Effect of penetration enhancers on the release and skin permeation of bupranolol from reservoir-type transdermal delivery systems

A reservoir-type transdermal delivery system (TDS) of bupranolol (BPL) was designed and evaluated for different formulation variables like gel reservoirs (made with anionic and nonionic polymers), rate controlling membranes and penetration enhancers on the drug release and in vitro skin permeation kinetics of the devices. Keshary-Chien type diffusion cells and pH 7.4 phosphate buffered saline (PBS) were used for drug release studies and excised rat skin was used as a barrier for permeation experiments. The release rate of BPL from nonionic polymer gel reservoirs [hydroxypropyl methyl cellulose (HPMC), hydroxypropyl cellulose (HPC)] was much higher than anionic polymer gel reservoirs [carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (Na CMC) and sodium alginate)]. Among different rate controlling membranes, Cotran-polyethylene microporous membrane demonstrated highest release rate for BPL than all other membranes. An optimized TDS formulation with HPC gel and Cotran-polyethylene microporous membrane was used to study the effect of penetration enhancers on the release and skin permeation rate of BPL from the TDS. Permeation rates of the devices containing 5% (w/v) pyrrolidone (PY) or 1-methyl-2-pyrrolidone (MPY) were about 3- and 1.5-fold higher than control (no enhancer, P<0.01) indicating PY to be better penetration enhancer for BPL than MPY. The permeation rates of devices containing partially methylated beta-cyclodextrin (PMbetaCD) and PMbetaCD-BPL complex were about 2.5- and 1.4-fold higher than control (P<0.01). Inclusion of 10 and 30% w/v propylene glycol (PG) in the devices increased the permeation rate by 1.4- and 1.8-fold higher than control (P<0.05). In conclusion, reservoir-type TDS of BPL was developed and penetration enhancers increased the skin permeation of BPL at 4-5 times higher levels than the desired target delivery rate.     

Design of improved permeation enhancers for transdermal drug delivery

One promising way to breach the skin's natural barrier to drugs is by the application of chemicals called penetration enhancers. However, identifying potential enhancers is difficult and time consuming. We have developed a virtual screening algorithm for generating potential chemical penetration enhancers (CPEs) by integrating nonlinear, theory-based quantitative structure–property relationship models, genetic algorithms, and neural networks. Our newly developed algorithm was used to identify seven potential CPE molecular structures. These chemical enhancers were tested for their toxicity on (a) mouse embryonic fibroblasts (MEFs) with MTT assay, and (b) porcine abdominal skin by histology using H/E staining at the end of a 48-h exposure period to the chemicals. Further, melatonin permeability in the presence of the enhancers was tested using porcine skin and Franz diffusion cells. Careful toxicity tests showed that four of the seven “general” CPEs were nontoxic candidate enhancers (menthone, 1-(1-adamantyl)-2-pyrrolidinone, R(+)-3-amino-1-hydroxy-2-pyrrolidinone, and 1-(4-nitro-phenyl)-pyrrolidine-2,5-dione). Further testing of these four molecules as potential melatonin-specific CPEs revealed that only menthone and 1-dodecyl-2-pyrrolidinone provided sufficient enhancement of the melatonin permeation. The results from our permeability and toxicity measurements provide validation of the efficacy and ability of our virtual screening algorithm for generating potential chemical enhancer structures by virtual screening algorithms, in addition to providing additional experimental data to the body of knowledge. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:4085–4099, 2009     

Effect of penetration enhancers on skin permeation of trazodone hydrochloride from matrix type transdermal formulation through mouse and human cadaver epidermis

A transdermal dosage form of trazodone hydrochloride (TZN) may be useful in the treatment of moderate to severe depression in schizophrenic patients by providing prolonged duration of action. It will also improve patient compliance and bioavailability. Controlled input of TZN would attenuate fluctuating plasma level of TZN resulting from oral therapy. The aim of the current investigation was to evaluate its flux and the effects of various penetration enhancers, viz., isopropyl myristate (IPM), isopropyl palmitate (IPP), butanol and octanol on transdermal permeation from matrix-based formulations through the skin. The enhancing effect on the permeation of TZN was determined using the mouse and human cadaver epidermis. In vitro permeation data were collected at 37 degrees C using Keshary-Chien diffusion cells. The skin permeation was then evaluated by measuring the steady state permeation flux of TZN, enhancement ratio and the diffusion parameter. The highest enhancing effect was obtained with IPM followed by butanol, octanol and IPP. In general, higher fluxes were observed through mouse epidermis as compared with the human cadaver epidermis. The skin retention of TZN for both the species in the presence of different enhancers was nearly 3 times higher than for the control formulation. Based on the observed results, a transdermal patch of about 70 cm2 consisting of 10 % IPM should be able to attain and maintain therapeutic plasma concentration of TZN at 0.75 mg/mL over a period of 24 h.     

Development of matrix based transdermal delivery system for ketotifen

The purpose of this study was to investigate the feasibility of developing transdermal drug delivery system for ketotifen used for asthma, allergic conjunctivitis, and rhinitis. The permeation of ketotifen in silicone, polyisobutylene, styrene–butadiene–styrene and acrylic-rubber hybrid and acrylic pressure sensitive adhesive matrix was evaluated. Due to good adhesion force and high permeability, acrylic-rubber hybrid adhesive was chosen. Permeation rate was found to increase linearly as the drug concentration in acrylic-rubber hybrid adhesive increased. However, when the drug concentration was 5 % or more in the matrix, recrystallization of ketotifen was observed. The recrystallization process was not inhibited by crystallization inhibitors tested. Significant increase in flux was obtained using Brij^® 30, Crovol^® A40, Span^® 80 and Lauroglycol^® FCC as permeation enhancers.     

Applications of ultrasonic skin permeation in transdermal drug delivery

Transdermal ultrasound-mediated drug delivery has been studied as a method for needle-less, non-invasive drug administration. Potential obstacles include the stratum corneum, which is not sufficiently passively permeable to allow effective transfer of many medications into the bloodstream without active methods. A general review of the transdermal ultrasound drug delivery literature has shown that this technology offers promising potential for non-invasive drug administration. Included in this review are the reported acoustic parameters used for achieving delivery, along with the known intensities and exposure times. Ultrasound mechanisms are discussed as well as spatial field characteristics. Accurate and precise quantification of the acoustic field used in drug delivery experiments is essential to ensure safety versus efficacy and to avoid potentially harmful bioeffects.     

Applications of ultrasonic skin permeation in transdermal drug delivery

Transdermal ultrasound-mediated drug delivery has been studied as a method for needle-less, non-invasive drug administration. Potential obstacles include the stratum corneum, which is not sufficiently passively permeable to allow effective transfer of many medications into the bloodstream without active methods. A general review of the transdermal ultrasound drug delivery literature has shown that this technology offers promising potential for non-invasive drug administration. Included in this review are the reported acoustic parameters used for achieving delivery, along with the known intensities and exposure times. Ultrasound mechanisms are discussed as well as spatial field characteristics. Accurate and precise quantification of the acoustic field used in drug delivery experiments is essential to ensure safety versus efficacy and to avoid potentially harmful bioeffects.     

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 degrees C with a circulating water jacket and magnetic stirring (180 rpm). Samples were analysed by UV-VIS spectrophotometer at 255 nm. Flux (Jm) 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.     

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.     

Effects of enantiomer and isomer permeation enhancers on transdermal delivery of ligustrazine hydrochloride

Enantiomers and isomers, such as D-limonene, L-limonene, and alpha-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 alpha-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 alpha-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.     

Experimental design for optimizing drug release from silicone elastomer matrix and investigation of transdermal drug delivery

Silicone elastomers are commonly used for medical devices and external prosthesis. Recently, there has been growing interest in silicone-based medical devices with enhanced function that release drugs from the elastomer matrix. In the current study, an experimental design approach was used to optimize the release properties of the model drug diclofenac from medical silicone elastomer matrix, including a combination of four permeation enhancers as additives and allowing for constraints in the properties of the material. The D-optimal design included six factors and five responses describing material properties and release of the drug. The first experimental object was screening, to investigate the main and interaction effects, based on 29 experiments. All excipients had a significant effect and were therefore included in the optimization, which also allowed the possible contribution of quadratic terms to the model and was based on 38 experiments. Screening and optimization of release and material properties resulted in the production of two optimized silicone membranes, which were tested for transdermal delivery. The results confirmed the validity of the model for the optimized membranes that were used for further testing for transdermal drug delivery through heat-separated human skin. The optimization resulted in an excipient/drug/silicone composition that resulted in a cured elastomer with good tensile strength and a 4- to 7-fold transdermal delivery increase relative to elastomer that did not contain excipients.     

Synergic enhancing-effect of DEET and dodecylamine on the skin permeation of testosterone from a matrix-type transdermal delivery system

The synergic in vitro skin permeation enhancing-effect of N,N-diethyl-m-toluamide (DEET) and dodecylamine was investigated in order to develop a novel non-scrotal matrix-type transdermal delivery system of testosterone (TS). When DEET was loaded in DuroTak^® 87-2510 together with 2% TS and 3% dodecylamine, the in vitro rat skin permeation rate of TS synergistically increased as DEET concentration increased up to 0.5%. No further increase in permeation was observed thereafter and a plateau was observed up to 3.8% DEET. Moreover, compared to 0.5% DEET concentration, the addition of 3.8% of DEET in combination with 3% dodecylamine and 6% TS further increased the permeation rate of TS, and the maximum permeation rate of 11.21 μg/cm²/h was achieved. The in vitro skin permeation rates of TS from a transdermal delivery system of DuroTak^® 87-2510 containing 6% TS, 3% dodecyamine, and 3.8% DEET were in the following order: hairless mouse skin > rat skin > human cadaver skin. Assuming that a system with a surface area of 60 cm² is applied, the human cadaver skin permeation rate of 5.74 μg/cm²/h achieved in this study can be interpreted as being equivalent to delivering ～ 8.?27?mg of TS per day. Considering that the commercially available product (Testoderm^®TTS) for non-scrotal skin of the same surface area is designed to administer 5?mg of TS per day, the new formulation could maintain therapeutic plasma concentration of TS at a smaller surface area of 40 cm².     

Effect of permeation enhancers and organic acids on the skin permeation of indapamide

The aim of present study was to investigate the transdermal properties of indapamide and to explore the efficacy of various permeation enhancers and organic acids with regard to the percutaneous absorption of indapamide. Permeation experiments were performed in vitro, using rat abdominal skin as a barrier. In the permeation studies, 2-chamber diffusion cells were used. The results obtained indicate that N-dodecylazepan-2-one, N-methyl-2-pyrrolidone, menthol and oleic acid had a strong enhancing effect on the permeation of indapamide and N-dodecylazepan-2-one exhibited the most potent enhancing effect. All eight of the organic acids chosen had a potent enhancing effect on the permeation of indapamide across rat abdominal skin. Among the organic acids examined, lactic acid had the greatest enhancing effect. The formation of an ion-pair between indapamide and organic acids may be responsible for the enhanced skin permeation of indapamide. Although the exact reason remains unknown, it is worth carrying out further investigations.     

Natural oils as skin permeation enhancers for transdermal delivery of olanzapine: in vitro and in vivo evaluation

The feasibility of development of transdermal delivery system of olanzapine utilizing natural oils as permeation enhancers was investigated. Penetration enhancing potential of corn (maize) oil, groundnut oil and jojoba oil on in vitro permeation of olanzapine across rat skin was studied. The magnitude of flux enhancement factor with corn oil, groundnut oil and jojoba oil was 7.06, 5.31 and 1.9 respectively at 5mg/ml concentration in solvent system. On the basis of in vitro permeation studies, eudragit based matrix type transdermal patches of olanzapine were fabricated using optimized concentrations of natural oils as permeation enhancers. All transdermal patches were found to be uniform with respect to physical characteristics. The interaction studies carried out by comparing the results of ultraviolet, HPLC and FTIR analyses for the pure drug, polymers and mixture of drug and polymers indicated no chemical interaction between the drug and excipients. Corn oil containing unsaturated fatty acids was found to be promising natural permeation enhancer for transdermal delivery of olanzapine with greatest cumulative amount of drug permeated (1010.68 μg/cm2/h) up to 24 h and caused no skin irritation. The fabricated transdermal patches were found to be stable. The pharmacokinetic characteristics of the final optimized matrix patch (T2) were determined after transdermal application to rabbits. The calculated relative bioavailability of TDDS was 113.6 % as compared to oral administration of olanzapine. The therapeutic effectiveness of optimized transdermal system was confirmed by tranquillizing activity in rotarod and grip mice model.     

Pulsed release of nitroglycerin from transdermal drug delivery systems

Non-ionic surfactant vesicles (niosomes) formed by a hexadecyl diglycerol ether (C16G2) and a series of polyoxyethylene alkyl ethers exhibit a variety of shapes dependent on their membrane composition. These surfactants form with an equimolar amount of cholesterol a mixture of largely spherical and tubular niosomes. In the absence of cholesterol, they form faceted polyhedral structures. The physicochemical and biological differences between polyhedral and spherical/tubular niosomes were studied. Polyhedral niosomes undergo a reversible shape transformation into spherical structures on heating above their phase transition temperature (Tm). The viscosity of polyhedral niosomes at room temperature is higher than their spherical counterparts due to their faceted and relatively rigid shape, and is more dependent on temperature due to shape transformation. At room temperature, polyhedral niosomes possess more rigid gel phase membranes and are less osmotically sensitive; however, they are more permeable because of a lack of or low levels of cholesterol in their membranes. Polyhedral niosomes loaded with luteinising hormone releasing hormone (LHRH), nonetheless, slow the release of drug compared to solution, albeit to a small extent.     

Formulation of transdermal drug delivery system: matrix type, and selection of polymer- their evaluation

Goatskin is used instead of rat-skin to study the permeation and the results are compared. The percentage of permeation is double in goatskin. We have five different oils to study, how they influence permeation and all of them have improved permeation when used on goatskin. To analyze further two parameters-percentage and rate of permeation are used. When these five oils are used with salicyclic acid on goatskin the following results are obtained. The percentage of permeation is as follows [Caraway oil (48%) > Lemon oil (36%) > Peppermint oil (29%) > Lemon Grass oil (22%) > Citronella oil (19%)]. The caraway oil has the highest percentage of permeation whereas citronella oil has the lowest percentage of permeation. Caraway oil has three times more permeation than that of citronella oil. The selection of polymer for the formulation of TDDS was done basing on a comparative study of five polymers and their various combinations using such parameters as uniformity of weight, thickness and content and percentage and rate of diffusion counted. Results show that methylcellulose and hydroxy propyl methyl cellulose record more control release of salicyclic acid than the other polymers. Except HPMC all other polymers follow zero order kinematics. Basing on this experimental evidence transdermal patch of salicyclic acid was formed with HPMC, MC polymer incombination with caraway oil has permeating enhancer and evaluated using goatskin. Comparative study shows that there is two fold increases in the percentage of permeation.     

透皮吸收促进剂在经皮给药系统中的质控和评价方法

透皮吸收制剂是国际上第三代药物制剂的研究重点领域。透皮吸收促进剂在处方中的合理应用和质量控制及其评价方法日益重要。通过对透皮促进机理、协同作用等的探讨,介绍透皮吸收促进剂的选用原则,并对透皮给药制剂和局部用药局部起效的皮肤外用制剂处方中使用的要求加以讨论,介绍了现有的评价方法和基本的技术要求。     

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。     

Effect of counter-ions and penetration enhancers on the skin permeation of flurbiprofen

The aim of this work was to investigate the percutaneous absorption of flurbiprofen (FP) using counter-ions as enhancers as well as to compare their enhancing activity with penetration enhancers in vitro. The in vitro permeation studies of FP were performed in isopropyl myristate (IPM) solution by two-chamber diffusion cells, using rat abdominal skin as a model. Among the penetration enhancers examined, including the cosolvents of propylene glycol and ethanol (EtOH), oleic acid, menthol, laurocapram, sorbitan monooleate, and N-methyl-2-pyrrolidone (NMP), 10% (w/w) EtOH and NMP exhibited the most potent solubilization and enhancing effects of FP from IPM, with a flux of (372.60 ± 45.12) µg/cm²/h and (474.21 ± 46.64) µg/cm²/h, respectively. Ten percent (w/w) EtOH/IPM binary system was used to investigate the effect of the counter-ions, namely diethylamine (DEA), triethylamine (TEA), ethanolamine (EtA), diethanolamine (DEtA), triethanolamine (TEtA), and N-(2′-hydroxyethanol)-piperdine (HEPP). The cumulative amounts were markedly increased in the presence of the counter-ions, and the highest flux of (1297.53 ± 121.81) µg/cm²/h was obtained by DEA. This was related to the decreased lipophilicity and different physicochemical properties of the ion-pairs. In particular, we proved the formation of an FP/amine ion-pair in solution by ¹H-NMR. The results suggest that the counter-ions are more efficient than penetration enhancers. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 1826–1837, 2010     

黄体酮透皮给药系统体外经皮渗透特性的研究

目的研究黄体酮透皮给药系统的体外经皮渗透特性。方法采用聚丙烯酸酯为骨架制备黄体酮透皮贴片,以离体人皮为透皮模型,采用Valia-Chien扩散池和高效液相色谱法研究促渗剂、药物含量对黄体酮透皮给药系统经皮渗透的影响。结果23%单月桂酸甘油酯与15%棕榈酸乙酯合用对黄体酮促渗效果明显,经皮渗透速率为1.50±0.64μg·cm-2·h-1,增渗倍数达到了21.4倍。贴片中黄体酮含量由0.75mg·cm-2提高到1.0mg·cm-2时,经皮渗透速率明显增大;含量提高到1.25mg·cm-2时,经皮渗透速率无明显变化。结论单月桂酸甘油酯和棕榈酸乙酯联用对黄体酮透皮给药系统体外经皮渗透具有显著的促进作用,黄体酮的最佳含量是1.0mg·cm-2。