Enhanced transdermal controlled delivery of glimepiride from the ethylene-vinyl acetate matrix

An ethylene-vinyl acetate (EVA) matrix containing glimepiride was prepared as a potential transdermal drug delivery system. Permeation studies of quinupramine through the EVA copolymer membrane were carried out using a two-chamber diffusion cell. The rate of drug permeation through the EVA membrane was proportional to the PEG 400 volume fraction. The release of glimepiride from the EVA matrix was examined using a modified Franz diffusion cell. A plasticizer was added to prepare the pore structure of the EVA matrix in order to increase the rate of drug release. The effects of PEG 400, drug concentration, temperature, and plasticizer on the drug release rate were investigated. Various types of enhancers were added to an EVA matrix containing 2% glimepiride in an attempt to increase the level of skin permeation of quinupramine through an EVA matrix. The effects of the enhancers on the level of glimepiride permeation through the skin were evaluated using Franz diffusion cells fitted with intact excised rat skin. The rate of drug release from the EVA matrix increased with increasing PEG 400 volume fraction, temperature, and drug loading. The estimated activation energy of drug release was 7.274 kcal/mol for 2% drug loading dose. The release of glimepiride from the EVA matrix followed a diffusion-controlled model, where the quantity released per unit area was proportional to the square root of time. The controlled release of glimepiride was achieved using the EVA polymer including the plasticizer. Among the plasticizers used, such as the alkyl citrates and phthalates groups, diethyl phthalate slightly increased the rate of glimepiride release. Among the various enhancers used, such as the non-ionic surfactants, the glycerides, the propylene glycol derivatives, fatty acids (saturated or unsaturated), and pyrrolidones, linoleic acid showed the highest permeation rate; 3.17-times higher than the control. In conclusion, an EVA matrix containing a permeation enhancer can be used for the transdermal controlled delivery of glimepiride.     

Enhanced Controlled Transdermal Delivery of Ambroxol from the EVA Matrix

To avoid the systemic adverse effects that might occur after oral administration, transdermal delivery of ambroxol was studied as a method for maintaining proper blood levels for an extended period. Release of ambroxol according to concentration and temperature was determined, and permeation of drug through rat skin was studied using two chamber-diffusion cells. The solubility according to PEG 400 volume fraction was highest at 40% PEG 400. The rate of drug release from the EVA matrix increased with increased temperature and drug loading doses. A linear relationship existed between the release rate and the square root of loading rate. The activation energy (Ea) was measured from the slope of the plot of log P versus 1000/T and was found to be 10.71, 10.39, 10.33 and 9.87 kcal/mol for 2, 3, 4 and 5% loading dose from the EVA matrix, respectively. To increase the permeation rate of ambroxol across rat skin from the EVA matrix, various penetration enhancers such as fatty acids (saturated, unsaturated), propylene glycols, glycerides, pyrrolidones, and non-ionic surfactants were used. The enhancing effects of the incorporated enhancers on the skin permeation of ambroxol were evaluated using Franz diffusion cells fitted with intact excised rat skin at 37° using 40% PEG 400 solution as a receptor medium. Among the enhancers used, polyoxyethylene-2-oleyl ether increased the permeation rate by 4.25-fold. In conclusion, EVA matrix containing plasticizer and permeation enhancer could be developed for enhanced transdermal delivery of ambroxol.     

Drug in adhesive type transdermal matrix systems of ondansetron hydrochloride: optimization of permeation pattern using response surface methodology

The present investigation aims at development of pressure sensitive adhesive (PSA) based drug in adhesive type transdermal systems of ondansetron hydrochloride with higher permeation flux. The effect of mixture of two chemical permeation enhancers (oleic acid and lauric acid diethanolamide); and drug loading dose on the ex vivo human cadaver skin permeation from the transdermal patches has been investigated using a d-optimal combined mixture design. Incorporation of chemical permeation enhancers significantly improved the permeability parameters and it was also found that blend of permeation enhancers is more effective than either permeation enhancer. Criterion of desirability was employed to numerically optimize the transdermal system. Optimized formulation was achieved with 67.5% lauric acid diethanolamide, 32.5% oleic acid and 10% drug loading in an acrylate based PSA matrix. Optimized formulation was found to be nonirritating and safe for dermatological application.     

Development and Biopharmaceutical Evaluation of Quinupramine-EVA Matrix Containing Penetration Enhancer for the Enhanced Transdermal Absorption in Rats

To increase the skin permeation of quinupramine through the rat skin, different types of enhancers were added to an ethylene-vinyl acetate (EVA) matrix containing 2% quinupramine. The effects of the enhancers on the level of quinupramine permeation through the skin were evaluated by using Franz diffusion cells that were fitted with the intact excised rat skin. Among the enhancers used, which included fatty acids (saturated and unsaturated), glycerides, pyrrolidones, and nonionic surfactants, polyoxyethylene-2-oleyl ether showed the best enhancement. The pharmacokinetics and bioavailability of quinupramine from an EVA matrix were examined to determine the level of percutaneous absorption in rats. The percutaneous absorption of quinupramine from the EVA matrix with or without an enhancer was investigated. Quinupramine was administered orally or intravenously to compare the pharmacokinetic parameters with that of the transdermal route. The relative bioavailability of quinupramine in the matrix containing polyoxyethylene-2-oleyl ether as an enhancer was approximately 2.81 times higher than the group without an enhancer. Histological examination revealed that the skin pretreated with the EVA matrix containing the enhancers had a loosely layered stratum corneum. These results show that the quinupramine-EVA matrix containing a permeation enhancer could be a good transdermal delivery system for providing sustained plasma concentrations.     

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。     

A combined approach of chemical enhancers and sonophoresis for the transdermal delivery of tizanidine hydrochloride

The effects of chemical enhancers and sonophoresis on the transdermal permeation of tizanidine hydrochloride (TIZ) across mouse skin were investigated. Parameters including drug solubility, apparent partition coefficient (APC), drug permeation, and degradation in skin were determined. Low frequency ultrasound was also applied in the presence and absence of chemical enhancers to assess whether drug permeation improved. APC values indicated that TIZ preferentially partitions into intercellular spaces and does not form a reservoir, with the drug also exhibiting good enzymatic stability in skin. Most of the enhancers studied significantly increased the permeation rate of TIZ through full thickness mouse skin in comparison with TIZ formulated in phosphate buffer. Maximum enhancement was observed for TIZ formulated as a suspension in 50% v/v aqueous ethanol containing 5% v/v citral. Sonophoresis significantly (p < 0.05) increased the cumulative amount of TIZ permeating through the skin at 15 and 30 min in comparison to passive diffusion. A synergistic effect was noted when sonophoresis was applied in the presence of chemical enhancers. The results suggest that the formulation of TIZ with an appropriate penetration enhancer may be useful in the development of a therapeutic system to deliver TIZ across the skin for a prolonged period, i.e. 24 hr. The application of ultrasound in association with chemical enhancers, such as the combination of 5% v/v citral in 50% v/v aqueous ethanol, could further serve as a non-oral and non-invasive drug delivery modality for the immediate therapeutic effect of muscle relaxants such as TIZ.     

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.     

Enhanced bioavailability and antihistamine effects by transdermal administration of loratadine gels containing an enhancer in rats

The present study examined the feasibility of transdermal administration of loratadine gels containing an enhancer to rats by comparing the pharmacokinetic parameters of loratadine after transdermal, oral, or intravenous administration. Transdermal administration of loratadine gel (12 mg/kg applied to the abdominal skin) with an enhancer produced a significantly higher plasma concentration of loratadine than the loratadine gel without the enhancer (control). The average areas under the serum concentration‐time curves (AUC) was 929±148 h·ng/ml for oral administration, and 3,318±530.9 h·ng/ml for intravenous administration. The AUC of transdermal administration with and without the enhancer was 2,054±328.0 h·ng/ml and 1,094±176.5 h·ng/ml, respectively. The enhancer increased the relative bioavailability by 1.88‐fold (P<0.01). Transdermal application of the loratadine gel containing polyoxyethylene 2‐stearyl ether inhibited the increase in vascular permeability induced by histamine by 28.62%, whereas the loratadine gel without enhancer inhibited the permeability by 20.33%. In conclusion, the loratadine gel system containing an enhancer could be developed as a transdermal delivery system providing the increased constant plasma concentration and antihistamine effects. Drug Dev Res, 2009. © 2009 Wiley‐Liss, Inc.     

皮肤给药的经皮吸收与测量技术研究进展

经皮给药系统（TDDS）可避免首关效应、胃肠道破坏，为新型皮肤给药系统，可通过控制释放而延长治疗效果，成为药物制剂开发研究的热点之一。但是，药物的理化性质以及皮肤屏障影响药物的经皮吸收。综述了TDDS常用的促渗透技术，包括化学、物理、纳米、天然促渗透技术；介绍了促渗透能力的测定方法，包括体外、离体和体内评估皮肤渗透性的方法。通过对经皮药物递送系统和经皮吸收能力测定方法的归纳与总结，以期为TDDS的合理使用和快速发展提供参考。     

三乙醇胺复合物促进氟比洛芬体外经皮透过

目的合成氟比洛芬三乙醇胺复合物(Flu-TEA),考察氟比洛芬(Flu)及Flu-TEA的体外经皮透过性。方法采用双室水平扩散池,大鼠腹部全皮为渗透膜,分别以增塑剂柠檬酸三乙酯或经皮穿透促进剂为溶剂,测定药物的体外经皮透过性。结果Flu-TEA的体外经皮透过系数均高于Flu,氮酮、肉豆蔻酸异丙酯(IPM)、1,2-丙二醇3种经皮穿透促进剂中,氮酮与1,2-丙二醇联用对药物的促透效果最佳。结论Flu与三乙醇胺成复合物盐后可明显增加体外经皮透过性。     

Evaluation of proniosomes as an alternative strategy to optimize piroxicam transdermal delivery

The current investigation aims to evaluate the transdermal potential of niosomes bearing a potent non-steroidal anti-inflammatory, piroxicam. Piroxicam-loaded niosomes were prepared and characterized for surface morphology, entrapment efficiency and in vitro permeation across excised rat skin from various proniosome gel formulations using Franz diffusion cells. Various non-ionic surfactants were used to achieve optimum encapsulation efficiency. The prepared proniosomes significantly improved drug permeation and reduced the lag time (p < 0.05). Proniosomes prepared with Span 60 provided a higher piroxicam flux across the skin than did those prepared with Tween 80. Niosomes prepared using Span 60 showed a higher release rate than those prepared using non-ionic surfactants, Span 20 and Span 80, while those prepared from Tween showed higher release rate than formula prepared with Span. This indicates that lipophilicity and hydrophilicity of surfactant has a main role in release rates of piroxicam. Particle size of piroxicam niosomal vesicles formed by proniosome was determined by scanning electron microscopy. The encapsulation efficiency was evaluated by a specific high performance liquid chromatography method. Niosomes formed from using Spans and Tweens exhibited very high encapsulation efficiency. The results are very encouraging and suggest that niosomes can act as promising carriers offering an alternative approach for transdermal delivery of piroxicam.     

Trypsin as a novel potential absorption enhancer for improving the transdermal delivery of macromolecules

Objectives The aim was to assess the effect of trypsin on the transdermal delivery of macromolecules by applying its specific biochemical properties to the stratum corneum of the skin. Methods Fluorescein isothiocyanate (FITC)‐labelled dextrans (FDs), with molecular weights of 4 to 250 kDa, and FITC‐insulin were used as model macromolecules and a model polypeptide, and the in‐vitro transdermal permeation experiments, with or without trypsin (0.1–2.5%), were carried out using rat skin and cultured human epidermis. The mechanism for the enhancement of trypsin was also studied using fluorescence and conventional light microscopy. Key findings Trypsin significantly increased the transdermal permeability of all FDs through the rat skin (2.0‐ to 10.0‐fold). It also markedly enhanced the permeation of FD4 through three‐dimensional cultured human epidermis (3.1‐fold), which was used to evaluate the transport pathways other than the transfollicular route. Furthermore, the permeation flux of FITC‐insulin was increased by 10.0‐fold with trypsin pretreatment (from 0.02 ± 0.00 to 0.20 ± 0.07 μg/cm² per h). Mechanistic studies indicated that trypsin affects both the intercellular pathway and the hair follicular route, and may alter stratum corneum protein structures, thereby affecting skin barrier properties. Conclusions This study suggests that trypsin could be effective as a biochemical enhancer for the transdermal delivery of macromolecules including peptide and protein drugs.     

Enhanced transdermal absorption and pharmacokinetic evaluation of pranoprofen-ethylene-vinyl acetate matrix containing penetration enhancer in rats

To increase the skin permeation of pranoprofen from the ethylene-vinyl acetate (EVA) matrix, different types of enhancers were added to an EVA matrix containing 2% pranoprofen. The pharmacokinetics and bioavailability of pranoprofen, an anti-inflammatory drug, were examined to determine the feasibility of an enhanced transdermal delivery system for pranoprofen from an EVA matrix containing caprylic acid as the enhancer in rats. The effects of the enhancers on the level of pranoprofen permeation through the skin were evaluated using Franz diffusion cells that were fitted with the intact excised rat skin. Among the enhancers used, including the fatty acids (saturated, unsaturated), the glycols, the glycerides, and the pyrrolidones, caprylic acid showed the best enhancement. A pranoprofen-EVA matrix system was formulated containing caprylic acid as an enhancer. The pranoprofen-EVA matrix system (8 mg/kg) was applied to the abdominal skin of rats. The blood samples were collected through the femoral artery for 24 h and the plasma concentrations of pranoprofen were determined by HPLC. The pharmacokinetic parameters were calculated using the MULTI computer program. The area under the curve (AUC) was significantly higher in the enhancer group (55.49 ± 13.87 ng/mL·h) than in the control group (22.48 ± 5.63 ng/mL·h), which was treated transdermally without the enhancer, showing about 246% increased bioavailability (p<0.05). As the pranoprofen-EVA matrix containing caprylic acid as an enhancer was administered to rats via the transdermal routes, the relative bioavailability increased about 2.46-fold compared to the control group, showing a relatively constant, sustained blood concentration. These results show that a pranoprofen-EVA matrix containing a permeation enhancer could be developed as a transdermal delivery system to provide a sustained plasma concentration.     

Comparative bioequivalence study between a novel matrix transdermal delivery system of fentanyl and a commercially available reservoir formulation

AIM: To determine the pharmacokinetics, safety and performance of a novel matrix formulation of fentanyl. METHODS: Transdermal fentanyl was administered as the novel matrix and the Durogesic reservoir formulations (24 subjects, 100 microg h(-1)) in a randomized, fully replicate, four-way crossover study. Serum concentrations of fentanyl were assayed by LC/MS/MS. Pharmacokinetic parameters of fentanyl and performance (adherence and skin irritability) were evaluated. RESULTS: Test/reference ratio (90% confidence intervals) for AUC(0-t), AUC(inf) and C(max) were 105.5% (99.4, 112.0), 105.3% (99.3, 111.6) and 111.4% (100.4, 123.6), respectively. Adherence and skin irritability results of the two formulations were similar. CONCLUSION: The two formulations are expected to result in similar efficacy for the management of severe pain.     

不同骨架型乌头总生物碱贴片的经皮渗透性比较研究

目的:对比研究4种不同骨架型乌头总碱贴片的透皮吸收行为,筛选最佳贴片并对其进行体外释放度实验。方法:采用改良的Franz扩散池,以生理氯化钠溶液为接收介质,以大鼠离体背部皮肤为透皮屏障,计算4种骨架型贴片中乌头总碱及新乌头碱的稳态流量及滞后时间。结果:4种经皮给药制剂(TDS)中,黏胶剂骨架型贴片(P-3)稳态流量最高,其中乌头总碱的稳态流量9.2μg.cm-2.h-1,滞后时间1.413 h;新乌头碱的稳态流量0.243 6μg.cm-2.h-1,滞后时间1.172 h。该贴片体外释放符合回归方程,Higuchi方程为S(t)=13.32t1/2 18.428,r=0.980 1,体外释药机制为药物扩散和骨架溶蚀的综合效应。结论:黏胶剂骨架型是乌头总碱经皮给药制剂的理想设计模型。     

Enhanced transdermal delivery of pranoprofen from the bioadhesive gels

Percutaneous delivery of NSAIDs has advantages of avoiding hepatic first pass effect and delivering the drug for extended period of time at a sustained, concentrated level at the inflammation site that mainly acts at the joint and the related regions. To develop the new topical formulations of pranoprofen that have suitable bioadhesion, the gel was formulated using hydroxypropyl methylcellulose (HPMC) and poloxamer 407. The effects of temperature on drug release was performed at 32 degrees C, 37 degrees C and 42 degrees C according to drug concentration of 0.04%, 0.08%, 0.12%, 0.16%, and 0.2% (w/w) using synthetic cellulose membrane at 37+/-0.5 degrees C. The increase of temperature showed the increased drug release. The activation energy (Ea), which were calculated from the slope of lop P versus 1000/T plots was 11.22 kcal/ mol for 0.04%, 10.79 kcal/mol for 0.08%, 10.41 kcal/mol for 0.12% and 8.88 kcal/mol for 0.16% loading dose from the pranoprofen gel. To increase the drug permeation, some kinds of penetration enhancers such as the ethylene glycols, the propylene glycols, the glycerides, the non-ionic surfactants and the fatty acids were incorporated in the gel formulation. Among the various enhancers used, propylene glycol mono laurate showed the highest enhancing effects with the enhancement factor of 2.74. The results of this study suggest that development of topical gel formulation of pranoprofen containing an enhancer is feasible.     

多肽透皮给药研究进展

针对近年来多种多肽类药物的透皮给药系统进行综述。通过查阅国内外多种相关期刊文献。将多肽类药物透皮给药方法分为化学促渗剂、多种物理促渗技术,以及透皮肽、微针技术并对其进行论述。反向离子导入技术应用前景广阔,微针给药系统研究逐步深入,出现了胰岛素智能化微针给药系统,透皮肽的研究发展迅速,相信未来多种蛋白质及多肽的透皮给药方式将应用于临床,极大地促进医疗事业的发展。     

Spray-on transdermal drug delivery systems

Introduction: Transdermal drug delivery possesses superior advantages over other routes of administration, particularly minimizing first-pass metabolism. Transdermal drug delivery is challenged by the barrier nature of skin. Numerous technologies have been developed to overcome the relatively low skin permeability, including spray-on transdermal systems.

Areas covered: A transdermal spray-on system (TSS) usually consists of a solution containing the drug, a volatile solvent and in many cases a chemical penetration enhancer. TSS promotes drug delivery via the complex interplay between solvent evaporation and drug–solvent drag into skin. The volatile solvent carries the drug into the upper layers of the stratum corneum, and as the volatile solvent evaporates, an increase in the thermodynamic activity of the drug occurs resulting in an increased drug loading in skin.

Expert opinion: TSS is easily applied, delivering flexible drug dosage and associated with lower incidence of skin irritation. TSS provides a fast-drying product where the volatile solvent enables uniform drug distribution with minimal vehicle deposition on skin. TSS ensures precise dose administration that is aesthetically appealing and eliminates concerns of residual drug associated with transdermal patches. Furthermore, it provides a better alternative to traditional transdermal products due to ease of product development and manufacturing.