壳聚糖对胰岛素透过Caco-2细胞单层的影响

目的：利用Caco-2细胞单层模型研究胰岛素的吸收机制。方法：利用Caco-2细胞单层模型研究壳聚糖浓度、胰岛素初始浓度、合用壳聚糖与羟丙-β-环糊精（HP-β-CD）、转运方向等条件对表观渗透系数的影响，测定了合用壳聚糖与HP．B。CD对跨上皮细胞电阻（TEER）的影响。结果：当壳聚糖浓度增加时，胰岛素的渗透量也随之增加，其中0％，0．5％及1．0％壳聚糖三者问的渗透系数有显著差异（P〈0．05），而1．0％及1．5％壳聚糖间的渗透系数没有差别（P〉0．05）；当胰岛素初始浓度增加时，胰岛素在单位时间内的累积渗透量也随之增加；5％HP—β—CD与1％壳聚糖共用时与单用1％壳聚糖相比，其渗透系数有所提高（P〈0．05）；顶端到底端方向上的渗透系数大于底端到顶端方向上的渗透系数（P〈0．05）；当1．0％壳聚糖与5％HP—β—CD台用时与单用1．0％壳聚糖相比，其跨上皮细胞电阻进一步降低（P〈0．05）。结论：胰岛素是以被动扩散的方式通过细胞旁路进行转运的，在吸收促进剂5％HP—β—CD和1％壳聚糖联合作用下，药物经细胞旁路的转运量增加。     

Caco-2细胞模型比较黄芩苷和黄芩苷滴丸在小肠的吸收

目的：比较黄芩苷和黄芩苷滴丸在小肠的吸收。方法：采用Caco-2细胞单层模型研究黄芩苷和黄芩苷滴丸由绒毛面到基底面的跨膜转运过程。通过测定黄芩苷和黄芩苷滴丸在Caco-2细胞模型的转运百分率及表观渗透系数（Papp）,比较二者的跨膜转运能力。结果：在细胞转运实验中,135min时,黄芩苷和黄芩苷滴丸的转运百分率分别为1.00%和6.25%,Papp分别为（0.664±0.103）×10-6cm·s-1和（4.462±1.10）×10-6cm·s-1,黄芩苷滴丸的Papp是黄芩苷的6倍。在跨膜转运180min内,黄芩苷滴丸的转运百分率与时间成正比。结论：将黄芩苷制成滴丸可能提高黄芩苷在小肠的吸收。     

复方黄甘颗粒对罗丹明123和6-羧基荧光素经肠黏膜转运的影响

目的：观察复方黄甘颗粒对P-糖蛋白（P-gp）底物罗丹明123（R123）和非P-gp底物6-羧基荧光素（CF）经肠黏膜转运的影响,为复方黄甘颗粒与P-gp底物药物合理联用提供依据。方法：20只SPF级SD雄性大鼠,体重（250±20）g,用随机数字表法分为生理盐水组和复方黄甘颗粒组,每组10只。分别给予生理盐水20mL/kg和1.0g/L复方黄甘颗粒溶液20mL/kg灌胃,2次/d,连续7d。1周后大鼠禁食16～18h,用10%水合氯醛（3mL/kg）腹腔麻醉,取空肠标本3～4cm,用体外扩散池法检测2组大鼠空肠黏膜对R123和CF透过性的影响,比较2组吸收方向转运[黏膜侧（M）-浆膜侧（S）]和分泌方向转运（S-M）的表观渗透系数（Papp）及泵出比（ER）。结果：生理盐水组与复方黄甘组R123吸收方向的Papp分别为（3.54±0.86）×10-6和（2.39±0.44）×10-6cm/s,分泌方向的Papp分别为（8.68±3.76）×10-6和（8.34±2.47）×10-6cm/s;生理盐水组与复方黄甘组CF吸收方向的Papp分别为（5.40±3.20）×10-6cm/s和（3.28±1.41）×10-6cm/s,分泌方向的Papp分别为（5.09±1.71）×10-6cm/s和（3.98±1.02）×10-6cm/s;差异均无统计学意义（均P〉0.05）。生理盐水组R123的ER为2.45,CF的ER为0.94;复方黄甘组R123的ER为3.50,CF的ER为1.21。结论：复方黄甘颗粒对肠黏膜P-gp的活性无明显影响,提示复方黄甘颗粒与R123类似的P-gp底物药物联合应用较为安全。     

5-氟尿嘧啶与卡莫氟的理化特性对其渗透性的影响

目的应用Caco－2细胞模型研究5－氟尿嘧啶（5－fluorouracil,5-FU）和卡莫氟（carmofur,HCFU）的渗透性并探讨物理化学性质如logP、pKa值、分子量及水溶性等对两者渗透性的影响。方法实验中应用的5-氟尿嘧啶和卡莫氟的pKa值、水溶性等由文献获得,logP值用HyperChemV5．0软件中的ChemPlus模块计算得到;用跨膜电阻值（transepithelial electrical resistance,TEER）和荧光黄检测细胞完整性,进行渗透实验,计算表观渗透系数（apparent permeability coefficients,Papp）。结果5－氟尿嘧啶和卡莫氟的logP值分别为－0．96和2.63;细胞的TEER值维持在760－965Ω·cm^-2之间;荧光黄的Papp值为（1．89±0．78）×10^-7cm．s^-1,细胞融合形成了连续的单层细胞膜,且其紧密性和完整性艮好;HCFU的Papp值约是5-Fu的Papp值的10倍。结论logP值对5-氟尿嘧啶和卡莫氟在Caco-2细胞模型中的渗透性起决定作用,5-氟尿嘧啶和卡莫氟的理化特性对两者的渗透性有不同的影响。     

月桂氮卓酮复合促吸收剂促胰岛素经舌下黏膜吸收的研究

目的研究促胰岛素经舌下黏膜吸收的月桂氮卓酮 (Azone)复合促吸收剂。方法应用正常大鼠的降血糖实验对Azone复合促吸收剂的组成进行正交筛选 ,研究胰岛素在不同组成的促吸收剂作用下对猪舌下黏膜的体外渗透扩散系数及促渗比。结果由正交实验确定了最佳组成中Azone复合促吸收剂的比例为 2 .5 %Azone、5 %丙二醇、2 .5 %吐温 80。胰岛素分别在 5 %丙二醇、5 %丙二醇 +2 .5 %吐温 80、5 %丙二醇 +2 .5 %吐温 80 +2 .5 %A zone促吸收剂作用下的促渗比分别为 1.9(P >0 .0 5 )、2 .6 (P >0 .0 5 )和 7.8(P <0 .0 5 )。结论Azone复合促吸收剂中Azone是使黏膜通透性发生变化的主要因素。     

大蒜素在Caco-2细胞模型转运特征的研究

目的研究大蒜素在Caco-2细胞的转运特征。方法应用Caco-2细胞模型考察转运时间、药物浓度时大蒜素吸收的影响,采用高效液相色谱法测定大蒜素浓度,计算其表观渗透系（Papp）。结果随着浓度增加和时间延长,大蒜素累积通透量逐渐增加;大蒜素的Papp在2个方向比值[Papp（BL→AP）,Papp（AP→BL）]为1．80,存在方向性差异。结论大蒜素的转运属于双向转运,且吸收良好。     

利用Caco-2细胞单层模型评价P-糖蛋白对安妥沙星转运的影响

目的 评价P-糖蛋白抑制剂酮康唑对安妥沙星转运的影响.方法 利用人源结肠腺癌系Caco-2细胞单层模型对安妥沙星进行双向转运,采用高效液相色谱法对安妥沙星进行定量分析,计算其表观渗透系数(Papp).结果 加入酮康唑后,低浓度安妥沙星(100μmol/L)Papp(B-A)/Papp(A-B)由4.12降至1.23(P＜0.01),高浓度安妥沙星(500μmol/L)Papp(B-A)/Papp(A-B)由3.54降至1.22(P＜0.01).结论 安妥沙星在Caco-2细胞单层模型中的转运机制可能以主动转运为主,P-糖蛋白参与其从细胞基底侧向管腔面的分泌.     

两种方法测定灯盏花素经Caco-2细胞模型的转运

目的研究灯盏花素经Caco-2细胞模型转运的特性。方法用培养于Transwell上的Caco-2单层细胞模型研究灯盏花素双向转运;采用生物活性测定及HPLC的方法测定介质中灯盏花素或灯盏乙素的转运量。结果两种方法测定结果显示灯盏花素与灯盏乙素的双向转运Papp具有高度一致性,两者Papp(A-B)均小于1×10-6cm.s-1,流出率ER均大于2。结论采用生物活性法测定灯盏花素Papp具可行性。灯盏花素在Caco-2细胞单层吸收上存在明显外排,这可能是其生物利用度极低的重要原因。     

锡兰绿茶中黄酮类成分对缺氧人脑上皮细胞的治疗作用

为研究从锡兰绿茶（Dilmah）提取纯化的黄酮类有效成分对缺氧人脑上皮细胞的治疗作用，体外培养人脑上皮细胞（HBEC），给与锡兰绿茶黄酮提取物治疗后造缺氧模型，检测锡兰绿茶中的黄酮类化合物的抗氧化活性及脑细胞的生存情况，探究其对缺氧脑细胞氧化应激的影响。生化检测显示锡兰绿茶提取物的自由基的清除抑制率（ABTS）为68％±2．8％，次氯酸漂白邻苯三酚红抑制率为79％±4．5％。缺氧后，空白对照组细胞生存率为29％±2．3％，而锡兰绿茶黄酮提取物治疗组为41％±4．7％，氯沙坦治疗组为39％±3．1％。同时，黄铜提取物与氯沙坦治疗组LDH释放分别减少75％±3．7％和79％±3．5％。锡兰绿茶的黄酮提取物治疗使细胞抗氧化酶活力显著增强，SOD：（1．5±0．6）μmol／min／mg蛋白，CAT：（0．61±0．06）μmol／min／mg蛋白，GPx：（2．6±0．41）μmol／min／mg蛋白，GST：（6．0±2．4）μmol／min／mg蛋白，显著高于缺氧对照组，其酶活力分别为：（0．5±0．52，51±0．04，1．2±0．35，3．1±1．6）μmol／min／mg蛋白。研究结果表明，锡兰绿茶有很大的临床应用价值。饮用锡兰绿茶可能成为预防中风的有效新方法，并能减少现代疾病对生命的威胁，提高人类生活质量。     

利用Caco-2细胞模型研究白鲜碱和茵芋碱在人小肠的吸收

目的:研究中药化学成分白鲜碱和茵芋碱的人小肠吸收情况。方法:利用人源结肠腺癌细胞系Caco-2细胞单层模型观察白鲜碱和茵芋碱由绒毛面(AP端)到基底面(BL端)、BL端到AP端2个方向的转运过程。应用偶联紫外检测器的高效液相色谱法对上述2种生物碱进行定量分析,计算转运参数和表观渗透系数,并与阳性对照药普萘洛尔和阿替洛尔进行比较。结果:由AP端到BL端,白鲜碱和茵芋碱的表观渗透系数(Papp)分别为(1.59±0.14)×10-5cm.s-1和(3.19±0.09)×10-5cm.s-1;由BL端到AP端,白鲜碱和茵芋碱的Papp分别为(2.57±0.33)×10-5cm.s-1和(5.86±0.49)×10-5cm.s-1,与在Caco-2单层细胞模型上呈良好吸收的阳性对照药普萘洛尔的基本一致。结论:白鲜碱和茵芋碱可以通过小肠上皮细胞被动吸收进入体内,属于吸收良好的化合物。     

Promoting effects of chemical permeation enhancers on insulin permeation across TR146 cell model of buccal epithelium in vitro

To find potential enhancers for facilitating the buccal delivery of insulin, a TR146 cell-culture model of buccal epithelium, cultured on commercially available insert plates, was used to evaluate the permeability-enhancing effects of several traditional and new types of chemical enhancers, including N-acetyl-L-cysteine (NAC), sodium deoxycholate (SDC), sodium nitroprusside (SNP), reduced glutathione (GSH), glutamine (Gln), chitosan (CS), L-arginine (Arg), 1-dodecylazacycloheptan-2-one (Azone), and soybean lecithin (SPC) (50 and 10 μg/mL respectively). Permeability studies were performed to determine the enhancing effects of these compounds on insulin permeation across the cell-culture model. The enhancing effects of the enhancers were assessed by calculating the apparent permeability coefficients and enhancement ratio. Cytotoxicity of the permeation enhancers at different concentrations was investigated by using the methylthiazolydiphenyl-tetrazolium bromide (MTT) assay. Results showed that 50 μg/mL of NAC, SDC, GSH, CS, Arg, Azone, SPC, SNP, and 10 μg/mL of SNP had a significant enhancing effect on promoting the transport of insulin across the TR146 cell model. MTT assays showed that 50 μg/mL of Gln, Azone, SDC, SNP, Arg, 10 μg/mL SDC, and Arg had obvious toxic effects on TR146 cells. Therefore, NAC, GSH, CS, SPC, and SNP appear to be safe, effective permeability enhancers that promote the transport of insulin across the TR146 cell-culture model of buccal epithelium and may be potential enhancers for buccal delivery of insulin with both low toxicity and high efficiency.     

TR146 cells grown on filters as a model of human buccal epithelium: V. Enzyme activity of the TR146 cell culture model, human buccal epithelium and porcine buccal epithelium, and permeability of leu-enkephalin

The objective of the present study was to characterise the TR146 cell culture model as an in vitro model of human buccal mucosa with respect to the enzyme activity in the tissues. For this purpose, the contents of aminopeptidase, carboxypeptidase and esterase in homogenate supernatants of the TR146 cell culture model, and human and porcine buccal epithelium were compared. The esterase activity in the intact cell culture model and in the porcine buccal mucosa was compared. Further, the TR146 cell culture model was used to study the permeability rate and metabolism of leu-enkephalin. The activity of the three enzymes in the TR146 homogenate supernatants was in the same range as the activity in homogenate supernatants of human buccal epithelium. In the TR146 cell culture model, the activity of aminopeptidase (13.70±2.10 nmol/min per mg protein) was approx. four times the activity of carboxypeptidase (3.73±0.53 nmol/min per mg protein), whereas the level of esterase activity was significantly higher (223.39±69.82 nmol/min per mg protein). In the TR146 cell culture model, the apical esterase activity was found significantly higher than the basal activity, and found comparable to the porcine buccal mucosa. However, the esterase activity on the serosal side of the porcine buccal mucosa was higher than in the TR146 cell culture model. Approx. 1.5% of leu-enkephalin permeated the TR146 cell layers within 5 h (P_app 7.38±0.83×10⁻⁷ cm/s) and approx. 77% of intact peptide was still present in the donor phase after 5 h. The present study suggests that the TR146 cell culture model is a valuable in vitro model for permeability and metabolism studies with enzymatically labile drugs, such as leu-enkephalin, intended for buccal drug delivery.     

The Potential of Chitosan in Enhancing Peptide and Protein Absorption Across the TR146 Cell Culture Model—An in Vitro Model of the Buccal Epithelium

Purpose. To investigate the potential of chitosan (CS) to enhance buccal peptide and protein absorption, the TR146 cell culture model, a model of the buccal epithelium, was used. Methods. The sensitivity of TR146 cells to several CS solutions (different salts with different MW) was investigated by using the MTS/PMS assay. Permeability studies were performed to determine the enhancing effect of CS glutamate (1, 20, 40, 60, and 100 g/mL) on the permeability of ³H-mannitol and fluorescein isothiocyanate labeled dextrans (FD) with various MW (4.4-19.5 kD) across the cell culture model. Results. Sensitivity of TR146 cells to CS solutions depended on the concentration, the pH, and the type of CS salt. CS glutamate solutions (pH 6.0) were found to be the least harmful. CS glutamate was able to increase the permeability of model substances with MW up to 9.5 kD across the cell model. An enhancing effect was found for CS concentrations of 20 g/mL and higher, correlating with a decrease in TEER values. The 20 g/mL CS concentration had a negligible effect on the enzyme activity of the cells as determined by the MTS/PMS assay. Conclusions. CS glutamate is effective in enhancing the transport of macromolecules across the buccal TR146 cell culture model. Therefore, it might be a promising vehicle for peptide and protein buccal administration.     

Nicotine permeability across the buccal TR146 cell culture model and porcine buccal mucosa in vitro: effect of pH and concentration.

The present study was conducted to investigate and compare the effect of pH and drug concentration on nicotine permeability across the TR146 cell culture model and porcine buccal mucosa in vitro. As a further characterization of the TR146 cell culture model, it was explored whether the results were comparable for bi-directional and uni-directional transport in the presence of a transmembrane pH gradient. Nicotine concentrations between 10(-5) and 10(-2) M were applied to the apical side of the TR146 cell culture model or the mucosal side of porcine buccal mucosa. Buffers with pH values of 5.5, 7.4 and 8.1 were used to obtain different fractions of non- and mono-ionized nicotine. The apparent permeability (P(app)) of nicotine across both models increased significantly with increasing pH, and the P(app) values obtained with the two models could be correlated in a linear manner. With increasing concentrations of nicotine, the P(app) values decreased, which can partly be explained by an effect on the paracellular pathway. Similar results were also obtained when using the models for bi-directional as well as for uni-directional studies. The TR146 cell culture model may be used as model for buccal epithelium in studies with ionized drugs and a transmembrane pH gradient.     

TR146 cells grown on filters as a model of human buccal epithelium: IV. Permeability of water, mannitol, testosterone and beta-adrenoceptor antagonists. Comparison to human, monkey and porcine buccal mucosa

The objective of the present study was to evaluate the TR146 cell culture model as an in vitro model of human buccal epithelium. For this purpose, the permeability of water, mannitol and testosterone across the TR146 cell culture model was compared to the permeability across human, monkey and porcine buccal mucosa. Further, the permeability rates of ten beta-adrenoceptor antagonists (acebutolol, alprenolol, atenolol, labetalol, metoprolol, oxprenolol, pindolol, propranolol, timolol and tertatolol) across the TR146 cell culture model and porcine buccal mucosa were related to their lipophilicity (logD(oct; 7.4)) and capacity factor (k') and to their polar water accessible surface area (PWASA). For water, mannitol, testosterone and some of the beta-adrenoceptor antagonists, the permeability enhancement across the TR146 cell culture model in the presence of sodium glycocholate (GC) was determined. The mannitol and testosterone permeability across the TR146 cell culture model could be related to the permeability across porcine and human buccal mucosa. The permeability of the beta-adrenoceptor antagonists across the TR146 cell culture model varied between 2.2 x 10(-6) cm/s (atenolol) and 165 x 10(-6) cm/s (metoprolol). For propranolol the cellular permeability value (P(c)) was lower than expected, probably due to accumulation in the TR146 cell layers. Limited correlation of permeability with k' was observed both for the TR146 cell culture model and the porcine buccal mucosa, although the porcine permeability values were approximately 100 times less than the values determined with the TR146 cell culture model. The permeability values were also found to decrease with increasing PWASA. The PWASA value seemed to be more predictable for permeability than k'. The presence of 12.5 mM GC increased the permeability only for the hydrophilic atenolol, which may help explain the mechanism for GC-induced enhancement. The present results indicate that the TR146 cell culture model can be used as an in vitro model for permeability studies and mechanistic studies of human buccal drug delivery of drugs with different lipophilicity.     

应用A549细胞单层模型研究蛋白多肽类药物肺部吸收的特性应用A549细胞单层模型研究蛋白多肽类药物肺部吸收的特性

药物通过呼吸进行吸收的路径依次为气管→支气管→肺泡,其中通过肺泡上皮细胞吸收占90％以上。由于肺泡上皮细胞使大分子的蛋白多肽类药物不易通过,是它们渗透的主要屏障,因此对肺泡膜屏障特性、药物透过过程及渗透特性的研究有助于更     

Evaluation of buccal methyl-beta-cyclodextrin toxicity on human oral epithelial cell culture model

Cyclodextrins, especially methylated beta-cyclodextrins offer several advantages for drug delivery which include improved drug solubilization, protection against physicochemical and enzymatic degradation, as well as a potential for absorption improvement. However, little or no data are available for their use as drug penetration enhancer via the buccal route. This study focuses on the toxicity of randomly methylated beta-cyclodextrin (RAMEB) on buccal mucosa using a reconstituted human oral epithelium model composed of TR 146 cells. Toxicity of RAMEB on TR 146 cells was evaluated by measuring cell viability (MTT assay) and membrane damages followed by LDH release after single and repeated exposures to RAMEB solutions. Inflammatory effects of RAMEB are also considered by measuring expression of interleukin-1alpha and are supported by histological examination. The present results indicate that 10% RAMEB results in cytotoxic and inflammatory effects depending on time exposure, whereas 2% and 5% RAMEB do not induce tissue damages even after 5 days of repeated exposures. Therefore, the highly water-soluble RAMEB is thought to be a safe candidate as an excipient for buccal mucosal drug delivery.     

Transport of leuprolide across rat intestine, rabbit intestine and Caco-2 cell monolayer

The purpose of this study was to investigate the transport mechanisms and causes of low bioavailability of leuprolide. The everted gut sac technique and Caco-2 cell monolayer were used to examine: (1) transport properties, enzyme degradation and apparent permeation coefficient (Papp); (2) the influence of trypsin inhibitor, EDTA, chitosan and alginate on drug transport; and (3) the effect of animal species on the intestinal transport. Results showed flux increased with increasing concentration of drug, showing a passive diffusion pathway. The enzyme degradation in rabbit gut was the highest. The Papp of (4.19 +/- 1.33) x 10(-5) cm/s in rat gut was the largest and the Papp of (5.20 +/- 0.20) x 10(-7) cm/s in Caco-2 cell the smallest. At a low concentration of drug, trypsin inhibitor had strong enhancement effect on the Papp by protecting enough drug for permeation. Chitosan had no effect on the activity of alpha-chymotrypsin. The increase in Papp was due to opening of the tight junctions and interaction with cells. In conclusion, both inhibition of proteolytic enzymes and opening the tight junctions to allow for paracellular transport improved the intestinal absorption. At low drug concentration, reduction of enzyme degradation is the most important factor.     

TR146 cells grown on filters as a model of human buccal epithelium: III. Permeability enhancement by different pH values, different osmolality values, and bile salts.

The aim of the present study was to evaluate the TR146 cell culture model as an in vitro model of human buccal epithelium with respect to the permeability enhancement by different pH values, different osmolality values or bile salts. For this purpose, the increase in the apparent permeability (P(app)) of the hydrophilic marker mannitol due to exposure to solutions with pH values or osmolality values different from the physiological values was studied. As in studies with solutions of either taurocholate (TC), glycocholate (GC) or glycodeoxycholate (GDC) the results were compared to the increase in P(app) of mannitol obtained in analog studies using porcine buccal mucosa in an Ussing chamber. The effect of the exposure on the electrical resistance of the TR146 cell culture model and the porcine buccal mucosa was measured, and the degree of protein leakage due to GC exposure was investigated in the TR146 cell culture model. The porcine buccal mucosa was approximately ten times less permeable to mannitol than the TR146 cell culture model. The P(app)TC. Increased P(app) values correlated with a decrease in the electrical resistance of the TR146 cell culture model and the porcine buccal mucosa. GC was shown to induce concentration dependent protein leakage in the TR146 cell culture but only from the site of application, and the results indicate that duration of exposure further than 120 min was of minor importance. The present results indicate that the TR146 cell culture model may be a suitable in vitro model for efficacy studies and mechanistic studies of enhancers with potential use in human buccal drug delivery.     

Effect of excipients on the stability and transport of recombinant human epidermal growth factor (rhEGF) across Caco-2 cell monolayers

The effect of sixteen excipients on the transport of recombinant human epidermal growth factor (rhEGF) across Caco-2 cell monolayers was examined at 37 degrees C. The apparent apical to basolateral (A-B) permeability (Papp) of 30 microM rhEGF was 8.15 x 10(-7) cm/sec, indicative of a poor level of absorption in the GI tract. The Papp was 1.7- and 6.3-fold greater than the Papp in the basolateral to apical (B-A) direction and the A-B permeability of mannitol, respectively, and decreased dramatically to a negligible level at 4 degrees C, consistent with a receptor mediated transcytosis of rhEGF. The stability of rhEGF was very poor, undergoing more than 85% degradation in 2 h in the transport medium at 37 degrees C. A significant increase in the Papp could be achieved by the addition of certain excipients, as exemplified by 23, 21, 20 and 16-fold increases, in the presence of sodium taurochenodeoxycholate (NaTCDC), sodium taurodeoxycholate (NaTDC), sodium glycodeoxycholate (NaGDC) and sodium laurylsulfate (SLS) (all at a concentration of 1% w/v), respectively. A significant increase in stability could also be achieved by the addition of some of the excipients, as represented by 1% SLS, which nearly completely stabilized the rhEGF. Unfortunately, however, an increase in the Papp of rhEGF could not be achieved without a simultaneous and extensive decrease in the integrity of the cell membranes. Thus, more efficient excipients, that specifically enhance the permeation of rhEGF and do not alter the membrane integrity, should be pursued in order to safely enhance the permeation of rhEGF.