白头翁素贴片的制备与体外经皮渗透试验

目的制备白头翁素贴片，为白头翁素经皮制剂的开发提供依据。方法采用Eudragit E100为骨架材料，流涎工艺制备骨架型贴片。以HPMC醇性凝胶为储库递质，EVA为控释膜，热封法制备储库型贴片。采用TK 6A型透皮扩散仪，用人皮进行体外渗透实验；采用高效液相色谱法测定各时间点接受室中药物浓度，求算经皮渗透的相关参数。结果白头翁素骨架型贴剂经皮给药的稳态透皮速率［(1.72±0.02) mg·(cm2) 1·h 1］是其饱和水溶液的1.47倍，是储库型贴剂的2.30倍。结论白头翁素骨架型贴剂制备简单，具有较高的经皮渗透速率，有望开发成一种新型的经皮给药制剂。     

In Vitro Skin Permeation of Osthol from Hydro-Alcohofic Gel Formulations

Aim To evaluate the in vitro percutaneous absorption behavior of osthol from a series of hydro-alcoholic gel formulations containing three penetration enhancers through excised human skin (stratum cormeum and epidermis,SCE). Methods Excised human skin was mounted in Franz-type diffusion cells. The samples withdrawn from the receptor cell were analyzed for osthol content by high-performance liquid chromatography (HPLC). Results The enhancers azone, menthol and chenopodium increased the osthol percutaneous steady-state fluxes 3.12, 2.00 and 1.25 times those of the enhancer-free formulations (controls), separately. Conclusions The main enhancement mechanism of the skin penetration enhancers azone, menthol and chenopodium is to destroy the barrier fimction of stratum corneum, reducing the resistance of drug transport through the skin and increasing the diffusion coefficients of osthol.     

蛇床子素凝胶药物经皮吸收的体外研究

目的体外测定含有渗透促进剂的蛇床子素凝胶经人体皮肤的吸收.方法以离体人皮肤为渗透模型,应用Franz扩散池进行实验.样品以高效液相法测定蛇床子素的含量.结果与对照组相比,渗透促进剂Azone、薄荷醇、土荆芥油可以使得蛇床子素的稳态流量分别提高3.12、2.00、1.25倍.结论三种渗透促进剂的作用机理为破坏了皮肤角质层的屏障作用,降低了药物的扩散阻力,因而提高了蛇床子素的扩散系数.     

In Vitro Human Skin Barrier Modulation by Fatty Acids: Skin Permeation and Thermal Analysis Studies

Purpose. This study aims to elucidate the skin permeation enhancement and the skin perturbation effects of a number of fatty acids, i.e. straight-chain saturated (SFA), monounsaturated (MUFA) and polyunsaturated acids (PUFA). Methods. The skin permeation enhancement effects were studied using human stratum corneum (SC) and p-aminobenzoic acid (PABA) as a model permeant. The fatty acids in propylene glycol (FA/PG) were applied according to a pre-treatment/co-treatment protocol. The perturbation effects were studied using differential thermal analysis (DTA) on SC after pretreatment with FA/PG. Results. SFA with 6 to 12 carbons exhibit a parabolic correlation between enhancement effect and chain-length, with a maximum at nonanoic-decanoic acids (with 9 and 10 carbons). Nonanoic and decanoic acids exert barely noticeable effects on the thermal behaviour of SC, suggesting that they easily mix with the skin lipids. All cis-6-, 9-, 11- or 13-octadecenoic acids (MUFA) enhance the permeation of PABA to the same extent. DTA revealed that the cis-9- and 13-isomers form a separate domain containing mostly the pure fatty acids within the SC lipids and suppress the lipid transitions at 70°/80°C. PUFA—linoleic (LA), -linolenic (ALA) and arachidonic acids—enhance PABA permeation stronger than MUFA but additional double bonds do not further increase the degree of enhancement. LA and ALA form separate domains but do not completely suppress the SC lipid transitions at 70°/ 80°C. Increase in the enthalpy changes of 70°/80° transitions linearly correlates to the decrease in the permeability coefficients, suggesting that an increased perturbation of the skin lipids not necessarily has to yield an increased PABA permeation. Conclusions. The enhancement effects of fatty acids on the PABA penetration through SC are structure-dependent, associated with the existence of a balance between the permeability of pure fatty acids across SC and the interaction of the acids to skin lipids.     

Encapsulation, Stability, and In Vitro Release Characteristics of Liposomal Formulations of Stavudine (D4T)

The objective of this study was to examine the encapsulation of stavudine (d4T), an approved drug for AIDS treatment, in liposomes composed of various lipids and the in vitro release characteristics, and to evaluate the stability. The reverse phase evaporation method was used to prepare liposomes and the effect of cholesterol on drug encapsulation was studied by adding different amounts of cholesterol to a constant amount of lipid. The effect of charge of the lipid bilayer on drug encapsulation was also studied. Stearylamine or dicetylphosphate (10 mol%) were used to induce positive or negative charges, respectively. The particle size of the liposomes was measured using dynamiclightscattering. Stabilitystudies were performed by storing formulations at 4, 25, and 37 C for 12 weeks, and then subjecting them to alternate heat-cool cycles and simulated transportation conditions. Encapsulation of stavudine was found to be maximum (48%) in DSPC liposomes containing equimolar amounts of cholesterol. Encapsulation generally increased with increasing amounts of cholesterol, and also with the incorporation of both positive and negative charge. In vitro release was found to be biphasic, the release controlled by the dialysis membrane and the lipid bilayer. The release of the drug was inhibited in the presence of charge (30%), compared to neutral liposomes. Particle size distribution ranged from 0.6 mu m to 1.4 mu m and was polydisperse. Liposomes were stable with respect to the amount to drug retained for a period of 4 weeks. Beyond 4 weeks, there was a leakage of entrapped drug independent of the temperature of storage. An increase in particle size during storage was observed in the case of neutral but not charged vesicles. A high degree of encapsulation of stavudine in liposomes is feasible by reverse-phase evaporation. Liposomal formulations may be beneficial in alleviating the longterm side effects of stavudine and enhancing in vivo cellular uptake in HIV therapy.     

In Vitro Skin Permeation and Bioassay of Chlorhexidine Phosphanilate,a New Antimicrobial Agent

An in vitro technique was developed to study the permeation and antimicrobial activity of graded concentrations of a new antibacterial agent, chlorhexidine phosphanilate (CHP), in cream formulations using Franz diffusion cells. Formulations containing from 0.2 to 2% CHP were quantitatively applied to intact excised skin and to skin from which the stratum corneum and partial epidermis had been enzymatically removed. Receptor fluids from diffusion cells were sampled over time and assayed by HPLC methods for chlorhexidine and phosphanilic acid; 24- and 48-hr samples of the diffusate from studies with damaged skin were also bioassayed using clinical isolates of appropriate microbial species. Through intact skin almost no permeation of CHP was observed over 48 hr. The failure of CHP to penetrate intact human skin suggests that normal stratum corneum is the rate-limiting barrier to penetration by this antimicrobial agent. In damaged skin lacking stratum corneum barrier, the release of CHP from the formulation becomes the rate-determining step. Coincident with penetrating damaged skin, CHP dissociates, and the molar ratio of the chlorhexidine and phosphanilate moieties in the diffusate changes to favor phosphanilic acid. The extent of changes in the permeation rates of both moieties of CHP was directly related to the CHP concentration in cream. Both CHP moieties were found to reach equilibrium in the dermis within 24 hr after application. It was also observed that CHP creams down to 0.2% concentration yielded diffusates with activity exceeding the minimum inhibitory concentration of all test microorganisms within 24 hr.     

An Examination of Excised Skin Tissues Used for In Vitro Membrane Permeation Studies

The morphology and layer thicknesses of excised human and hairless mouse skin have been examined. Excised tissues were prepared either by heating at 60°C or by incubation in an ethylenediamine-tetracetic acid (EDTA) solution. Either process yielded spearated sheets of stratum corneum plus attached viable epidermis (SCE), the thicknesses of which were determined microscopically. These measurements indicated that initial skin separation occurred at the dermal/epidermal junction for both separation processes. The two techniques produced SCE sections showing consistent differences in thickness of the attached viable epidermis layer. This effect depended upon the presence or absence of epidermal invaginations. In the former case, EDTA-separated tissue gave narrower viable epidermis of more uniform thickness than that seen with heat-separated tissue. In the latter case, both techniques produced SCE having viable epidermis layers of similar thickness.     

Enhanced in Vitro Skin Permeation of Cationic Drugs

The lipophilicity of cationic drugs can be increased by forming ion pairs with the carboxylate anion of fatty acids. Transport of cations across an isopropyl myristate (IPM) membrane was facilitated in the presence of oleic acid and lauric acid, providing an appropriate pH gradient existed. Enhancement of in vitro skin permeation of various drugs, in the presence of fatty acids, was shown to be more dramatic with the slow-permeating neutral caffeine and anionic salicylate. Since both molecules are unable to form ion pairs it is probable that the fatty acids are capable of exerting a disruptive influence on the skin. The cationic drugs appeared to traverse excised human skin more rapidly than predicted by the model membrane data. This may be due to ion pairing with free fatty acids or other anionic groups within the skin. Consequently, the enhancing ability of fatty acids was less marked for neutral or anionic permeants.     

A Mechanistic Bayesian Inferential Workflow for Estimation of In Vivo Skin Permeation from In Vitro Measurements

Computational models can play an integral role in the chemical risk assessment of dermatological products. However, a limitation on the ability of mathematical models to extrapolate from in vitro measurements to in human predictions arises from context-dependence: modeling assumptions made in one setting may not carry over to another scenario. Mechanistic models of dermal absorption relate the skin penetration kinetics of permeants to their partitioning and diffusion across elementary sub-compartments of the skin. This endows them with a flexibility through which specific model components can be adjusted to better reflect dermal absorption in contexts that differ from the in vitro setting, while keeping fixed any context-invariant parameters that remain unchanged in the two scenarios. This paper presents a workflow for predicting in vivo dermal absorption by integrating a mechanistic model of skin penetration with in vitro permeation test (IVPT) measurements. A Bayesian approach is adopted to infer a joint posterior distribution of context-invariant model parameters. By populating the model with samples of context-invariant parameters from this distribution and adjusting context-dependent parameters to suit the in vivo setting, simulations of the model yield estimates of the likely range of in vivo dermal absorption given the IVPT data. This workflow is applied to five compounds previously tested in vivo. In each case, the range of in vivo predictions encompassed the range observed experimentally. These studies demonstrate that the proposed workflow enables the derivation of mechanistically derived upper bounds on dermal absorption for the purposes of chemical risk assessment.     

博莱霉素脂质体凝胶的制备和体外透皮性比较

目的：研制博莱霉素（BLM）脂质体凝胶,并对其皮肤靶向性进行体外评价。方法：采用逆相蒸发-冻融法制备BLM脂质体,再用卡渡姆940为基质制成BLM脂质体凝胶;以离心法测定BLM脂质体的包封率;以体外透皮渗透释药法,比较BLM脂质体凝胶与BLM普通凝胶的透过作用。结果：BLM脂质体平均粒径为（885．20±12．08）nm,平均包封率为（66．80±1．38）％。在24h内,BLM脂质体凝胶累积透过量（Q）及稳态透皮速率（J）与BLM普通脂质体相比,均明显提高,而在皮肤中的滞留药量也显著提高（P〈0．05）。结论：BLM脂质体凝胶在体外可显著增加BLM的透皮吸收,增加皮肤中的滞留量,值得进一步研究。     

Improved Statistical Methods for Evaluation of Stability of In Vitro Diagnostic Reagents

In vitro diagnostic (IVD) reagent stability is typically evaluated using regression analysis of measurand drift across time following CLSI guideline EP25-A. The corresponding stability duration establishment has several limitations. The stability duration conclusion is based on a two-stage acceptance criteria using the p-value of the regression slope followed by the 95% confidence interval (CI) on the fitted regression line if the p-value <0.05. This analysis technique is based on traditional statistical hypothesis testing; however, the statistical equivalence testing framework better represents the goals of IVD reagent stability evaluation. The resulting stability duration CI does not achieve 95% coverage probability and the statistical properties of the estimated stability duration are substantially impacted by presence of common variance components not accounted for during power analysis and by not accounting for variability in the baseline estimate. The current proposal based on the equivalence testing framework uses a one-stage acceptance criteria based on the 95% CI for proportional measurand drift derived from the regression fit. The proposed methodology was applied to automated immunoassay data (Akbas, Budd, and Klee 2016 Akbas, N., Budd, J., and Klee, G. (2016), “Multiple Calibrator Measurements Improve Accuracy and Stability Estimates of Automated Immunoassays,” Scandinavian Journal of Clinical and Laboratory Investigation, 76, 177–180.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]). Monte Carlo simulation studies are presented to illustrate the improved statistical properties of the current proposal along with an example power analysis for study design. Supplementary materials for this article are available online.     

甲氧沙林皮肤用微乳的制备及体外透皮研究

目的：制备甲氧沙林微乳透皮给药系统,对其体外理化性质及透皮行为进行考察。方法：分别以聚氧乙烯蓖麻油为非离子型表面活性剂,无水乙醇为助表面活性剂,油酸乙酯为油相,水相溶液逐滴加入油相的方法制备甲氧沙林微乳,并对其形态、粒径大小及分布,稳定性等进行了考察。采用Valia—Chien水平扩散池考察微乳的体外透皮过程。结果：制得的甲氧沙林微乳为淡黄色透明液体,平均粒径（90．5±8．2）nm。12h的累积释放量为（1023．00±56．92）μg·cm^-1。结论：甲氧沙林微乳质量稳定,具有良好的体外透皮效果,值得进一步研究。     

Unusual Reduction of the In Vitro Skin Permeation of [3H]dexetimide by Atropine

Pharmaceutical Research -     

不同来源胶原蛋白对人真皮成纤维细胞生长的影响

目的:探讨不同来源胶原蛋白对体外培养人真皮成纤维细胞(HDF-a细胞)生长的影响.方法:用不同浓度、不同来源胶原蛋白的培养基培养HDF-a细胞,考察样品对体外HDF-a细胞生长的影响.结果:12批不同来源胶原蛋白中,4批样品能抑制HDF-a细胞生长,其他8批样品则能促进HDF-a细胞的生长.结论:胶原蛋白对HDF-a细...     

甲氧沙林脂质体凝胶的体外释药与稳定性研究

目的 对甲氧沙林脂质体凝胶体外释药模式进行定量考察。方法 以相同浓度甲氧沙林凝胶为对照，用透析法检测甲氧沙林脂质体凝胶的体外释药模式，并对其在4 ℃下贮存3周的释药稳定性进行研究。结果与甲氧沙林凝胶比较，甲氧沙林脂质体凝胶具有明显的缓释及长效作用，且前3 h释药符合Higuchi扩散模式（k＝4.07%·h 1/2），3 h后遵循零级释药模式（k＝0.66%·h 1）。而甲氧沙林凝胶在实验24 h内释药均符合Higuchi扩散模式（k＝6.91%·h 1/2）。在贮存期内，甲氧沙林脂质体凝胶的释药模式及包封率均维持稳定。结论 甲氧沙林脂质体凝胶体外释药具有明显的缓释特征，稳定性理想，值得进一步研究开发。     

An in Vitro Study of Diamorphine Permeation Through Premature Human Neonatal Skin

The permeation kinetics of diamorphine through human premature neonatal cadaver skin over a range of gestational ages between 24 and 36 weeks was investigated using small diffusion cells. A strong inverse correlation was noted between the apparent permeability coefficient and the gestational age of the skin (P < 0.01; n = 26). The calculated apparent permeability coefficients decreased with gestational age from 6.0 × 10 ^–2 cm · hr^–1 at 24 weeks' gestation to 5.2 × 10^–6 cm · hr^–1 at 36 weeks' gestation. The amount of diamorphine remaining bound within the skin at the end of the in vitro experiments did not change significantly with gestational age of the skin. Diamorphine was subject to degradation over the course of the in vitro experiments to produce significant amounts of 6-mono-acetylmorphine and evidence is presented to suggest that this was due to residual skin esterase activity. It is calculated that the steady-state flux rate of diamorphine through neonatal skin observed in these experiments would be sufficient to obtain a therapeutic plasma concentration of morphine assuming a 2-cm² area for application and a delivery rate of 15 µg hr ^–1 kg^–1. However, the prolonged half-life of morphine in the premature neonate would result in a delay of some hours before the attainment of this level.     

In Vitro Percutaneous Absorption of Pine Bark Extract (Pycnogenol) in Human Skin

One promising class of antioxidant compounds is polyphenols, contained abundantly in pine bark extract (Pycnogenol®—pine bark extract). This medicinal extract is utilized for its anti‐inflammatory properties. Its pharmacological action in skin depends on the kinetics of its absorption. In this study the dermal bioavailability of pine bark extract was investigated. Viable human skin, adapted on continuously perfused Franz cells, was applied with 5% (w/v) pine bark solution. Samples were taken at 0.5, 1, 2, 4, 6, 8, 10, and 12‐hour intervals and analyzed for detection of pine bark extract constituents by high performance liquid chromatography (HPLC) (reversed phase column, isocratic conditions) coupled with an electrochemical detector (EC). Several constituents of pine bark extract such as gallic acid, protocatechuic acid, catechin, p‐hydroxybenzoic acid, vanillin, and one unidentified constituent were detected. These findings indicate that pine bark extract is readily absorbed by human skin and can be used for topical application.     

N-Trimethylated Chitosan Chloride (TMC) Improves the Intestinal Permeation of the Peptide Drug Buserelin In Vitro (Caco-2 Cells) and In Vivo (Rats)

Purpose. To evaluate N-trimethyl chitosan chloride (TMC) of highdegrees of substitution as intestinal permeation enhancers for thepeptide drug buserelin in vitro using Caco-2 cell monolayers, and toinvestigate TMCs as enhancers of the intestinal absorption of buserelinin vivo, in rats. Methods. TMCs were tested on Caco-2 cells for their efficiency toincrease the paracellular permeability of the peptide buserelin. For thein vivo studies male Wistar rats were used and buserelin wasadministered with or without the polymers intraduodenally. Both types ofexperiments were performed at pH 7.2. Results. Transport studies with Caco-2 cell monolayers confirmed thatthe increase in buserelin permeation is dependent on the degree oftrimethylation of TMC. In agreement with the in vitro results, in vivodata revealed highly increased bioavailability of buserelin followingintraduodenal co-administration with 1.0% (w/v) TMCs.Intraduodenally applied buserelin resulted in 0.8% absolute bioavailability,whereas co-administrations with TMCs resulted in mean bioavailabilityvalues between 6 and 13 %. Chitosan HCl (1.0% pH = 7.2) did notsignificantly increase the intestinal absorption of buserelin. Conclusions. Both the in vitro and in vivo results indicate that TMCsare potent mucosal permeation enhancers of the peptide drug buserelinat neutral pH values.