Investigating effect of microemulsion components: In vitro permeation of ketoconazole

The purpose of this study was to evaluate the effect of oil, surfactant/co-surfactant mixing ratios and water on the in vitro permeation of ketoconazole (KTZ) applied in O/W microemulsion vehicle through intact rat skin. Lauryl Alcohol (LA) was screened as the oil phase of microemulsions, due to a good solubilizing capacity of the microemulsion system. The pseudo-ternary phase diagrams for microemulsion regions were constructed using LA as the oil, Labrasol (Lab) as the surfactant (S) and ethanol (EtOH) as the cosurfactant (CoS). The formulation which showed a highest permeation rate of 54.65?±?1.72 µg/cm²/h¹ and appropriate physico-chemical properties was optimized as containing 2% KTZ, 10% LA, 20% Lab/EtOH (1:1) and 68% double distilled water (w/w). The efficiency of microemulsion formulation in the topical delivery of KTZ was dependent upon the contents of water and LA as well as Lab/EtOH mixing ratio. It was concluded that the percutaneous absorption of KTZ from microemulsions was enhanced with increasing the LA and water contents, and with decreasing the Lab/EtOH ratio in the formulation. Candida albicans was used as a model fungus to evaluate the antifungal activity of the best formula achieved, which showed the widest zone of inhibition as compared to KTZ reference. The studied microemulsion formulation showed a good stability for a period of three months. Histopathological investigation of rat skin revealed the safety of microemulsion formulations for topical use. These results indicate that the studied microemulsion formulation might be a promising vehicle for topical delivery of KTZ.     

Formulation and evaluation of flurbiprofen microemulsion

The purpose of the present study was to investigate the microemulsion formulations for topical delivery of Flurbiprofen (FP) in order to by pass its gastrointestinal adverse effects. The pseudoternary phase diagrams were developed and various microemulsion formulations were prepared using Isopropyl Myristate (IPM), Ethyl Oleate (EO) as oils, Aerosol OT as surfactant and Sorbitan Monooleate as cosurfactant. The transdermal permeability of flurbiprofen from microemulsions containing IPM and EO as two different oil phases was analyzed using Keshary-Chien diffusion cell through excised rat skin. Flurbiprofen showed higher in vitro permeation from IPM as compared to that of from EO microemulsion. Thus microemulsion containing IPM as oil phase were selected for optimization. The optimization was carried out using 2(3) factorial design. The optimized formula was then subjected to in vivo anti-inflammatory study and the performance of flurbiprofen from optimized formulation was compared with that of gel cream. Flurbiprofen from optimized microemulsion formulation was found to be more effective as compared to gel cream in inhibiting the carrageenan induced rat paw edema at all time intervals. Histopathological investigation of rat skin revealed the safety of microemulsion formulation for topical use. Thus the present study indicates that, microemulsion can be a promising vehicle for the topical delivery of flurbiprofen.     

Microemulsion-based gel of fluorouracil for transdermal delivery

This study is to prepare the microemulsion-based gel based on the W/O microemulsion and fluorouracil (5-Fu) as a model drug to study the transdermal characterization and observe its skin irritation of the microemulsion-based gel in vitro. IPM acted as oil phase, AOT as surfactant, Tween 85 as cosurfactant, water was added dropwise to the oil phase to prepare W/O microemulsion at room temperature using magnetic stirring, then 5-Fu powder was added. The gelatin was used as substrate to prepare 5-Fu microemulsion-based gel. The permeation flux of 5-Fu from 5-Fu microemulsion-based gel across excised mice skin was determined in vitro using Franz diffusion cell to study the influence of the amount of gelatin and the drug loading capacity. Refer to 5-Fu cream, the irritation of microemulsion and microemulsion-based gel on the rat skin was studied. Based on the water/AOT/Tween 85/IPM microemulsion, only the gelatin can form the microemulsion-based gel. At 25 degrees C, 32 degrees C and 40 degrees C, the amount of gelatin required for the formation of microemulsion-based gel were 7%, 14% and more than 17%, respectively. The 12 h transdermal cumulated permeation amount of 5-Fu from microemulsion-based gel containing 14% gelatin and 0.5% drug loading were (876.5 +/- 29.1) microg x cm(-2), 12.3 folds and 4.5 folds more than 0.5% 5-Fu aqueous solution and 2.5% (w/w) 5-Fu cream, respectively. Microemulsion-based gel exhibited some irritation, but could be subsided after drug withdrawal. Microemulsion-based gel may be a promising vehicle for transdermal delivery of 5-Fu and other hydrophilic drug.     

Microemulsion-based hydrogel formulation of ibuprofen for topical delivery

The purpose of this study was to construct microemulsion-base hydrogel formulation for topical delivery of ibuprofen. Ethyl oleate (EO) was screened as the oil phase of microemulsions, due to a good solubilizing capacity of the microemulison systems and excellent skin permeation rate of ibuprofen. The pseudo-ternary phase diagrams for microemulsion regions were constructed using ethyl oleate as the oil, Tween 80 as the surfactant, propylene glycol as the cosurfactant. Various microemulsion formulations were prepared and the abilities of various microemulsions to deliver ibuprofen through the skin were evaluated in vitro using Franz diffusion cells fitted with porcine skins. The in vitro permeation data showed that microemulsions increased the permeation rate of ibuprofen 5.72-30.0 times over the saturated solution. The optimum formulation consisted of 3% ibuprofen, 6% EO, 30% Tween 80/PG (2:1) and water, showed a high permeation rate of 38.06 microg cm(-2) h(-1). Xanthan gum as a gel matrix was used to construct the microemulsion-based hydrogel for improving the viscosity of microemulsion for topical administration. The studied microemulsion-based hydrogel showed a good stability. These results indicate that the studied microemulsion-based hydrogel may be a promising vehicle for topical delivery of ibuprofen.     

Topical gels of etofenamate: in vitro and in vivo evaluation

Abstract

Non-steroid anti-inflammatory drugs (NSAIDs), such as etofenamate, are among the most prescribed drugs used for their analgesic, anti-rheumatic, antipyretic and anti-inflammatory properties. Topical formulations have the main advantage of targeted delivery. However, drugs must overcome the skin due to its role as a physical and chemical barrier against the penetration of chemicals and microorganisms. This barrier must be altered to allow the permeation of drugs at a suitable rate to the desired site of activity. Permeation modulators can intercalate the skin outer layers causing structure disruption, opening an energetically favourable route for the drug to diffuse through. The aim of this work was the development of hydroalcoholic gels containing 5.0% (w/w) of etofenamate for topical administration with anti-inflammatory activity and enhanced drug delivery. The physical and chemical characterization, in vitro release and permeation studies and in vivo anti-inflammatory activity were assessed. The gel with 30% ethanol showed in vivo anti-inflammatory activity with suitable physical chemical and microbiologic characteristics. In vitro release and permeation studies revealed that the different amounts of ethanol used influenced the release profiles of etofenamate. Moreover, it was demonstrated that this formulation is an adequate vehicle for the etofenamate skin permeation.     

Investigation of different emulsion systems for dermal delivery of nicotinamide

Nicotinamide (NA) has been shown to have beneficial effects on several skin diseases such as tumor, acne vulgaris, photodamage, cellulite and atopic dermatitis. The purpose of this study was to develop a multiple emulsion and a microemulsion formulation as delivery systems for NA. A two-step process was used to prepare the W/O/W multiple emulsion. Optimum microemulsion formulation was selected by using construction of pseudo-ternary phase diagram. The physicochemical properties such as droplet size and viscosity measurements, stability studies were also evaluated. Ex-vivo permeation studies were performed with Franz-type diffusion cells and the samples were analysed by high performance liquid chromatography (HPLC). The permeation data showed that there was no significant difference between multiple emulsion and microemulsion (p > 0.05). Transepidermal water loss (TEWL) was also measured. As a result of TEWL studies, a slight increase of TEWL values was observed for microemulsion formulation on rat skin when compared with multiple emulsion and commercial formulation. The results suggested that microemulsion and multiple emulsion formulations could be new and alternative dosage forms for topical application of NA.     

Rapid human skin permeation and topical anaesthetic activity of a new amethocaine microemulsion

We developed a fast-acting, topical, 4% (w/w) amethocaine microemulsion and tested its in vitro permeation in isolated human skin. Comparison with a commercial amethocaine gel (Ametop((R)) ) was performed using Franz diffusion cells. Permeability coefficient (k(p)), flux (J) and percentage permeation after 10 h of microemulsion application were, in all cases, 1.5 times higher than those of the gel. The values obtained for the P(1) parameter [1], 1.06.10(-2) cm (microemulsion) and 0.724.10(-2) cm (gel) indicate that the microemulsion excipients favour amethocaine deposition in the skin, increasing the permeability coefficient, amount of drug retained in the skin, and the flux achieved. Analgesic activity was also examined in rats made hyperalgesic or allodynic after carrageenan-induced inflammation. The rats were distributed into four groups (n = 5-9 per group), each group receiving topically either amethocaine microemulsion, amethocaine gel (Ametop), amethocaine subcutaneous infiltration or nothing (controls). In edematous paws, anti-hyperalgesic activity appeared at 4.2 and 13.8 min after application of amethocaine microemulsion and gel, respectively. These effects are lower than after 0.5% w/w amethocaine infiltration. Amethocaine microemulsion was the only topical formulation with an anti-allodynic effect, although this effect was less than with amethocaine infiltration. These results suggest that microemulsion could be a valuable formula for improving amethocaine permeation and thus bringing rapid pain relief.     

Topical delivery of celecoxib using microemulsion

The topical delivery of celecoxib has been studied using microemulsion as the vehicle for the treatment of UV B induced skin cancer. Pseudotemary phase diagrams were constructed at different oil to cosurfactant ratios to identify the formulation variables for microemulsion formation, and the effect of these variables on skin permeation of celecoxib was evaluated with excised rat skin. Topical anti-inflammatory effect of celecoxib has been assessed using the arachidonic acid induced ear oedema model. Formulation E consisting of 3% celecoxib, 22% propylene glycol dicaprylate/dicaprate + caprylic/capric mono-/di-glycerides (2:1), 30% polysorbate 80 and water (all w/w) showed higher permeation rate and significant anti-inflammatory activity. The studied microemulsion formulations have a prospect for use as a potential vehicle for treatment of UV B induced skin cancer.     

长春西汀微乳的优化及其理化性质的考察

目的选择适宜比例的油相、表面活性剂、助表面活性剂和水相制备长春西汀微乳制剂以增加药物的溶解度和经皮渗透量，优化处方，并对其理化性质和刺激性进行研究。方法绘制伪三元相图，确定各相的比例，以经皮稳态渗透流量为指标，利用单纯形网格法优化处方，并考察优化微乳的pH、粘度、电导率、折光率、粒径分布等理化性质。采用MTT法考察微乳制剂对人体皮肤细胞系模型Hacat细胞的毒性。结果O/W微乳在相图中的区域随着表面活性剂和助表面活性剂比例的增加而增加；单纯形网格优化法预测的指标值与实测值相近，所得的优化微乳性质稳定，对Hacat细胞无刺激性，与阴性组无显著性差异。结论长春西汀微乳制剂中药物的溶解度极大提高，经皮稳态渗透流量显著增大，安全稳定，可作为经皮给药的新型载体。     

Antipsoriatic microemulsion gel formulations for topical drug delivery of babchi oil (Psoralea corylifolia)

The aim of this study was to investigate and evaluate a microemulsion gel-based system of babchi oil (Psoralea corylifolia) for the treatment of psoriasis, which could provide improved permeation of the drug through the skin and increased patient compliance. Babchi oil is used because its chief constituent psoralen is a photoactive furocoumarin that binds to DNA when exposed to UV light to form photoproducts with pyrimidine base. This action inhibits DNA synthesis and causes decrease in cell proliferation. Moreover, babchi oil, in addition to providing psoralen, also acts as an oily phase for microemulsion system. The presence of surfactant and cosurfactant increases the permeation. On the basis of qualitative and quantitative estimation of all eight brands of babchi oil, Bakuchi Tail was selected for microemulsion formulation. Microemulsions were prepared by aqueous phase-titration method. Pseudoternary phase diagrams were constructed for the identification of microemulsion existence zones. Prepared microemulsions were subjected to different thermodynamic stability tests and characterized for droplet size, viscosity and refractive index. In vitro skin permeation of babchi oil through rat abdominal skin was determined by the Franz diffusion cell. The in vitro skin permeation profile of formulation F2, which consisted of 1.67% v/v of babchi oil, 8.33% v/v of oleic acid, S(mix) 55% v/v of Tween 80 Transcutol-P (S/Co ratio 1:1) and 35% v/v of distilled water, was significant when compared with other microemulsion formulations (p < 0.05). Formulation F2 was converted into microemulsion gel by adding 1% Carbopol-940 and coded as MGF2. Formulation MGF2 was selected for its in vivo antiinflammatory effects determined by footpad edema. The results suggested that microemulsion gel is a potential vehicle for improved topical delivery of psoralen and that microemulsion gels are potential vehicles for improved topical delivery of babchi oil.     

Preparation and in vitro evaluation of an ilomastat microemulsion gel by a self-microemulsifying system

The purpose of this study was to construct a microemulsion gel formulation by a self-microemulsifying system for transdermal topical delivery of ilomastat. The optimum formulations were screened by penetration evaluation in vitro. Ilomastat microemulsion gel was prepared by drawing a ternary phase diagram and Pluronic F127 was added as gel matrix for the formulation. The optimal formulations had wide microemulsion existent field and good self-microemulsifying efficiency. The droplet size was within 100 nm. Statistical comparison of the permeation throughout 24 h showed that the two microemulsion gel preparations of ilomastat provided higher permeation than that of the normal gel which had only a low cumulative amount of ilomastat (6.03 microg x cm(-2)) 24 h after application. Cumulative amount of ilomastat from microemulsion gels A and B was 2.2 times and 1.8 times that of the normal gel at 24 h respectively. These results indicate that the microemulsion gel may be a promising vehicle for topical delivery of ilomastat.     

Tazarotene versus tazarotene plus clindamycin/benzoyl peroxide in the treatment of acne vulgaris: a multicenter, double-blind, randomized parallel-group trial

Topical retinoids offer highly effective treatment for both inflammatory and non-inflammatory acne, with tazarotene demonstrating greater efficacy than other topical retinoids. A multicenter, double-blind, randomized, parallel-group trial has been performed to evaluate whether the adjunctive use of clindamycin/benzoyl peroxide could enhance the efficacy of tazarotene still further. Patients with moderate to severe inflammatory acne applied tazarotene 0.1% cream each evening and were randomly assigned to morning applications of vehicle gel or a ready-to-dispense formulation of clindamycin 1%/benzoyl peroxide 5 % gel containing 2 emollients. Tazarotene/clindamycin/benzoyl peroxide achieved a significantly greater reduction in comedo count than tazarotene monotherapy and, among patients with a baseline papule plus pustule count of > or =25 (the median value), a significantly greater reduction in inflammatory lesion count. The combination therapy was also at least as well-tolerated as tazarotene monotherapy. The adjunctive use of clindamycin/benzoyl peroxide gel with tazarotene cream promotes greater efficacy and may also enhance tolerability. Any improvements in tolerability could be due to the emollients in the clindamycin/benzoyl peroxide gel formulation.     

Clinical pharmacokinetics and drug metabolism of tazarotene: a novel topical treatment for acne and psoriasis.

Tazarotene (AGN 190168) is a new acetylenic retinoid which is effective for the topical treatment of patients with stable plaque psoriasis and mild to moderate acne vulgaris. Topical gel application provides direct delivery of tazarotene into the skin. At 10 hours after a topical application of 0.1% tazarotene gel to the skin of healthy individuals and patients with psoriasis, approximately 4 to 6% of the dose resided in the stratum corneum and 2% of the dose distributed to the viable epidermis and dermis. Tazarotene is rapidly hydrolysed by esterases to its active metabolite, tazarotenic acid. Tazarotenic acid does not accumulate in adipose tissue, but undergoes further metabolism to its sulfoxide and to other polar metabolites and is rapidly eliminated via both urinary and faecal pathways with a terminal half-life of about 18 hours. Percutaneous absorption is similar between healthy individuals and patients with facial acne, leading to plasma concentrations below 1 microg/L. The systemic bioavailability of tazarotene (measured as tazarotenic acid) is low, approximately 1% after single and multiple topical applications to healthy skin. In patients with psoriasis under typical conditions of use, systemic bioavailability increased during the initial 2 weeks of treatment from 1% (single dose) to 5% or less (steady state). The increased bioavailability is probably related to decreases in plaque elevation and scaling due to successful treatment, resulting in a less effective skin penetration barrier to tazarotene. Steady-state concentrations of tazarotenic acid are achieved within 2 weeks of topical treatment in both healthy and psoriatic skin types. The large variability in plasma concentrations observed in patients with psoriasis is probably because of the large differences in lesional skin condition, the amount of drug applied and the surface area of application. There was no significant drug accumulation in the body with long term treatment of patients with psoriasis. Topical administration of tazarotene requires dosages much smaller than those usually required for oral retinoids, such as isotretinoin, acitretin and etretinate, and it delivers the drug directly into the target skin tissues. The low systemic absorption and rapid systemic elimination of tazarotene and tazarotenic acid results in limited systemic exposure. Thus, topical tazarotene has a low potential for systemic adverse effects and is effective in the treatment of patients with acne and psoriasis.     

Phospholipid microemulsion-based hydrogel for enhanced topical delivery of lidocaine and prilocaine: QbD-based development and evaluation

Topical delivery of local anesthetics has been an area of interest for researchers considering the barrier properties of skin and unfavorable physicochemical properties of drugs. In the present study, efforts have been made to modify the in vivo efficacy of eutectic mixture of lidocaine and prilocaine by exploiting the phospholipid modified microemulsion based delivery systems. The strategic QbD (D-optimal mixture design) enabled systematic optimization approach, after having obtained the isotropic area of interest by ternary phase diagram, has resulted into the system with most desirable attributes. Latter include nano-scale, globular structures with an average size of 40.6?nm, as characterized by TEM and DLS. The optimized microemulsion systems in gel dosage forms revealed the better permeability over commercial cream (CC) through abdominal rat skin. Enhancement in the flux from M_OPT-NMP gel was 3.22-folds for prilocaine and 4.94-folds for lidocaine, in comparison to that of CC. This enhanced skin permeability is very well reflected in the in vivo studies, wherein intensity and duration of action was augmented significantly. The skin compliance of the optimized formulation was revealed in histopathological studies. The overall benefit relating to efficacy and safety-compliance could be correlated to the uniqueness of the carriers, composed of phospholipids and other components. Hence, the developed phospholipid-microemulsion based gel formulation has been proposed as more useful alternative for the topical delivery of lidocaine and prilocaine.     

Preparation and evaluation of microemulsion of vinpocetine for transdermal delivery

Poorly soluble vinpocetine was selected as the model drug to prepare a microemulsion in order to increase solubility and in vitro transdermal delivery of the drug. Oleic acid was chosen as the oil phase due to its excellent solubilizing capacity. PEG-40 hydrogenated castor oil (Cremophor RH40) was employed as a surfactant (S) and purified diethylene glycol monoethyl ether (Transcutol P) was used as a cosurfactant (CoS). The effects of diverse types of oil, different weight ratios of surfactant to cosurfactant (S/CoS) on the solubility and permeation rate of vinpocetine were investigated. The optimized microemulsion consisted of 1% vinpocetine, 4% oleic acid, 20% Cremophor RH40, 10% Transcutol P and 65% distilled water (w/w), in which drug solubility was about 2,100 fold compared to that in water and the apparent permeation rate across the excised rat skin was 15.0 +/- 2.5 microg/cm2/h. Finally the physicochemical properties of the optimized microemulsion including pH, viscosity, refractive index, conductivity and particle size distribution were examined, which showed stable behavior after more than 12 months at ambient temperature. The irritation study showed that optimized microemulsion was a safe transdermal delivery system.     

Effect of microemulsion in topical sertaconazole hydrogel: in vitro and in vivo study

Purpose: A topical microemulsion (ME)-based hydrogel was developed to enhance permeation of an antifungal drug, sertaconazole (STZL) for effective eradication of cutaneous fungal infection.

Methods: Pseudo-ternary phase diagrams were used to determine the existence of MEs region. ME formulations were prepared with oleic acid, Tween 80, propylene glycol (PG) and water. Carbopol 940 (0.75% w/w) was used for preparation of hydrogel of STZL microemulsion (HSM) and characterized. The in vitro and in vivo evaluation of prepared HSM and commercial cream of STZL were compared.

Results: The viscosity, average droplet size and pH of HSM were 154.23?±?0.54 to 162.52?±?0.21?Pas, 42.3–91.7?nm and 6.9–7.2?, respectively. Permeation rate of STZL from optimized formulation (HSM-4), composed with oleic acid (8.75 % w/w), Tween 80 (33.35% w/w), PG (33.35% w/w) and water (24.55% w/w) was observed higher in compare with other HSMs and commercial cream. HSM-4 was stable, three times higher drug retention capacity in skin than commercial cream and did not caused any erythema or edema based on skin sensitivity study on rabbit. The average zone of inhibition of HSM-4 (23.54?±?0.72?mm) was higher in compare with commercial cream (16.53?±?0.63?mm) against Candida albicans.

Conclusion: The results of study showed that ME played a major role in permeation enhancing and skin retention effect of HSM and the concentration of STZL used for cutaneous fungal infection could be decreased by using ME based hydrogel preparation.     

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.     

遗传算法在经皮给药微乳载体处方优化中的应用

以萘普生为模型药物，用遗传算法优化经皮给药微乳载体的处方。用伪三元相图法确定由Tween 80、IPM、乙醇和水组成的微乳区域。用3因素3水平的中心设计法制备载药量为1.12%的萘普生模型微乳，并进行离体兔皮的体外渗透实验。以稳态渗透速率的二次回归模型为目标函数，用遗传算法对中心设计结果进行优化，筛选出具有最大透皮速率的萘普生微乳载体处方。所得优化处方的组成为：21.41% Tween 80、15.17%乙醇、4.14% IPM和59.28%水，预计的稳态渗透速率为183.57 μg·cm^-2·h^-1。回代试验表明，以优化处方制备的萘普生微乳，其稳态渗透速率的平均值为189.43 μg·cm^-2·h^-1，高于预测值。结果表明，用遗传算法筛选微乳经皮给药载体处方，方法可行，结果合理、可靠。     

Percutaneous delivery of α-melanocyte-stimulating hormone for the treatment of imiquimod-induced psoriasis

Purpose: α-Melanocyte-stimulating hormone (α-MSH) is an endogenous peptide hormone with anti-inflammatory responses. We developed topical formulation(s) of α-MSH to reduce psoriasis-related inflammation.

Methods: Transcutol (TC) and n-methyl 2-pyrrolidone (NMP) were used to formulate a gel for α-MSH. Skin permeation and dermal microdialysis of the solution and optimized gel were performed. The inflammatory response of α-MSH gel was investigated in imiquimod-induced psoriasis mouse model. Histology and immunohistochemistry were then performed on treated skin.

Results: Solution comprising 50%w/w TC and 10%w/w NMP showed higher (p?<?0.05) skin retention (0.27?±?0.024?µg of α-MSH/mg of skin) than solutions containing either 50% w/w TC or 10% w/w NMP at 24?h. Dispersion of α-MSH in Carbopol Ultrez 10 produced a uniform dispersion. α-MSH gel showed pseudoplastic flow with thixotropic behavior. Dermal microdialysis results suggested that skin permeation of gel after 5?h was 1.9-folds higher than the solution. Further, gel-treated psoriatic-like plaque skin sections showed significant (p?<?0.05) decrease in the expression of a melanocortin receptor, in the psoriasis area and severity index score and transepidermal water loss compared to the solution.

Conclusion: TC, NMP and Carbopol Ultrez 10 form a stable gel with improved skin permeation of α-MSH for a reduction in psoriasis-associated inflammation.     

Self-double-emulsifying drug delivery system incorporated in natural hydrogels: a new way for topical application of vitamin C

This study aimed at the in vitro evaluation of topical hydrogels containing vitamin C-loaded self-double-emulsifying drug delivery system (SDEDDS). The liquid SDEDDS was converted into suitable unmodified xanthan gum hydrogels formulation and the prepared semi-solid hydrogels provided appropriate gel characteristics like pH, viscosity, spreadability, etc. The 5-week storage test displayed that the prepared hydrogels possessed good physicochemical stability. In addition, no significant cytotoxicity to L929 cells was observed for the vitamin C-loaded SDEDDS-based hydrogels, and the prepared hydrogels depicted a sustained drug release over an 8-h period. In vitro permeation study showed that the vitamin C-loaded SDEDDS-based hydrogels could significantly enhance vitamin C retention in the skin and permeation through the skin. The overall results demonstrated that the hydrogels containing vitamin C-loaded SDEDDS could be considered as a promising formulation for topical application.