Design of New Formulations for Topical Ocular Administration: Polymeric Nanocapsules Containing Metipranolol

To investigate the potential of polymeric nanocapsules for ocular delivery of beta-blockers, several formulations of polyisobutylcyanoacrylate and polyepsiloncaprolactone nanocapsules containing metipranolol base were developed. These formulations differed in the polymer forming the coating and in the type and volume of the oil encapsulated. Analysis of particle-size distribution, electrophoretic mobility, and loading efficiency of the nanocapsules revealed that the type of oil is the most important factor influencing these properties. From the in vitro release studies, we concluded that drug diffusion through a dialysis membrane is delayed as a consequence of the encapsulation process. However, the release profiles were not influenced by the polymeric coating, suggesting that drug release from these systems is governed mainly by the partition of the drug between the oily core and the aqueous release medium. Nevertheless, despite the inability of the polymer coat to control the release of the drug, its contribution to the stabilization of the emulsion was noted. Finally, the suitability of these formulations for ophthalmic administration was investigated. Although the pharmacologic response was not affected by the encapsulated metipranolol compared with the commercial eye drops, a drastic reduction of the drugs systemic side effects was observed.     

环孢素A眼用制剂的研究近况

环孢素A(cyclosporin A,CyA)为新一代强效免疫抑制剂,目前已应用于眼科临床。临床研究证实,CyA在治疗干眼症、葡萄膜炎、巩膜炎、春季过敏性结膜炎、角膜移植排斥反应等眼部疾病方面具有显著的疗效。综述CyA眼用制剂的研究现状,包括滴眼液、凝胶等常规眼用制剂,以及乳剂、微球、纳米粒等新型眼用制剂的特点和应用,以期为进一步开发高效、低毒、稳定、方便的新型CyA眼用制剂提供参考。     

提高角膜滞留性的策略：黏附材料及递药系统的应用进展

由于眼睛复杂的解剖结构和特殊的保护屏障使得眼部给药存在很多挑战。传统的眼用制剂普遍存在剂量损失大、停留时间短等亟待解决的关键问题。通过改善药物在眼部的滞留性能,可以提高药物的眼内生物利用度。一方面是使用黏膜黏附聚合物,如壳聚糖及其季铵衍生物、聚乙二醇、透明质酸和卡波姆等,增强制剂与角膜的黏附作用;另一方面利用纳米递药体系及原位凝胶系统与眼部黏膜的相互作用,延长药物在眼部的停留时间。因此,本文基于改善药物角膜滞留性,对新型眼部递药体系及可修饰制剂性能的生物黏附性材料进行综述,并结合二者优势,旨在为新材料和新制剂用于眼部疾病的治疗提供有效参考。     

Enhanced Selective Lymphatic Delivery of Cyclosporin A by Solubilizers and Intensified Immunosuppressive Activity Against Mice Skin Allograft

The absorption and lymphatic delivery of a new immunosuppressive drug, cyclosporin A (CsA), were studied in rats by administering CsA orally after solubilization with HCO-60 (polyoxyethylated hydrogenated castor oil), sugar ester, and oils. After the administration of solubilized CsA (7 mg/kg) to rats with thoracic lymph duct cannulas, both plasma and lymph CsA levels were measured over 6 hr. The lymph CsA levels were strongly affected by the solubilizers. The rank order of the solubilizers in enhancing lymph absorption was HCO-60 (57 µg/ml) > sugar ester (46 µg/ml) > sesame oil (3.5 µg/ml) > linoleic acid (0.4 µg/ml), where the parentheses show the maximum lymph CsA levels. Plasma CsA levels were below 2 µg/ml in each group of animals and were barely altered by the solubilizers. These results support the selective lymphatic delivery of CsA with solubilizers such as HCO-60 and sugar ester. The immunosuppressive activity of CsA (1 mg/kg) solubilized with HCO-60 was nearly equivalent to the sesame oil solution with 7 to 15 mg/kg CsA in the skin-allograft mice model.     

Polyisobutylcyanoacrylate Nanocapsules Containing an Aqueous Core as a Novel Colloidal Carrier for the Delivery of Oligonucleotides

Purpose. The goal of the present paper was to encapsulateoligonucleotides in a new particulate carrier in order to protect them fromenzymatic degradation. Methods. Nanocapsules with an aqueous core containingoligonucleotides were prepared by interfacial polymerization ofisobutylcyanoacry late in a W/O emulsion. Ultracentrifugation and re-suspensionin water yielded a dispersion of these containing an aqueous core nanocapsules.Zeta potential measurements and quenching of fluorescence offluorescein-bounded oligonucleotides were used to study the localization ofthe oligonucleotides. Oligonucleotide degradation studies were carriedout in fetal calf serum. Results. Polydisperse nanocapsules of size ranging from 20 to 400 nmwere obtained. Oligonucleotide loading did not significantly influencethe zeta potential, suggesting they were located within the core of thenanocapsules. Fluorescence quenching assays confirmed thislocalization. When encapsulated in the nanocapsules and incubated in thepresence of serum, the oligonucleotides were efficiently protected fromdegradation by nucleases, whereas oligonucleotides adsorbed ontonanospheres were protected less efficiently. Conclusions. This paper describes, for the first time, ananotechnologyable to encapsulate oligonucleotides rather than adsorbing them at thesurface of a solid support. Such a formulation has great potential foroligonucleotide delivery.     

Reverse Hexagonal Phase Nanodispersion of Monoolein and Oleic Acid for Topical Delivery of Peptides: in Vitro and in Vivo Skin Penetration of Cyclosporin A

Purpose To obtain and characterize reverse hexagonal phase nanodispersions of monoolein and oleic acid, and to evaluate the ability of such system to improve the skin penetration of a model peptide (cyclosporin A, CysA) without causing skin irritation. Methods The nanodispersion was prepared by mixing monoolein, oleic acid, poloxamer, and water. CysA was added to the lipid mixture to obtain a final concentration of 0.6% (w/w). The nanodispersion was characterized; the skin penetration of CysA was assessed in vitro (using porcine ear skin mounted in a Franz diffusion cell) and in vivo (using hairless mice). Results The obtainment of the hexagonal phase nanodispersion was demonstrated by polarized light microscopy, cryo-TEM and small angle X-ray diffraction. Particle diameter was 181.77 ± 1.08 nm. At 0.6%, CysA did not change the liquid crystalline structure of the particles. The nanodispersion promoted the skin penetration of CysA both in vitro and in vivo. In vitro, the maximal concentrations (after 12 h) of CysA obtained in the stratum corneum (SC) and in the epidermis without stratum corneum (E) + dermis (D) were ∼2 fold higher when CysA was incorporated in the nanodispersion than when it was incorporated in the control formulation (olive oil). In vivo, 1.5- and 2.8-times higher concentrations were achieved in the SC and [E+D], respectively, when the nanodispersion was employed. No histopathological alterations were observed in the skin of animals treated with the nanodispersion. Conclusion These results demonstrate that the hexagonal phase nanodispersion is effective in improving the topical delivery of peptides without causing skin irritation.     

环孢素A脂质体喷雾凝胶的研制

采用空白脂质体法制备环孢素A脂质体喷雾凝胶。用正交设计筛选制备工艺。高效液相色谱法测定包封率；并以包封率在不同温度下的变化考察制剂的稳定性。结果表明最佳工艺所得制剂的包封率为86.7％。在4℃冰箱保存较为稳定。     

Cyclosporin A analogues: recent advances

Cyclosporin A (Sandimmune^®, Neoral^®; Novartis) is a cyclic hydrophobic undecapeptide used to prevent and treat organ transplantation rejection. Cyclosporin A has potential therapeutic applications in the treatment of diseases such as asthma, psoriasis, atopic dermatitis and rheumatoid arthritis, but its wide use is limited by its poor bioavaliability and toxicity, the most significant of which is nephrotoxicity. There has been a tremendous research effort in producing cyclosporin analogues with better pharmacological profiles. This paper will give a general overview of the recent advances (1999 – 2002) made in producing novel semisynthetic cyclosporin analogues with improved bioavailability and therapeutic index.     

改良RP-HPLC测定全血中环孢素A的浓度

目的 建立一种简便的RP-HPLC法测定全血中环孢素A(CsA)的浓度,为临床合理应用CsA提供依据。方法 全血样品1 mL经乙醚提取,正己烷洗涤去干扰后,采用Zorbax SB-C₁₈ 柱 (4.6 mm×150 mm,3.5 μm) 分离,流动相为乙腈-甲醇-水-异丙醇(60∶10∶29∶1),流速1.5 mL·min^-1,柱温70 ℃,检测波长210 nm;环孢素D(CsD)为内标。结果 CsA全血浓度在25~1 600 ng·mL^-1内线性关系良好(r=0.999 8),平均方法回收率99.51%,日内、日间RSD均小于5%,最低检测限5 ng·mL^-1。结论 本法简便快速,灵敏度高,重复性好,线性范围广。用于患者全血中CsA浓度监测,效果良好。     

Cyclosporin A and cardioprotection: from investigative tool to therapeutic agent

Ischaemic heart disease (IHD) is the leading cause of death and disability worldwide. The pathophysiological effects of IHD on the heart most often result from the detrimental effects of acute ischaemia-reperfusion injury (IRI) on the myocardium. Therefore, novel therapeutic targets for protecting the myocardium against acute IRI are required to reduce injury to the heart, preserve cardiac function and improve clinical outcomes in patients with IHD. In this regard, the mitochondrial permeability transition pore (mPTP) has emerged as a critical target for cardioprotection which is readily amenable to intervention at the time of myocardial reperfusion. The formation and opening of the mPTP at the onset of myocardial reperfusion is a major determinant of mitochondrial dysfunction and cardiomyocyte death in the setting of acute IRI. The seminal discovery in the late 1980s that mPTP opening could be pharmacologically inhibited by the immunosuppressive agent, cyclosporin A (CsA), has been fundamental in the elucidation of the critical role of the mPTP as a mediator of acute IRI and, therefore, a viable target for cardioprotection. Its initial role as an investigative tool was used to identify mitochondrial cyclophilin D to be a regulatory component of the mPTP. The mPTP as a viable target for cardioprotection has recently been translated into the clinical setting with CsA reducing myocardial infarct size in patients. In this article, we review the intriguing role of CsA as a tool for investigating the mPTP as a target for cardioprotection and its potential role as a therapeutic agent for patients with IHD.     

环孢素A脂质体制备及其体外释药方法学考察

目的：考察环孢素A（cyclosporinA,csA）脂质体的制备方法、理化性质及其体外释放行为。方法：比较薄膜分散法、逆向蒸发法、乙醇注入法、乙醚注入法所得的环孢素A脂质体（CsA—Lip）,并以包封率和载药量为综合指标,正交设计优化CsA—Lip处方工艺;分别采用动态透析法和超速离心法研究CsA—Lip的体外释放行为。结果：乙醇注入法制备CsA—Lip的平均粒径为（80．41±3．12）nm,包封率为（87．09±0．03）％,载药量为（4．98±0.45）％,24h释放44％。结论：经优化制备的CsA脂质体具有较高的包封率和载药量,并具有缓释作用。     

基于群体药动学的环孢素A个体化给药研究进展

环孢素A是一种钙调神经磷酸酶抑制剂,目前常用于预防移植后的免疫排斥反应以及治疗再生障碍性贫血、类风湿性关节炎、肾病综合征等疾病。因环孢素A治疗窗窄,体内药动学过程受多种因素影响,药动学个体差异大,在临床上需个体化用药。群体药动学采用非线性混合效应模型法建立药动学参数群体值模型,定量考察人口学特征、遗传因素及联合用药等对药动学参数的影响,在个体化用药中发挥着重要的作用。综述环孢素A的药动学特点及群体药动学相关研究进展,分析归纳影响环孢素A药动学过程的可能因素,为临床制定环孢素A个体化用药方案提供参考。     

Suppression of Inflammation by Cyclosporin A Is Mediated via a T Lymphocyte-Independent Process

An athymic mutant rat strain was used to examine the hypothesis that modification of diseases with an inflammatory component by cyclosporin A (CsA) results from the suppression of nonspecific inflammatory mechanisms, rather than T-lymphocyte function, as is commonly inferred. Confirmation that the animal host was grossly depleted of T cells was obtained from anatomic and morphologic examination and functional tests of T-lymphocyte responsiveness. The experimental approach was to determine the effect of CsA on the course of experimentally induced infection with Escherichia coli, and extracellular pathogen. Host protection against this microorganism is dependent on an effective nonspecific inflammatory response. CsA administration prior to bacterial challenge resulted in a highly significant increase in bacterial numbers in the kidneys of both euthymic and athymic hosts. The data have provided a direct demonstration that modulation of the nonspecific inflammatory response by CsA can occur via a T lymphocyte-independent process.     

Absorption and Disposition of Colloidal Drug Delivery Systems. I. High-Performance Liquid Chromatographic (HPLC) Analysis of a Cyclosporin Emulsion

The amount of cyclosporin A in an oil-in-water emulsion drug delivery system was determined by HPLC. The direct extraction and analysis of an intact emulsion were compared to the analysis of a cracked emulsion and an olive oil solution of the drug. The intra- and interday variability for the intact emulsion was less than 10% from 35 to 150 µg/ml, with recovery of 94%. Comparison of the assay results obtained with the emulsion and the olive oil solution gave a highly correlated regression line with a small intercept and a slope close to unity. Thus, the direct extraction and HPLC analysis of drugs in emulsions may be a viable approach to evaluate drug content     

壳聚糖及其衍生物在眼部给药系统中的研究进展

壳聚糖是一种阳离子型天然黏多糖,具有无毒、生物黏附性、生物相容性、促渗透性、生物可降解性和假塑性等优点,己被广泛应用于眼部给药系统中.本文综述了壳聚糖有关性质及其在眼部给药系统中的研究状况和局限性,旨在为壳聚糖在眼部给药系统中的进一步应用提供参考.     

肝移植患者术后环孢素A血药浓度分析

目的探讨肝移植患者术后环孢素A(CsA)的合适用量及有效血药浓度范围。方法采用荧光偏振免疫法对7例肝移植患者术后1～790dCsA全血谷浓度进行监测,共136次,并对监测结果进行分析。结果肝移植患者术后出现不良反应的谷浓度为(542.09±97.36)ng/mL,出现排斥反应的谷浓度为(67.05±33.92)ng/mL。结论跟踪监测肝移植患者术后不同时间段的CsA血药浓度,对临床提高肝移植患者的生存率,减少CsA的不良反应具有积极意义。     

The Binding of Cyclosporin A to Human Plasma: An in Vitro Microdialysis Study

Purpose. The human plasma binding of cyclosporin A was studied in vitro using the technique of microdialysis. The effect of temperature on the overall binding interaction between cyclosporin A and human plasma was also investigated. Methods. Flow-through loop-type microdialysis probes were constructed from fused silica tubing and regenerated cellulose tubing with a MWCO of 13000 daltons. Probes were perfused with phosphate buffer (0.5 µl/min) and the concentration of ³H-cyclosporin A in the well-mixed medium (plasma or buffer) was 1200 ng/ml. Relative recoveries of cyclosporin A from plasma or buffer were determined for each probe by separate experiments to measure the solute gain or loss with reference to the perfusate. Results. Recoveries determined by loss were significantly greater than those determined by gain and in each case temperature dependent, with higher recoveries at higher temperatures. The plasma free fraction of cyclosporin A calculated from the recovery data and the perfusate to plasma concentration ratios was dependent on temperature in a log-linear fashion. Mean ± s.d. plasma free fractions expressed in percent were 33.5 ± 4.6, 17.9 ± 3.6, 6.2 ± 0.8, 3.0 ± 0.6, and 1.5 ± 0.2 at temperatures of 4, 10, 20, 30, and 37°C, respectively. Assuming that the enthalpy of binding is constant over the temperature range studied and pseudo-first order conditions exist, the binding reaction at these temperatures was spontaneous, endothermic (H = 74.0 kJ/mole), and entropically driven (S = 0.274 kJ/mole/deg). Conclusions. These results show that the free fraction of cyclosporin A in human plasma is dependent on temperature with the fraction unbound decreasing with temperature in the range of 4 to 37°C. The thermodynamic parameters for the binding of cyclosporin A to plasma components indicate that the reaction is a spontaneous endothermic reaction that is mainly entropy driven, similar to the partitioning of lipophilic molecules from an aqueous to a hydrophobic phase. Moreover, these results show that microdialysis is a feasible method to determine the binding interactions between plasma and cyclosporin A, which indicates the method may be suitable for other difficult binding studies where the solutes have nonspecific binding to separation devices.     

土茯苓对环孢素A诱导的免疫抑制小鼠免疫功能的影响

目的 探讨土茯苓水提液对环孢素A诱导的免疫抑制小鼠免疫功能的影响。方法 小鼠腹腔注射环孢素A 5 d致免疫抑制模型,造模成功后随机分为模型组、左旋咪唑组（3.79 g·kg^-1,阳性药）和土茯苓低、中、高剂量组（4.55,9.1,13.65 g·kg^-1）（n=16）,连续给药治疗5 d后,处死小鼠,取脾、胸腺,称重计算脾指数和胸腺指数,流式细胞术检测CD3⁺CD4⁺,CD3⁺CD8⁺;酶联免疫吸附法检测IL-2,IL-6,IFN-γ。结果 造模后小鼠脾指数显著高于正常对照组（P<0.05）,胸腺指数明显降低,脾T细胞CD3⁺CD4⁺显著降低（P<0.05）;与模型组比较,各治疗组小鼠脾指数均有不同程度降低,土茯苓水提液中剂量组差异显著（P<0.05）,但胸腺指数无显著变化;左旋咪唑组、土茯苓中、高剂量组脾T细胞CD3⁺CD4⁺数目显著增加（P<0.01）,各治疗组脾脏IFN-γ均显著下降（P<0.05）。结论 土茯苓水提液能通过降低脾指数、增加脾T细胞CD3⁺CD4⁺的数目,增强机体免疫功能,并下调脾脏内较高的IFN-γ,其调节机制可能与左旋咪唑类似。     

Kinetics and Mechanism of Isomerization of Cyclosporin A

The kinetics of isomerization of cyclosporin A to isocyclosporin A were studied in various nonaqueous solvents as a function of temperature and added methanesulfonic acid. The rate of isomerization was found to be acid-catalyzed over the acid concentration range studied. The choice of organic solvent significantly altered the rate of isomerization. For a series of alcohols, the rate was enhanced with increasing dielectric constant of the media, however, this correlation did not hold upon introduction of the dipolar aprotic solvent, tetrahydrofuran. Conversion of cyclosporin A to isocyclosporin A in tetrahydrofuran was found to contain diminished side reactions as compared to alcoholic solvents. The rate of conversion of isocyclosporin A to cyclosporin A was determined in aqueous buffers as a function of pH, buffer concentration, and temperature. The rates of conversion were extremely rapid compared to the forward reaction. Based on the pH dependencies of dilute solution reactivities, isocyclosporin A displayed a kinetically generated pK _a value of 6.9 for the secondary amine moiety. From pH 8 to pH 10 the pH–rate profile plot is linear, with a slope approximately equal to unity, indicating apparent hydroxide ion catalysis. The break in pH–rate profile suggests a change in the rate-determining step upon protonation of isocyclosporin A. The rate of isomerization in plasma was comparable with that found in a pH 7.4 buffer solution, indicating that plasma proteins do not significantly alter the isomerization kinetics of isocyclosporin A to cyclosporin A.     

Influence of Nonionic Liposomal Composition on Topical Delivery of Peptide Drugs into Pilosebaceous Units: An in Vivo Study Using the Hamster Ear Model

Purpose. The purpose of this study was to test the hypothesis that nonionic liposomes facilitate the topical delivery of peptide drugs into pilosebaceous units. Methods. The hamster ear was used as a model for human pilosebaceous units. The deposition of a hydrophilic protein, alpha-interferon (-IFN), into pilosebaceous units and other strata of the hamster ear 12 hours after topical in vivo application of three nonionic liposomal formulations, one composed of glyceryl dilaurate/cholesterol/polyoxyethylene-10-stearyl ether (Non-1), the second composed of glyceryl distearate/cholesterol/ polyoxyethylene-10-stearyl ether (Non-2) and the third composed of polyoxyethylene-10-stearyl ether/cholesterol (Non-3), a phospho-lipid-based liposomal formulation (PC) and an aqueous control solution (AQ) was determined. We also determined the deposition of a hydrophobic peptide, cyclosporin-A (CsA), into pilosebaceous units and other strata of the hamster ear after topical in vivo application of these liposomal formulations and a hydroalcoholic control solution (HA). Results. The deposition of -IFN into the pilosebaceous units was in the order: Non-1 PC > Non-2 > Non-3 = AQ. The deposition of CsA into the pilosebaceous units was in the order: Non-1 HA > PC > Non-2 = Non-3. Conclusions. Despite differences in the hydrophobicities and size of the drug molecules, deposition into the various ear strata was significantly enhanced by the Non-1 liposomal system.