Microemulsions for topical delivery of estradiol

Synergistic Skin Penetration Enhancer and Nanoemulsion Formulations Promote the Human Epidermal Permeation of Caffeine and Naproxen

We examined the extent of skin permeation enhancement of the hydrophilic drug caffeine and lipophilic drug naproxen applied in nanoemulsions incorporating skin penetration enhancers. Infinite doses of fully characterized oil-in-water nanoemulsions containing the skin penetration enhancers oleic acid or eucalyptol as oil phases and caffeine (3%) or naproxen (2%) were applied to human epidermal membranes in Franz diffusion cells, along with aqueous control solutions. Caffeine and naproxen fluxes were determined over 8 h. Solute solubility in the formulations and in the stratum corneum (SC), as well as the uptake of product components into the SC were measured. The nanoemulsions significantly enhanced the skin penetration of caffeine and naproxen, compared to aqueous control solutions. Caffeine maximum flux enhancement was associated with a synergistic increase in both caffeine SC solubility and skin diffusivity, whereas a formulation-increased solubility in the SC was the dominant determinant for increased naproxen fluxes. Enhancements in SC solubility were related to the uptake of the formulation excipients containing the active compounds into the SC. Enhanced skin penetration in these systems is largely driven by uptake of formulation excipients containing the active compounds into the SC with impacts on SC solubility and diffusivity.

Physicochemical, in vitro and in vivo evaluation of flurbiprofen microemulsion

Flurbiprofen, a potent nonsteroidal anti-inflammatory drug, is widely used for relief of pain in patients suffering from rheumatic diseases, migraine, sore throat and primary dysmenorrheal. However, this drug has many gastrointestinal side effects produced by its oral administration, such as gastric bleeding and peptic ulcer. These effects were responsible for non-compliance among patients, which ultimately results in treatment failure. The physicochemical properties of flurbiprofen, make it a suitable candidate for transdermal drug delivery, which can overcome the drawbacks of oral administration. In this sense, microemulsions have been proved to increase the cutaneous absorption of lipophilic drugs when compared to conventional drug delivery systems. The purpose of this study was to formulate and characterize gel based microemulsions, for topical delivery of flurbiprofen. Different gel bases, containing microemulsion and hydro-alcoholic solution of flurbiprofen, were developed and compared. In vitro study showed that gels containing microemulsion had a higher permeation rate than those containing hydro-alcoholic solutions. Additionally, formulation of Carbopol-I (microemulsion) showed higher percent of inhibition of inflammation than others bases. Further, skin irritation study demonstrated that Carbopol-I was none irritating. Flurbiprofen microemulsion incorporated on Carbopol-I showed physicochemical, in vitro and in vivo characteristics suitable for the development of alternative transdermal delivery formulation.

Role of simplex lattice statistical design in the formulation and optimization of microemulsions for transdermal delivery

Microemulsions (ME) have gained attention as an alternative pharmaceutical formulation for transdermal delivery systems. However, the complicated relationships between various ME compositions (causal factors) and their characteristics (response variable) have not been fully comprehended. To overcome this problem, the design and development of ME for transdermal delivery was performed in our study using Design Expert(®) Software. The model formulations of ME were prepared according to the ME region obtained from pseudo-ternary phase diagrams using the simplex lattice design as an optimization technique. In this study, ketoprofen-loaded ME composed of oleic acid, Cremophor(®) RH40, ethanol and water were prepared, and their characteristics (e.g., size, charge, conductivity, pH, viscosity, drug content, loading capacity and skin permeation flux) were evaluated. The ME having an appropriate skin permeation flux was used as the basis for optimization. The skin permeation flux of the experimental ME was very close to the flux predicted by Design Expert(®) Software and was significantly greater than that for the commercial product. Possible mechanisms for the enhancement of the skin permeation of the ME were also investigated using Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD). This finding provided an understanding of the relationship between the causal factors and response variables, as shown in the response surfaces. Moreover, these results indicated that the simple lattice design was beneficial for the pharmaceutical development of ME for transdermal delivery.

Preparation of a mixed-matrix hydrogel of vorinostat for topical administration on the rats as experimental model

Oral vorinostat has the remarkable curative effect on aggravated and recurrent cutaneous T-cell lymphoma (CTCL), but is accompanied by serious adverse effects. Therefore, oral vorinostat is not applicable to the treatment of early stage CTCL. The aim of this study is to develop a novel vorinostat formulation which is effective for early stage CTCL and free of the serious adverse effects. A mixed-matrix hydrogel of vorinostat was prepared and characterized as a potential topical skin delivery system. Moisture retention, swelling behavior, viscosity, real-time morphology and differential scanning calorimeter analysis (DSC) of hydrogel were evaluated to select the solvent, matrix and humectant. The optimal HPMC/HPC ratio, pH, additive, dose and drug loading of vorinostat hydrogel were determined by evaluating the cumulative vorinostat amount of skin retention and transdermal amount of vorinostat through the skin in vitro. The optimal hydrogel presented a low transdermal amount of vorinostat through the skin, suggesting that the hydrogel reduced the amount of vorinostat that was absorbed in the systemic circulation. More importantly, in vivo percutaneous permeation experiments were also performed to evaluate the permeation behavior of vorinostat into the skin. The topical application with a much lower dose showed higher AUC (the cumulative vorinostat amount of skin retention) than oral application and the hydrogel achieved a sustained permeation of vorinostat in the skin for 24h in vivo. It indicated that a higher relative bioavailability for hydrogel was achieved compared with oral vorinostat. Moreover, there was no damage, inflammation or cell swelling of the skin after administration. Thus, the mixed-matrix vorinostat hydrogel prepared in this study could deliver vorinostat into local skin more efficiently than oral administration.

Curcumin-loaded colloidal carrier system: formulation optimization, mechanistic insight, ex vivo and in vivo evaluation

The present work investigated the topical delivery potential of nanoemulsion gel loaded with curcumin (CR). CR nanoemulsion (CR-NE) was prepared by spontaneous emulsification method using oil (Labrafac PG/glyceryl triacetate), surfactant:cosurfactant (S_mix) (tween 80/polyethylene glycol [PEG] 400) and water. The pseudo-ternary phase diagrams were constructed and thermodynamic stability testing was performed. Droplet size and zeta potential were evaluated using photon correlation spectroscopy and transmission electron spectroscopy. Six formulations selected with an average droplet size ≤70±2.72 nm showed a fourfold increase in skin permeation as compared to crude CR solution in oil. The formulation CR-NE4 having a flux of 117.04±2.32 µg/cm²/h and with maximum retention (42.87%) was selected, characterized (droplet size =41.13±3.34 nm and zeta potential =−33.1±1.45 mV), and incorporated into gel using carbopol-980 (1% w/v). Skin dynamics analyzed by confocal laser scanning microscopy showed maximum deposition of CR up to a depth of 86.98 µm and was in concordance with differential scanning calorimetry and Fourier transform infrared spectroscopy studies that confirmed lipid bilayer disruption, enhancing permeation. A 28-day anti-arthritic evaluation (body weight, paw edema, tibiotarsal joint thickness, TNF-α and IL-1β levels, and histopathology) on Freund’s complete adjuvant induced arthritic rat model after topical application of CR-NE gel in Wistar rats demonstrated substantial reversal of arthritic symptoms. Thus, CR-NE gel possesses potential for therapeutic effects locally in inflammatory arthritic disorders with improved topical bioavailability.

Biocompatible lidocaine and prilocaine loaded-nanoemulsion system for enhanced percutaneous absorption: QbD-based optimisation, dermatokinetics and in vivo evaluation

Barrier properties of the skin and physicochemical properties of the drugs are the main hiccups in delivering local anaesthetic molecules topically. The present work endeavours for systematic optimisation and evaluation of nanoemulsions (NEs) of local anaesthetic drugs, lidocaine and prilocaine, employing the systematic approach of Quality by Design. A 3(3) Box-Behnken design was employed for systematic optimisation of the factors obtained from screening studies employing Plackett-Burman design and risk assessment studies. The superior permeation rates, and higher concentrations of the drugs in skin layers from the optimised NE carriers, were achieved in permeation and dermatokinetic studies, when compared to marketed cream. Furthermore, rapid onset of action was demonstrated by the NE system in rabbit eye corneal reflex model and biocompatibility was confirmed from the absence of any marked skin change(s) in the normal skin histology. The developed NE systems demonstrated it as a promising carrier for topical delivery of lidocaine and prilocaine.

Microemulsion-loaded hydrogel formulation of butenafine hydrochloride for improved topical delivery

Topical microemulsion systems for the antifungal drug, butenafine hydrochloride (BTF) were designed and developed to overcome the problems associated with the cutaneous delivery due to poor water solubility. The solubility of BTF in oils, surfactants and co-surfactants was evaluated to screen the components of the microemulsion. Isopropyl palmitate was used as the oil phase, aerosol OT as the surfactant and sorbitan monooleate as co-surfactant. The pseudoternary diagrams were constructed to identify the area of microemulsion existence and optimum systems were designed. The systems were assessed for drug-loading efficiency and characterized for pH, robustness to dilution, globule size, drug content and stability. Viscosity analysis, spreadability, drug content assay, ex vivo skin permeation study and antifungal activity assay were performed for the optimized microemulsion-loaded hydrogel. The optimized BTF microemulsion had a small and uniform globule size. The incorporation of microemulsion system into Carbopol 940 gel was found to be better as compared to sodium alginate or hydroxyl propyl methyl cellulose (HPMC K4 M) gel. The developed gel has shown better ex vivo skin permeation and antifungal activity when compared to marketed BTF cream. Thus, the results provide a basis for the successful delivery of BTF from microemulsion-loaded hydrogel formulation, which resulted in improved penetration of drug and antifungal activity in comparison with commercial formulation of BTF.

Application of Design Expert for the investigation of capsaicin-loaded microemulsions for transdermal delivery

Our previous study reported that the Design Expert® Software showed a beneficial role in the development of microemulsions (ME) for transdermal drug delivery. To fully confirm the reproducibility and the reliability of simultaneous optimal ME formulations, the optimal ME formulations predicted by the Design Expert® Software were experimentally formulated and verified for their skin permeability. Ternary phase diagrams were used to predict the optimal ME area, and the ME formulations selected from outside this area were considered as candidate ME systems. Our ME systems were formulated with isopropyl myristate (IPM) as the oil phase, cocamide diethanolamine (DEA) as the surfactant, ethanol as a co-surfactant and water as the aqueous phase. The droplet size, size distribution, electrical conductivity, pH, drug content and skin permeability of the candidate ME systems were monitored. Our findings indicated that the skin permeability of the optimal ME and all of the candidate ME formulations was significantly greater than that of the commercial capsaicin (CAP) product. Our study succeeded in predicting and developing the ME systems for the transdermal delivery of CAP. The simplex lattice design used in this study is experimentally useful for the development of pharmaceutical formulations.

Microemulsion-based antifungal gel delivery to nail for the treatment of onychomycosis: formulation, optimization, and efficacy studies

Onychomycosis is the most common nail disease affecting nail plate and nail bed. Onychomycosis causes onycholysis which creates cavity between the nail plate and nail bed, where drug formulations could be applied, providing a direct contact of drug with the nail bed facilitating drug delivery on the infected area. The purpose of the present study was to design and evaluate the potential of microemulsion-based gel as colloidal carrier for itraconazole for delivery into onycholytic nails for effective treatment of onychomycosis. Itraconazole-loaded microemulsions were prepared and optimized using D-optimal design. The microemulsion containing 6.24 % oil, 36 % Smix, and 57.76 % water was selected as the optimized batch (MEI). The globule size and drug loading of the optimized batch were 48.2 nm and 12.13 mg/ml, respectively. Diffused reflectance FTIR studies were performed to study drug-excipient incompatibility. Ex vivo permeation studies were carried out using bovine hoof and human cadaver skin as models for nail plate and nail bed, respectively. Microemulsion-based itraconazole gel (MBGI) showed better penetration and retention in human skin as well as bovine hoof as compared to commercial preparation (market formulation, MFI). The cumulative amount of itraconazole permeated from the MBGI after 12 h was 73.39 ± 3.55 μg cm(-2) which was 1.8 times more than MF. MBGI showed significantly higher ex vivo antifungal activity (P < 0.05) against Candida albicans and Trichophyton rubrum when compared to MFI. Stability studies showed that MBGI was stable at refrigeration and room temperature for 3 months. It was concluded that drug-loaded gel could be a promising formulation for effective treatment of onychomycosis.

Preparation and evaluation of submicron-carriers for naringenin topical application

Submicron emulsion system is one kind of submicron-carrier that can ensure close contact and increase the amount of drug transport into the skin. In the present study, naringenin was loaded into a submicron emulsion system for topical applications. The enhancement effect of drug permeability through skin, stability, and skin irritation of naringenin-loaded submicron emulsions were evaluated. The results showed that the transdermal amount and deposition amount in skin of naringenin from submicron emulsion formulations were significantly increased when compared to the control group of saturated aqueous solution of naringenin. The drug-loaded submicron emulsions showed thermodynamic stability after centrifugation and cooling-heating cycle tests. The level of drug was more than 98% after 3 months of storage at 25°C and 40°C. In skin irritation test, the result also demonstrated that naringenin-loaded submicron emulsion had less skin irritation, indicating that the formulation can possibly be developed for topical application.

Development of liposomal and microemulsion formulations for transdermal delivery of clonazepam: effect of randomly methylated β-cyclodextrin

Transdermal administration of clonazepam, a poorly water-soluble benzodiazepine, is an interesting strategy for overcoming the drawbacks of its oral administration. With this aim, two nano-carrier formulations, based on ultra-deformable liposomes and microemulsions, have been developed to favour clonazepam transdermal delivery. Considering the solubilizing power of methyl-βcyclodextrin (Me-βCD) toward clonazepam and its potential positive influence on transdermal drug delivery, the effect of its addition to these formulations was investigated. Artificial lipophilic membranes simulating the skin allowed a rapid evaluation of the drug permeation properties from the systems, compared with those from an aqueous drug suspension, with or without Me-βCD. The best formulations were further characterized by permeation through excised rabbit ear skin. All the formulations increased drug permeability, ranging from 2-fold (liposomes without Me-βCD), up to over 4-fold (microemulsions containing Me-βCD). The different formulations allowed for pointing out different possible permeation enhancing mechanisms of Me-βCD: increase in drug solubility and thermodynamic activity in the vehicle, when added to the drug aqueous suspension; interactions with the vesicle bilayer, in case of liposomal formulations; interactions with the skin membrane lipids, as evidenced in experiments with excised rabbit ear for microemulsions containing Me-βCD, that were then selected for further in vivo studies.

Development of novel ionic liquid-based microemulsion formulation for dermal delivery of 5-Fluorouracil

The present study was aimed at synthesizing an imidazole-based ionic liquid 1-butyl-3-methylimidazolium bromide (BMIMBr) and subsequent development of a novel ionic liquid-in-oil (IL/o) microemulsion (ME) system for dermal delivery of a poorly permeating drug 5-fluorouracil (5-FU). A significant enhancement in the solubility of 5-FU was observed in BMIMBr. IL/o MEs of 5-FU were prepared using isopropyl myristate, Tween 80/Span 20, and BMIMBr. Results of ex vivo skin permeation studies through mice skin indicated that the selected IL/o ME exhibited 4-fold enhancement in percent drug permeation as compared to aqueous solution, 2.3-fold as compared to hydrophilic ointment, and 1.6-fold greater permeation than water in oil (w/o) ME. The results of in vivo studies against dimethylbenz(a)anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mice skin carcinogenesis demonstrated that the IL/o ME could effectively treat skin cancer in 4 weeks. In addition, the side effects such as erythema and irritation associated with the conventional formulations were not observed. Histopathological studies showed that the use of IL/o ME caused no anatomic and pathological changes in the skin structure of mice. These studies suggest that the use of IL-based ME system can efficiently enhance the solubility and permeability of 5-FU and hence its therapeutic efficacy.

The effect of nanoemulsion as a carrier of hydrophilic compound for transdermal delivery

The purpose of the present study was to investigate the effect of nanoemulsions as a carrier vehicle of hydrophilic drug for transdermal delivery. The response surface methodology with a mixture design was used to evaluate the effect of ingredient levels of nanoemulsion formulations including cosurfactant (isopropyl alcohol, 20 ∼ 30%), surfactant (mixed of Brij 30 and Brij 35, 20 ∼ 30%), and distilled-water (34.5 ∼ 50.0%) on properties of the drug-loaded nanoemulsions including physicochemical characters and drug permeability through rat skin. The result showed that the hydrophilic drug in aqueous solution with or without penetration enhancer could not transport across rat skin after 12 h of application. Used nanoemulsions as carrier vehicle, the permeation rate of drug was significantly increased from 0 to 63.23 µg/cm2/h and the lag time was shortened from more than 12 h to about 2.7 ∼ 4.0 h. Moreover, the drug-loaded nanoemulsion formulation also showed physicochemical stability after 3 month storage at 25°C and 40°C.

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 MOPT-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.

Overcoming the cutaneous barrier with microemulsions

Microemulsions are fluid and isotropic formulations that have been widely studied as delivery systems for a variety of routes, including the skin. In spite of what the name suggests, microemulsions are nanocarriers, and their use as topical delivery systems derives from their multiple advantages compared to other dermatological formulations, such as ease of preparation, thermodynamic stability and penetration-enhancing properties. Composition, charge and internal structure have been reported as determinant factors for the modulation of drug release and cutaneous and transdermal transport. This manuscript aims at reviewing how these and other characteristics affect delivery and make microemulsions appealing for topical and transdermal administration, as well as how they can be modulated during the formulation design to improve the potential and efficacy of the final system.

Lecithin-based nanostructured gels for skin delivery: an update on state of art and recent applications

Conventional carriers for skin delivery encounter obstacles of drug leakage, scanty permeation and low entrapment efficiency. Phospholipid nanogels have recently been recognized as prominent delivery systems to circumvent such obstacles and impart easier application. The current review provides an overview on different types of lecithin nanostructured gels, with particular emphasis on liposomal versus microemulsion gelled systems. Liposomal gels investigated encompassed classic liposomal hydrogel, modified liposomal gels (e.g. Transferosomal, Ethosomal, Pro-liposomal and Phytosomal gels), Microgel in liposomes (M-i-L) and Vesicular phospholipid gel (VPG). Microemulsion gelled systems encompassed Lecithin microemulsion-based organogels (LMBGs), Pluronic lecithin organogels (PLOs) and Lecithin-stabilized microemulsion-based hydrogels. All systems were reviewed regarding matrix composition, state of art, characterization and updated applications. Different classes of lecithin nanogels exhibited crucial impact on transdermal delivery regarding drug permeation, drug loading and stability aspects. Future perspectives of this theme issue are discussed based on current laboratory studies.

Amphotericin B topical microemulsion: formulation, characterization and evaluation

The present studies were designed to develop a microemulsion (ME) formulation of Amphotericin B (Amp B) for the treatment of invasive fungal infections. The oil phase was selected on the basis of drug solubility whereas the surfactant and co-surfactant were screened and selected on the basis of their oil solubilizing capacity as well as their efficiency to form ME. Pseudo-ternary phase diagrams were constructed and on the basis of ME existence ranges various formulations of Amp B were developed. The influence of surfactant and co-surfactant mass ratio (Smix) on the ME formation and permeation of ME through excised rat skin was studied. The optimized formulation (ME 7) consisting of 0.1% (w/w) Amp B, 5% (w/w) Isopropyl Myristate and 35% (w/w) Smix (3:1, Tween 80 and Propylene glycol), has shown a globule size of 84.20 ± 2.13 nm, a polydispersity index of 0.164 ± 0.031, pH 7.36 ± 0.02 and conductance of 229.3 ± 1.95 μS. ME 7 exhibited 2-fold higher drug permeation as compared to plain drug solution. Besides this, the formulation was also evaluated for drug content, stability, skin retention, skin sensitivity and anti-fungal activity. In vitro anti-fungal activity in Trichophyton rubrum fungal species have shown that ME7 has higher zone of inhibition and the formulation was found stable at 2-8°C and at room temperature (25 ± 2°C) for the period of three months. The results indicate that, the investigated ME may be used as a promising alternative for Amp B therapy.

Effect of microemulsions on transdermal delivery of citalopram: optimization studies using mixture design and response surface methodology

The aim of this study was to evaluate the potential of microemulsions as a drug vehicle for transdermal delivery of citalopram. A computerized statistical technique of response surface methodology with mixture design was used to investigate and optimize the influence of the formulation compositions including a mixture of Brij 30/Brij 35 surfactants (at a ratio of 4:1, 20%-30%), isopropyl alcohol (20%-30%), and distilled water (40%-50%) on the properties of the drug-loaded microemulsions, including permeation rate (flux) and lag time. When microemulsions were used as a vehicle, the drug permeation rate increased significantly and the lag time shortened significantly when compared with the aqueous control of 40% isopropyl alcohol solution containing 3% citalopram, demonstrating that microemulsions are a promising vehicle for transdermal application. With regard to the pharmacokinetic parameters of citalopram, the flux required for the transdermal delivery system was about 1280 μg per hour. The microemulsions loaded with citalopram 3% and 10% showed respective flux rates of 179.6 μg/cm(2) and 513.8 μg/cm(2) per hour, indicating that the study formulation could provide effective therapeutic concentrations over a practical application area. The animal study showed that the optimized formulation (F15) containing 3% citalopram with an application area of 3.46 cm(2) is able to reach a minimum effective therapeutic concentration with no erythematous reaction.

Characterization and evaluation of an oral microemulsion containing the antitumor diterpenoid compound ent-11alpha-hydroxy-15-oxo-kaur-16-en-19-oic-acid

The objective of this study was to develop an oral microemulsion formulation of the antitumor diterpenoid agent, ent-11α-hydroxy-15-oxo-kaur-16-en-19-oic-acid (henceforth referred to as 5F), to enhance its bioavailability and evaluate its hepatotoxicity. Pseudoternary phase diagrams showed that the optimal microemulsion formulation contained 45% water, 10% castor oil as the oil phase, 15% Cremophor EL as the surfactant, and 30% as a cosurfactant mixture of 1,2-propanediol and polyethylene glycol (PEG)-400 (2:1, w/w). The microemulsion preparation was characterized and its droplet diameter was within 50 nm. Release of 5F in vitro from the microemulsion was slightly increased compared with a suspension containing the same amount of active drug. Pharmacokinetic parameters in vivo indicated that bioavailability was markedly improved, with the relative bioavailability being 616.15% higher for the microemulsion than for the suspension. Toxicity tests showed that the microemulsion had no hepatotoxicity in mice. These results suggest the potential for 5F microemulsion to be administered by the oral route.

Design and evaluation of microemulsion gel system of nadifloxacin

Topical microemulsion systems for the antiacne agent, nadifloxacin were designed and developed to overcome the problems associated with the cutaneous delivery due to poor water solubility. The solubility of nadifloxacin in oils, surfactants and cosurfactants was evaluated to screen the components of the microemulsion. Various surfactants and cosurfactants were screened for their ability to emulsify the selected oily phase. The pseudoternary diagrams were constructed to identify the area of microemulsion existence. The influence of k_m (surfactant/cosurfactant) ratio on the microemulsion existence region was determined and optimum systems were designed. The systems were assessed for drug-loading efficiency and characterised for optical birefringence, pH and refractive index, robustness to dilution, globule size, drug content and thermodynamic stability. Optimised microemulsion systems were formulated into gel form and evaluated for viscosity, spreadability, drug content, ex vivo skin permeation and antibacterial activity. The maximum solubility of nadifloxacin in the microemulsion system was found to be 0.25%. The nadifloxacin microemulsions had a small and uniform globule size (67.3-121.23 nm). The stability results revealed that all formulations showed a stable globule size and the polydispersity index under stress conditions. Incorporation of nadifloxacin in microemulsion gel increased the ex vivo skin permeation and antibacterial activity when compared to marketed cream.

The effect of submicron emulsion systems on transdermal delivery of kaempferol

In this study, submicron emulsions have been employed as a carrier for the topical application of kaempferol. The effect of components of submicron emulsions on the physicochemical properties and permeation capability of drug were evaluated. In case of drug-loaded submicron emulsions, the cumulative amount over 12 h (Q(12 h)), lag time and deposition in skin amount ranged from 13.0±3.4 to 236.1±21.2 µg/cm(2), 1.7 to 5.3 h, and 1.10 to 7.76 µg/cm(2), respectively, which indicated that the permeation parameters of kaempferol were markedly influenced by the component ratio. Kaempferol dispensed in isopropyl myristate was used as the control. The Q(12 h), lag time and deposition amount in skin were 4.2±1.8 µg/cm(2), 6.0 h and 2.25±0.60 µg/cm(2), respectively. The data showed that used appropriate submicron emulsions as vehicle could significantly increase the Q(12 h) and deposition amount in skin and shorten the lag time, demonstrating that submicron emulsions have a potent enhancement effect for kaempferol transdermal delivery.

Design and characterization of microemulsion systems for naproxen

PURPOSE

This research was aimed to formulate and characterize a microemolsion systems as a topical delivery system of naproxen for relief of symptoms of rheumatoid arthritis, osteoarthritis and treatment of dysmenorrheal.

METHODS

ME formulations prepared by mixing of appropriate amount of surfactant including Tween 80 and Span 80, co-surfactant such as propylene glycol (PG) and oil phase including Labrafac PG - transcutol P (10:1 ratio). The prepared microemolsions were evaluated regarding their particle size, zeta potential, conductivity, stability, viscosity, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), refractory index (RI) and pH.

RESULTS

The mean droplets size of microemulsion formulation were in the range of 7.03 to 79.8 nm, and its refractory index (RI) and pH were 1.45 and 6.75, respectively. Viscosity range was 253.73- 802.63cps. Drug release profile showed that 26.15% of the drug released in the first 24 hours of experiment. Also, Hexagonal and bicontinuous structures were seen in the SEM photograph of the microemulsions.

CONCLUSION

characterization, physicochemical properties and in vitro release were dependent upon the contents of S/C ratio, water and, oil phase percentage in formulations. Also, ME-6 may be preferable for topical naproxen formulation.