化学促渗剂预处理与电致孔联用促进大鼠皮肤滞留环孢素A

目的：考察化学促渗剂预处理与电致孔联用对大鼠皮肤滞留环孢素A的促进作用。方法：使用化学促渗剂预处理大鼠皮肤2h后，将含有0．5％环孢素A的40％乙醇混悬液应用于离体大鼠皮肤，同时在大鼠皮肤上施加电致孔。结果：氮酮和薄荷醇预处理皮肤和电致孔联用可明显提高环孢素A在大鼠表皮和真皮的滞留，与对照组相比，滞留量分别是对照组的10．4和11．7倍。结论：氮酮和薄荷醇预处理皮肤和电致孔联用具有协同作用，能够显著提高环孢素A在大鼠表皮和真皮中的滞留。     

环孢素A双连续型微乳在大鼠皮肤中的药物滞留量考察

目的考察环孢素A双连续型微乳经大鼠皮肤给药的可行性及对药物体内分布的影响,并与大鼠灌胃给予新山地明比较。方法将环孢素A双连续型微乳非封闭的应用于大鼠皮肤,给药皮肤用胶带剥离法分离角质层,得到的全血、肾脏、肝脏、皮肤(除去角质层)经提取后用RP-HPLC法测定药物的含量,观察药物在血液中质量浓度的经时变化以及在肾脏、肝脏和皮肤的分布状况。结果与灌胃给予同剂量新山地明的体内行为相比,微乳经皮给药后皮肤中药物的含量显著高于口服组(P<0.01),而血液及肝脏、肾脏中药物的含量明显低于口服组。结论双连续型微乳能够有效的提高环孢素A在大鼠皮肤中的滞留量,同时可以降低药物在肝肾的蓄积。     

蛇床子素在人皮肤角质层和去角质层皮肤中的分布测定

目的：研究抗银屑病蛇床子素贴剂经皮渗透后蛇床子素在人皮肤角质层和去角质层皮肤中的分布。方法：采用了胶带剥离、皮肤萃取法分别获取了人皮肤角质层、去角质层皮肤样本，用HPLC法测定了样本中的蛇床子素含量。结果：蛇床子素在人皮肤角质层的滞留量远大于去角质层皮肤的量。结论：蛇床子素在人皮肤内的滞留量与贴剂使用的时间呈线性，药物可以缓慢地扩散到皮肤的更深层而产生缓释效果。     

肾移植患者术后牙龈增生与环孢素A浓度的相关性

目的:研究肾移植患者术后牙龈增生与其应用环孢素A(cyclosporine A)的关系.方法:记录肾移植患者术后药物使用情况,监测环孢素A血药浓度和唾液中浓度.结果:应用环孢素A的肾移植患者术后牙龈增生的发生率为28.9%.牙龈增生发生率随着术后年限的增加而增加.患者发生牙龈增生时环孢素A血药浓度与未发生的血药浓度差异无显著性(P＞0.05);而唾液中环孢素A浓度与未发生的血药浓度差异具显著性(P＜0.05).结论:肾移植患者术后牙龈增生与使用环孢素A的时间、唾液中环孢素A高浓度有关.     

皮肤中蛇床子素分布的测定

目的 研究抗银屑病蛇床子素贴剂经皮渗透后蛇床子素在皮肤中不同深层的分布。方法 将抗银屑病蛇床子素贴剂经皮渗透一定时间后，分别采用了胶带剥离技术、皮肤萃取法测定了角质层、去角质层皮肤中蛇床子素含量。结果 蛇床子素在皮肤内的滞留量与贴剂使用的时间呈依赖性，用药时间越长，皮肤药物量达到平台期的深度越深，即意味着药物透过皮肤的量越大。结论 蛇床子素在角质层的滞留量远大于去角质皮肤的量，蛇床子素在角质层中的浓度较高，可以形成贮库效应。在贴剂取下后，角质层中的药物可能缓慢地扩散到皮肤的更深层而产生缓释的效果。     

环孢素A微乳口服液的制备及稳定性研究

目的以环孢素A为模型药物,研究微乳制剂在药剂学上的应用.方法根据微乳的拟三元相图,筛选微乳的处方,制备环孢素A微乳,以冷冻蚀刻电镜法和动态光散射法分别考察其形态和粒径,采用高效液相方法测定微乳中环孢素A浓度,考察含量及稳定性.结果环孢素A微乳制备简单,粒径分布均匀,是一稳定的制剂.结论微乳在药学上有广阔的应用前景.     

环孢素A滴眼液的制备及稳定性考察

目的：建立环孢素A滴眼液的制备方法。方法：采用蓖麻油制备环孢素A滴眼液，用HPLC法测定制剂中环孢素A的含量，并对制剂的稳定性进行了考察。结果：本方法研制的环孢素A滴眼液制备工艺简单，质量稳定，含量测定快速、准确。结论：该制剂工艺可用于常规制备环孢素A滴眼液。     

精氨酸、尼莫地平、细胞生长肽对环孢素毒性及其血药浓度的影响

目的：探讨精氨酸、尼莫地平、细胞生长肽(bFGF)对环孢素的肝、肾、睾丸毒性的防护作用和对体内药物浓度的影响。方法：雄性大鼠给予环孢素后，再分别给予精氨酸、尼莫地平和bFGF，测定大鼠环孢素浓度、细胞凋亡指数、血清谷丙转氨酶(ALT)、肌肝(Cr)、生精功能等。结果：精氨酸明显升高大鼠血中环孢素浓度，尼莫地平和bFGF则降低环孢素浓度。精氨酸、尼莫地平和bFGF具有明显降低肝、肾、睾丸细胞凋亡指数、血清ALT和Cr，以及减轻精子发生障碍的作用。结论：精氨酸、尼莫地平、bFGF可影响血中环孢素浓度，并减轻环孢素引起肝、肾、睾丸的毒性，而以精氨酸的作用较明显。     

高效液相色谱法测定环孢素A滴眼剂中环孢素A的含量

目的：采用HPLC法测定环孢素A滴眼剂环孢素A的含量。方法：采用C18色谱柱,流动相为甲醇－水（80：20）,检测波长为210nm,结果：环孢素A在5－40μg.ml^-1浓度范围内,r=0.9998,回收率100．3％,RSD0．8％,结论：该方法简便准确,可作为测定滴眼剂中环孢素A含量的方法。     

混合胶团增溶的环孢素A经小鼠皮肤的渗透作用

目的研究由不同表面活性剂和磷脂所组成的混合胶团(mixedmicelles)对环孢素A经小鼠皮肤给药的渗透促进作用。方法将含药混合胶团溶液封闭性应用于离体或在体小鼠皮肤,测定接收介质和血液中环孢素A含量。结果离体条件下,不同表面活性剂和磷脂所形成的混合胶团的皮肤渗透作用强度为:胆酸钠-磷脂混合胶团>脱氧胆酸钠-磷脂混合胶团>TritonX-100-磷脂混合胶团>Tween-20-磷脂混合胶团。在体条件下,用胆酸钠-磷脂混合胶团后,5h血药浓度达峰值,随后血药浓度缓慢下降。结论混合胶团在水溶液状态下对大分子难溶药物环孢素A具有一定的皮肤促渗效果。     

Investigation into the potential of electroporation facilitated topical delivery of cyclosporin a

Purpose: The potential for electroporation-facilitated topical transport of cyclosporin A (CysA) was investigated using rat skin. Methods: Studies of various electrical factors acting on the deposition of CysA into the stratum corneum and deeper skin of in vitro electroporation were performed. We also tested the synergistic effect of electroporation and other approaches such as chemical enhancers and low-frequency ultrasound on topical drug delivery of CysA. Results: Electroporation increased the amount of CysA retained in the skin by only 3 times that of passive diffusion. We found that the efficacy of electroporation in enhancing topical delivery can be further increased by pretreatment of skin with chemical enhancers, such as Azone and menthol. Meanwhile, only a small amount was seen to transport across the full skin into the receiver compartment. Trimodality treatment comprised of pretreatment with Azone and ultrasound in combination followed by electroporation was not effective in enhancing the topical delivery of CysA. However, this combination strategy increased the penetration of CysA through rat skin by an order of 15. Conclusion: In general, the enhanced skin accumulation of CysA by the combination of electroporation and chemical enhancers could help significantly to optimize the targeting of the drug without a concomitant increase in systemic side effects.     

Investigation into the potential of low-frequency ultrasound facilitated topical delivery of Cyclosporin A

The potential for low-frequency ultrasound facilitated topical transport of Cyclosporin A was investigated using rat skin. Studies of intensity and exposure time acting on the deposition of Cyclosporin A into deeper skin of in vitro sonophoresis were performed. Low-frequency ultrasound increased the amount of Cyclosporin A retained in the skin only seven times than the passive diffusion. Furthermore, we also tested the synergistic effect of ultrasound and other approaches such as chemical enhancers and electroporation on topical drug delivery of Cyclosporin A. We found that the efficacy of low-frequency ultrasound in enhancing topical delivery could be further increased by pretreatment of skin with chemical enhancers, such as laurocapram (Azone) and sodium lauryl sulfate (SLS). Meanwhile only a small amount was seen to across the full skin into the receiver compartment. Trimodality treatment comprising of pretreatment with Azone+ultrasound in combination followed by electroporation was not effective in enhancing the topical delivery of Cyclosporin A. However, this combination strategy increased the penetration of Cyclosporin A through rat skin by order of 15. The histopathological findings revealed that there was almost no change observed in the structure of skin after ultrasound or combination with ultrasound and enhancers as compared with the control group. In general, the enhanced skin accumulation of Cyclosporin A by the combination of low-frequency ultrasound and chemical enhancers could help significantly to optimize the targeting of the drug without of a concomitant increase of the systemic side effects.     

Transdermal delivery of nalbuphine and its prodrugs by electroporation.

The aim of this study was to assess the effects of electroporation on transdermal permeation of nalbuphine (NA) and its prodrugs. The permeation characteristics were investigated under various electrical factors and skin barriers to elucidate the mechanisms involved in transdermal delivery of NA and its prodrugs by skin electroporation. The in vitro permeation studies were performed using side-by-side diffusion cells. The various electrical factors investigated were pulse voltage, pulse duration and pulse number; the different skin barriers studied were intact hairless mouse skin, stratum corneum (SC)-stripped skin, delipid skin as well as furry Wistar rat skin. The prodrugs were fully converted to parent drug after skin permeation. Application of electroporation significantly enhanced transdermal permeation of NA and its prodrugs. The enhancement ratios were highest for NA and the four prodrugs showed the similar permeability after electroporation. The permeation amounts of NA and its prodrugs may be increased by application of higher pulse voltage, pulse duration as well as pulse number. Various kinetics and mechanisms were observed for the permeation of the hydrophilic NA and lipophilic nalbuphine enanthate through different skin barriers by applying electroporation. This study demonstrated that electroporation may enhance and control transdermal permeation of NA and its prodrugs. The results also indicated that the physicochemical properties of prodrug had significant effects on kinetics as well as mechanisms of transdermal permeation by electroporation.     

Transdermal Delivery of Metoprolol by Electroporation

Electroporation, i.e., the creation of transient pores in lipid membranes leading to increased permeability, could be used to promote transdermal drug delivery. We have evaluated metoprolol permeation through full thickness hairless rat skin in vitro following electroporation with an exponentially decaying pulse. Application of electric pulses increased metoprolol permeation as compared to diffusion through untreated skin. Raising the number of twin pulses (300 V, 3 ms; followed after 1 s by 100 V, 620 ms) from 1 to 20 increased drug transport. Single pulse (100 V, 620 ms) was as effective as twin pulse application (2200 V, 1100 V or 300 V, 3 ms; followed after 1 s by 100 V, 620 ms). In order to investigate the effect of pulse voltage on metoprolol permeation, 5 single pulses (each separated by 1 min) were applied at varying voltages from 24 to 450 V (pulse time 620 ms). A linear correlation between pulse voltage and cumulative metoprolol transported after 4 h suggested that voltage controls the quantity of drug delivered. Then, the effect of pulse time on metoprolol permeation was studied by varying pulse duration of 5 single 100 V pulses from 80 to 710 ms (each pulse also separated by 1 min). Cumulative metoprolol transported after 4 h increased linearly with the pulse time. Therefore, pulse time was also a control factor of the quantity of drug delivered but to a lesser extent than the voltage at least at 100 V. The mechanisms behind improved transdermal drug delivery by electroporation involved reversible increased skin permeability, electrophoretic movement of drug into the skin during pulse application, and drug release from the skin reservoir formed by electroporation. Thus, electroporation did occur as shown by the increased transdermal permeation, on indicator of structural skin changes and their reversibility. Electroporation has potential for enhancing transdermal drug delivery.     

Effect of vehicles and enhancers on the topical delivery of cyclosporin A

Topical delivery of cyclosporin a (CysA) is of great interest for the treatment of autoimmune skin disorders. The purpose of this study was to investigate the effect of various vehicles and enhancers on the topical delivery across rat skin. The topical (to the skin) delivery of CysA was evaluated in vitro using rat skin mounted in a Franz diffusion cell. CysA was analyzed by UV-HPLC. As vehicles, CysA vehicle containing 40% ethanol showed significantly enhanced deposition of CysA into the stratum corneum (SC) and deeper skin, as compared to other vehicles. The efficiency of the vehicles to improve the topical delivery of CysA was sequenced in the order of: 40% ethanol>ethyl oleate>Transcutol>isopropyl myristate>ethanol>Labrasol>propylene glycol>Lauroglycol FCC. Next, we tested effect of pre-treatment with chemical enhancers on the penetration of CysA. The permeation-enhancer effect of enhancers was in the following order: 10% menthol approximately 0.05% SLS>5% Azone>5% NMP>5% DEMO. Moreover, chemical enhancers shortened the lag time of the penetration of CysA into deeper skin. The present study suggests that the suspension of 40% ethanol containing 0.5% drug can more effectively enhance the topical delivery of CysA after skin pre-treatment with 10% menthol or 0.05% SLS.     

Transdermal drug delivery by electroporation applied on the stratum corneum of rat using stamp-type electrode and frog-type electrode in vitro

Transdermal enhancement effects of electroporation applied only on the stratum corneum by two electrode types, the stamp-type electrode and the frog-type electrode, were investigated in vitro using excised rat skin. Carboxyfluorescein (CF) was selected as a model compound. The excised skin was set in a Franz type diffusion cell and a square wave electric pulse was applied to the stratum corneum under various electric pulse conditions. We determined the permeability of CF to the receptor compartment under these conditions. Voltage, electric pulse length, and number of electric pulses, were varied from 10 to 1000 V, 50 micros to 15 ms and 5 to 30 pulses, respectively. Flux rate was enhanced as the electric pulse condition strengthened. However, the maximum value was attained in the flux rate, above which no increase was observed despite strengthening of the electric pulse. Although at low electric pulses, the enhancement effect of the frog-type electrode was superior to that of the stamp-type electrode, the maximum flux rates were the same. These results indicate that electroporation on the stratum corneum using the stamp-type electrode or frog-type electrode, is useful for transdermal drug delivery.     

Electric field analysis on the improved skin concentration of benzoate by electroporation

The objective in the present study was to understand the relationship between the increased skin concentration of benzoate as a model drug after topical application of its sodium salt and the electric field intensity produced in the skin barrier, the stratum corneum, by electroporation. A piece of excised abdominal hairless rat skin was set in a Franz type diffusion cell, and 0.5% sodium benzoate and physiological saline were applied to the stratum corneum and dermis sides, respectively. Two needle electrodes made of Ag were connected to an electrical power source, which produced exponentially decaying pulses. The electrodes were placed on the skin surface with a distance of 0.5 cm between both electrodes. After the 4 h passive permeation experiment, an electrical pulse was applied to the rat skin at 300 V every minute for 10 min. The skin was then removed from the diffusion cell, and the amounts of benzoate in different positions of the skin specimen were measured. Field intensity generated in the stratum corneum by electroporation was determined by a finite element method using a computer program. The amounts of benzoate at different sites in the skin were almost proportional to the mean field intensity in the corresponding stratum corneum. These results suggested that the enhancing effect of electroporation can be evaluated by the field intensity more directly than the application voltage.     

Transdermal drug delivery using electroporation. I. Factors influencing in vitro delivery of terazosin hydrochloride in hairless rats

The use of electroporation pulses as a physical means of enhancing the permeability of skin to deliver drugs is in the early stages of development. In this article, a systematic study examining the parameters influencing electroporative transdermal delivery of terazosin hydrochloride to hairless rat skin are reported. It was found that voltage, pulse length (tau), and number of pulses were the three most important parameters, in that order. For creating a significant enhancement in drug delivery to the skin, without causing any apparent change in its external appearance, it was necessary to deliver five or more exponentially decaying electroporation pulses, at 88 +/- 2.5 V (voltage across the skin), with a decay time constant of 20 ms. Electrodes with larger area could attain the same voltages across the skin with a much lower applied voltage and possessed other advantages with regard to performance of the drug delivery system.     

Lecithin vesicular carriers for transdermal delivery of cyclosporin A

Two kinds of vesicles with and without the presence of sodium cholate (flexible vesicles and conventional vesicles) were prepared, using cyclosporin A as model drug. When applied onto the excised abdominal skin of mice non-occlusively, the enhancing effects of vesicles on the penetration of cyclosporin A were assessed by an in vitro permeation technique. The effect of sodium cholate micelles was also studied. In vivo study was carried out by topical application of vesicles onto the mice skin and drug serum concentration was detected. Results showed that after 8 h of administration, flexible vesicles transported 1.16 microg of cyclosporin A through per cm(2) mice skin and amounted to 1.88 microg 24 h later. The residual amount in the skin was 1.78+/-0.51 microg/cm(2). However, flexible vesicles failed to transport measurable amount of drug through pre-hydrated skin while deposited 2.39+/-0.26 microg/cm(2) into the skin. Conventional vesicles failed to transfer cyclosporin A into the receiver while accumulated 0. 72+/-0.19 microg/cm(2) of drug in the skin. Furthermore, 1 and 40% sodium cholate micelles precluded the transport of cyclosporin A. In vivo studies indicated that with the application of flexible vesicles, serum drug concentration of 53.43+/-9.24 ng/ml was detected 2 h later. After the stratum corneum of mouse skin has been destroyed by shaving, flexible vesicles transferred large amount of drug into blood, up to 187.32+/-53.21 ng/ml after 1 h of application. Conventional vesicles failed to deliver measurable amount of drug into the blood under normal skin condition. In conclusion, flexible vesicle is better than conventional vesicle as the carrier for transdermal delivery of cyclosporin A. Penetration and fusion have been suggested to be two major functional mechanisms. Hydration is detrimental to the enhancement effect. Stratum corneum constitutes main barrier to the transport of lipophilic cyclosporin A.