Effects of Dimethylformamide and L-Menthol Permeation Enhancers on Transdermal Delivery of Quercetin

In this work a feasibility study of transdermal delivery system for quercertin (Q) in carbopol gel through abdominal hairless pig skin in vitro was performed. Dimethylformamide (DMF) and L-menthol (M) were selected as enhancers. Permeation experiences were carried out by using Franz-type diffusion cells. Phosphate saline buffer (pH 7.4) was used in the receptor compartments. All the system was maintained at 32 ± 0.5°C with a circulating water jacket and magnetic stirring (180 rpm). Samples were analysed by UV-VIS spectrophotometer at 255 nm. Flux (J_m) values, permeation (P) and diffusion (D) coefficients were obtained. Results of Q in CG permeation experiences with different percentages of DMF and M showed that 16.7% DMF and 1.95% L-menthol enhancers were the best quantities for the system tested. Enhancer effect can be attributed to direct action on membrane structure by promoting its distension. Therefore, enhancer substitutes for water in pores, improving active principal permeation through pig skin. M significantly increases Q permeation about 17 times higher than control. The results of permeation experiments with M and DMF using the same enhancer concentration (1.42%) conclude that M action is 9 times higher than DMF, approximately, indicating that M is an effective enhancer for a transdermal therapeutic system of Q in CG as vehicle.     

Effects of Enantiomer and Isomer Permeation Enhancers on Transdermal Delivery of Ligustrazine Hydrochloride

Enantiomers and isomers, such as D-limonene, L-limonene, and α-terpinene, were selected as enhancers. The effects and mechanisms of penetration enhancers on in vitro transdermal delivery of ligustrazine hydrochloride (LH) across hairless porcine dorsal skin were investigated. Transdermal fluxes of LH through porcine skin were determined in vitro by Franz-type diffusion cells. D-limonene, L-limonene, and α-terpinene could significantly promote the transdermal fluxes of LH, but no statistical difference (p > 0.05) between them was found. The lag time of L-limonene and α-terpinene were 2.55 and 2.20 times compared with that of D-limonene. Fourier transform-infrared (FTIR) was carried out to analyze the effects of enhancers on the biophysical natures of the stratum corneum (SC) and the permeation enhancement mechanism. FTIR spectra revealed that the changes of peak shift and peak area due to C-H stretching vibrations in the SC lipids were associated with the selected enhancers. All of them could perturb and extract the SC lipids to different extent and L-limonene showed obvious changes. Morphological changes of the skin treated with enhancers were monitored by a scanning electron microscope (SEM). The extraction of the SC lipids by the enhancers led to the disruption of SC and the desquamated SC flake. Apparent density (AD) was newly proposed to estimate the desquamated extent of SC flake. The results showed that the enantiomers and isomers enhanced the permeation of LH by pleiotropic mechanisms.     

Dimethylamino Acid Esters as Biodegradable and Reversible Transdermal Permeation Enhancers: Effects of Linking Chain Length,Chirality and Polyfluorination

Purpose  Series of N,N-dimethylamino acid esters was synthesized to study their transdermal permeation-enhancing potency, biodegradability and reversibility of action. Effects of chirality, linking chain length and polyfluorination were investigated. Materials and Methods   In vitro activities were evaluated using porcine skin and four model drugs—theophylline, hydrocortisone, adefovir and indomethacin. Biodegradability was determined using porcine esterase, reversibility was measured using electrical resistance. Results  No differences in activity were found between (R), (S) and racemic dodecyl 2-(dimethylamino)propanoate (DDAIP). Substitution of hydrocarbon tail by fluorocarbon one resulted in loss of activity. Replacement of branched linking chain between nitrogen and ester of DDAIP by linear one markedly improved penetration-enhancing activity with optimum in 4–6C acid derivatives. Dodecyl 6-(dimethylamino)hexanoate (DDAK) was more potent than clinically used skin absorption enhancer DDAIP for theophylline (enhancement ratio of DDAK and DDAIP was 17.3 and 5.9, respectively), hydrocortisone (43.2 and 11.5) and adefovir (13.6 and 2.8), while DDAIP was better enhancer for indomethacin (8.7 and 22.8). DDAK was rapidly metabolized by porcine esterase, and displayed low acute toxicity. Electrical resistance of DDAK-treated skin barrier promptly recovered to control values. Conclusion  DDAK, highly effective, broad-spectrum, biodegradable and reversible transdermal permeation enhancer, is promising candidate for future research.     

Safe and Effective Permeation Enhancers for Oral Drug Delivery

PURPOSE: The use of intestinal permeation enhancers to overcome the absorption challenges associated with oral drug delivery has been hampered by the notion that enhancer efficacy is directly linked to toxicity. This study attempts to gain insight into the principles governing the potency and toxicity behavior of enhancers. METHODS: Fifty-one enhancers were selected from 11 chemical categories and their potency and toxicity were analyzed in Caco-2 monolayers at concentrations spanning three orders of magnitude. RESULTS: A small but significant fraction of the 153 enhancer formulations studied demonstrated unexpected but desired behavior, that is, substantial efficacy without marked toxicity. Our results revealed that both chemical category and concentration proved critical in determining the usefulness of many enhancers, and the concept of an enhancer's 'therapeutic window' is discussed. Several of the most promising enhancers identified by the study were tested for their effect on the transport of the marker molecules mannitol and 70 kDa dextran across Caco-2 cells and were capable of increasing permeability more than 10-fold. CONCLUSIONS: The results presented here underscore the potential of chemical permeation enhancers while providing valuable direction as to what classes and concentrations of compounds are of interest when searching for safe and effective additions to oral formulations.     

Liquid Crystalline Systems Based on Glyceryl Monooleate and Penetration Enhancers for Skin Delivery of Celecoxib: Characterization,In Vitro Drug Release,and In Vivo Studies

Celecoxib (CXB) is a widely used anti-inflammatory drug that also acts as a chemopreventive agent against several types of cancer, including skin cancer. As the long-term oral administration of CXB has been associated with severe side effects, the skin delivery of this drug represents a promising alternative for the treatment of skin inflammatory conditions and chemoprevention of skin cancer. We prepared and characterized liquid crystalline systems based on glyceryl monooleate and water containing penetration enhancers which were primarily designed to promote skin delivery of CXB. Analysis of their phase behavior revealed the formation of cubic and hexagonal phases depending on the systems' composition. The systems' structure and composition markedly affected the in vitro CXB release profile. Oleic acid reduced CXB release rate, but association oleic acid/propylene glycol increased the drug release rate. The developed systems significantly reduced inflammation in an aerosil-induced rat paw edema model. The systems' composition and liquid crystalline structure influenced their anti-inflammatory potency. Cubic phase systems containing oleic acid/propylene glycol association reduced edema in a sustained manner, indicating that they modulate CXB release and permeation. Our findings demonstrate that the developed liquid crystalline systems are potential carriers for the skin delivery of CXB.     

基质pH及促渗剂对阿昔洛韦水凝胶贴剂体外透皮性能的影响

分别制备了基质pH为5.0、6.0、7.5的不含促渗剂的阿昔洛韦水凝胶贴剂,在基质pH 6.0的处方中加入不同浓度的月桂氮革酮、Ⅳ.甲基吡咯烷酮(NMP)、薄荷醇、吐温-80、聚乙二醇(PEG)400作为促渗荆,以考察基质pH及促渗剂对阿昔洛韦透过离体小鼠皮肤的影响.结果表明,基质pH升高,阿昔洛韦的透皮速率增大.与不含促渗剂的基质pH6.0处方组对照,NMP、PEG 400单用不能提高阿昔洛韦的渗透速率,4%的吐温-80、薄荷醇和月桂氮革酮均可提高阿昔洛韦的经皮渗透.     

增渗剂和离子导入对尼莫地平体外经皮渗透性的影响

研究了增渗剂和离子导入技术对尼莫地平（ＮＭ）体外经皮渗透性的作用,渗透促进剂如３％和５％月桂氮卓酮及１０％油酸的２０％丙二醇溶液能增加药物的渗透性（Ｐ＜００５）,其增渗比分别为４６６、４３９及１２６４．离子导入技术能够显著增加药物的渗透性（Ｐ＜００１）,渗透比为８０３．同时表明１０％油酸和３％的月桂氮卓酮丙二醇溶液与离子导入并用,渗透比为１５、８５、８９２．     

透皮促渗剂对醋酸地塞米松壳聚糖凝胶透皮特性的影响

目的观察透皮促渗剂对醋酸地塞米松壳聚糖凝胶透皮特性的影响。方法实验分为无促渗剂组和促渗剂组。无促渗剂组为0.75%药物5%壳聚糖凝胶剂;促渗剂组根据含促渗剂不同又分为月桂氮酮+丙二醇、月桂氮酮、丙二醇+二甲亚砜、二甲亚砜+月桂氮酮组。以无毛大鼠皮肤为渗透屏障,进行体外渗透实验,分析该凝胶稳态透皮速率（Js）和Js提高率。结果无促渗剂组①Js为（3.75±0.56） μg•（cm2） 1•h 1。促渗剂组效果明显,其中二甲亚砜+月桂氮酮组②Js为（8.12±0.58） μg•（cm2） 1•h 1,月桂氮酮+丙二醇组③Js为（5.41±0.74） μg•（cm2） 1•h 1,丙二醇+二甲亚砜组④Js为（4.31±0.42） μg•（cm2） 1•h 1,月桂氮酮组⑤Js为（4.35±0.36） μg•（cm2） 1•h 1。与①比较,②的Js提高率为2.17%（P＜0.01）,与③④⑤比较,②的Js分别为1.51,1.89,1.87倍（P＜0.05或P＜0.01）。结论混合促渗剂具有比单一促渗剂更好的促渗效果。     

Permeation enhancer strategies in transdermal drug delivery

Abstract

Today, ～74% of drugs are taken orally and are not found to be as effective as desired. To improve such characteristics, transdermal drug delivery was brought to existence. This delivery system is capable of transporting the drug or macromolecules painlessly through skin into the blood circulation at fixed rate. Topical administration of therapeutic agents offers many advantages over conventional oral and invasive techniques of drug delivery. Several important advantages of transdermal drug delivery are prevention from hepatic first pass metabolism, enhancement of therapeutic efficiency and maintenance of steady plasma level of the drug. Human skin surface, as a site of drug application for both local and systemic effects, is the most eligible candidate available. New controlled transdermal drug delivery systems (TDDS) technologies (electrically-based, structure-based and velocity-based) have been developed and commercialized for the transdermal delivery of troublesome drugs. This review article covers most of the new active transport technologies involved in enhancing the transdermal permeation via effective drug delivery system.     

Mechanistic Analysis of Chemical Permeation Enhancers for Oral Drug Delivery

Purpose Traditionally, the oral route cannot be employed for the delivery of macromolecular drugs such as proteins and peptides due, in large part, to limited transport across the epithelial membrane. This particular challenge can potentially be addressed through the use of chemical permeation enhancers, which affect transcellular and/or paracellular transport routes. Although certain permeation enhancers have been proposed for use in oral delivery, potential for application is often unclear when the route of enhancer action is unknown. Methods A combination of theory and experiments was developed for determining mechanism of enhancer action. The effect of 51 enhancers on Caco-2 cells was studied using TEER, MTT, and LDH assays. Results The mechanistic details of intestinal permeability enhancement were uncovered for a broad set of enhancers in vitro. Understanding gained from enhancer mechanisms enabled the deduction of structure–function relationships for hydrophilic and hydrophobic permeation enhancers as well as the identification of a transcellular enhancer, 0.01% (w/v) palmityldimethyl ammonio propane sulfonate, which enabled the non-cytotoxic intracellular delivery of a model drug. Conclusions The results presented here emphasize the importance of understanding enhancer mechanism and uncover a zwitterionic surfactant capable of safely and effectively achieving intraepithelial drug delivery in vitro. Electronic supplementary material The online version of this article (doi:) contains supplementary materials, which is available to authorized users.     

Effect of the Dispersion States of Azone in Hydroalcoholic Gels on Its Transdermal Permeation Enhancement Efficacy

The objective of this study was to investigate the effect of dispersion states of azone in gels on the transdermal permeation of levamisole hydrochloride (LH). LH hydroalcoholic gels containing azone of different dispersion states were prepared by varying the contents of azone and Tween 80, and the in vitro transdermal permeation of LH across excised rat skin was evaluated. Depending on the content of azone, mixed solvents, and solubilizer used, azone presented as dissolved molecules, solubilized in micelles, and fine or coarse emulsion droplets in gels. Dramatically increased transdermal permeation of LH within the azone contents between 0.25% and 0.75% indicated high transdermal enhancement efficiency of the molecular or micellar azone, and extra azone that existed as oil droplets did not fully exert transdermal penetration enhancement of LH. Although solubilizer (Tween 80) can greatly increase the solubility of azone, only small amount of Tween 80 (0.5%) in the gel significantly increased the steady-state flux of LH. Addition of extra amount of Tween 80 (>0.5%) reduced the amount of azone distributed in the skin, and thus decreased the transdermal drug permeation. The results partly elucidated the versatile effects of the dispersion states of azone on the transdermal permeation of hydrophilic drug from semisolid gels.     

Electrochemical Characterization of Human Skin by Impedance Spectroscopy: The Effect of Penetration Enhancers

The electrochemical properties of human cadaver skin were studied in a diffusion cell with impedance spectroscopy as a function of time in the absence and presence of penetration enhancers dodecyl N,N-dimethylamino acetate and Azone. An improved electrochemical model of skin is presented, and combining the novel model with modern fractal mathematics, the effect of enhancers on the surface of skin is demonstrated. The enhancers appeared to open new penetration routes and increase the ohmic resistance, capacitive properties, and fractal dimension of skin, which means a rougher or more heterogeneous surface.     

尼莫地平贴剂体外渗透性及皮肤刺激性考察

尼莫地平经皮吸收贴剂选用丙烯酸酯为骨架材料 ,由背衬层、压敏胶层、覆盖层组成 .通过人体皮肤刺激性实验和体外经皮渗透实验对几组以不同浓度的油酸和月桂氮酮 (azone ,AZ)为渗透促进剂的处方进行了筛选 .结果表明含 5 %azone的尼莫地平贴剂对皮肤有轻度刺激性 ,其它处方对皮肤无刺激性 ;尼莫地平贴剂的体外经皮渗透符合零级动力学过程 ,含 10 %油酸的处方渗透性最好 .     

Estimation of Transdermal Permeation Parameters in Non-stationary Diffusion Experiments. Application to Pre-treatment Studies with Terpenes

No HeadingPurpose. To estimate the applicability of transdermal drug permeation parameters in a finite-dose model for skin pre-treated with terpenes and to evaluate the enhancing effect of some terpene formulations on alprazolam permeation.Methods. In vitro enhancement of alprazolam human skin permeation was investigated using a pre-treatment with different terpene solutions. Vertical diffusion, Franz-type cells were used. Intrinsic drug permeation was also investigated. Transdermal permeation parameters were estimated from the per-meation tabulates using different theoretical approaches for their calculation. Two groups of permeation parameters were calculated: modelistic (diffusion of a finite-dose of drug model) and parameters non-dependent of a diffusional model.Results. In control experiments, all approaches of data treatment satisfactorily described the experimental permeation profiles. When skin pre-treatment was investigated, the fitting of a mathematical sigmoid function was much better than the diffusional approach. Pre-treatment of the skin with Limonene dissolved in ethanol / propylene glycol and Menthol dissolved in propylene glycol increased 15 and 10 times respectively the permeation parameters of alprazolam.Conclusions. Using enhancers that are rapidly cleared from the skin, skin permeability does not remain constant during the permeation experiment and therefore it is not possible to calculate parameters that are usually true coefficients or definite values. In this case, non-modelistic parameters can be used to estimate an enhancing effect.     

Novel Microemulsion Enhancer Formulation for Simultaneous Transdermal Delivery of Hydrophilic and Hydrophobic Drugs

Purpose. Microemulsion (ME) systems allow for the microscopic co-incorporation of aqueous and organic phase liquids. In this study, the phase diagrams of four novel ME systems were characterized. Methods. Water and IPM composed the aqueous and organic phases respectively, whereas Tween 80 served as a nonionic surfactant. Transdermal enhancers such as n-methyl pyrrolidone (NMP) and oleyl alcohol were incorporated into all systems without disruption of the stable emulsion. Results. A comparison of a W/O ME with an O/W ME of the same system for lidocaine delivery indicated that the O/W ME provides significantly greater flux (p < 0.025). The water phase was found to be a crucial component for flux of hydrophobic drugs (lidocaine free base, estradiol) as well as hydrophilic drugs (lidocaine HCl, diltiazem HCl). Furthermore, the simultaneous delivery of both a hydrophilic drug and a hydrophobic drug from the ME system is indistinguishable from either drug alone. Enhancement of drug permeability from the O/W ME system was 17-fold for lidocaine free base, 30-fold for lidocaine HCl, 58-fold for estradiol, and 520-fold for diltiazem HCl. Conclusions. The novel microemulsion systems in this study potentially offers many beneficial characteristics for transdermal drug delivery.     

经皮给药系统促渗方法研究的新进展

促渗方法的发展对于经皮给药的研究意义重大。笔者从化学促渗技术，包括化学促渗剂、前体药物、传递体、含醇脂质体、非离子表面活性剂脂质体和微乳；以及物理促渗技术，包括离子导入、电致孔、超声波促渗、微针、照相波、热致孔和磁场导入等诸多方面综述了近年来经皮给药促渗方法研究的新进展。     

Studies on Optimizing In Vitro Transdermal Permeation of Ondansetron Hydrochloride Using Nerodilol,Carvone, and Limonene as Penetration Enhancers

The present investigation was carried out to formulate a terpene-based hydroxypropyl cellulose (HPC) gel drug reservoir system for its optimal transdermal permeation of ondansetron hydrochloride. The HPC gel formulations containing ondansetron hydrochloride (3% w/w) and selected concentrations of either nerodilol (0% w/w, 1% w/w, 2% w/w, 3% w/w, and 4% w/w), carvone (0% w/w, 2% w/w, 4% w/w, 8% w/w, and 10% w/w), or limonene (0% w/w, 2% w/w, 3% w/w, and 4% w/w) were prepared and subjected to in vitro permeation of the drug across rat epidermis. All the 3 terpene enhancers increased the transdermal permeation of ondansetron hydrochloride. The optimal transdermal permeation was observed with 3% w/w of nerodilol (175.3 ± 3.1 μg/cm^2.h), 8% w/w of carvone (87.4 ± 1.6 μg/cm^2.h), or 3% w/w of limonene (181.9 ± 0.9 μg/cm^2.h). The enhancement ratio (ER) in drug permeability with 3% w/w nerodilol, 8% w/w carvone, and 3% w/w limonene were 21.6, 10.8, and 22.5, respectively, when compared with that obtained without a terpene enhancer (control). However, there was 1.04-, 2.09-, and 2.17-fold increase in the optimal drug flux obtained with carvone, nerodilol, and limonene, respectively, when compared with the desired drug flux (84 μg/cm^2.h). It was concluded that the HPC gel drug reservoir systems containing either 3% w/w nerodilol or 3% w/w limonene act as optimal formulations for use in the design of membrane-controlled transdermal therapeutic system (TTS) of ondansetron hydrochloride.     

Reservoir Based Fentanyl Transdermal Drug Delivery Systems: Effect of Patch Age on Drug Release and Skin Permeation

Purpose  To understand and evaluate the stability and skin permeation profiles of fentanyl reservoir systems as a function of patch age. Methods  Drug release and skin permeation studies were performed using a modified USP apparatus 5 with a novel sample preparation technique. Results  The amount of fentanyl present in the EVA/adhesive layer (EAL) increased from about 17% of label claim (LC) at 5 months to 25% LC at 22 months. The increase in the drug concentration was mainly observed in the peripheral EAL. Simultaneously, the alcohol content of the patch decreased as a function of patch age. A significant effect of patch age on the drug content in the EAL and the drug release from the system was observed; however, skin permeation studies did not indicate an increase in drug delivery rate. Conclusions  Novel sample preparation technique with USP Apparatus 5 allowed determination of in vitro skin permeation rates for fentanyl transdermal patches with different designs. Permeation rates with cadaver skin as substrate were found not to change with patch age despite changing drug concentration in the EAL.