阿霉素脂质体腹腔内注射的药动学动物实验研究

应用薄膜法制备小单层脂质体，阿霉素包封率为３８．４３％±３．４６％，平均每个单抗携带阿霉素分子９．６个，每个单抗携带脂质体阿霉素分子３３６个。应用ＡＤＭ、ＡＤＭ脂质体、ＭｃＡｂ－ＡＤＭ－脂质体各４ｍｇ／４ｍｌ，分别给三组家兔腹腔注射。结果发现腹腔组织中，ＡＵＣ（μｇ·ｈｒ／ｇ）０～２４在脂质体ＡＤＭ组为３１１．９３３，ＡＤＭ组为１１１．８６（Ｐ＜０．０１）。心肌组织中ＡＵＣ（μｇ·ｈｒ／ｇ）０～２４在ＡＤＭ组为７５．３３，脂质全ＡＤＭ组为１１．２９（Ｐ＜０．０１）。说明脂体ＡＤＭ腹腔注射后能在腹腔组织中形成较高浓度，心肌组织内浓度较低，有利于提高化疗效果，降低心肌毒性。     

经淋巴管灌注卡铂脂质体的药代动力学实验研究

目的 :研究卡铂脂质体 (CPL)经淋巴管内灌注 (ILVP)的体内药代动力学。方法 :随机将 6 0只雌性新西兰白兔分为 3组 :ILVP组 ,经兔窝淋巴结输出管穿刺置管给药 ;腹腔内注射 (IPI)组及静脉内注射 (IVI)组。每只给予CPL 30ml混悬液 ,存活 16 8h后处死。用石墨炉原子吸收分光光度法测定每组各时点的外周血及盆腔腹膜后淋巴结组织中铂总 (Pt)浓度 ,并摘取兔淋巴结及心、肝、脾、肾组织作病理学检查CPL的毒性作用。结果 :ILVP组淋巴结铂峰最大浓度 (Cmax)为 6 8.4 μg/g(湿重 ) ,药时曲线下面积 (AUC)为2 117.5 μg·h/g(湿重 ) ,外周血铂Cmax为 12 .8μg/ml,AUC为 2 10 .6 μg·h/ml ;IPI组淋巴结铂Camx为 35 .2 μg/g(湿重 ) ,AUC为 94 4 .2 μg·h/g(湿重 ) ,外周血铂Cmax为 11.4 μg/ml,AUC为 2 76 .3μg·h/ml;IVI组淋巴结铂Cmax为 18.4 μg/g(湿重 ) ,AUC为 319.9μg·h/g(湿重 ) ,外周血铂Cmax为 4 0 .7μg/ml,AUC为 6 6 8.0 μg·h/ml。各实验组间兔淋巴结铂浓度分布差异有显著性 (P <0 .0 5 )。其中ILVP组淋巴结铂Camx是IPI组的 1.9倍 (P =0 .0 4 ) ,是IVI组的 3.7倍 (P =0 .0 13)。外周血中铂浓度 :IVI组高于ILVP组 (P =0 .0 4 4 ) ,但IPI组与ILVP组差异无显著性 (P =0 .6 3)。淋巴结病理形态学检     

Transdermal lontophoretic delivery of colchicine encapsulated in liposomes

Iontophoresis is useful for the transdermal delivery of charged drugs. However, nonionized drugs either have a low flux (due to electro-osmosis) or cannot be delivered using this technique. Because ionized or nonionized drugs can be encapsulated in charged liposomes, it was hypothesized that charged liposomes can deliver neutral or nonionized drug efficiently by iontophoresis. Colchicine, a neutral drug, was encapsulated in large unilamellar vesicles (LUVs), prepared with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) along with cholesterol (1:0.5 mole ratio). Multilamellar vesicles (MLVs) were prepared by the thin-film hydration method and LUVs were obtained by extruding MLVs through polycarbonate filters of 200 nm pore size. Positive charge was induced in the liposomes by adding stearylamine and negative charge by adding dicetyl phosphate. Nonencapsulated drug was separated from LUVs by the Ficoll density gradient method. Positively charged LUVs were delivered under the anode, negatively charged LUVs under the cathode, and neutral LUVs without current using Franz cells and human cadaver skin. Plain colchicine as well as colchicine encapsulated in positively charged LUVs was delivered better under the anode compared with the cathode and passive conditions. Delivery of colchicine encapsulated in positively charged DSPC liposomes was four to five times greater than that of plain colchicine and two to three times greater than that of colchicine encapsulated in DMPC or DPPC liposomes. Because LUVs prepared with DMPC and DPPC were fluid at 37°C, the encapsulated drug leaked during iontophoresis and therefore the delivery was less. Delivery of colchicine was lower under the cathode due to the change in pH during iontophoresis, which, as observed in high-performance liquid chromatographic analysis, caused degradation of the drug. Thus, it can be concluded that iontophoresis of colchicine encapsulated in positively charged DSPC liposomes can improve its delivery across human cadaver skin     

氨甲喋呤(MTX)脂质体的制备及其稳定性

本文探讨了提高MTX脂质体包裹率、影响它对热稳定性的因素,并自行设计了简便、迅速、重现性好的测定MTX脂质体的方法。结果表明:采用二次乳化蒸发法制备MTX脂质体,在控制乳化温度及有机相比例的条件下,可获得50%左右较高的包裹率。另外提示,脂质体分散溶媒的离子强度和脂质体中胆固醇的含量是影响MTX脂质体对热稳定性的重要因素。以选用50mM的磷酸盐缓冲液为分散溶媒和PC/CHOL/SA的脂质体组成,则100℃加热30分钟灭菌,所包MTX可滞留90%。且灭菌前后的脂质体经电镜观察形态无明显变化。     

Effect of Propranolol and Related Drugs on Transmembraneous pH Differences in Liposomes

Abstract Propranolol (1-isopropylamino-3-(1-naphtoloxy)-propan-2-ol) a β-adren-ergic receptor blocking agent was found to cause changes of transmembraneous pH in liposomes prepared from Soy-lecithin and cardiolipin. When the external pH was neutral and the internum of the liposomes acidic, the drug decreased the pH gradient. When the externum was acidic and the internum neutral, the gradient was increased by the drug. The effect of butacaine was similar to that of propranolol, while procaine, timolol and practolol were ineffective. It is suggested that the charged form of propranolol is bound to the membrane and dislocates protons from binding sites in the membrane and that the uncharged form of propranolol penetrates the membrane. After penetration it could associate with protons in the intraliposomal compartment and hence increase the pH of the interior. Depending on the direction of the pre-existing proton gradient propranolol would thus be able to increase or decrease the pH difference across the liposomal membrane.     

Synthesis, characterization and transfection activity of new saturated and unsaturated cationic lipids

We synthesized new cationic lipids, analogue to N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTMA) and 1,2-dimyristyloxypropyl-3-dimethyl-hydroxyethylammonium bromide (DMRIE), in order to compare those containing a dodecyl chain with those having a relatively long chain with two or five double bonds, such as squalenyl and dihydrofarnesyl derivatives, or complex saturated structures, such as squalane derivatives. The fusogenic helper lipid dioleoylphosphatidylethanolamine (DOPE) was added to cationic lipids to form a stable complex. Liposomes composed of 50:50 w/w cationic lipid/DOPE were prepared and incubated with plasmidic DNA at various charge ratios and the diameter and zeta potential of the complexes were measured. The surface charge of the DNA/lipid complexes can be controlled by adjusting the cationic lipid/DNA ratio. Finally, we tested the in vitro transfection efficiency of the cationic lipid/DNA complexes using different cell lines. The transfection efficiency was highest for the dodecyloxy derivative containing a single hydroxyethyl group in the head, followed by the dodecyloxy and the farnesyloxy trimethylammonium derivatives. Instead the C27 squalenyl and C27 squalanyl derivatives resulted inactive.     

Incorporation of antibiotics in liposomes designed for tuberculosis therapy by inhalation

Liposomal encapsulation of tuberculostatic drugs can potentially increase their therapeutic index. The incorporation of isoniazid, pyrazinamide, rifampicin, ethionamide, and streptomycin in extruded distearoylphosphatidylcholine/cholesterol liposomes designed for administration through inhalation was evaluated. Ethionamide and rifampicin were incorporated during lipid film formation, whereas solutions of the remaining drugs were used to hydrate preformed lipid bilayers. Final drug to lipid ratios around 0.3 were achieved for isoniazid and pyrazinamide, and mean vesicle diameters varied from 286 to 329 nm. No expressive drug leakage or mean vesicle diameter changes occurred during 3 weeks. No significant incorporation was achieved for streptomycin, ethionamide, and rifampicin.     

Pegylated liposomal doxorubicin: metamorphosis of an old drug into a new form of chemotherapy

Pegylated liposomal doxorubicin (Doxil, Caelyx) is a formulation of doxorubicin in poly(ethylene glycol)-coated (stealth) liposomes with a prolonged circulation time and unique toxicity profile. We review the preclinical and clinical pharmacology as well as recent clinical data obtained in specific cancer types. Doxil liposomes retain the drug payload during circulation and accumulate preferentially in tissues with increased microvascular permeability, as often is the case of tumors. Doxil toxicity profile is drastically different from that of doxorubicin, and is characterized by dominant and dose-limiting mucocutaneous toxicities, mild myelosupression, minimal alopecia, and no apparent cardiac toxicity. Although the single maximum tolerated dose (MTD) of Doxil is actually lower than that of conventionally administered doxorubicin, the cumulative MTD dose of Doxil may be substantially greater than that of free doxorubicin. Doxil is probably one of the most active agents in AIDS-related Kaposi's sarcoma and has a definite role in management of recurrent ovarian cancer. The potential of Doxil in the treatment of other cancer types and the opportunities it offers in combination with other drugs and therapeutic modalities are under active investigation.     

Effect of Neutral Liposomes on Corneal and Conjunctival Transport of Didanosine

The objective of this study is to determine the effect of various neutral liposomes on corneal and conjunctival permeability of didanosine (ddI), an antiviral drug. Multi-lamellar vesicles (MLVs), large unilamellar vesicles (LUVs), and sonicated multi-lamellar vesicles (SMLVs) encapsulating ddI (with trace quantities of 3HddI) were prepared using distearoyl phosphatidylcholine (DSPC), a neutral lipid. The liposomes contained 14C-cholesteryl oleate as a lipid tracer. Liposome formulations containing free and encapsulated drug (f + e) and those containing only encapsulated drug (e) of an equal quantity were compared with free drug in this study. The permeability studies were conducted in the mucosal to serosal direction across excised rabbit cornea and conjunctiva. The percent encapsulation of ddI in MLVs, LUVs, and SMLVs was 25.66 0.30, 26.56 0.57, and 19.41 0.30, respectively. The mean particle size of MLVs, LUVs, and SMLVs containingfree and encapsulated drug was 3058, 774, and 270 nm, respectively. With all liposome formulations tested, the percent uptake of lipid by tissues was higher compared to ddI uptake. While ddI permeated across the tissues, the lipid tracer did not permeate in detectable quantities.The SMLV(e) formulation was better than the SMLV(f + e) formulation with respect to initial flux and tissue uptake in both tissues and permeability across conjunctiva. In general, the permeability coefficient, initial flux, and tissue levels of ddI at the end of the transport study were lower in the presence of all liposome formulations compared to free drug. Thus, neutral liposomal encapsulation is not a suitable approach to enhance the corneal or conjunctival transport or uptake of ddI.     

Photodynamic therapy of experimental tumours with Zn(II)-phthalocyanine and pulsed laser irradiation

The effectiveness of a pulsed dye laser (673 nm) for photodynamic therapy (PDT) of tumours in the presence of Zn(II)-phthalocyanine (ZnPc) was evaluated using Lewis lung carcinoma-bearing mice. The tumours were irradiated with different pulse energies (from 0.4 to 10 mJ) at a constant fluence of 0.6 J cm^–2 at 24 h after administration of 0.25 mg kg^–1 body weight liposome-incorporated ZnPc. Maximal PDT effect, as evaluated by changes in mean tumour diameter, animal survival time and histological evaluation of tumour necrosis, was observed after 3.0 mJ pulse energy irradiation which appears to yield a deeper light penetration and a more efficient sensitizer excitation when compared with lower or higher pulse energies. Electron microscopic analysis of photo-treated tumour indicates preferential damage to malignant tissue as compared to endothelial cells.