Microemulsions as topical drug delivery vehicles: in-vitro transdermal studies of a model hydrophilic drug

Development of erlotinib-loaded nanotransferosomal gel for the topical treatment of ductal carcinoma in situ

Aims: This study was aimed to formulate erlotinib (ERL)-loaded transferosomal gel (ERL@TG) intended for topical application for the treatment of ductal carcinoma in situ. Materials & methods: The optimized process involved a thin-film hydration method to generate ERL-loaded transferosomes (ERL@TFS), which was incorporated into a carbopol gel matrix to generate ERL@TG. The optimized formulation was characterized in vitro followed by cytotoxicity evaluation on MCF-7 breast cancer cell lines and acute toxicity and skin irritation studies was performed in vivo. Results: In a comparative assessment against plain ERL, ERL@TG displayed enhanced efficacy against MCF-7 cell lines, reflected in considerably lower IC50 values with an enhanced safety profile. Conclusion: Optimized ERL@TG was identified as a promising avenue for addressing ductal carcinoma in situ breast cancer.

Microemulsion-based gel for the transdermal delivery of rasagiline mesylate: In vitro and in vivo assessment for Parkinson's therapy

Rasagiline mesylate (RSM) is a selective and irreversible monoamine oxidase B inhibitor used for the treatment of Parkinson's disease (PD). However, its unfavorable biopharmaceutical properties, such as extensive degradation in the gastrointestinal tract and first-pass metabolism are responsible for its low oral bioavailability and suboptimal therapeutic efficacy. Here, we report the feasibility of delivering RSM via the transdermal route using RSM containing microemulsion-based gel (RSM-MEG) to achieve effective management of PD. Our in vitro skin permeation studies of RSM-MEG showed significantly higher (at least ~1.5-fold) permeation across rat skin compared to the conventional RSM hydrogel. Our skin irritation studies in rabbits showed that RSM-MEG is safe for transdermal application. Finally, using the rat model of rotenone-induced Parkinsonism, we demonstrated that the topical application of RSM-MEG was equally effective in reversing PD symptoms when compared to oral RSM therapy. Thus, our study confirmed the feasibility and potential of transdermal delivery of RSM via simple topical application of RSM-MEG, and this approach could be an alternative therapeutic intervention for the treatment of Parkinson's disease.

Fabrication of Alginate-Based O/W Nanoemulsions for Transdermal Drug Delivery of Lidocaine: Influence of the Oil Phase and Surfactant

Transdermal drug delivery of lidocaine is a good choice for local anesthetic delivery. Microemulsions have shown great effectiveness for the transdermal transport of lidocaine. Oil-in-water nanoemulsions are particularly suitable for encapsulation of lipophilic molecules because of their ability to form stable and transparent delivery systems with good skin permeation. However, fabrication of nanoemulsions containing lidocaine to provide an extended local anesthetic effect is challenging. Hence, the aim of this study was to address this issue by employing alginate-based o/w nanocarriers using nanoemulsion template that is prepared by combined approaches of ultrasound and phase inversion temperature (PIT). In this study, the influence of system composition such as oil type, oil and surfactant concentration on the particle size, in vitro release and skin permeation of lidocaine nanoemulsions was investigated. Structural characterization of lidocaine nanoemulsions as a function of water dilution was done using DSC. Nanoemulsions with small droplet diameters (d < 150 nm) were obtained as demonstrated by dynamic light scattering (DLS) and cryo-TEM. These nanoemulsions were also able to release 90% of their content within 24-h through PDMS and pig skin and able to the drug release over a 48-h. This extended-release profile is highly favorable in transdermal drug delivery and shows the great potential of this nanoemulsion as delivery system.

Effect of Processing/Formulation Parameters on Particle Size of Nanoemulsions Containing Ibuprofen - An Artificial Neural Networks Study

Background: Nanoemulsions are colloidal transparent systems for the delivery of hydrophobic drugs. This study aimed to determine the effect of parameters affecting particle size of a nanoemulsion containing ibuprofen using artificial neural networks (ANNs). Methods: Nanoemulsion samples with different values of independent variables, namely, concentration of ethanol, ibuprofen and Tween 80 as well as exposure (homogenization) time were prepared and their particle size was measured using dynamic light scattering (DLS). The data were then modelled by ANNs. Results: From the results, increasing the exposure time had a positive effect on reducing droplet size. The effect of concentration of ethanol and Tween 80 on droplet size depended on the amount of ibuprofen. Our results demonstrate that ibuprofen concentration also had a reverse relation with the size of the nanoemulsions. Conclusion: It was concluded that to obtain minimum particle size, exposure (homogenization)time should be maximized.

Salvianolic Acid B in Microemulsion Formulation Provided Sufficient Hydration for Dry Skin and Ameliorated the Severity of Imiquimod-Induced Psoriasis-Like Dermatitis in Mice

Psoriasis is a chronic inflammatory skin disorder with a pathogenesis involving the interleukin-23/interleukin-17 axis. Salvianolic acid B exerts several pharmacological effects, such as antioxidation, anti-inflammation, and antitumor effects. The anti-psoriatic effects of salvianolic acid B have not been reported. In this study, we aimed to determine the optimum vehicle for salvianolic acid B, investigate its therapeutic effect on psoriatic-like skin conditions, and explore its underlying mechanisms of action. BALB/c mice were administered topical imiquimod to induce psoriasis-like skin and were then randomly assigned to control, vehicle control, salvianolic acid B in vehicles, and 0.25% desoximetasone ointment treatment groups. Barrier function, cytokine expression, histology assessment, and disease severity were evaluated. The results showed that salvianolic acid B-containing microemulsion alleviated disease severity, reduced acanthosis, and inhibited interleukin-23/interleukin-17 (IL-23/IL-17) cytokines, epidermal proliferation, and increased skin hydration. Our study suggests that salvianolic acid B represents a possible new therapeutic drug for the treatment of psoriasis. In addition, such formulation could obtain high therapeutic efficacy in addition to providing sufficient hydration for dry skin.

Formation of stable nanoemulsions by ultrasound-assisted two-step emulsification process for topical drug delivery: Effect of oil phase composition and surfactant concentration and loratadine as ripening inhibitor

Nanoemulsions are very interesting systems as they offer capacity to encapsulate both hydrophilic and lipophilic molecules in a single particle, as well as the controlled release of chemical moieties initially entrapped in the internal droplets. In this study, we propose a new two-step modified ultrasound-assisted phase inversion approaches-phase inversion temperature (PIT) and self-emulsification, to prepare stable o/w nanoemulsions from a fully water-dilutable microemulsion template for the transdermal delivery of loratadine (a hydrophobe and as Ostwald ripening inhibitor). Firstly, the primary water-in-oil microemulsion concentrate (w/o) was formed using loratadine in the oil phase (oleic acid or coconut oil) and Tween 80 in the aqueous phase and by adjusting the PIT around 85 °C followed by stepwise dilution with water at 25 °C to initiate the formation the nanoemulsions (o/w). To assure the long-term stability, a brief application of low frequency ultrasound was employed. Combining the two low energy methods resulted in nanoemulsions prepared by mixing constant surfactant/oil ratios above the PIT with varying water volume fraction (self-emulsification) during the PIT by stepwise dilution. The kinetic stability was evaluated by measuring the droplet size with time by dynamic light scattering (DLS). The droplet size ranged 15-43 nm and did not exceed 100 nm over the period of 6 months indicating the system had high kinetic stability. Cryo-TEM showed that the nanoemulsions droplets were monodispersed and approaching micellar structure and scale. All nanoemulsions had loratadine crystals formed within 20 days after preparation, which tended to sediment during storage. Nanoemulsions improved the in vitro permeation of loratadine through porcine skin up to 20 times compared to the saturated solution.

Nanoemulsion: A Review on Mechanisms for the Transdermal Delivery of Hydrophobic and Hydrophilic Drugs

Nanoemulsions (NEs) are colloidal dispersions of two immiscible liquids, oil and water, in which one is dispersed in the other with the aid of a surfactant/co-surfactant mixture, either forming oil-in-water (o/w) or water-in-oil (w/o) nanodroplets systems, with droplets 20–200 nm in size. NEs are easy to prepare and upscale, and they show high variability in their components. They have proven to be very viable, non-invasive, and cost-effective nanocarriers for the enhanced transdermal delivery of a wide range of active compounds that tend to metabolize heavily or suffer from undesirable side effects when taken orally. In addition, the anti-microbial and anti-viral properties of NE components, leading to preservative-free formulations, make NE a very attractive approach for transdermal drug delivery. This review focuses on how NEs mechanistically deliver both lipophilic and hydrophilic drugs through skin layers to reach the blood stream, exerting the desired therapeutic effect. It highlights the mechanisms and strategies executed to effectively deliver drugs, both with o/w and w/o NE types, through the transdermal way. However, the mechanisms reported in the literature are highly diverse, to the extent that a definite mechanism is not conclusive.

Metal Coated Colloidosomes as Carriers for an Antibiotic

Colloidosomes are polymer shell microcapsules. They are stable and easy to prepare and have been used to encapsulate drugs for release at specific areas in the body. Traditional polymer shell capsules cannot totally seal drugs, since they are porous, and small molecules diffuse through the polymer shell. In this paper, we report a method for encapsulating an antibiotic kanamycin using gold or silver coated colloidosomes. The colloidosomes are impermeable and can be triggered using ultrasound. To investigate the application of the capsules in a biological system, Escherichia Coli (E. coli) was chosen as a model organism. After triggering, the released antibiotic, as well as the metal shell fragments, kill E. coli. Both the silver and gold shells colloidosomes are toxic to this bacterial system and the gold coated colloidosomes can load a higher concentration of kanamycin.

Minoxidil Skin Delivery from Nanoemulsion Formulations Containing Eucalyptol or Oleic Acid: Enhanced Diffusivity and Follicular Targeting

In this work, we examined enhanced skin delivery of minoxidil applied in nanoemulsions incorporating skin penetration enhancers. Aliquots of fully characterized oil-in-water nanoemulsions (1 mL), containing minoxidil (2%) and the skin penetration enhancer oleic acid or eucalyptol as oil phases, were applied to full-thickness excised human skin in Franz diffusion cells, while aqueous solutions (1 mL) containing minoxidil were used as controls. Minoxidil in the stratum corneum (SC), hair follicles, deeper skin layers, and flux through the skin over 24 h was determined, as well as minoxidil solubility in the formulations and in the SC. The nanoemulsions significantly enhanced the permeation of minoxidil through skin compared with control solutions. The eucalyptol formulations (NE) promoted minoxidil retention in the SC and deeper skin layers more than did the oleic acid formulations, while the oleic acid formulations (NO) gave the greatest hair follicle penetration. Minoxidil maximum flux enhancement was associated with increases in both minoxidil SC solubility and skin diffusivity in both nanoemulsion systems. The mechanism of enhancement appeared to be driven largely by increased diffusivity, rather than increased partitioning into the stratum corneum, supporting the concept of enhanced fluidity and disruption of stratum corneum lipids.

Fatty acid microemulsion for the treatment of neonatal conjunctivitis: quantification, characterisation and evaluation of antimicrobial activity

Fatty acids (FAs) are used by many organisms as defence mechanism against virulent bacteria. The high safety profile and broad spectrum of activity make them potential alternatives to currently used topical antibiotics for the treatment of eye infections in neonates. The current study utilised a Design of Experiment approach to optimise the quantification of five fatty acids namely; lauric acid, tridecanoic acid, myristoleic acid, palmitoleic acid and α-linolenic acid. The significance of the influence of the experimental parameters such as volume of catalyst, volume of n-hexane, incubation temperature, incubation time and the number of extraction steps on derivatisation was established by statistical screening with a factorial approach. Derivatisation was confirmed using attenuated total reflectance infrared (ATR) and 1H NMR spectrum. A gas chromatographic method (GC-FID) was developed and validated according to ICH guidelines for the identification and quantification of fatty acids. The results were found to be linear over the concentration range studied with coefficient of variation greater than 0.99 and high recovery values and low intra-day and inter-day variation values for all FAs. Then, different α-linolenic acid-based microemulsions (MEs) were prepared using Tween 80 as surfactant, polyethylene glycol 400 (PEG 400) as co surfactant and water as aqueous phase. The developed GC method was used to quantify the FA content in ME formulations. The results indicated that the developed GC method is very effective to quantify the FA content in the ME formulations. The antimicrobial efficacy of FA-based MEs were tested against Staphylococcus aureus. It was concluded that the FA-based MEs have strong antimicrobial effect against S. aureus.

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.

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.

Nanocarrier-based topical drug delivery for an antifungal drug

OBJECTIVE

The conventional liposomal amphotericin B causes many unwanted side effects like blood disorder, nephrotoxicity, dose-dependent side effects, highly variable oral absorption and formulation-related instability. The objective of the present investigation was to develop cost-effective nanoemulsion as nanocarreir for enhanced and sustained delivery of amphotericin B into the skin. METHODS AND CHARACTERIZATIONS: Different oil-in-water nanoemulsions were developed by varying the composition of hydrophilic (Tween(®) 80) surfactants and co-surfactant by the spontaneous titration method. The developed formulation were characterized, optimized, evaluated and compared for the skin permeation with commercial formulation (fungisome 0.01% w/w). Optimized formulations loaded with amphotericin B were screened using varied concentrations of surfactants and co-surfactants as decided by the ternary phase diagram.

RESULTS AND DISCUSSION

The maximum % transmittance obtained were 96.9 ± 1.0%, 95.9 ± 3.0% and 93.7 ± 1.2% for the optimized formulations F-I, F-III and F-VI, respectively. These optimized nanoemulsions were subjected to thermodynamic stability study to get the most stable nanoemulsions (F-I). The results of the particle size and zeta potential value were found to be 67.32 ± 0.8 nm and -3.7 ± 1.2 mV for the final optimized nanoemulsion F-I supporting transparency and stable nanoemulsion for better skin permeation. The steady state transdermal flux for the formulations was observed between 5.89 ± 2.06 and 18.02 ± 4.3 µg/cm(2)/h whereas the maximum enhancement ratio were found 1.85- and 3.0-fold higher than fungisome and drug solution, respectively, for F-I. The results of the skin deposition study suggests that 231.37 ± 3.6 µg/cm(2) drug deposited from optimized nanoemulsion F-I and 2.11-fold higher enhancement ratio as compared to fungisome. Optimized surfactants and co-surfactant combination-mediated transport of the drug through the skin was also tried and the results were shown to have facilitated drug permeation and skin perturbation (SEM).

CONCLUSION

The combined results suggested that amphotericin B nanoemulsion could be a better option for localized topical drug delivery and have greater potential as an effective, efficient and safe approach.

Ondansetron HCl Microemulsions for Transdermal Delivery: Formulation and In Vitro Skin Permeation

Ondansetron HCl delivery through oral route suffers due to its low bioavailability due to first-pass metabolism. Therefore, the microemulsion-based transdermal delivery may be a better substitute for it. The pseudoternary phase diagrams were constructed to determine compositions of microemulsions, and ondansetron HCl microemulsions for transdermal delivery were developed using isopropyl myristate or oleic acid as the oil phase, Tween 80 as the surfactant, and isopropyl alcohol as the cosurfactant evaluated for in vitro skin permeation through excised porcine skin. The in vitro skin permeation from these formulated microemulsions was sustained over 24 hours. The microemulsion F-8 (contained 10% of isopropyl myristate as oil phase, 8% of aqueous phase, and 82% of surfactant phase containing Tween 80 and isopropyl alcohol, 3 : 1) showed the highest permeation flux of 0.284 ± 0.003 μg/cm(2)/hour. All these microemulsions followed the Korsmeyer-Peppas model (R(2) = 0.971  to  0.998) with non-Fickian, "anomalous" mechanism over a period of 24 hours.

Formulation, characterization, and clinical evaluation of microemulsion containing clotrimazole for topical delivery

The objective of the present study was to formulate and evaluate microemulsion systems for topical delivery of clotrimazole (CTM). The solubility of CTM in various oils was determined to select the oil phase of the microemulsion systems. Pseudoternary phase diagrams were constructed to identify the area of microemulsion existence. Five CTM microemulsion formulations (M1-M5) were prepared and evaluated for their thermodynamic stability, pH, refractive index, droplet size, viscosity, and in vitro release across cellulose membrane. Among the prepared microemulsion formulations, M3 (lemon oil/Tween 80/n-butanol/water) and M4 (isopropyl myristate/Tween 80/n-butanol/water) microemulsion systems were found to be promising according to their physical properties and CTM cumulative percentage release. Gel form of M3 and M4 were prepared using 1% Carbopol 940 as the hydrogel matrix. Both formulations were evaluated in the liquid and gel forms for drug retention in the skin in comparison to the marketed CTM topical cream and their stability examined after storage at 40°C for 6 months. Microemulsion formulations achieved significantly higher skin retention for CTM over the CTM cream. Stability studies showed that M4 preparations were more stable than M3. The in vitro anti-fungal activity of M4 against Candida albicans was higher than that of the conventional cream. Moreover, clinical evaluation proved the efficacy and tolerability of this preparation in the treatment of various topical fungal infections.

Preparation and evaluation of microemulsion systems containing salicylic acid

Microemulsions (MEs) are clear, thermodynamically stable systems. They were used to solubilize drugs and to improve topical drug availability. Salicylic acid (SA) is a keratolytic agent used in topical products with antimicrobial actions. The objective of this work was to prepare and evaluate SA ME systems. Different concentrations of SA were incorporated in an ME base composed of isopropyl myristate, water, and Tween 80: propylene glycol in the ratio of 15:1. Three ME systems were prepared: S2%, S5%, and S10% which contain 2%, 5%, and 10% of SA, respectively. Evaluation by examination under cross-polarizing microscope, measuring of percent transmittance, pH measurement, determination of the specific gravity, assessment of rheological properties, and accelerated stability study were carried out. The data showed that the addition of SA markedly affected the physical properties of the base. All systems were not affected by accelerated stability tests. Stability study for 6 months under ambient conditions was carried out for S10%. No remarkable changes were recorded except a decrease in the viscosity value after 1 month. The results suggested that ME could be a suitable vehicle for topical application of different concentrations of SA.

Effect of formulation components on the in vitro permeation of microemulsion drug delivery system of fluconazole

The purpose of this study was to evaluate the effect of formulation components on the in vitro skin permeation of microemulsion drug delivery system containing fluconazole (FLZ). Lauryl alcohol (LA) was screened as the oil phase of microemulsions. The pseudo-ternary phase diagrams for microemulsion regions were constructed using LA as the oil, Labrasol (Lab) as the surfactant and ethanol (EtOH) as the cosurfactant. The formulation which showed a highest permeation rate of 47.15 +/- 1.12 microg cm(-2) h(-1) and appropriate physicochemical properties was optimized as containing 2% FLZ, 10% LA, 20% Lab/EtOH (1:1), and 68% double-distilled water (w/w). The efficiency of microemulsion formulation in the topical delivery of FLZ was dependent upon the contents of water and LA as well as Lab/EtOH mixing ratio. It was concluded that the percutaneous absorption of FLZ 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 FLZ reference. The studied microemulsion formulation showed a good stability for a period of 3 months. These results indicate that the studied microemulsion formulation might be a promising vehicle for topical delivery of FLZ.

Enhancement of the Skin Permeation of Clindamycin Phosphate by Aerosol OT/1-Butanol Microemulsions

Microemulsions of water/isopropyl palmitate (IPP)/Aerosol OT (AOT)/1-butanol were developed as alternative formulations for topical delivery of clindamycin phosphate. Effect of AOT:1-butanol ratios on microemulsion region existence in the pseudoternary phase diagrams was investigated. The 2:1 AOT:1-butanol provided the largest microemulsion region. Five microemulsions of 1% w/w clindamycin phosphate were prepared and characterized. The permeation through human epidermis of the microemulsions was evaluated and compared with the 70% isopropanol solution using modified Franz diffusion cells. The drug permeation from all microemulsions was found to be significantly greater than that from the solution, indicating the enhancement of the skin permeation by the microemulsions. Within the same microemulsion type, the drug permeation increased with increasing the amount of AOT:1-butanol. The drug permeation from oil-in-water (o/w) microemulsions was relatively higher than that from water-in-oil (w/o) microemulsions. In addition, all microemulsions were stable for at least three months at 30 +/- 1 degrees C.

Bicontinuous Water-AOT/Tween85-Isopropyl Myristate Microemulsion: A New Vehicle for Transdermal Delivery of Cyclosporin A

The purpose of this study was to investigate the influence of structure and composition of microemulsions (AOT/Tween85/isopropyl myristate/water) on their transdermal delivery potential of a lipophilic model drug (Cyclosporin A), and to compare the drug delivery potential of microemulsion to the suspension of drug in normal saline containing 20% ethanol. Their type and structure were examined by measuring surface tension, density, viscometry, and electric conductivity; the degree of agreement between the techniques was assessed. Transdermal flux of Cyclosporin A through rat skin was determined in vitro using Franz-type diffusion cells. Results of conducting, viscosity, and surface tension measurement confirmed the prediction transition to a bicontinuous structure. The microemulsions increased transdermal drug delivery of Cyclosporin A up to 10 times compared to the suspension. The increased transdermal delivery was found to be due mainly to water concentration and appeared to be dependent on the structure of the microemulsions.

Microemulsions--modern colloidal carrier for dermal and transdermal drug delivery

Microemulsions are modern colloidal drug carrier systems. They form spontaneously combining appropriate amounts of a lipophilic and a hydrophilic ingredient, as well as a surfactant and a co-surfactant. Due to their special features, microemulsions offer several advantages for pharmaceutical use, such as ease of preparation, long-term stability, high solubilization capacity for hydrophilic and lipophilic drugs, and improved drug delivery. The article summarizes the level of research with respect to dermal and transdermal application. A large number of in vitro as well as some in vivo studies demonstrated that drugs incorporated into microemulsions penetrate efficiently into the skin. The enhancing activity seems to be attributable to a variety of factors depending on the composition and the resulting microstructure of the formulations. However, an extended use in practice depends on the choice of well-tolerated ingredients, mainly surfactants, and the restriction of their amounts in order to guarantee skin compatibility.

Nanoemulsions as vehicles for transdermal delivery of aceclofenac

The aim of the present study was to investigate the potential of a nanoemulsion formulation for transdermal delivery of aceclofenac. Various oil-in-water nanoemulsions were prepared by the spontaneous emulsification method. The nanoemulsion area was identified by constructing pseudoternary phase diagrams. The prepared nanoemulsions were subjected to different thermodynamic stability tests. The nanoemulsion formulations that passed thermodynamic stability tests were characterized for viscosity, droplet size, transmission electron microscopy, and refractive index. Transdermal permeation of aceclofenac through rat abdominal skin was determined by Franz diffusion cell. The in vitro skin permeation profile of optimized formulations was compared with that of aceclofenac conventional gel and nanoemulsion gel. A significant increase in permeability parameters such as steady-state flux (J(ss)), permeability coefficient (K(p)), and enhancement ratio (E(r)) was observed in optimized nanoemulsion formulation F1, which consisted of 2% wt/wt of aceclofenac, 10% wt/wt of Labrafil, 5% wt/wt of Triacetin, 35.33% wt/wt of Tween 80, 17.66% wt/wt of Transcutol P, and 32% wt/wt of distilled water. The anti-inflammatory effects of formulation F1 showed a significant increase (P < .05) in percent inhibition value after 24 hours when compared with aceclofenac conventional gel and nanoemulsion gel on carrageenan-induced paw edema in rats. These results suggested that nanoemulsions are potential vehicles for improved transdermal delivery of aceclofenac.

Comparison of different water/oil microemulsions containing diclofenac sodium: preparation, characterization, release rate, and skin irritation studies

The aim of the present study was to make a comparison of the in vitro release rate of diclofenac sodium (DS) from microemulsion (M) vehicles containing soybean oil, nonionic surfactants (Brij 58 and Span 80), and different alcohols (ethanol [E], isopropyl alcohol [I], and propanol [P]) as cosurfactant. The optimum surfactant:cosurfactant (S:CoS) weight ratios and microemulsion areas were detected by the aid of phase diagrams. Three microemulsion formulations were selected, and their physicochemical properties were examined for the pH, viscosity, and conductivity. According to the release rate of DS, M prepared with P showed the significantly highest flux value (0.059 +/- 0.018 mg/cm(2)/h) among all formulations (P < .05). The conductivity results showed that DS-loaded microemulsions have higher conductivity values (18.8-20.2 microsiemens/cm) than unloaded formulations (16.9-17.9 microsiemens/cm), and loading DS into the formulation had no negative effect on system stability. Moreover, viscosity measurements were examined as a function of shear rate, and Newtonian fluid characterization was observed for each microemulsion system. All formulations had appropriate observed pH values varying from 6.70 to 6.85 for topical application. A skin irritation study was performed with microemulsions on human volunteers, and no visible reaction was observed with any of the formulations. In conclusion, M prepared with P may be a more appropriate formulation than the other 2 formulations studied as drug carrier for topical application.

Design, development and evaluation of novel nanoemulsion formulations for transdermal potential of celecoxib

The aim of the present study was to investigate the potential of nanoemulsion formulations for transdermal delivery of celecoxib (CXB). The in vitro skin permeation profile of optimized formulations was compared with CXB gel and nanoemulsion gel. Significant increase in the steady state flux (Jss), permeability coefficient (Kp) and enhancement ratio (Er) was observed in nanoemulsion formulations T1 and T2 (p < 0.05). The highest value of these permeability parameters was obtained in formulation T2, which consisted of 2% (m/m) of CXB, 10% (m/m) of oil phase (Sefsol 218 and Triacetin), 50% (m/m) of surfactant mixture (Tween-80 and Transcutol-P) and 40% (m/m) water. The anti-inflammatory effects of formulation T2 showed a significant increase (p < 0.05) in inhibition after 24 h compared to CXB gel and nanoemulsion gel on carrageenan-induced paw edema in rats. These results suggested that nanoemulsions are potential vehicles for improved transdermal delivery of CXB.