International Journal of Pharmaceutics (v.315, #1-2)

The quaternized chitosan was synthesized by the reaction of chitosan and glycidyltrimethylammonium chloride (GTMAC) and named as N-[(2-hydroxy-3-trimethylammonium) propyl] chitosan chloride (HTCC). A novel hydrogel system composed of HTCC/glycerophosphate (HTCC/GP) with thermo- and pH-sensitivity was synthesized and used as an intelligent drug carrier. The formulation was solution below or at room temperature, which allowed it injectable and to incorporate living cells, proteins, enzymes or other therapeutic drugs easily. Once the surrounding temperature was up to 37 °C, the system was transformed to a non-flowing hydrogel, and the formed hydrogel can release the trapped drug as a function of pH values. The swelling behavior of the system and the release profiles of doxorubicin hydrochloride (DX) as a model drug at different pH values were investigated. At acidic condition the hydrogel dissolved and released drug quickly, while it absorbed water and released drug slowly at neutral or basic conditions. Hydrogel composed of chitosan hydrochloride and glycerophosphate (CS/GP) was also prepared to compare with HTCC/GP hydrogel. The HTCC/GP hydrogel in this study was transparent which made it suitable for some specific uses such as ocular drug formulation.
Keywords: Quaternized chitosan; Hydrogel; Injectable implant; Thermosensitivity; pH-sensitivity; Controlled release;

Study of an alginate/HPMC-based in situ gelling ophthalmic delivery system for gatifloxacin by Zhidong Liu; Jiawei Li; Shufang Nie; Hui Liu; Pingtian Ding; Weisan Pan (12-17).
The poor bioavailability and therapeutic response exhibited by conventional ophthalmic solutions due to rapid pre-corneal elimination of the drug may be overcome by the use of in situ gel-forming systems that are instilled as drops into the eye and then undergo a sol–gel transition in the cul-de-sac. The present work describes the formulation and evaluation of an ophthalmic delivery system of an antibacterial agent, gatifloxacin, based on the concept of ion-activated in situ gelation. Alginate (Kelton®) was used as the gelling agent in combination with HPMC (Methocel E50Lv) which acted as a viscosity-enhancing agent. The rheological behaviors of all formulations were not affected by the incorporation of gatifloxacin. Both in vitro release studies and in vivo pre-corneal retention studies indicated that the alginate/HPMC solution retained the drug better than the alginate or HPMC E50Lv solutions alone. These results demonstrate that the alginate/HPMC mixture can be used as an in situ gelling vehicle to enhance ocular bioavailability and patient compliance.
Keywords: Ophthalmic delivery system; In situ gelling; Alginate; HPMC; Gatifloxacin;

GW275919X, a central muscle relaxant for the treatment of lower back pain, exists in a monohydrate. Knowledge of the solid state dehydration behavior and the crystal structure is essential for determining its relative physical stability. Thermal analysis and hot-stage powder X-ray diffraction were used to study the solid state phase transformation during the dehydration process. Crystal structure was determined by single crystal X-ray analysis. Molecular modeling with Cerius2 software was used to visualize the hydrate crystal structure and to construct the molecular packing and hydrogen bond diagram. Morphology prediction was performed using the BFDH calculation. Crystallographic data: monoclinic, space group, P21/c, a (Å) = 14.3734, b (Å) = 5.0336, c (Å) = 15.4633 and β  = 105.11°. Water molecules in the hydrate crystal of GW275919X are involved in the hydrogen bonds and these hydrogen bonds contribute to the coherence of the crystal structure. The longest dimension of the predicted morphology is in the b-direction, which would correspond to the needle axis of the experimental crystals.
Keywords: GW275919 monohydrate; Dehydration; Hydration; Thermal analysis; PXRD; Modeling;

Arsenic release from glass containers by action of intravenous nutrition formulation constituents by Denise Bohrer; Emilene Becker; Paulo Cícero Nascimento; Vanessa Mörschbächer; Leandro Machado de Carvalho; Marieli da Silva Marques (24-29).
Pharmacopoeias prescribe tests to determine the levels of arsenic in raw materials and glass containers. In this study, glass ampoules for injectables containing individually the main components of intravenous nutrition formulations were submitted to the hydrolytic resistance test by heating at 121 °C for 30 min. As(V) and As(III) levels in these solutions after heating were determined by hydride generation atomic absorption spectrometry. The arsenic content of substances used in these formulations was previously determined, as well as the arsenic content of the glass containers. The results showed that raw substances as well as glass containers contain arsenic. Moreover, arsenic is released during the heating (hydrolytic resistance test). However, the amount released and the arsenic species present in solution depend on the solution composition. While As(V) was the predominant specie in glass, solutions containing reducing substances such as glucose and vitamins had As(III) in higher concentration. Therefore, arsenic is released from glass containers during the heating for sterilization, and reacts with formulation constituents depending on their reducing properties.
Keywords: Arsenic species; Intravenous nutrition; Glass; Contaminants;

Prototype daptomycin–dextran macromolecular conjugates were prepared in an attempt to modify the biodistribution and protein-binding properties of daptomycin. Synthesis of daptomycin macromolecular conjugates involved dextran activation, daptomycin–dextran coupling, and purification. The reaction mixtures were separated on a Sephadex G-100 column using 10% acetronitrile in water as a mobile phase. UV and fluorescence characteristics of high molecular weight fractions demonstrated imine product formation while the lower molecular weight fractions contained free daptomycin, imine, and anilide products. Daptomycin macromolecular conjugates were characterized by drug loading, drug release, and binding affinity for fibrinogen using HPLC analysis and surface plasmon resonance. Drug loading was calculated to be 160 mg of daptomycin per gram of macromolecule. Approximately 9% of the conjugated daptomycin was released from the macromolecular conjugates in aqueous media in the pH range of 1–7.4. The conjugates possessed higher affinity for fibrinogen than that of daptomycin.
Keywords: Aldehyde amine reaction; Surface plasmon resonance; Macromolecule; Drug loading; In vitro release; Peptide conjugation;

In vitro characterization and transfection of IL-2 gene complexes by Güzin Özgel; Jülide Akbuğa (44-51).
Interleukin-2 used in the treatment of malignant tumors has an anti-tumor efficacy. In this study, we have studied in vitro characterization and transfection efficiency of a plasmid encoding hIL-2, pCXWN–hIL-2, complexed to chitosan, polyethylenimine or DOTAP with varying ratios.Plasmid DNA was amplified in Escherichia coli DH5α and isolated by alkali lysis method. The pDNA/chitosan, pDNA/PEI or pDNA/DOTAP complexes were analyzed by agarose gel electrophoresis for complex formation and by ESEM image analysis system for the morphology and DNA/medium relationship of complexes. DNase stability, the particle size and zeta potential values of complexes were determined. Transfection efficiencies of resulting complexes in two different cell lines were assayed by ELISA method.Conclusively, a transfection activity was observed in both cell lines (HeLa and Swiss3T3) with the order of pDNA/DOTAP > pDNA/PEI > pDNA/chitosan complexes. We have observed that the transfection efficiency was higher in HeLa cell line compared to Swiss3T3 cell line.The physicochemical studies like stability, particle size and zeta potential, showed a relationship between the properties of a complex and its transfection efficiency.
Keywords: Interleukin-2; Chitosan; Polyethylenimine; DOTAP; Gene delivery; Non-viral;

Microemulsion-based hydrogel formulation of ibuprofen for topical delivery by Huabing Chen; Xueling Chang; Danrong Du; Jin Li; Huibi Xu; Xiangliang Yang (52-58).
The purpose of this study was to construct microemulsion-base hydrogel formulation for topical delivery of ibuprofen. Ethyl oleate (EO) was screened as the oil phase of microemulsions, due to a good solubilizing capacity of the microemulison systems and excellent skin permeation rate of ibuprofen. The pseudo-ternary phase diagrams for microemulsion regions were constructed using ethyl oleate as the oil, Tween 80 as the surfactant, propylene glycol as the cosurfactant. Various microemulsion formulations were prepared and the abilities of various microemulsions to deliver ibuprofen through the skin were evaluated in vitro using Franz diffusion cells fitted with porcine skins. The in vitro permeation data showed that microemulsions increased the permeation rate of ibuprofen 5.72–30.0 times over the saturated solution. The optimum formulation consisted of 3% ibuprofen, 6% EO, 30% Tween 80/PG (2:1) and water, showed a high permeation rate of 38.06 μg cm−2  h−1. Xanthan gum as a gel matrix was used to construct the microemulsion-based hydrogel for improving the viscosity of microemulsion for topical administration. The studied microemulsion-based hydrogel showed a good stability. These results indicate that the studied microemulsion-based hydrogel may be a promising vehicle for topical delivery of ibuprofen.
Keywords: Microemulsion; Hydrogel; Ibuprofen; Xanthan gum; Ethyl oleate; Topical delivery;

In vitro antimicrobial activity of liposomal meropenem against Pseudomonas aeruginosa strains by Zuzanna Drulis-Kawa; Jerzy Gubernator; Agata Dorotkiewicz-Jach; Wlodzimierz Doroszkiewicz; Arkadiusz Kozubek (59-66).
Twelve lipid formulations of liposomal meropenem were tested on six drug-susceptible and two drug-resistant Pseudomonas aeruginosa strains to determine their antibacterial activity. Cationic liposomes, especially PC/DOPE/SA 4:4:2 and PC/DOTAP/Chol 5:2:3, were more effective than anionic ones against sensitive isolates as the MICs of those formulations were two to four times lower than those of the free drug. None of the studied liposomal forms of meropenem exhibited bactericidal activity against isolates, which are drug-resistant due to low permeability. Even Fluidosomes® (liposomes made of DPPC/DMPG 18:1), which demonstrated fusion with P. aeruginosa membranes, showed 4–16 times higher MICs for sensitive and resistant strains than did the free meropenem.
Keywords: Pseudomonas aeruginosa; Liposomes; Meropenem;

Removal of chloroform from biodegradable therapeutic microspheres by radiolysis by S.W. Zielhuis; J.F.W. Nijsen; L. Dorland; G.C. Krijger; A.D. van het Schip; W.E. Hennink (67-74).
Radioactive holmium-166 loaded poly(l-lactic acid) microspheres are promising systems for the treatment of liver malignancies. These microspheres are loaded with holmium acetylacetonate (HoAcAc) and prepared by a solvent evaporation method using chloroform. After preparation the microspheres (Ho-PLLA-MS) are activated by neutron irradiation in a nuclear reactor. It was observed that relatively large amounts of residual chloroform (1000–6000 ppm) remained in the microspheres before neutron irradiation. Since it is known that chloroform is susceptible for high-energy radiation, we investigated whether neutron and gamma irradiation could result in the removal of residual chloroform in HoAcAc-loaded and placebo PLLA-MS by radiolysis. To investigate this, microspheres with relatively high and low amounts of residual chloroform were subjected to irradiation. The effect of irradiation on the residual chloroform levels as well as other microsphere characteristics (morphology, size, crystallinity, molecular weight of PLLA and degradation products) were evaluated.No chloroform in the microspheres could be detected after neutron irradiation. This was also seen for gamma irradiation at a dose of 200 kGy phosgene, which can be formed as the result of radiolysis of chloroform, was not detected with gas chromatography–mass spectrometry (GC–MS). A precipitation titration showed that radiolysis of chloroform resulted in the formation of chloride. Gel permeation chromatography and differential scanning calorimetry showed a decrease in molecular weight of PLLA and crystallinity, respectively. However, no differences were observed between irradiated microsphere samples with high and low initial amounts of chloroform.In conclusion, this study demonstrates that neutron and gamma irradiation results in the removal of residual chloroform in PLLA-microspheres.
Keywords: Holmium; Microspheres; PLLA; Irradiation; Residual solvents; Chloroform;

Extractables/leachables from plastic tubing used in product manufacturing by Dennis R. Jenke; James Story; Rukhsana Lalani (75-92).
While the ability of packaging systems to contribute leached substances to finished drug products is well established, increasing interest is being focused on the potential contamination of drug substances by plastic materials encountered during their production. The direct contact of such plastic parts (such as tubing, gaskets, filters and temporary storage containers) with the drug substance at some point in its production raises the possibility that plastic-related contaminants (leachables) may be present in the finished drug product. In this study, eight tubing materials potentially encountered in pharmaceutical production facilities, including six silicone materials and two Santoprene materials, were characterized for their extractable substances by static extraction coupled with comprehensive chemical characterization of the resulting extracts. Based on the extractables profiles thus generated, target leachables were identified for each tubing material. The accumulation of these target leachables was studied by subjecting the tubing to dynamic flow, simulated use extractions. The primary organic extractables from the silicone tubing were a homologous series of silicone oligomers, with most of the tubings demonstrating a unique distribution of oligomers. Several of the silicone tubings also possessed extractable dioctyl phthalate and dioctyl adipate. The primary organic extractables from the Santoprene-type tubing included a number of phthalates, a series of alkyl phenols and decomposition products of Irganox-type antioxidants. Inorganic extractables associated with many of the tubings included Ca, Mg, Zn and B. In general, the levels of targeted leachables extracted from the tubing materials under simulated use (flow) conditions was much smaller than the total amount of these leachables in the tubing.
Keywords: Extractables; Leachables; Tubing; Plastic processing materials;

Supercritical carbon dioxide (sc-CO2) was used to impregnate indomethacin (a non-steroidal anti-inflammatory drug) into chitosan thermosets for the preparation of controlled release formulations. The products were analyzed by a range of methods including powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of the experimental temperature and pressure of the sc-CO2 on the thermal behavior of chitosan–indomethacin drug composites (DCs) was investigated via differential scanning calorimeter (DSC). The interaction of chitosan and indomethacin after impregnation was then studied by Fourier transform infrared (FTIR) and Raman spectroscopy, respectively. Our results suggest that the supercritical fluid impregnation process results in indomethacin being amorphously dispersed within the chitosan matrix. FTIR data suggest that the aliphatic carbonyl group of indomethacin interacts with the NH2 group of the chitosan backbone. In vitro dissolution studies (via UV–vis spectroscopy) reveal that the dissolution rate of indomethacin substantially increases after processing in sc-CO2, particularly, under the experimental conditions 20.7 MPa and 70 °C.
Keywords: Chitosan; Indomethacin; sc-CO2; Supercritical fluid; Amorphous; Impregnation; Drug;

This study explored the feasibility of predicting the quality of microcrystalline cellulose (MCC) pellets prepared by extrusion–spheronization using torque rheological characterization. Rheological properties of eleven MCC grades as well as their binary mixtures with lactose (3:7) at various water contents were determined using a mixer torque rheometer (MTR). Derived torque parameters were: maximum torque and cumulative energy of mixing (CEM). CEM values of MCC powders (CEM(MCC)) could be attributed to their physical properties such as crystallinity, V low P and V total (volumes of mercury intruded in their pores at low pressure and the total intrusion volume), bulk and tapped densities. For both MCC powders and their binary mixtures, strong correlation was observed between their torque parameters and the properties of their pellets formed with 30 and 35% (w/w) water. Since this relationship was valid over a broad water content range, rheological assessment for pre-formulation purposes need not be performed at optimized water contents. These results demonstrated the usefulness of torque rheometry as an effective means of comparing and evaluating MCC grades especially when substitution of equivalent grades is encountered. In so doing, the tedious and expensive pre-production (pre-formulation and optimization) work can be considerably reduced.
Keywords: Torque rheometry; Pre-formulation; Extrusion–spheronization; Microcrystalline cellulose;

The objective of this study was to evaluate the effect of some processing parameters on the release of lipid formulation from a tablet dosage form. A 17-run, face-centered cubic design was employed to evaluate the effect of colloidal silicates (X 1), magnesium stearate mixing time (X 2), and compression force (X 3) on flow, hardness, and dissolution of Coenzyme Q10 (CoQ10) lipid formulation from a tablet dosage form. The optimized formulation was subsequently subjected to a short-term accelerated stability study. All preparations had a flowability index values ranging from 77 to 90. The cumulative percent of CoQ10 released within 8 h (Y 5) ranged from 40.6% to 90% and was expressed by the following polynomial equation: Y 5 = 49.78 − 16.36 X 1 + 2.90 X 2 − 3.11 X 3 − 0.37 X 1 X 2 + 1.06 X 1 X 3 − 1.02 X 2 X 3 + 11.98 X 1 2 + 10.63 X 2 2 − 7.10 X 3 2 . When stored at 4 °C, dissolution rates were retained for up to 3 months. Storage at higher temperatures, however, accelerated lipid release and caused leakage, and loss of hardness. Processing parameters have a profound effect on the release of lipid formulations from their solid carriers. While optimized controlled release formulations could be attained, further considerations should be made to prepare “liquisolids” that are physically stable at higher storage temperatures.
Keywords: Self-emulsified drug delivery system; Coenzyme Q10; Optimization; Controlled release; Face-centered cubic design; Stability;

Plasmid DNA and siRNA transfection of intestinal epithelial monolayers by electroporation by Esi B. Ghartey-Tagoe; Brian A. Babbin; Asma Nusrat; Andrew S. Neish; Mark R. Prausnitz (122-133).
This study was conducted to evaluate the ability of electroporation to efficiently transfect differentiated intestinal epithelial monolayers with plasmid DNA and to determine whether electroporation can transfect these monolayers with short-interfering RNA (siRNA) to cause gene silencing. Confluent T84 monolayers were transfected with reporter plasmids expressing luciferase or green-fluorescent protein or with siRNA directed against the nuclear envelope proteins lamin A/C using electroporation. Optimized electroporation conditions resulted in luciferase and GFP expression. Both intracellular uptake of fluorescently labeled plasmid and expression of the reporter genes increased with increasing electroporation strength and DNA concentration. When monolayers were transfected by lipofection with the reporter plasmids, expression and DNA uptake were less than for electroporation. Electroporation was also found to transfect monolayers with siRNA, which resulted in up to 90% inhibition of targeted protein production. Silencing occurred within 24 h of transfection and increased with increasing siRNA concentration. These results suggest that electroporation can provide a valuable research tool for transfection of intestinal epithelial monolayers and other differentiated cell systems, and may ultimately be useful for clinical gene therapy applications.
Keywords: Electroporation; Lipofection; Intestinal epithelium; Plasmid DNA gene transfection; siRNA gene silencing;

Release characteristics of quinupramine from the ethylene–vinyl acetate matrix by Jin Kim; Woong-Jang Kim; Seong-Jin Kim; Cheong-Weon Cho; Sang-Chul Shin (134-139).
An ethylene–vinyl acetate (EVA) matrix containing quinupramine was prepared in an attempt to develop a controlled delivery system for quinupramine. Permeation studies of quinupramine through the EVA copolymer membrane were carried out using a two-chamber diffusion cell. The rate of drug permeation through the EVA membrane was proportional to the PEG 400 volume fraction. The release of quinupramine from the EVA matrix was examined using a modified Franz diffusion cell. A plasticizer was added to prepare the pore structure of the EVA matrix in order to increase the rate of drug release. The effects of PEG 400, membrane thickness, drug concentration, temperature, and plasticizer on drug release rate were investigated. The drug release rate from the EVA matrix increased with increasing PEG 400 volume fraction, temperature and drug loading dose. The activation energy for drug release was 5.91, 5.39, 4.68 and 4.52 kcal/mol for a loading dose of 0.5%, 1%, 1.5%, and 2%, respectively. Among the plasticizers used, diethyl phthalate showed the best results. The release of quinupramine from the EVA matrix follows a diffusion-controlled model, where the quantity released per unit area is proportional to the square root of time. The controlled release of quinupramine was achieved using the EVA polymer including a plasticizer.
Keywords: Quinupramine; Ethylene–vinyl acetate; Membrane; Matrix; Controlled release; Plasticizer;

Improved targeting of antimony to the bone marrow of dogs using liposomes of reduced size by Dante A. Schettini; Raul R. Ribeiro; Cynthia Demicheli; Olguita G.F. Rocha; Maria N. Melo; Marilene S.M. Michalick; Frédéric Frézard (140-147).
A novel liposomal formulation of meglumine antimoniate (MA), consisting of vesicles of reduced size, has been evaluated in dogs with visceral leishmaniasis to determine its pharmacokinetics as well as the impact of vesicle size on the targeting of antimony to the bone marrow. Encapsulation of MA in liposomes was achieved through freeze-drying of empty liposomes in the presence of sucrose and rehydration with a solution of MA. The resulting formulation, with a mean vesicle diameter of about 400 nm, was given to mongrel dogs with visceral leishmaniasis as an i.v. bolus injection at 4.2 mg Sb/kg of body weight. The pharmacokinetics of antimony were assessed in the blood and in organs of the mononuclear phagocyte system and compared to those achieved with the free drug and the drug encapsulated in large sized liposomes (mean diameter of 1200 nm). The targeting of antimony to the bone marrow was improved (approximately three-fold) with the novel liposomal formulation, when compared to the formulation of MA in large sized liposomes. This study provides the first direct experimental evidence that passive targeting of liposomes to the bone marrow of dogs is improved by the reduction of vesicle size from the micron to the nanometer scale.
Keywords: Liposomes; Dogs; Leishmaniasis; Bone marrow; Antimony; Size;

Mixed micelles prepared of poly(ethylene glycol)2000–phosphatidyl ethanolamine conjugate (PEG2000–PE) and d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) in 1:1 molar ratio have been investigated. Micelle formation was confirmed by NMR spectroscopy. CMC of the micelles was found to be 1.5 × 10−5  M. Poorly soluble anti-cancer drug paclitaxel (PCL) was efficiently solubilized in 15 nm non-toxic PEG–PE/TPGS micelles. PCL entrapment was quite stable with only about 20% of the incorporated drug released from micelles after 48 h at 37 °C. In addition, PCL-containing PEG2000–PE/TPGS micelles were stable in vitro under various conditions modeling the physiological ones, in particular, at low pH values and in the presence of bile acids, which is especially important for their possible oral administration. Fluorescently labeled micelles demonstrated time-dependent internalization by human colon adenocarcinoma cell line, Caco-2. The internalization of PEG2000–PE/TPGS micelles loaded with P-glycoprotein (P-gp) substrate, rhodamine-123 (RH-123), opposite to the internalization of the free RH-123, was not influenced by the inhibition of the P-gp pump with verapamil hydrochloride, which assumes a P-gp-independent micelle internalization.
Keywords: Paclitaxel; Mixed micelles; PEG–PE; TPGS; Caco-2 cells; P-glycoprotein;

A novel chitosan oligosaccharide–stearic acid micelles for gene delivery: Properties and in vitro transfection studies by Fu-Qiang Hu; Meng-Dan Zhao; Hong Yuan; Jian You; Yong-Zhong Du; Su Zeng (158-166).
Stearic acid (SA) grafted chitosan oligosaccharide (CSO) (CSO–SA), which was synthesized by an 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)-mediated coupling reaction, was demonstrated to form micelle like structure by self-aggregation in aqueous solution. The critical micelle concentration (CMC) of CSO–SA with 15.4% amino substituted degree of CSO was about 0.035 mg/ml. The micelles with 1 mg/ml CSO–SA concentration had 70.6 nm volume average hydrodynamic diameter with a narrow size distribution and 46.4 ± 0.1 mV surface potential. Due to the cationic property, the micelles could compact the plasmid DNA to form micelle/DNA complexes nanoparticles, which can efficiently protect the condensed DNA from enzymatic degradation by DNase I. The volume average hydrodynamic diameter of CSO–SA micelle/DNA complex increased from 203 nm to 318 nm and decreased to 102 nm due to the variation of zeta potential when the N/P ratio increased from 0.25 to 3.6 and from 3.6 to 58. The IC50 value of the CSO–SA micelle against A549 cells was 543.16 μg/ml, while the IC50 of Lipofectamine™ 2000 was about 6 μg/ml. The in vitro transfection efficiency of CSO–SA micelles was investigated by using plasmid DNA (pEGFP-C1). The transfection efficiency with CSO–SA/DNA (N/P ratio is 29) was increased with the post-transfection time (in 76 h), while the optimal transfection of Lipofectamine™ 2000/DNA was obtained at 24 h. The transfection of CSO–SA was not interfered in the presence of 10% fetal bovine serum, which showed remarkable enhancement effect. The optimal transfection efficiency of CSO–SA micelles in A549 cells was about 15%, which was higher than that of CSO (about 2%) and approach to that of Lipofectamine™ 2000 (about 20%). The low cytotoxic biodegradable CSO–SA micelles could be used as an effective DNA condensation carrier for gene delivery system.
Keywords: Non-viral vector; Chitosan oligosaccharide; Micelle; Transfection efficiency; Lipofectamine™ 2000;

Chemotherapy with hybrid liposomes for lymphoma without drugs in vivo by Hideaki Nagami; Yoko Matsumoto; Ryuichi Ueoka (167-172).
Hybrid liposomes composed of dimyristoylphosphatidylcholine (DMPC) and polyoxyethylene (n) dodecyl ether (C12(EO) n , n  = 21 and 25) were prepared with the method of sonication. Clear solution of hybrid liposomes having hydrodynamic diameter of 80–100 nm could be maintained over 3 weeks. Hybrid liposomes induced apoptosis for human lymphoma (MOLT-4 and RAJI) cells in vitro. No toxicity was observed in the rats after intravenously injecting hybrid liposomes in vivo. We clearly demonstrated that a mouse model of lymphoma was established and prolonged survival was obtained in mice models of lymphoma after the treatment with hybrid liposomes without drugs in vivo. The results in this study should support the prolonged survival for patients with lymphoma in clinical applications.
Keywords: Liposome; Lymphoma; Chemotherapy; Apoptosis;

Noticeboard (173-174).