by the pH gradient active drug loading method using dipalmitoyl phosphatidylcholine myristoyl lyso-phosphocholine and 1, 2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy (polyethylene glycol)-2000 as membrane materials. The encapsulation efficiency and drug loading were determined for the F7 thermosensitive liposome by HPLC. The phase transition temperature of F7 thermosensitive liposome was investigated by differential scanning calorimetry;the liposome morphology was observed by atomic force microscopy;the drug release of liposome was examined by dialysis;and the particle size and zeta potential were measured through Malvern particle size analyzer. The cytotoxicity of F7 and F7 thermosensitive liposome was determined by the MTT method, and the freeze-drying process was optimized using the designexpert software. Results The encapsulation efficiency of F7 thermosensitive liposomes was (97.56±0.22) ％, and the drug loading ratio was (1.51±0.01) ％. The phase transition temperature of F7 thermosensitive liposome was 39.9℃, the zeta potential was (-15.10±0.85) mV, the particle size was (86.94±1.21) nm, and the poly disperse coefficient was 0.17±0.01. Compared with the F7 injection, the F7 thermosensitive liposomes showed a stronger, dose-dependent inhibitory effect on the growth of lung cancer H1299 and breast cancer MCF-7 cells. The freeze-dried powder of liposomes dissolved well with the encapsulation efficiency of 95％ and the particle size of approximately 130 nm. Conclusion The F7 thermosensitive liposome prepared by the pH gradient active drug loading method has high encapsulation efficiency and good stability. The preparation method is simple and feasible for further development of the F7 preparation.

Mitochondrial ATPase activity and membrane fluidity changes in rat liver in response to intoxication with Buckthorn (Karwinskia humboldtiana)

BACKGROUND: Karwinskia humboldtiana (Kh) is a poisonous plant of the rhamnacea family. To elucidate some of the subcellular effects of Kh toxicity, membrane fluidity and ATPase activities as hydrolytic and as proton-pumping activity were assessed in rat liver submitochondrial particles. Rats were randomly assigned into control non-treated group and groups that received 1,1.5 and 2 g/Kg body weight of dry powder of Kh fruit, respectively. Rats were euthanized at day 1 and 7 after treatment. RESULTS: Rats under Kh treatment at all dose levels tested, does not developed any neurologic symptoms. However, we detected alterations in membrane fluidity and ATPase activity. Lower dose of Kh on day 1 after treatment induced higher mitochondrial membrane fluidity than control group. This change was strongly correlated with increased ATPase activity and pH gradient driven by ATP hydrolysis. On the other hand, membrane fluidity was hardly affected on day 7 after treatment with Kh. Surprisingly, the pH gradient driven by ATPase activity was significantly higher than controls despite an diminution of the hydrolytic activity of ATPase. CONCLUSIONS: The changes in ATPase activity and pH gradient driven by ATPase activity suggest an adaptive condition whereby the fluidity of the membrane is altered.

Preparation and Characterization of Vinorelbine Bitartrate Long-circulation Liposome / 医药导报

Objective To prepare vinorelbine bitartrate long-circulation liposomes by pH gradient loading methods and make characterization. Methods The impact of hydration temperature and extrusion times on the blank liposome particle size was investigated;and the incubation temperature and in duration on size and encapsulation percentage of drug loading liposome particle was tested. The vinorelbine bitartrate long-circulation liposome was characterized for particle size,polydispersion index, Zeta potential,morphology,and was studied for long term stability. Results The particle size,Zeta potential,polydispersion in-dex of long-circulation liposomes were (96. 4±27. 2) nm,(0. 162±0. 042),(-26. 7±3. 5) mV,respectively. The liposomes were small,unilamellar and spherical with smooth surface under transmission electron microscopy. Long term stability studies showed that the liposomes were stable for up to 3 months after storage at 5 ℃ . Conclusion The preparation technology for the vinorel-bine bitartrate long-circulation liposome by pH gradient loading methods is feasible.

Preparation of vinorelbine tartrate liposomes injection by different methods and their properties and antitumor effects / 中国药学杂志

RESULTS: All EEs of the three VLIs were over 93%. The mean diameters, Zeta potentials and entrapment efficiencies of the three VLIs were similar. Meanwhile the three VLIs were stable in the long-term stability test. The cryo-TEM showed that almost all vesicles had spherical structure and uniform nanosize. Furthermore, some colloid substances and acicular crystal were found inside VLI-2 and VLI-3, respectively. The release rate of VLI-3 was slower, which indicated that the drug crystal probably influence the in vitro drug release. The pharmacodynamic test showed that the antitumor effect of VLI-3 was better than VLI-2 and VLI-1, while those of the latter two were superior to VI.

Preparation of berberine hydrochloride liposomes by a new pH gradient method / 中国药学杂志

OBJECTIVE: To prepare berberine hydrochloride liposomes and investigate the influence of different factors on the entrapment efficiency. METHODS: Berberine hydrochloride liposomes were prepared by a novel pH gradient method. The transmembrane gradient was set up by ion exchange resin. UV-visible spectrophotometry and laser particle analyzer were applied to determine the entrapment efficiency and the size of berberine hydrochloride liposomes, respectively. The influences of various factors, including exterior pH values, the basic solutions of external water phase, phospholipids, incubation temperature and time, adding sequence and the ratio of drug to lipid, on the entrapment efficiency were investigated. RESULTS: Entrapment efficiency increaced with higher pH values, the best basic solution is phosphate buffer and HSPC is the most suitable phospholipid, the entrapment efficiency was enhanced by increacing incubation temperature and time, not affected by adding sequence, and the optimal ratio of drug to lipid was 1: 10. The entrapment efficiency of berberine hydrochloride liposomes under the optimum conditions was (98.6 ± 0.68)% (n = 3), and the mean diameter was 124.1 nm. CONCLUSION: The berberine hydrochloride liposomes with high entrapment efficiency are prepared by a novel pH gradient method, and the method is proved to be feasible. Copyright 2013 by the Chinese Pharmaceutical Association.

Preparation and in vitro evaluation of ofloxacin liposomes for increasing bacteria sensitivity / 中国药学杂志

OBJECTIVE: To prepare ofloxacin liposomes for increasing bacteria sensitivity, and lo evaluate its in vitro properly. METHODS: Ofloxacin liposomes were prepared by pH gradient method using phospholipid and cholesterol as materials. The effects of pH value and the warming temperature and time on encapsulation efficiency were investigated. The particle size of liposomes was determined and the morphology was investigated by transmission electric microscope (TEM). The in vitro release experiment was carried out vising physiological saline as the medium. The bacteriostatic action against Staphylococcus aureus was investigated using disc diffusion test and dilution test. RESULTS: The maximum encapsulation efficiency of 82.40% could be achieved when pH value was 7.0, warming temperature was 50°C and warming time was 5 min. The average particle size of the liposomes was 174nm, and the ofloxacin liposomes showed good morphology under TEM. The liposomes could release ofloxacin in a sustained manner in vitro. The ofloxacin liposomes and solution showed same inhibition zones in disc diffusion test, while their minimal inhibitory concentrations determined by dilution test were 0.39 and 0.78μg · mL-1, respectively. CONCLUSION: Ofloxacin liposomes can be prepared by pH gradient method with high encapsulation efficiency, and the bacteriostatic effect of ofloxacin against Staphylococcus aureus can be improved by incorporating it into liposomes.

Preparation technology of sinomenine hydrochloride liposomes / 中草药

Objective: To prepare sinomenine hydrochloride (SIN-HCl) liposomes with high entrapment efficiency (EE) and to illustrate the effects of drug quantity and particle size on EE. Methods: Centrifugation sedimentation-centrifugation ultrafiltration was employed to determine EE of liposomes. Thin film hydration (TFH), reverse phase evaporation (REV), and ether injection (EI) were screened based on EE and formability of liposomes. The effects of water type, pH value, ion concentration of hydration liquid, pH gradient active drug loading, lecithin-cholesterol ratio, and drug-lipid ratio on EE of liposomes were investigated. The relationship between EE and the factors affecting the drug quantity and particle size was probed with a comprehensive design experiment. The stability of typical liposomes was evaluated at 4 °C. Results: The optimal preparation technology was TFH for SIN-HCl liposomes and citrate buffer solution (CBS) was the best hydration liquid. The liposome EE increased with the increase of pH values of CBS. When the pH value of CBS was fixed, the EE increased as a result of decrease in the ion concentration of CBS. pH gradient active drug loading led to increase of EE. The preferable hydration liquid for liposomes was CBS with pH value of 2.5. The optimal ratio of soybean lecithin to cholesterol was 6:1. Increasing ratios of SIN-HCl to soybean lecithin from 1:6 to 6:6 led to a slight decrease in EE of liposomes without probe signification. A quantitative relationship was established between the EE and drug quantity and liposome size. The EE of SIN-HCl liposomes prepared by certain particle size and drug quantity could reach over 80%. The typical liposomes showed a good stability. Conclusion: The technology of pH gradient active drug loading is able to prepare SIN-HCl liposomes with high EE.

Establishment of differential expression profiles from invasive and non-invasive pituitary adenomas / 中南大学学报(医学版)

Objective To establish high resolution, reproducible 2-dimensional electrophoresis (2-DE) profiles of invasive and non-invasive pituitary adenoma tissues and to identify differentially ex-pressed proteins between the invasive and non-invasive tissues. Methods The proteome from invasive and non-invasive pituitary adenomas tissues was dissected and analyzed by: (1) immobilized pH gradient two-dimensional polyacrylamide gel electrophoresis, (2) silver staining, (3) imageMaster 2-D software analysis, (4) peptide mass fingerprint based (PMS) on matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), and (5) database comparison. Results High-resolution 2-D patterns of invasive and non-invasive pituitary adenoma tissues were successfully produced and re-peated 3 times for each sample. An average of 1080±24 and 1035±28 spots were detected for invasive and non-invasive pituitary adenoma tissues, respectively. Additionally, 975±45 and 918±56 spots were found to have an average matching rate of 90.3% and 88.7% for invasive and non-invasive tissues, re-spectively. The spot positional deviation was (1.563±0.259) mm for IEF and (1.088±0.206) mm for SDS-PAGE. A total of 99 spots of differential expression were matched between the invasive and non-in-vasive pituitary adenoma tissues. Thirty differential proteins, some of which were involved in the regula-tion of cells cycle and signal transduction, were initially characterized by PMS. Conclusion The acquisi-tion of well-resolved and reproducible 2-D patterns of invasive and non-invasive pituitary adenoma tissues and the identification of differentially expressed proteins provides a proteome database for invasive pituita-ry adenomas.

Preparation of tetrandrine-doxorubicin complex liposomes and its release property in vitro / 中草药

Objective Selecting doxorubicin and tetrandrine as model drug to prepare complex liposomes, study the methods of preparation, and research its release property in vitro. Methods The formulation of tetrandrine-doxorubicin complex liposomes was optimized by three different kinds of methods. And the optimum formula was selected through the orthogonal test according to the entrapment efficiency. Results Tetrandrine-doxorubicin complex liposomes were prepared by (NH4)2SO4-gradient method combined with pH gradient method. One optimum recipe was founded that tetrandrine-doxorubicin complex liposomes/ egg phosphatidyl choline was 1∶20, egg phosphatidyl choline/cholesterol was 3∶1, pH value was 7.6, incubation temperature was 50 ℃, concentration of (NH4)2SO4 was 250 mmol/L. The doxorubicin completely released within 24 h, and the tetrandrine released within 16 h. Conclusion Tetrandrine-doxorubicin complex liposomes have high entrapment efficiency with fine-looking, which is better for the further studies

Preparation of harmine hydrochloride liposome by active loading method / 中草药

Objective To prepare a harmine hydrochloride liposome formulation with high encapsulation efficiency. Methods Preformulation investigation was carried out to obtain the drug physicochemical properties such as solubility and lgD in buffers of different pH value. Harmine hydrochloride was encapsulated into liposomes by active loading method. Encapsulation efficiency of liposomes was determined after the free drug was separated from liposome by ultrafiltration. The influence factors on the encapsulation efficiency including drug-lipid weight ratio, incubation temperature, pH value of external water phase were investigated. Results As the pH value increasing, the solubility of harmine hydrochloride was decreased, while the apparent oil-water distribution coefficient was increased. By active loading method, the encapsulation efficiency could be over 80% when the drug to lipid weight ratio was under 1∶5. The pH gradient between intervesicle and intravesicle obviously influenced the encapsulation efficiency, while incubation temperature had little effect on encapsulation efficiency. Conclusion Active loading is suitable for preparing harmine hydrochloride liposome with high encapsulation efficiency.

Preparation and quality control of tetrandrine-doxorubicin complex liposomes / 重庆医科大学学报

Objective:To prepare doxorubicin-tetrandrine complex liposomes for technology study and quality control.In order to provide a new idea to reverse the tumor multidrug resistance in clinic.Methods:The formulations of doxorubicin-tetrandrine complex liposomes were optimized by three different kinds of methods.And the optimum formula was selected according to the entrapment efficiency.Re- sults:The complex liposomes were prepared by(NH4)2SO4-gradient method combined with pH gradient method according to optimum recipe.The optimum recipe of DOX-TET liposome was founded as DOX-TET/EPC of 1∶10,EPC/Ch of 3∶1,pH value of 7.6,incubation temperature of 50℃,(NH4)2SO4 concentration of 250 mmol/L.Under the formulation,DOX and TET were encapsulated 90.77%and 80.12%,respectively.Conclusion:The doxorubicin-tetrandrine complex liposomes have high entrapment efficiency with fine looking, which provides basis for the further studies.