In vitro and in vivo evaluation of topical delivery and potential dermal use of soy isoflavones genistein and daidzein

Genistein, daidzein, and glycitein are soy isoflavones. These compounds can be used to protect the skin from oxidative stress induced by UVB radiation. To this end, the feasibility of skin absorption of soy isoflavones was evaluated in the present study. As assayed by flow cytometry, UVB-induced H(2)O(2) production in keratinocytes was inhibited by genistein and daidzein, confirming that these two compounds can act as free radical scavengers when keratinocytes are photodamaged. Glycitein showed no protective activity against photodamage. The effects of vehicles on the in vitro topical delivery from saturated solutions such as aqueous buffers and soybean oil were investigated. The isoflavones in a non-ionized form (pH 6) showed higher skin deposition compared to the ionized form (pH 10.8). Soybean oil reduced the isoflavone amount retained in the skin, especially for genistein. Genistein generally exhibited greater skin absorption than did daidzein. However, daidzein permeation was enhanced when an aglycone mixture was used as the active ingredient. An eutectic effect was proposed as the enhancing mechanism. In vivo skin deposition showed a linear correlation with the in vitro results. The safety profiles suggested no or only negligible stratum corneum disruption and skin erythema by topical application of soy isoflavones. It was concluded that topical delivery may serve as a potent route for soy isoflavones against photoaging and photodamage.     

Evaluation of transdermal iontophoresis of enoxacin from polymer formulations: in vitro skin permeation and in vivo microdialysis using Wistar rat as an animal model

Polymers were used in vehicles to form hydrogel matrices in this study to evaluate the in vitro permeation and in vivo microdialysis of enoxacin. The highest transdermal delivery determined by area under flux-time curve (AUC) and intracutaneous enoxacin concentration were observed in methylcellulose (MC) and polyvinylpyrrolidone (PVP) hydrogels, respectively. To avoid the pH shift in vehicles during iontophoresis, buffer species were added to formulations to increase the buffer capacity. As expected, the permeability of enoxacin of anodal iontophoresis was larger than that of cathodal iontophoresis. Combination of benzalkonium chloride, a cationic surfactant as an enhancer, and iontophoresis exerted an enhancing effect for anionic enoxacin at pH 10.0. However, no effect or a negative effect was detected for cationic enoxacin in deionized water or pH 5.0 buffer, due to the shielding of the negative charge in the skin. The skin residue of enoxacin was slightly increased after the incorporation of Azone in PVP hydrogel. The result of in vivo microdialysis was in accordance with that of in vitro study. The effect of Azone on the intracutaneous enoxacin was more significant for in vivo microdialysis than in the in vitro study indicating the clinical feasibility of Azone for iontophoretic delivery. Microdialysis can be considered as a useful technique to investigate the pharmacokinetics of transdermal iontophoresis in vivo.     

Deoxycholate hydrogels of betamethasone-17-valerate intended for topical use: In vitro and in vivo evaluation

The aim of this study was to evaluate the suitability of sodium-deoxycholate (Na-DOC) gels containing betamethasone-17-valerate (BMV) for topical application. The gels were characterized for rheological and textural properties. The in vitro flux of BMV from Na-DOC gels across rat skin was 2.5 (0.05% gel) and 8.5 times (0.1% gel) higher compared to the commercial cream (0.1%), respectively. The pharmacodynamic responses after in vivo topical application in rats were also determined. A significant correlation between anti-inflammatory activity and in vitro permeation of BMV was observed. Na-DOC gels produced significantly higher edema inhibition compared to commercial cream at all time intervals. Finally, according to the results of histology studies, Na-DOC gel has no irritant effect on the skin. In conclusion, Na-DOC gel formulation could be suggested as a promising alternative system for the topical application of BMV.     

Formulation and in vivo evaluation for anti-aging effects of an emulsion containing basil extract using non- invasive biophysical techniques

Background and the purpose of study

Skin aging is a complex process induced by constant exposure to ultraviolet (UV) irradiation and damages human skin. UV generates reactive oxygen species leading to collagen deficiency and eventually skin wrinkling. Basil contains a number of phenolics and favonoids which possess antioxidant properties. The aim of this study was to formulate and investigate the antiaging potential of a cream containing Basil extract.

Methods

A single blinded study was conducted using non-invasive methods. Formulation containing 3% of the concentrated extract of Basil was developed by entrapping in the inner aqueous phase of w/o emulsion and base contained no extract. Both creams were stored at different storage conditions of 8°C, 25°C, 40°C and 40°C+ 75% relative humidity to predict their stabilities. The formulation and base were evaluated for their effects on various skin parameters i.e., moisture and trans epidermal water loss (TEWL), volume, energy and surface evaluation of the living skin (SELS).

Results

Significant effects (p≤0.05) were observed for both creams in the case of TEWL. The base showed insignificant (p≤0.05) while formulation showed significant effects on skin moisture. Volume, SELS SEr (skin roughness), SEsc (skin scaliness), SEsm (skin smoothness), SEw (skin wrinkles) parameter showed significant decline while texture parameter of ‘Energy’ showed significant increase.

Conclusion

The results statistically indicated that the active formulation containg extract of Basil exert antiaging effects when applied topically.     

Formulation of meloxicam gel for topical application: In vitro and in vivo evaluation

Skin delivery of NSAIDs offers several advantages over the oral route associated with potential side effects. In the present investigation, topical gel of meloxicam (MLX) was formulated using N-methyl pyrrolidone (NMP) as a solubilizer and Carbopol Ultrez 10? as a gelling polymer. MLX gel was evaluated with respect to different physicochemical parameters such as pH, viscosity and spreadability. Irritation potential of MLX gel was studied on rabbits. Permeation of MLX gel was studied using freshly excised rat skin as a membrane. Anti-inflammatory activity of MLX gel was studied in rats and compared with the commercial formulation of piroxicam (Pirox? gel, 0.5% m/m). Accelerated stability studies were carried out for MLX gel for 6 months according to ICH guidelines. MLX gel was devoid of any skin irritation in rabbits. After 12 h, cumulative permeation of MLX through excised rat skin was 3.0 ± 1.2 mg cm-2 with the corresponding flux value of 0.24 ± 0.09 mg cm-2 h-1. MLX gel exhibited significantly higher anti-inflammatory activity in rats compared to Pirox? gel. Physicochemically stable and non-irritant MLX gel was formulated which could deliver significant amounts of active substance across the skin in vitro and in vivo to elicit the anti-inflammatory activity.     

Silver sulfadiazine based cubosome hydrogels for topical treatment of burns: Development and in vitro/in vivo characterization

The present study is concerned with the development and characterization of a novel nanaoparticulate system; cubosomes, loaded with silver sulfadiazine (SSD), which is the metallic salt of a sulfonamide derivative, and is considered as the drug of choice for topical treatment of infected burns. Cubosome dispersions were formulated by an emulsification technique using different concentrations of a lipid phase monoolein and the nonionic surfactant, Poloxamer 407, with or without polyvinyl alcohol. The prepared cubosomal dispersions were characterized regarding physical morphology, dimensional distribution, particle size, and in vitro drug release. The optimum formulae were incorporated in a chitosan, carbopol 940 or chitosan/carbopol mixture based hydrogels, to form cubosomal hydrogels (cubogels). The cubogels were characterized regarding in vitro release of SSD, rheological properties, pH, and mucoadhesion. For the optimal cubogel formulae, an in vivo histopathological study was conducted on rats to predict the effectiveness of the newly prepared cubogels in comparison with the commercially available cream (Dermazin®). In vivo histopathological study results showed that prepared cubogels were successful in the treatment of deep second degree burn which may result in better patient compliance and excellent healing results with least side effects in comparison with the commercially available product.     

Transdermal delivery of meloxicam using niosomal hydrogels: in vitro and pharmacodynamic evaluation

Abstract

Non-ionic surfactant vesicles were prepared using Span-60 and cholesterol in the mass ratios of 1:1, 2:1, 1:2 and 3:1 for transdermal delivery of an anti-inflammatory drug meloxicam (MXM). The drug encapsulation efficiencies and particle size were observed in the range of 32.9–80.7% and 56.5–133.4?nm, respectively. Three different gel bases were also prepared using Poloxamer-407, Chitosan and Carbopol-934 as polymers to study the performance of the in vitro release of the drug. Prepared gels were also converted into niosomal gels. In vitro release characteristics of MXM from different gels were carried out using dialysis membrane in phosphate buffer (pH 7.4). The poloxamer-407 gel or niosomal poloxamer-407 gel showed the superior drug release over the other formulations. The release data were treated with various mathematical models to assess the relevant parameters. The results showed that the release of MXM from the prepared gels and niosomal gels followed Higuchi’s diffusion model. The flux of MXM was found to be independent on the viscosity of the formulations. The anti-inflammatory effects of MXM from different niosomal gel formulations were evaluated using carrageenan-induced rat paw edema method, which showed superiority of niosomal gels over conventional gels.     

In vitro and in vivo evaluation of three metronidazole topical products

Abstract

Two 1% and one 0.75% metronidazole cream products were approved as bioequivalent products. These products were evaluated for their in vivo cutaneous penetration characteristics by dermatopharmacokinetic (DPK) and dermal microdialysis (DMD) sampling methodologies. The same three products were also evaluated for their rheological and in vitro drug release (IVR) properties. Structural differences were observed in the resulting flow curves. However, similar IVR profiles were obtained for the two topical semisolid dosage forms containing 1% metronidazole. For the lower strength product, a higher IVR rate was associated with the lower DPK profile. All three products exhibited similar values of area under the curve when investigated by DMD. This in vitro evaluation corroborated the divergent penetration characteristics found using in vivo methodologies.     

In vitro and in vivo evaluation of caffeic and ferulic acids as topical photoprotective agents

Topically-applied antioxidant drugs represent a successful strategy for protecting the skin against UV-mediated oxidative damage. However, they can afford to the skin a satisfactory photoprotection only if able to permeate through the stratum corneum and thus to reach deeper cutaneous layers. Caffeic and ferulic acids, dissolved in saturated aqueous solutions at pH 3 or 7.2, have been tested for their capability to permeate through excised human skin mounted in Franz cells. At both pH values, ferulic and, at a lower degree, caffeic acids appeared able to permeate through the stratum corneum. The known higher lipophilicity of ferulic acid may explain the fact that it permeates through the stratum corneum better than caffeic acid. However, vehicle pH values proved to have no influence on biophenol skin permeation profile; this observed lack of pH effect may reflect the drug higher concentration attainable in saturated solutions at high pH. On the basis of the findings obtained in these in vitro experiments, we designed the schedule of a series of in vivo experiments, carried out to evaluate the ability of caffeic and ferulic acids to reduce, in healthy human volunteers, UVB-induced skin erythema, monitored by means of reflectance spectrophotometry. Caffeic and ferulic acids, dissolved in saturated aqueous solution pH 7.2, proved to afford a significant protection to the skin against UVB-induced erythema. To conclude, we have confirmed, by means of in vitro and in vivo experiments, that caffeic and ferulic acids may be successfully employed as topical protective agents against UV radiation-induced skin damage; however their skin absorption is not influenced by the pH of the formulation.     

以c-Met为靶点的抗肿瘤系列化合物体内外药效筛选

目的　从8个LY系列肝细胞生长因子受体（c-Met）酪氨酸激酶抑制剂中筛选具有抗肿瘤活性的化合物,并进一步评价其体内外抗肿瘤作用。方法　首先采用均相时间分辨荧光技术（HTRF）对LY系列化合物进行初步筛选,观察它们对c-Met酪氨酸激酶的抑制作用;采用CCK8法观察筛选出的活性化合物在体外对人胃癌MKN-45、人神经胶质瘤U87MG、人肾癌Caki-1、人前列腺癌PC-3细胞株的增值抑制作用。建立人恶性胶质母细胞瘤U87MG裸小鼠移植瘤模型,考察活性化合物的抑瘤效果。结果　HTRF结果显示有4个活性较好的化合物（LY22,LY25,LY28,LY32）,其中LY28对c-Met抑制作用优于阳性对照药Crizotinib;CCK8结果显示这些活性化合物对选用的4种靶细胞均有不同程度的抑制作用,其中LY28对肿瘤细胞增殖抑制作用最明显;裸小鼠移植瘤实验显示,LY28可显著抑制U87MG裸小鼠移植瘤的增殖,40 mg/kg LY28抑瘤率达到78.13%。结论　化合物LY28具有较好抗肿瘤活性,具有进一步研发的价值。     

In vivo retention of poloxamer-based in situ hydrogels for vaginal application in mouse and rat models

The purpose of this study is to evaluate the in vivo retention capabilities of poloxamer-based in situ hydrogels for vaginal application with nonoxinol-9 as the model drug. Two in situ hydrogel formulations, which contained 18% poloxamer 407 plus 1% poloxamer 188 (GEL1, relative hydrophobic) or 6% poloxamer 188 (GEL2, relative hydrophilic), were compared with respect to the rheological properties, in vitro hydrogel erosion and drug release. The vaginal retention capabilities of these hydrogel formulations were further determined in two small animal models, including drug quantitation of vaginal rinsing fluid in mice and isotope tracing with ^99mTc in rats. The two formulations exhibited similar phase transition temperatures ranging from 27 to 32 °C. Increasing the content of poloxamer 188 resulted in higher rheological moduli under body temperature, but slightly accelerated hydrogel erosion and drug release. When compared in vivo, GEL1 was eliminated significantly slower in rat vagina than GEL2, while the vaginal retention of these two hydrogel formulations behaved similarly in mice. In conclusion, increases in the hydrophilic content of formulations led to faster hydrogel erosion, drug release and intravaginal elimination. Rats appear to be a better animal model than mice to evaluate the in situ hydrogel for vaginal application.     

Effects of penetration enhancers on Shuangwu traumatic formula: In vitro percutaneous absorption and in vivo pharmacodynamic evaluation of an herb medicine

The purposes of this study were to improve the transdermal permeation of the Shangwu traumatic formula by chemical penetration enhancers and to investigate the pharmacodynamic changes of the formula caused by incorporated enhancers. The effects of different enhancers on the transdermal absorption of piperine, the representative component of formula, were investigated by in vitro permeation studies. The tests showed an increasing enhancement effect in the following order: Azone/N-methylpyrrolidone (NMP) > oleic acid > Azone/peppermint oil > Azone/oleic acid > Azone/propylene glycol > Azone > peppermint oil > NMP > propylene glycol. The ratio and the content of the most effective enhancer Azone/NMP were determined subsequently. The results suggested that the most significant penetration enhancement was achieved by 3% (w/w) Azone/NMP (3:7). Furthermore, the in vivo pharmacodynamic responses of the formula suspension with or without Azone/NMP were compared using hot-plate assay and xylene-induced ears edema test as models. The data indicated that the formula had positive effect on analgesis and anti-inflammatory, which can be enhanced with the addition of enhancers.     

Nanoemulsion gel-based topical delivery of an antifungal drug: in vitro activity and in vivo evaluation

Abstract

Objective: In this study, attempt has been focused to prepare a nanoemulsion (NE) gel for topical delivery of amphotericin B (AmB) for enhanced as well as sustained skin permeation, in vitro antifungal activity and in vivo toxicity assessment.

Materials and methods: A series of NE were prepared using sefsol-218 oil, Tween 80 and Transcutol-P by slow spontaneous titration method. Carbopol gel (0.5%?w/w) was prepared containing 0.1%?w/w AmB. Furthermore, NE gel (AmB-NE gel) was characterized for size, charge, pH, rheological behavior, drug release profile, skin permeability, hemolytic studies and ex vivo rat skin interaction with rat skin using differential scanning calorimeter. The drug permeability and skin irritation ability were examined with confocal laser scanning microscopy and Draize test, respectively. The in vitro antifungal activity was investigated against three fungal strains using the well agar diffusion method. Histopathological assessment was performed in rats to investigate their toxicological potential.

Results and discussion: The AmB-NE gel (18.09?±?0.6?µg/cm²/h) and NE (15.74?±?0.4?µg/cm²/h) demonstrated the highest skin percutaneous permeation flux rate as compared to drug solution (4.59?±?0.01?µg/cm²/h) suggesting better alternative to painful and nephrotoxic intravenous administration. Hemolytic and histopathological results revealed safe delivery of the drug. Based on combined results, NE and AmB-NE gel could be considered as an efficient, stable and safe carrier for enhanced and sustained topical delivery for AmB in local skin fungal infection.

Conclusion: Topical delivery of AmB is suitable delivery system in NE gel carrier for skin fungal infection.     

Formulation,characterization, and in vitro/ex vivo evaluation of quercetin-loaded microemulsion for topical application

The aim of this study was to develop a new microemulsion formulation for topical application of poorly soluble drug named quercetin. In order to design suitable microemulsion system, the pseudo-ternary phase diagrams of microemulsion systems were constructed at different surfactant/co-surfactant ratios using tween 80 as surfactant, transcutol^® P as a co-surfactant and oleic acid as an oil phase. Some physicochemical properties such as droplet size, density, refractive index, electrical conductivity, pH, surface tension, and viscosity of the microemulsion systems were measured at 298.15 K. The average hydrodynamic droplet size of the optimized microemulsions was obtained by dynamic light scattering method. Morphology assessment of the optimized quercetin-loaded microemulsion by transmission electron microscopy analysis indicated that the particles have the size of about 25?nm and spherical with narrow size distribution. Equilibrium solubility, in vitro drug release at a 24?h time period, release kinetic evaluation as well as ex vivo permeation and retention of quercetin-loaded microemulsions through rat skin has been investigated. The obtained results showed a slow release behavior without any transdermal delivery. Most of the formulations fitted best with zero-order kinetic model with a non-Fickian mechanisms. This study illustrated that the proposed QU-microemulsion has a good potential for use in sunscreen formulations.

     

In vitro percutaneous absorption and in vivo protoporphyrin IX accumulation in skin and tumors after topical 5-aminolevulinic acid application with enhancement using an erbium:YAG laser

5-aminolevulinic acid (ALA) is used as a precursor of protoporphyrin IX (PpIX) for photodynamic therapy (PDT) of superficial skin cancers and subcutaneous metastases of internal malignancies. The permeability of ALA across intact skin is always low, making it difficult to achieve the desired therapeutic benefits. Hence new methods for enhancing ALA permeation are urgently needed. The aim of this study was to determine the in vivo kinetics of PpIX generation in mouse tissues after topical ALA application enhanced by an erbium (Er):yttrium-aluminum-garnet (YAG) laser. The in vitro permeation of ALA was also used to screen the optimal method for the in vivo study. The efficacy of the improved drug delivery was determined as a function of various laser fluences and cancer models. ALA applied to laser-treated skin produced a higher accumulations of PpIX within superficial skin and subcutaneous tumors as compared to those of the non-treated group (t-test, p < 0.05). The enhancement ratios (ER) of laser-treated skin ranged from 1.7 to 4.9 times as compared to the control depending to the fluences used. The enhanced PpIX level of laser-treated skin was generally more pronounced in normal and lesional skin than in subcutaneous nodular tumors. Confocal laser scanning microscopy (CLSM) of laser-treated skin revealed intense red fluorescence within the epidermis and upper dermis, and a much-weaker fluorescence within the bottom layers of the skin. On the other hand, the fluorescence intensity of the control group was much lower than that of laser-treated group. The barrier properties of the skin irradiated by the laser had completely recovered within 3 days. Pretreatment of skin using an Er:YAG laser was useful in increasing the amount of Pp IX within skin tumors.     

Nanoemulsions as vehicles for topical administration of glycyrrhetic acid: Characterization and in vitro and in vivo evaluation

Nano-emulsions are innovative colloidal systems characterized by high kinetic stability, low viscosity, and optical transparency, which make them very attractive in many dermatological applications. Furthermore their small size seems to favor the topical administration of actives which scarcely cross the skin. In the light of these interesting features, the present study was aimed to the evaluation, in vitro and in vivo, of glycyrrhetic acid (GA) release through the skin from the nanoemulsion system. GA-loaded nanoemulsion (GA_N) was prepared by phase inversion temperature (PIT) method, and was characterized in order to determine mean droplet size and its stability during a well-defined storage period. Further Cryo-TEM studies were performed to obtain information regarding nanoemulsion structure. The GA release pattern from nanoemulsion was evaluated in vitro, to determine its percutaneous absorption through excised human skin (stratum corneum and epidermis, SCE), and in vivo evaluating GA topical anti-inflammatory activity on healthy human volunteers by the UVB-induced erythema model. Nanoemulsions prepared by PIT method showed a mean droplet diameter of 210?nm that drastically changed during a storage of 5 weeks at room temperature. In vitro and in vivo evidence showed that the nanoemulsion system significantly increased the transdermal permeability of GA in comparison to a control O/W emulsion (GA_O/W) containing the same amount of active compound.     

长春西汀s-PLGA长效缓释微球的体内外评价

目的:本研究以星状聚乳酸羟基乙酸共聚物(star poly D,L-lactide-co-glycolide,s-PLGA)为载体制备长春西汀长效缓释微球,对其体内外性质进行评价。方法:采用开环聚合法制备s-PLGA,以此作为载体材料,采用乳化-溶剂挥发法制备长春西汀s-PLGA长效缓释微球(VIN-MS),并对其包封率、粒径和体内外性质进行了考察。结果:本研究制备的VIN-MS的平均粒径为(18±2)μm,包封率为62.20%,载药量为37.43%。扫描电镜观察结果表明,微球外观圆整、均匀,流动性好,分散性好。体外释放结果表明,VIN-MS具有明显的缓释特性,其突释率为6.96%。体内结果表明,VIN-MS制剂体内周期能维持15 d,与长春西汀普通注射剂相比,VIN-MS的曲线下面积(AUC)和平均滞留时间(MRT)分别是普通注射剂的40倍和38倍。结论:长春西汀s-PLGA长效缓释微球的成功制备将有利于脑血管病的治疗。     

In vitro and in vivo percutaneous absorption of seleno-L-methionine, an antioxidant agent, and other selenium species

Aim:

To investigate the in vitro and in vivo percutaneous absorption of seleno-L-methionine (Se-L-M), an ultraviolet (UV)-protecting agent, from aqueous solutions.

Methods:

Aqueous solutions of Se-L-M were prepared in pH 4, 8, and 10.8 buffers. The pH 8 buffer contained 30% glycerol, propylene glycol (PG) and polyethylene glycol (PEG) 400. The in vitro skin permeation of Se-L-M via porcine skin and nude mouse skin was measured and compared using Franz diffusion cells. The in vivo skin tolerance study was performed, which examined transepidermal water loss (TEWL), skin pH and erythema.

Results:

In the excised porcine skin, the flux was 0.1, 11.4 and 8.2 μg·cm⁻²·h⁻¹ for the pH 4, 8, and 10.8 buffers, respectively. A linear correlation between the flux and skin deposition was determined. According to permeation across skin with different treatments (stripping, delipidation, and ethanol treatments), it was determined that the intracellular route comprised the predominant pathway for Se-L-M permeation from pH 8 buffer. Aqueous solutions of seleno-DL-methionine (Se-DL-M), selenium sulfide and selenium-containing quantum dot nanoparticles were also used as donor systems. The DL form showed a lower flux (7.0 vs 11.4 μg·cm⁻²·h⁻¹) and skin uptake (23.4 vs 47.3 μg/g) as compared to the L form, indicating stereoselective permeation of this compound. There was no or only negligible permeation of selenium sulfide and quantum dots into and across the skin. With in vivo topical application for 4 and 8 h, the skin deposition of Se-L-M was about 7 μg/g, and values were comparable to each other. The topical application of Se-L-M for up to 5 d did not caused apparent skin irritation. However, slight inflammation of the dermis was noted according to the histopathological examination.

Conclusion:

Se-L-M was readily absorbed by the skin in both the in vitro and in vivo experiments. The established profiles of Se-L-M skin absorption will be helpful in developing topical products of this compound.     

In vitro and in vivo evaluations of the efficacy and safety of skin permeation enhancers using flurbiprofen as a model drug

The efficacy and safety of commonly used enhancers were systemically evaluated by in vitro and in vivo methods in this study. Flurbiprofen was used as the model drug to examine the enhancing capacity of these enhancers. Both in vitro permeation by Franz cells and in vivo kinetics of skin disposition were performed to determine the flurbiprofen permeation by enhancers. Unsaturated fatty acids showed the greatest enhancement of flurbiprofen permeation. The enhancing effect of D-limonene was slightly lower than that of the fatty acids. Azone and L-alpha-lecithin even reduced the skin deposition by flurbiprofen application. In vitro prostaglandin E(2) (PGE(2)) release by cell culture, in vivo transepidermal water loss (TEWL) and colorimetry, and skin morphological changes were determined to examine the irritation of the skin by enhancers. The results showed that skin disruption and inflammation did not necessary correspond to the enhancing efficiency of the enhancers. Moreover, some discrepancies were observed in these irritant profiles when using various methods. The fatty acids generally showed the most irritating properties, followed by Azone, D-limonene, and L-alpha-lecithin. A complete portrait of the efficacy and safety of commonly used enhancers was therefore established in this study.     

In vitro and in vivo evaluation of WGA-carbopol modified liposomes as carriers for oral peptide delivery

Surface modification of liposomal nanocarriers with a novel polymer-lectin conjugate was proposed for enhancing the systemic uptake of encapsulated peptide and protein therapeutics after oral administration. Wheat germ agglutinin (WGA) was covalently attached to carbopol (CP) using the carbodiimide method. The prepared WGA-CP conjugate retained the biological cell binding activity of WGA without any evidence of cytotoxicity to Caco-2 monolayers. Cationic liposomes in the size range of 100 nm were prepared by the lipid film hydration method followed by probe sonication and surface modification with negatively charged WGA-CP. The uptake of WGA-CP liposomes by Caco-2 cells was significantly higher than that of non-modified or CP liposomes. The uptake was dependent on the surface concentration of WGA, temperature, and incubation period and was significantly inhibited in the presence of chlorpromazine and 10-fold excess of free WGA. These results suggest the involvement of active transport mechanism for the cellular uptake of the modified liposomes, mediated mainly by binding of WGA to its specific cell membrane receptors. Dual channel confocal microscopy confirmed the simultaneous association and internalization of the polymer conjugate and the liposomal carrier by Caco-2 cells and intestinal membrane of rats. In addition, the pharmacological efficacy of calcitonin, a model peptide drug, was enhanced by more than 20- and 3-fold following peroral administration of calcitonin-loaded WGA-CP liposomes when compared to non-modified and CP liposomes, respectively.