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.     

Effect of hydrophobic permeation enhancers on the release and skin permeation kinetics from matrix type transdermal drug delivery system of ketotifen fumarate

Ketotifen fumarate is effective in low doses in the treatment of bronchial asthma particularly of allergic origin. However, it is substantially metabolized in the liver when administered orally. Hence transdermal patches of combination of ethylcellulose/polyvinylpyrrolidone and Eudragits RS 100/RL 100 were prepared and their drug release kinetics and skin permeation profiles were evaluated. However, the skin permeation profiles were found to be low and subtherapeutic. Hence three hydrophobic biocompatible substances, viz, isopropyl myristate, isopropyl palmitate and linoleic acid and also combination of isopropyl myristate and linoleic acid were used as permeation enhancers in the film. It was found that isopropyl myristate and linoleic acid combination and isopropyl myristate alone produced promising results compared to isopropyl palmitate and linoleic acid.     

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。     

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     

Effect of cyclodextrins on the complexation and transdermal delivery of bupranolol through rat skin

Bupranolol (BPL) is a potent beta-blocking agent, the extensive first-pass metabolism (>90%) and rapid elimination half-life (1.5-2.0 h) of this drug make it well suited to be developed as a transdermal delivery system (TDS). Hydroxypropyl betaCD (HPbetaCD) and partially methylated betaCD (PMbetaCD) were used as penetration enhancers for BPL. The formation of inclusion complex of BPL with these cyclodextrins (CDs) was characterized in solution and solid states by phase solubility, X-ray diffractometry and differential scanning calorimetry (DSC) analyses. The effect of CDs on the permeation enhancement of BPL through rat skin was studied using side-by-side diffusion cells and pH 7.4 phosphate-buffered saline (PBS). CDs were employed at different concentrations with 0.4% (w/v) BPL as well as with excess quantity of BPL (1.0%, w/v) that CDs could not complex all the BPL and the drug was in the form of an aqueous suspension. The permeation of BPL from its aqueous suspension (0.4%, w/v) significantly increased when CDs were used at low concentrations (up to 2 and 5%, w/v concentration for HPbetaCD and PMbetaCD, respectively) (P < 0.01). At higher CD concentrations, the permeation of BPL decreased; and both CDs at 10% (w/w), showed similar flux values to that of control (no enhancer, P > 0.05). The permeation of BPL from its 1.0% (w/v) aqueous suspension increased with increase in concentration of CD up to 10% (w/v) for HPbetaCD and PMbetaCD. At 10% (w/v) concentration of HPbetaCD and PMbetaCD, the flux of BPL from its 1.0% aqueous suspension increased 3.8- and 4.6-fold (P < 0.01 and P < 0.001, respectively). The permeation data of skin pretreatment with CDs indicate that HPbetaCD had no effect on the skin, whereas PMbetaCD significantly reduced the skin barrier for BPL, as shown by 1.7-fold increase in the flux by PMbetaCD pretreatment (P < 0.001). Overall, both HPbetaCD and PMbetaCD were found to be suitable for improving the solubility and penetration enhancement of BPL.     

透皮促进剂对肤康祛斑凝胶体外透皮吸收的影响

目的考察透皮促渗剂对肤康祛斑凝胶的主药熊果苷体外经皮渗透的影响。方法对优化后的肤康祛斑凝胶处方,以大鼠离体皮肤作为渗透屏障,用高效液相色谱法测定凝胶中熊果苷经皮透入接收液含量。考察氮酮、氮酮-薄荷油、氮酮-冰片作为促渗剂对熊果苷透皮吸收的影响。结果肤康祛斑凝胶中熊果苷的体外累积渗透率符合Weibull分布,以氮酮-薄荷油作为促渗剂的处方中,熊果苷累积渗透率最高,渗透促进剂的促透效果为:氮酮-薄荷油>氮酮-冰片>氮酮。结论以氮酮-薄荷油作为促渗剂,对熊果苷有较好的促渗作用。     

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.     

Biomaterials as novel penetration enhancers for transdermal and dermal drug delivery systems

Abstract

The highly organized structure of the stratum corneum provides an effective barrier to the drug delivery into or across the skin. To overcome this barrier function, penetration enhancers are always used in the transdermal and dermal drug delivery systems. However, the conventional chemical enhancers are often limited by their inability to delivery large and hydrophilic molecules, and few to date have been routinely incorporated into the transdermal formulations due to their incompatibility and local irritation issues. Therefore, there has been a search for the compounds that exhibit broad enhancing activity for more drugs without producing much irritation. More recently, the use of biomaterials has emerged as a novel method to increase the skin permeability. In this paper, we present an overview of the investigations on the feasibility and application of biomaterials as penetration enhancers for transdermal or dermal drug delivery systems.     

Novel chemical permeation enhancers for transdermal drug delivery

Transdermal drug delivery has been accepted as a potential non-invasive route of drug administration, with advantages of prolonged therapeutic action, decreased side effect, easy use and better patient compliance. However, development of transdermal products is primarily hindered by the low permeability of the skin. To overcome this barrier effect, numerous new chemicals have been synthesized as potential permeation enhancers for transdermal drug delivery. In this review, we presented an overview of the investigations in this field, and further implications on selection or design of suitable permeation enhancers for transdermal drug delivery were also discussed.     

透皮促进剂预处理皮肤对环孢素A经皮渗透的影响

目的：考察透皮促进剂对环孢素Ａ经皮渗透的影响。方法：用透皮促进剂预处理离体小鼠皮肤,以改良的Ｆｒａｎｚ扩散装置进行体外渗透实验。结果：环孢素Ａ经皮渗透符合零级动力学过程,几种透皮促进剂的促渗作用大小依次为月桂氮Ｚｈｕｏ酮－丙二醇（１：１）〉月桂氮Ｚｈｕｏ酮〉水溶性月桂氮Ｚｈｕｏ酮〉二甲基亚砜〉Ｎ－甲基吡咯烷酮〉薄荷油。结论：体外实验证明,透皮促进剂可增加环孢素Ａ的透皮吸收。     

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     

透皮促进剂对白花前胡甲素体外经皮渗透的影响

目的:考察透皮促进剂对白花前胡甲素(dl-praeruptorin A,Pd-Ia)体外经皮渗透的影响。方法:采用改进的Franz扩散池,以大鼠离体皮肤为渗透屏障,用高效液相色谱法对Pd-Ia进行含量测定,考察月桂氮酮(Azone)及1%Azone与不同浓度丙二醇(PG)混合物对Pd-Ia透皮吸收的影响。结果:使用Azone对Pd-Ia有促透作用,1%Azone效果较好,平均渗透速率达到4.064μg.cm-2.h-1;1%Azone与15%PG合用促透效果最好,平均渗透速率达到4.889μg.cm-2.h-1,且与单用1%Azone有显著性差异(P<0.05)。结论:1%Azone与15%PG合用时,含0.5%Pd-Ia溶液体外渗透具有最大促透效果,体现出协同作用。     

Enhancement of transdermal delivery of progesterone using medium-chain mono and diglycerides as skin penetration enhancers

We evaluated whether medium-chain mono and diglycerides (MCG) can be utilized to optimize the transdermal delivery of progesterone (PGT). MCG was studied at 10–70% (w/w) in propylene glycol (a polar solvent) or Myvacet oil (nonpolar solvent); PGT was used at 1% (w/w). The topical (to the skin) and transdermal (across the skin) delivery of PGT were evaluated in vitro using porcine ear skin. When incorporated in propylene glycol, MCG at 10% enhanced the topical and transdermal delivery of PGT by 2.5- and 7-fold, respectively. At 20–50%, topical delivery was further enhanced while transdermal delivery gradually returned towards baseline. At 70%, MCG enhanced neither the delivery to viable skin nor the transdermal delivery of PGT. Similar concentration-dependent effects were observed when MCG was incorporated in Myvacet oil, but their magnitudes were 2- to 3-fold smaller. The relative safety of MCG was assessed in cultured fibroblasts and compared to propylene glycol (regarded as safe) and sodium lauryl sulfate (moderate-to-severe irritant). Both MCG and propylene glycol were substantially less cytotoxic than sodium lauryl sulfate. We conclude that formulations containing 10% MCG in propylene glycol may be a simple and safe method to improve the transdermal delivery of progesterone and promote its use in hormone replacement therapy.     

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 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.     

罂粟碱凝胶的研制及不同透皮促进剂对其透皮作用的影响

目的：探讨透皮吸收促进剂对罂粟碱凝胶透皮吸收的影响。方法：采用简单扩散小室，用紫外分光光度测定了5种处方罂粟碱凝胶离体鼠皮透皮吸收药量。结果：罂粟碱透皮累积释药量与时间呈线性关系，与不含吸收促进剂的凝胶比较，吸收促进剂对罂粟碱透皮吸收的影响为油酸＞油酸＋月桂氨卓酮＞二甲亚砜＞月桂氮卓酮。结论：油酸能明显促进罂粟碱的透皮吸收，而水溶性的透皮吸收促进剂对罂粟碱的透皮吸收作用不明显。     

盐酸丁卡因凝胶剂经皮渗透作用

目的：制备盐酸丁卡因凝胶剂，并考察不同透皮促进剂对其透皮吸收的影响。方法：配制含不同透皮促进剂的盐酸丁卡因凝胶剂，采用简单扩散小室和紫外分光光度法测定药物透皮吸收量。结果：加1%月桂氮Zhuo酮，加1%，3%，5%薄荷脑或加两者混合透皮促进剂，将药物碱化均可显著增加盐酸丁卡因凝胶剂的透皮吸收量，其累积释药量与时间呈线性关系。结论：单独使用1%月桂氮Zhuo酮对盐酸丁卡因凝胶透皮吸收作用不明显，3%，5%薄荷脑或加1%月桂氮Zhuo酮两者混合透皮保进剂对盐酸丁卡因凝胶透皮吸收作用明显，1%月桂氮Zhuo酮 3%薄荷脑对盐酸丁卡因凝胶透皮吸收作用最明显。     

Effect of polyunsaturated fatty acids and some conventional penetration enhancers on transdermal delivery of atenolol

The aim of our present study was to evaluate the in vitro percutaneous absorption of atenolol, a well-known antihypertensive, from a series of formulations containing various penetration enhancers. Particularly the promoting effect of EPA and DHA, two polyunsaturated fatty acids (PUFAs), has been studied, and drug permeation data have been compared with those obtained with the other formulations containing "classic" penetration enhancers such as transcutol, d-limonene, and PG. Not all the penetration enhancers tested were effective in increasing atenolol percutaneous flux and the best permeation profile for atenolol was obtained with the formulation containing transcutol (B) and PUFA (E). To explain the enhancer mechanism, the atenolol diffusion and partitioning coefficients from the different formulations were calculated. The results indicated that PUFAs increased the apparent diffusion coefficient of the drugs but did not affect their apparent stratum corneum (SC)/vehicle partition coefficient (K(m)). At this same time transcutol exerted its enhancer effect increasing significantly the apparent SC/vehicle partition coefficient (K(m)) and in a minor amount the apparent diffusion coefficient of skin permeation process (D(m)). The potential application of formulations B and E in atenolol percutaneous absorption was determined from the calculation of the steady-state plasma concentrations (C(ss)). These values resulted within the drug therapeutic range and suggest that atenolol transdermal delivery could be feasible.     

Influence of nanosized delivery systems with benzyl nicotinate and penetration enhancers on skin oxygenation

Many novel nanosized delivery systems have been designed for topical application of drugs since they can overcome the skin barrier and improve drug bioavailability. The increased absorption is often a consequence of a reversibly disrupted barrier function of the skin by the vehicle itself or by specific ingredients that act as penetration enhancers. This paper reports the effects of two nanosized systems (microemulsion and liposomes), in the presence and absence of penetration enhancers (PE), on the topical delivery of a lipophilic drug in vivo and compares that to classical hydrogel formulation. A vasodilator benzyl nicotinate (BN), which increases the blood flow of the skin, was incorporated into the formulations, and skin oxygenation was followed by electron paramagnetic resonance oximetry. It was found that microemulsions and liposomes (with or without PE) accelerate the rate of BN action when compared to hydrogel. However, incorporation of PE in microemulsion also improves the effectiveness of BN action. To understand why PE enhances the action of BN, its effect on the structure of the stratum corneum was investigated in vitro. The increased fluidity of the stratum corneum lipids provides an explanation for the greater penetration of BN into the skin when the drug and PE are together incorporated into the appropriate formulation.     

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.