Occlusive and Non-Occlusive Application of Microemulsion for Transdermal Delivery of Progesterone: Mechanistic Studies

This work evaluated the occlusive versus non-occlusive application of microemulsion (ME) for the transdermal delivery of progesterone. The mechanisms of enhanced skin penetration were investigated. ME comprised of oleic acid, Tween 80, propylene glycol, and water, was used neat or with ethanol as a volatile cosurfactant. The ME formulations enhanced progesterone transdermal flux compared to the saturated drug solution in 14% aqueous propylene glycol (control). Ethanol-containing ME (EME) was better than the ethanol-free system (EFME). Open application of EFME produced a marginal reduction in flux compared to occlusive application. For EME, open application reduced the flux by 26–28% with the flux remaining significantly higher than that obtained with EFME. The mechanistic studies revealed synergism between ethanol and EFME with EME, producing greater flux than the sum of fluxes obtained from 40% ethanol in water and EFME. Penetration enhancement and supersaturation played a role in enhanced transdermal delivery, but other mechanisms were also possible. This study thus introduced EME as a transdermal delivery system for progesterone with good potential for open application as a spray.     

An investigation into the transdermal delivery of nifedipine

A systematic attempt to develop a transdermal delivery system for nifedipine is presented. Measured physicochemical properties influencing percutaneous absorption such as solubility and partition coefficient confirmed the drug's potention for such a formulation approach. However, studies involving permeation through hairless mouse skin from a range of hydrophilic and hydrophobic donor vehicles indicated inadequate penetration. Attempts to increase the drug flux through the animal skin or a range of artificial membranes alone or in parallel by use of the penetration enhancers sodium lauryl sulphate 1% and propylene glycol 20% in a sodium carboxymethylcellulose 3% gel base failed to raise the drug flux to an acceptable level. Likewise increase in the drug thermodynamic gradient across the skin by use of mixed solvents or supersaturated drug solutions was ineffective if an aqueous receiving phase was used. Collectively the results suggest that the development of a transdermal delivery system for the chemically unmodified drug in humans is unlikely to be successful.     

乙醇和丙二醇单用与联用对曲安奈德喷雾溶液透皮性能的影响

目的 对曲安奈德喷雾溶液进行体外透皮试验,考察乙醇和丙二醇单用与联用时对曲安奈德喷雾溶液体外透皮功能的影响。方法 选取新西兰白兔腹部皮肤,用Franz扩散池法对曲安奈德喷雾溶液进行体外透皮试验,用高效液相色谱法（HPLC）测定曲安奈德含量,用单因素方差分析法对各组间的透皮吸收速率进行对比分析。结果 乙醇和丙二醇联用时的透皮吸收速率均显著高于单用时的透皮吸收速率（P<0.05）,且乙醇和丙二醇联用时对曲安奈德喷雾溶液的促透作用顺序为10%乙醇+25%丙二醇>10%乙醇+20%丙二醇>15%乙醇+25%丙二醇>15%乙醇+20%丙二醇。结论 10%乙醇和25%丙二醇联用时可使曲安奈德喷雾溶液的透皮功能达到最佳化。     

Effect of enhancers and retarders on percutaneous absorption of flurbiprofen from hydrogels

The effect of enhancers/retarders on the transdermal absorption of flurbiprofen from cellulose hydrogels was studied in vitro. The release rate of flurbiprofen and the viscosity of hydrogel matrices were also examined. The flux of flurbiprofen from cellulose hydrogels approximated that from aqueous buffers, whereas the skin reservoir of flurbiprofen was lower with hydrogels. Incorporation of the cosolvents, propylene glycol (PG) and ethanol, did not significantly increase skin absorption of flurbiprofen. Ethanol even reduced the skin reservoir of the drug. Oleic acid, an unsaturated fatty acid, produced the largest skin reservoir of the drug when incorporated into the hydrogels. D-Limonene, a cyclic monoterpene, showed the greatest ability to enhance the flux of flurbiprofen. However, phospholipids as retarders markedly reduced the skin absorption of flurbiprofen. The mechanisms by which enhancers/retarders govern flurbiprofen permeation were elucidated by in vitro permeation studies using various skin types (enhancers/retarders-pretreated skin, stratum corneum (SC)-stripped skin, and delipidized skin) and histological examination. The results suggest different mechanisms and skin structural modifications caused by different enhancers/retarders.     

Transdermal delivery of venlafaxine hydrochloride: the effects of enhancers on permeation across pig ear skin

Venlafaxine representing a new class of antidepressants is a potent serotonin/ norepinephrine reuptake inhibitor. Transdermal delivery of venlafaxine hydrochloride (VHCl) may result in proper patient compliance by reducing the incidence of the undesirable GI problems generally associated with its plural oral dosing. The present study is an attempt to investigate the improvement of the transdermal flux of the hydrophilic VHCl by certain permeation enhancers viz. glycerin, urea, propylene glycol and mixture of propylene glycol and ethanol across pig ear skin. The cumulative drug release was the highest from the formulation F5 consisting of the mixture of propylene glycol and ethanol in sodium alginate gel with a load of 25% w/w VHCl with 96% permeation enhancement. The steady state flux observed with F5 was 0.203 mg cm(-2) hr and an area of 15.27 cm(2) would suffice to arrive at a required therapeutic concentration of VHCl in the blood.     

Transdermal delivery of nicardipine: an approach to in vitro permeation enhancement

Nicardipine hydrochloride (NC-HCl), a calcium channel blocker for the treatment of chronic stable angina and hypertension, seems to be a potential therapeutic transdermal system candidate, mainly due to its low dose, short half-life, and high first-pass metabolism. The objective of the present study was to evaluate its flux and elucidate mechanistic effects of formulation components on transdermal permeation of the drug through the skin. Solubility of NC-HCl in different solvent systems was determined using a validated HPLC method. The solubility of drug in various solvent systems was found to be in decreasing order as propylene glycol (PG)/oleic acid (OA)/dimethyl isosorbide (DMI) (80:10:10 v/v) > PG > PG/OA (90:10 v/v) > polyethylene glycol 300 > ethanol/PG (70:30 w/w) > transcutol > dimethyl isosorbide (DMI) > ethanol > water and buffer 4.7 > 2-propanol. Propylene glycol was then selected as the main vehicle in the development of a transdermal product. As a preliminary step to develop a transdermal delivery system, vehicle effect on the percutaneous absorption of NC-HCl was determined using the excised skin of a hairless guinea pig. Vehicles investigated included pure solvents alone and their selected blends, chosen based on the solubility results. In vitro permeation data were collected at 37 degrees C, using Franz diffusion cells. The skin permeation was then evaluated by measuring the steady state permeation rate (flux) of NC-HCl, lag time, and the permeability constant. The results showed that no individual solvent was capable of promoting NC-HCl penetration. Permeation profiles of the drug through hairless guinea pig skin using saturated solutions of drug were constructed. Among the systems studied, the ternary mixture of PG/OA/DMI and binary mixture of PG/OA showed excellent flux. The flux value of the ternary system was nearly three times higher than the corresponding values obtained for the binary solvent. A similar trend also was observed for the permeation constant, while the values of lag time were reversed. The ternary mixture was then selected as a potential absorption enhancement vehicle for the transdermal delivery of drug. In general, higher fluxes were observed through hairless guinea pig skin as compared with the human stratum corneum. Based on the results obtained from the release study of NC-HCl from saturated solutions of the drug, a novel lecithin organogel (microemulsion-based gel) composed of soybean lecithin, propylene glycol, oleic acid, dimethyl isosorbide, and isopropyl myristate was developed as a possible matrix for transdermal delivery of NC-HCl. In vitro percutaneous penetration studies from this newly developed gel system through giunea pig skin and human stratum corneum revealed that the organogel system has skin-enhancing potential and could be a promising matrix for the transdermal delivery of nicardipine. Furthermore, higher permeation rates were observed when nicardipine free base was incorporated into the gel matrix instead of hydrochloride salt.     

Topical delivery of cyclosporin A: an in vitro study using monoolein as a penetration enhancer.

Topical delivery of cyclosporin A (CysA) is of great interest for the treatment of autoimmune skin disorders, but it is frequently ineffective due to poor drug penetration in the skin. The present study was aimed at investigating whether the presence of monoolein (a lipidic penetration enhancer) in a preparation of propylene glycol can improve CysA delivery to the skin. CysA was incorporated in a propylene glycol preparation containing 5-70% (w/w) of monoolein. The topical (to the skin) and transdermal (across the skin) delivery of CysA were evaluated in vitro using porcine ear skin mounted in a Franz diffusion cell. CysA was quantified by UV-HPLC. At 5%, monoolein increased only the transdermal delivery of CysA. At 10%, it increased both topical and transdermal delivery. When the concentration of monoolein was further increased (20-70% w/w), an interesting phenomenon was observed: the topical delivery of CysA was still elevated but its transdermal delivery was substantially reduced. It was concluded that monoolein (in propylene glycol formulations) can promote the topical delivery of CysA, with reduced transdermal delivery.     

不同基质和透皮促进剂对秋水仙碱凝胶剂体外透皮特性的影响

目的优选秋水仙碱凝胶剂基质和相应的透皮促进剂,为制备秋水仙碱透皮给药新制剂提供参考资料。方法采用改良的Franz扩散池法,并通过RP-HPLC法测定接收液中秋水仙碱的含量。结果3种基质的秋水仙碱凝胶体外透皮比率为Carbopol基质凝胶>HPMC基质凝胶>CMC-Na基质凝胶。以Carbopol为基质,加入几种透皮促进剂后,秋水仙碱凝胶的体外透皮速率为丙二醇>冰片>氮酮>薄荷油。结论凝胶剂作为秋水仙碱透皮吸收新剂型可行。     

Formulation optimization of meloxicam sodium gel using response surface methodology

The influences of a combination of different mechanisms of penetration enhancers on the penetration absorption properties of meloxicam sodium formulations through rat skin were investigated using response surface methodology. A uniform design was applied to prepare model formulations systematically that were composed of four independent variables: the content of ethanol (x(1)), propylene glycol (x(2)), menthol (x(3)), and azone (x(4)). The penetration rate (flux) of meloxicam sodium gel through rat skin was chosen as the response which had to be higher than 400microg/hcm(2) the required flux of meloxicam gel to maintain a therapeutic concentration. The result showed optimal formulation could be obtained from this response surface methodology. Menthol had the greatest potential influence on the penetration absorption of meloxicam sodium, followed by azone, ethanol and PG, respectively. By in vivo study, meloxicam could be determined 1h after topical administration and reached steady-state concentration at about 12h. The bioavailability (%) of the optimal meloxicam sodium gel was about 50.1%.     

Effect of some penetration enhancers on the permeation of glibenclamide and glipizide through mouse skin

The purpose of this investigation was to study the effect of some penetration enhancers on in vitro permeation of glibenclamide and glipizide through mouse skin. Ethanol in various concentrations, N-methyl-2-pyrrolidinone, transcutol, propylene glycol and terpenes like citral, geraniol and eugenol were used as penetration enhancers. The in vitro skin permeation experiments were conducted by both simultaneous application of drug and enhancer solution and by pretreatment of the skin with neat enhancer. At the end of the experiment drug retained in the skin was estimated. The flux values (microg/cm2/h) of both drugs significantly (p < 0.05) increased in the presence of penetration enhancers, except transcutol and propylene glycol. The glibenclamide flux values ranged from 1.42 +/- 0.09 without enhancer, to 18.25 +/- 1.21 in a combination of 50% ethanol and 5% eugenol. Glipizide flux values ranged from 3.21 +/- 0.51 without enhancer, to 57.21 +/- 5.25 in a combination of 50% ethanol and 5% eugenol. Skin retention and solubility of both drugs increased with all penetration enhancers compared to control (except propylene glycol). As the target permeation rates for glibenclamide and glipizide were calculated to be 193.8 and 184.8 microg/h respectively, the present study showed that the required permeation rates for both drugs could be achieved with the aid of enhancers by increasing the area of application in an appreciable range.     

Evaluation of penetration enhancement of lidocaine by nonionic surfactants through hairless mouse skin in vitro

The effect of two nonionic surfactants (polyoxyethylene sorbitan monoesters) on percutaneous absorption of lidocaine in the presence of various concentrations of propylene glycol is reported. Comparisons were made in vitro using excised hairless mouse skin as the barrier membrane. Under infinite dose conditions, steady-state flux was enhanced by surfactants at high propylene glycol concentrations. The same trend was observed following application of a thin layer of formulation to the skin (finite-dose conditions). However, penetration behavior was complex due to: (a) changes in vehicle composition following application, (b) temperature changes resulting from evaporation or moisture uptake, and (c) depletion of lidocaine as a result of penetration with compositions that lost water by evaporation. Two peaks in the flux versus time curve were observed. Surfactant monomer concentration in the vehicles was increased in the presence of propylene glycol.     

Effect of oleic acid/ethanol and oleic acid/propylene glycol on the in vitro percutaneous absorption of 5-fluorouracil and tamoxifen and the macroscopic barrier property of porcine epidermis

Transdermal delivery of most drugs is precluded due to the impervious nature of the stratum corneum. Chemical penetration enhancers offer an approach to enhance the transdermal transport of drugs by partitioning into and interacting with skin constituents, inducing a temporary reversible increase in skin permeability. The effect of penetration enhancers (e.g. oleic acid/ethanol and oleic acid/propylene glycol) was investigated on the in vitro percutaneous absorption of a hydrophilic (5-fluorouracil) and a lipophilic (tamoxifen) anticancer drug through porcine epidermis. In vitro transepidermal water loss (TEWL) studies were undertaken to investigate the effect of the above enhancers on the macroscopic barrier properties of the epidermis. Oleic acid/ethanol and oleic acid/propylene glycol significantly enhanced (P<0.05) the permeability coefficient of 5-fluorouracil (5-FU) and tamoxifen in comparison to their controls. In vitro TEWL was significantly greater (P<0.01) through epidermis treated with the above enhancers in comparison with control (epidermis that was not treated). However, neither oleic acid/ethanol nor oleic acid/propylene glycol enhanced (P>0.05) TEWL in comparison with ethanol and propylene glycol alone. Thus, changes in the permeability of 5-FU and tamoxifen caused by oleic acid/ethanol or oleic acid/propylene glycol could not be correlated with the in vitro TEWL.     

马钱子巴布剂体外透皮实验及促透剂的筛选

目的:考察不同促透剂对马钱子巴布剂中马钱子碱、士的宁的体外透皮吸收的影响,筛选合适的促透剂。方法:采用改良Franz扩散池对离体大鼠皮肤进行体外透皮实验,RP-HPLC法测定含不同促透剂的马钱子巴布剂中活性成分的累积渗透量(Q_n)和透过率(T)。结果:马钱子巴布剂体外透皮吸收符合零级动力学方程,不同的促透剂对透皮吸收影响的顺序为:DMF>月桂氮芯卓酮(氮酮)>丙二醇>薄荷醇。在给定的范围内(≤5%),氮酮和薄荷醇的促透性能均是随着浓度增大而先升后降,二甲基甲酰胺和丙二醇的促透效果都是随着浓度增大而增强。结论:不同浓度的促透剂均能一定程度促进马钱子巴布剂活性成分的透皮吸收,其中以5%DMF的促渗效果最好。     

Transdermal delivery of hydrocortisone from eucalyptus oil microemulsion: effects of cosurfactants

This study investigated the effects of cosurfactants on the transdermal delivery of hydrocortisone (model drug) from eucalyptus oil microemulsion. Eucalyptus oil which was successfully employed for steroidal drugs was used as the oil. Tween 80 which was readily miscible with eucalyptus oil was used as surfactant. Ethanol, isopropanol and propylene glycol which are relatively tolerable by the skin were employed as cosurfactants. Pseudo-ternary phase diagrams were constructed in the presence and absence of cosurfactants. Microemulsion formulations containing 20% oil, 20% water and 60% of either Tween 80 or 1:1 surfactant/cosurfactant mixture were compared. Incorporation of cosurfactants expanded the microemulsion zone. The cosurfactant free microemulsion was viscous showing pseudo-plastic flow. The cosurfactant containing preparations were less viscous with Newtonian flow. The drug loading and release rate were increased in the presence of cosurfactants with the release depending on the viscosity. Incorporation of hydrocortisone in microemulsion increased the transdermal flux compared to saturated aqueous solution. The presence of cosurfactants increased the transdermal drug flux compared to the cosurfactant free formulation. Ethanol produced the greatest effect followed by propylene glycol and isopropanol. The presence of cosurfactant and its type can thus affect both the phase behavior and the transdermal delivery potential of microemulsion.     

渗透促进剂对胰岛素体外经皮离子导入渗透性的影响

本文考察了某些渗透促进剂如月桂氮Zhuo酮（AZ）、油酸（OA）、泊洛沙姆（POL）和丙二醇（PG）等对胰岛素体外经皮离子导入渗透性的影响。结果表明AZ对离子导入具有协同作用，PG能够增强这种作用，三者并用对胰岛素的经皮渗透具有特别显著的促渗效果。5％AZ／PG与离子导入并用后，较单独离子导入处理组的促渗因子为2.75。OA不能增强离子导入的作用，离子导入与某些渗透促进剂并用为胰岛素等大分子多肽类药物的透皮给药提供了新的思路和可能。     

Biopharmaceutics: Topical Delivery of Keloid Therapeutic Drug,Tranilast, by Combined Use of Oleic Acid and Propylene Glycol as a Penetration Enhancer: Evaluation by Skin Microdialysis in Rats

Topical delivery of tranilast (N-(3,4-dimethoxycinnamoyl)anthranic acid), an inhibitor of collagen synthesis and a therapeutic drug for keloid and hypertrophic scar, was examined, in rats, with oleic acid alone or a combination of oleic acid and propylene glycol as penetration enhancer. Evaluation was by measurement of the concentration of tranilast in plasma and in the dialysate from skin microdialysis. When tranilast at a dose of 1.5 mg was applied topically as an ethanol solution containing 5% polyvinylpyrrolidone on a dorsal skin surface (2.25 cm²), the maximum concentration of tranilast in skin dialysate was approximately 2 μM. When 10 or 20% oleic acid was added to the same ethanol solution the maximum concentration of tranilast in the dialysate increased to 10–20 μM, and this value was further increased to 60 μM by the addition of a combination of oleic acid (10 or 20%) and propylene glycol (10%) to the solution. With the combination of oleic acid and propylene glycol the area under the plot of the concentration of tranilast in skin dialysate against time between 0 and 4 h (AUC_0–4) was more than 400-fold that after intravenous administration. The transdermal bioavailability of tranilast as assessed by the AUC_0–4 of tranilast in plasma, was 0.2% of the dose applied in the ethanol solution, 3–5% of that applied in the ethanol solution containing oleic acid, and 14–16% of that applied in the ethanol solution containing both oleic acid and propylene glycol. These results suggest that the topical delivery of tranilast with an absorption enhancer such as a mixture of oleic acid and propylene glycol might be a more effective medication than oral administration of tranilast for the treatment of keloid and hypertrophic scar.     

Penetration enhancers in proniosomes as a new strategy for enhanced transdermal drug delivery

The aim of this work is to investigate penetration enhancers in proniosomes as a transdermal delivery system for nisoldipine. This was performed with the goal of optimising the composition of proniosomes as transdermal drug delivery systems. Plain proniosomes comprising sorbitan monostearate, cholesterol, ethanol and a small quantity of water were initially prepared. Subsequently, proniosomes containing lecithin or skin penetration enhancers were prepared and evaluated for transdermal delivery of nisoldipine. The plain proniosomes significantly enhanced the transdermal flux of nisoldipine to reach 12.18 μg cm⁻² h⁻¹ compared with a saturated aqueous drug solution which delivered the drug at a rate of 0.46 μg cm⁻² h⁻¹. Incorporation of lecithin into such proniosomes increased the drug flux to reach a value of 28.51 μg cm⁻² h⁻¹. This increase can be attributed to the penetration enhancing effect of lecithin fatty acid components. Replacing lecithin oleic acid (OA) produced proniosomes of comparable efficacy to the lecithin containing system. The transdermal drug flux increased further after incorporation of propylene glycol into the OA based proniosomes. Similarly, incorporation of isopropyl myristate into plain proniosomes increased drug flux. The study introduced enhanced proniosomes as a promising transdermal delivery carrier and highlighted the role of penetration enhancing mechanisms in enhanced proniosomal skin delivery. The study opened the way for another line of optimisation of niosome proconcentrates.     

不同透皮吸收促进剂对左旋肉碱透皮特性的影响

目的:选择适宜的透皮吸收促进剂增加左旋肉碱的透皮百分率。方法:使用改良Franz体外释药装置,用RP-HPLC法检测接收液中左旋肉碱的浓度,计算药物的透皮累积释放量,采用滞留时间法求算经皮渗透相关系数,考察不同用量的丙二醇、尿素、氮酮对左旋肉碱的促透作用。结果:左旋肉碱的溶液在体外透皮释放试验中有透皮吸收。不同种类及不同用量的吸收促进剂对左旋肉碱的促透作用不同,且随着透皮时间的延长,促透量显著增加。3种透皮吸收促进剂中尿素和丙二醇的促透作用较好,氮酮的促透作用稍差。结论:透皮吸收促进剂能够增加左旋肉碱的透皮百分率,其中2.5%的丙二醇促透作用最强。     

Effect of penetration enhancers on the transdermal delivery of bupranolol through rat skin

Bupranolol (BPL) is a suitable drug candidate for transdermal drug delivery system development based on its favorable physicochemical and pharmacokinetic properties. The effect of different penetration enhancers on the permeation of BPL across rat skin was studied using side-by-side diffusion cells. 2-Pyrrolidone (PY), 1-methyl-2-pyrrolidone (MPY), and propylene glycol (PG) at various concentrations were used as penetration enhancers along with 0.4% w/v aqueous suspension of BPL. Menthol at different concentrations in isopropanol-water (6:4) mixture also was used as an enhancer wherein BPL at 0.4% w/v was completely solubilized. Skin pretreatment studies were carried out with all the above enhancers to understand their role in the penetration enhancement effect. PY and MPY at 5% w/v concentrations increased the permeation of BPL by 3.8- and 2.4-fold, respectively, versus control (p < .01). PG at 10% and 30 w/v concentrations increased the flux of BPL by 2.5- and 5.0-fold, respectively, versus control (p < .001). Menthol at 2% w/v concentration increased the flux of BPL by 3.8-fold (p < .01) and further increase in menthol concentration significantly decreased the flux of BPL. Overall, pyrrolidones and menthol at low concentrations (5% w/v or less) and PG at 30% w/v concentration were effective as penetration enhancers for BPL.     

透皮促进剂对萘普生的促透效果研究

目的研究透皮促进剂月桂氮酮、油酸、月桂醇与1,2-丙二醇单独使用或混合使用对萘普生经皮渗透的促透效果。方法采用Valia-Chien双室渗透池,以10%聚乙二醇400生理盐水为接收介质,经大鼠腹部离体皮肤渗透,高效液相色谱法测定接受液中药物含量,计算药物累积透皮量和稳态透皮速率。结果 5%月桂氮酮+20%1,2-丙二醇达最大促透效果。结论脂溶性促进剂月桂氮酮、油酸,联合1,2-丙二醇使用对萘普生促透效果显著。