Overcoming the cutaneous barrier with microemulsions

Novel Microemulsion Containing Benzocaine and Fusidic Acid Simultaneously: Formulation, Characterization, and In Vitro Evaluation for Wound Healing

Modern drug carrier technologies, such as microemulsions with small droplet sizes and high surface areas, improve the ability of low water solubility active ingredients to permeate and localize. The goal of this study was to create microemulsion formulations for wound healing that contained both fusidic acid (FA), an antibacterial agent, and benzocaine (BNZ), a local anesthetic. Studies on characterization were carried out, including viscosity, droplet size, and zeta potential. The drug-loaded microemulsion had a stable structure with -3.014 ± 1.265 mV of zeta potential and 19.388 ± 0.480 nm of droplet size. In both in vitro release and ex vivo permeability studies, the microemulsion was compared with Fucidin cream and oily BNZ solution. According to the drug release studies, BNZ release from the microemulsion and the BNZ solution showed a similar profile (p > 0.05), while FA release from the microemulsion had a higher drug release compared to Fucidin cream (p < 0.001). The microemulsion presented lower drug permeation (p > 0.05) for both active ingredients, on the other hand, provided higher drug accumulation compared to the control preparations. Moreover, according to the results of in vitro wound healing activity, the microemulsion indicated a dose-dependent wound healing potential with the highest wound healing activity at the highest concentrations. To the best of our knowledge, this developed BNZ- and FA-loaded microemulsion would be a promising candidate to create new opportunities for wound healing thanks to present the active ingredients, which have low water solubility, in a single formulation and achieved higher accumulation than control preparations.

In vivo and in vitro transdermal availability of Ibuprofen using novel solubility enhancing fluid nanosized carrier systems

The objective of this study was to explore the benefits of transdermal drug delivery systems as an alternative option for patients who are unable to tolerate oral administration of drugs, such as ibuprofen (IB). To achieve this, nonionic surfactants and three cosolvents were employed to develop new microemulsions (MEs) that contained IB as nanocarriers. The aim was to enhance the solubility and bioavailability of the drug after transdermal administration. The MEs were characterised by droplet size, polydispersity index (PDI), and rheological properties. Furthermore, the flux of IB was evaluated by Franz diffusion cells using excised rat skin and in vivo bioavailability using rats. The results showed that the MEs had ideal viscosity and droplet size below 100 nm. Moreover, using the developed MEs, an improvement in the solubility (170 mg/mL) and flux through the rat skin (94.6 ± 8.0 µg/cm2.h) was achieved. In addition, IB demonstrated a maximum plasma level of 0.064 mg/mL after 8 h of transdermal administration in rats using the ME with an increase in the bioavailability of about 1.5 times in comparison to the commercial IB gel. In conclusion, the developed nonionic MEs containing IB can be ideal nanocarriers and promising formulations for the transdermal administration of IB.

Acacetin-loaded microemulsion for transdermal delivery: preparation, optimization and evaluation

CONTEXT

Acacetin is reported as a potential drug candidate for the treatment of atrial fibrillation. However, clinical applications are limited by poor water solubility, limited ethanol solubility, and extremely low oral bioavailability.

OBJECTIVE

The present study prepared and evaluated acacetin-loaded microemulsion (ME) to achieve efficient pharmacokinetics together with no or minimal invasiveness for transdermal delivery.

MATERIALS AND METHODS

The formulation of ME was determined by the water titration method based on solubility results. The optimized formulation was achieved by the simplex lattice experiment design. The optimized ME formulations FA, FB and FC (FA with 10% and 50% DMSO as enhancers, respectively) were evaluated by ex vivo permeation with Franz diffusion cell and excised mice skin. In vivo pharmacokinetic studies were also performed at 8 mg/kg in rats within 6 h by transdermal administration.

RESULTS

The optimal ME (FA) was comprised of 12.2% caprylic acid decanoate monoditriglyceride (MCF-NF), 39.8% Smix (RH40: Trans = 2:1 w/w) and 48% water, respectively. Acacetin-loaded FA with particle size 36.0 ± 3.6 nm and drug solubility 803.7 ± 32.1 mg/g was prepared. FB had significantly higher cumulative amounts and higher AUC_0-∞ (196.6 ± 11.0 min × μg/mL, p < 0.05) than that FA alone (121.4 ± 33.1 min × μg/mL).

DISCUSSION AND CONCLUSIONS

The formulation of ME combined with the penetration enhancer can effectively improve the solubility and percutaneous absorption efficiency of acacetin, providing a new option for the non-invasive delivery of acacetin.

Tackling acne vulgaris by fabrication of tazarotene-loaded essential oil-based microemulsion: In vitro and in vivo evaluation

This study aimed to formulate and optimize an anti-acne drug namely tazarotene (TZR) in essential oil-based microemulsion (ME) using either Jasmine oil (Jas) or Jojoba oil (Joj). TZR-MEs were prepared using two experimental designs (Simplex Lattice Design®) and characterized for droplet size, polydispersity index, and viscosity. Further in vitro, ex vivo, and in vivo investigations were performed for the selected formulations. Results revealed that TZR-selected MEs exhibited suitable droplet size, homogenous dispersions, and acceptable viscosity, in addition to spherical-shaped particles in morphology. The ex vivo skin deposition study showed a significant TZR accumulation in all skin layers for the Jas-selected ME over the Joj one. Further, TZR didn't show any antimicrobial activity against P. acnes, however, it was boosted when it was incorporated into the selected MEs. The in vivo study results of the infected mice ears induced by P. acnes revealed that our selected MEs successfully reached a high level of ear thickness reduction of 67.1% and 47.4% for Jas and Joj selected MEs, respectively, versus only 4% for the market product. Finally, the findings confirmed the ability to use essential oil-based ME, particularly with Jas, as a promising carrier for topical TZR delivery in the treatment of acne vulgaris.

Topical Microemulsions: Skin Irritation Potential and Anti-Inflammatory Effects of Herbal Substances

Microemulsions (MEs) have gained prominence as effective drug delivery systems owing to their optical transparency, low viscosity, and thermodynamic stability. MEs, when stabilized with surfactants and/or co-surfactants, exhibit enhanced drug solubilization, prolonged shelf life, and simple preparation methods. This review examines the various types of MEs, explores different preparation techniques, and investigates characterization approaches. Plant extracts and bioactive compounds are well established for their utilization as active ingredients in the pharmaceutical and cosmetic industries. Being derived from natural sources, they serve as preferable alternatives to synthetic chemicals. Furthermore, they have demonstrated a wide range of therapeutic effects, including anti-inflammatory, antimicrobial, and antioxidant activities. However, the topical application of plant extracts and bioactive compounds has certain limitations, such as low skin absorption and stability. To overcome these challenges, the utilization of MEs enables enhanced skin absorption, thereby making them a valuable mode of administration. However, considering the significant surfactant content in MEs, this review evaluates the potential skin irritation caused by MEs containing herbal substances. Additionally, the review explores the topical application of MEs specifically for herbal substances, with an emphasis on their anti-inflammatory properties.

An experimental workflow to assess the applicability of microemulsions for conformance improvement in oil-bearing reservoir

A comprehensive workflow approach is necessary to link multiple experimental tasks and identify microemulsion (ME) formulations with 'optimal' stability, displacement behavior and technical feasibility in the petroleum industry. In this paper, a systematic approach is described with the aid of a case study which involves the formulation of an anionic sodium dodecyl sulfate-based microemulsion. The design of such ME systems requires a proper methodology, substantial laboratory work, and functional assessment from research/industrial viewpoints. The surfactant has been screened in terms of its micellization potential, followed by phase behavior analysis and Winsor classification of prepared microemulsions. The desired composition(s) are characterized via several tools to determine droplet size, morphology, oil/water solubilization potentials and salinity scan results. The suitability of the microemulsion system for conformance improvement technology (CIT) is proposed to be assessed via physicochemical evaluation studies encompassing two attributes: rheology and stability. For a favorable 'conforming' drive, the microemulsion must exhibit phase stability, sufficient injectivity, and moderate-to-high viscosity under shear. Technical assessment by the industry and research team must also include factors related to cost, availability of chemicals, environmental degradation, and reservoir considerations. The article demonstrates a comprehensive all-inclusive workflow methodology to design and formulate surfactant-stabilized microemulsions via case study analysis for application in CIT. This represents a sound approach to identifying efficient, cost-effective injection fluid systems and provides a framework to identify useful parameters for ME formulation design and employ the proposed (effective) strategy for conformance control.

Exploring the Versatility of Microemulsions in Cutaneous Drug Delivery: Opportunities and Challenges

Microemulsions are novel drug delivery systems that have garnered significant attention in the pharmaceutical research field. These systems possess several desirable characteristics, such as transparency and thermodynamic stability, which make them suitable for delivering both hydrophilic and hydrophobic drugs. In this comprehensive review, we aim to explore different aspects related to the formulation, characterization, and applications of microemulsions, with a particular emphasis on their potential for cutaneous drug delivery. Microemulsions have shown great promise in overcoming bioavailability concerns and enabling sustained drug delivery. Thus, it is crucial to have a thorough understanding of their formulation and characterization in order to optimize their effectiveness and safety. This review will delve into the different types of microemulsions, their composition, and the factors that affect their stability. Furthermore, the potential of microemulsions as drug delivery systems for skin applications will be discussed. Overall, this review will provide valuable insights into the advantages of microemulsions as drug delivery systems and their potential for improving cutaneous drug delivery.

Development and cytotoxicity evaluation of multiple nanoemulsions for oral co-delivery of 5-fluorouracil and short chain triglycerides for colorectal cancer

Colorectal cancer (CRC) is the third most common cancer in the world, but current chemotherapy options are limited due to adverse effects and low oral bioavailability of drugs. In this study, we investigated the obtainment parameters and composition of new multiple nanoemulsions (MN) based on microemulsions for oral co-delivery of 5-fluorouracil (5FU) and short-chain triglycerides (SCT, either tributyrin or tripropionin). The area of microemulsion formation was increased from 14% to 38% when monocaprylin was mixed with tricaprylin as oil phase. Addition of SCT reduced this value to 24-26%. Using sodium alginate aqueous dispersion as internal aqueous phase (to avoid phase inversion) did not further affected the area but increased microemulsion viscosity by 1.5-fold. To obtain the MN, selected microemulsions were diluted in an external aqueous phase; droplet size was 500 nm and stability improved using polyoxyethylene (den Besten et al., 2013) oleyl ether at 1-2.5% as surfactant in the external phase and a dilution ratio of 1:1 (v/v). 5FU in vitro release could be better described by the Korsmeyer-Peppas model. No pronounced changes in droplet size were observed when selected MNs were incubated in buffers mimicking gastrointestinal fluids. The 5FU cytotoxicity in monolayer cell lines presenting various mutations was influenced by its incorporation in the nanocarrier, presence of SCT and cell mutation status. The MNs selected reduced the viability of tumor spheroids (employed as 3D tumor models) by 2.2-fold compared to 5FU solution and did not affect the survival of the G. mellonella, suggesting effectiveness and safety.

Global Trends of Cosmeceutical in Nanotechnology: A Review

Nanotechnology suggests different innovative solutions to augment the worth of cosmetic products through the targeted delivery of content that manifests scientific innovation in research and development. Different nanosystems, like liposomes, niosomes, microemulsions, solid lipid nanoparticles, nanoform lipid carriers, nanoemulsions, and nanospheres, are employed in cosmetics. These nanosystems exhibit various innovative cosmetic functions, including site-specific targeting, controlled content release, more stability, improved skin penetration and enhanced entrapment efficiency of loaded compounds. Thus, cosmeceuticals are assumed as the highest-progressing fragment of the personal care industries that have progressed drastically over the years. In recent decades, cosmetic science has widened the origin of its application in different fields. Nanosystems in cosmetics are beneficial in treating different conditions like hyperpigmentation, wrinkles, dandruff, photoaging and hair damage. This review highlights the different nanosystems used in cosmetics for the targeted delivery of loaded content and commercially available formulations. Moreover, this review article has delineated different patented nanocosmetic formulation nanosystems and future aspects of nanocarriers in cosmetics.

Itraconazole-loaded microemulsions: formulation, characterization, and dermal delivery using shed snakeskin as the model membrane

Microemulsions (MEs) were developed for dermal delivery of 1% w/w itraconazole (ITZ). Solubility of ITZ in various oils was investigated and clove oil was selected as oil phase. Pseudoternary phase diagrams were constructed by titration method. The system containing clove oil as oil phase, Tween^®80 as surfactant, and 1:1 mixture of water and polyethylene glycol 400 as aqueous phase provided the largest ME region. It was selected for the formulation development of ITZ-loaded MEs. Physicochemical stability was evaluated at 4 °C, room temperature (25 °C), and 45 °C for three months. In vitro permeation and retention studies were assessed using shed snakeskin as a model membrane. Antifungal activity was investigated by agar diffusion method. Results indicated that incorporation of ITZ in the selected MEs did not affect physical properties. Physicochemical data after storage periods revealed that the most suitable storage temperature was 4 °C. Skin permeation and retention data indicated that water-in-oil (w/o) ITZ-loaded MEs had superior dermal delivery of ITZ than oil-in-water (o/w) ITZ-loaded ME and ITZ-oily solution. Moreover, w/o ITZ-loaded MEs showed larger inhibition zones against C. albicans and T. rubrum than a commercial gel. Therefore, w/o ITZ-loaded MEs possibly provided effective dermal delivery and antifungal activity to treat superficial fungal infections.

Ultraviolet Radiation Protective and Anti-Inflammatory Effects of Kaempferia galanga L. Rhizome Oil and Microemulsion: Formulation, Characterization, and Hydrogel Preparation

Long-term UV radiation exposure can induce skin disorders such as cancer and photoallergic reactions. Natural products have been considered as non-irritate and potential sunscreen resources due to their UV absorption and anti-inflammatory activities. This study aimed to evaluate the in vitro ultraviolet radiation protective effect and anti-inflammatory activity of K. galanga rhizome oil and microemulsions. The chemical components of K. galanga rhizome oil was analyzed via gas chromatography coupled with mass spectrometry. Microemulsions containing K. galanga rhizome oil were formulated using a phase-titration method. The microemulsion was characterized for droplet size, polydispersity index, and zeta potential, using a dynamic light-scattering technique. The physical and chemical stability of the microemulsion were evaluated via a dynamic light scattering technique and UV-Vis spectrophotometry, respectively. The UV protection of K. galanga rhizome oil and its microemulsion were investigated using an ultraviolet transmittance analyzer. The protective effect of K. galanga rhizome oil against LPS-induced inflammation was investigated via MTT and nitric oxide inhibitory assays. In addition, a hydrogel containing K. galanga rhizome oil microemulsion was developed, stored for 90 days at 4, 30, and 45 °C, and characterized for viscosity, rheology, and pH. The chemical degradation of the main active compound in the microemulsion was analyzed via UV-Vis spectrophotometry. The formulated O/W microemulsion contained a high loading efficiency (101.24 ± 2.08%) of K. galanga rhizome oil, suggesting a successful delivery system of the oil. The size, polydispersity index, and zeta potential values of the microemulsion were optimized and found to be stable when stored at 4, 30, and 45 °C. K. galanga rhizome oil and microemulsion demonstrated moderate sun protective activity and reduced the nitric oxide production induced by LPS in macrophage cells, indicating that microemulsion containing K. galanga rhizome oil may help protect human skin from UV damage and inflammation. A hydrogel containing K. galanga rhizome oil microemulsion was developed as a topical preparation. The hydrogel showed good physical stability after heating and cooling cycles and long-term storage (3 months) at 4 °C. The use of K. galanga rhizome oil as a natural sun-protective substance may provide a protective effect against inflammation on the skin. K. galanga rhizome oil microemulsion was successfully incorporated into the hydrogel and has the potential to be used as a topical sunscreen preparation.

Hyaluronic acid nanoemulsions improve piplartine cytotoxicity in 2D and 3D breast cancer models and reduce tumor development after intraductal administration

Nanoemulsions modified with chitosan (NE-Q) or hyaluronic acid (NE-HA), developed for intraductal administration of piplartine (piperlongumine) and local breast cancer treatment, were evaluated for cytotoxic effects in vitro in 2D and 3D breast cancer models and in vivo in a chemically induced carcinogenesis model. Droplet size was lower than 100 nm, and zeta potential varied from +17.9 to -25.5 mV for NE-Q and NE-HA, respectively. Piplartine nanoencapsulation reduced its IC₅₀ up to 3.6-fold in T-47D and MCF-7 monolayers without differences between NE-Q and NE-HA, and up to 6.6-fold in cancer spheroids. Cytotoxicity improvement may result from a more efficient NE-mediated delivery, as suggested by stronger fluorescent staining of cells and spheroids. In 1-methyl-1-nitrosourea -induced breast cancer models, intraductal administration of piplartine-loaded NE-HA inhibited breast tumor development and histological alterations. These results support the potential applicability of piplartine-loaded NE-HA for intraductal treatment of breast cancer.

Lornoxicam-Loaded Chitosan-Decorated Nanoemulsion: Preparation and In Vitro Evaluation for Enhanced Transdermal Delivery

Nanoemulsions are promising drug delivery systems for the administration of poorly soluble drugs like lornoxicam (LRX) by oral or parenteral routes. Such formulations work perfectly for transdermal delivery of lornoxicam-type drugs. It has also been established that formulating such a delivery system is highly dependent on the presence, type, and concentration of excipients taking part in the formulation. The inherent characteristics of nanoemulsion (NE), i.e., smaller globule size and excipient nature, facilitate the drug's passage through skin. The current study was aimed at the development of an NE-based formulation of LRX to improve the drug solubility in vitro as well as to enhance drug skin permeation to promote therapeutic outcome in appropriate time. Spontaneous self-emulsification technique was utilized to develop optimized LRX-encapsulated NE-based formulations. ATR-FTIR spectra of the pure drug and various formulations did not show any interaction between the drug and various formulation excipients showing compatibility. Globule size for stable formulations ranged between 63-168 nm. These formulations were characterized for viscosity, surface tension, pH, drug encapsulation efficiency, in vitro drug release, and drug skin permeation studies. Chitosan-decorated optimized NE formulation of LRX showed about 58.82% cumulative drug release, showing an anomalous non-Fickian diffusion mechanism of drug release. Drug encapsulation efficiency, in vitro drug release, and skin permeation studies exhibited promising results. An appreciable drug entrapment efficiency was exhibited by optimized NE formulations LRX-6, 71.91 ± 3.17% and C-LRX, 65.25 ± 4.89%. Permeability parameters like enhancement ratio (Er), permeability constant (Kp), and steady state flux (Jss) showed higher values and exhibited good results based on formulation type. The selected promising formulation type "LRX-6" showed significantly different results as compared to other formulations (LRX-4, 5, and 7). The skin permeation property of the LRX-6 formulation was compared to similar chitosan-based formulations and was found to have better skin permeation results than chitosan-based formulations. This study clearly exhibited that an LRX-containing NE-based formulation can be formulated to form a stable drug delivery system. Such formulations are promising in terms of physicochemical characteristics, improved solubility, and high skin permeation potential.

Phospholipid-Based Microemulsions for Cutaneous Imiquimod Delivery

Imiquimod (IMQ) is a potent immune response modifier with antiviral and antitumor properties. IMQ’s low aqueous solubility and unsatisfactory cutaneous permeability limit its formulation into effective dosage forms. This work aimed to develop IMQ-loaded microemulsions (MEs) based on phospholipids and oleic acid to improve IMQ penetration into the epidermis. A pseudo-ternary phase diagram was constructed, and the microstructure of the formulations was examined by measuring the conductivity values. Selected MEs were characterized and studied for their ability to deliver IMQ into and through ex vivo human skin. ME1 with 1% IMQ (bicontinuous ME with Bingham rheology) delivered similar IMQ quantities to the human epidermis ex vivo as the commercial product while having a 5-fold lower IMQ dose. IMQ was not detected in the acceptor phase after the permeation experiment, suggesting a lower systemic absorption risk than the established product. Infrared spectroscopy of the stratum corneum revealed less ordered and less tightly packed lipids after ME1 application. The ME1-induced barrier disruption recovered within less than 5 h after the formulation removal, as detected by transepidermal water loss measurements. In conclusion, our findings demonstrate that phospholipid and oleic acid-based MEs could become a promising alternative for topical IMQ administration.

Skin permeability, a dismissed necessity for anti-wrinkle peptide performance

The skin offers various benefits and potential for peptide delivery if its barrier performance can be reduced temporarily and reversibly. Since peptides possess high molecular weight, hydrophilic nature (in most cases), and ionizable groups in the structure, their skin delivery is highly challenging. Apart from this, they are susceptible to the proteolytic enzymes in the skin. Anti-wrinkle peptides, like other peptides, suffer from insufficient skin permeability, while most of them must penetrate deep in the skin to present their efficacy. Although the cellular studies indicate the effectiveness of such peptides, without the ability to permeate the skin sufficiently, this efficacy is useless. Poor skin permeability of anti-wrinkle peptides has led to ongoing research for finding feasible and noninvasive enhancement methods that would be desirable for consumers of cosmetic products. In this paper, the possibility of skin permeation of anti-wrinkle peptides as well as the chemical, physical, and encapsulation approaches that have been employed to date to increase permeability of these difficult molecules are thoroughly reviewed.

Formulation Development, Characterization and Antifungal Evaluation of Chitosan NPs for Topical Delivery of Voriconazole In Vitro and Ex Vivo

This study aims to develop chitosan-based voriconazole nanoparticles (NPs) using spray-drying technique. The effect of surfactants and polymers on the physicochemical properties, in vitro release, and permeation of NPs was investigated. The prepared NPs containing various surfactants and polymers (e.g., Tween 20 (T20), Tween 80 (T80), sodium lauryl sulfate (SLS), propylene glycol (PG), and Polyethylene glycol-4000 (PEG-4000)) were physiochemically evaluated for size, zeta potential, drug content, percent entrapment efficiency, in vitro release, and permeation across rats' skin. A Franz diffusion cell was used for evaluating the in vitro release and permeation profile. The voriconazole-loaded NPs were investigated for antifungal activity against Candida albicans (C. albicans). The prepared NPs were in the nano range (i.e., 160-500 nm) and positively charged. Images taken by a scanning electron microscope showed that all prepared NPs were spherical and smooth. The drug content of NPs ranged from 75% to 90%. Nanoparticle formulations exhibited a good in vitro release profile and transport voriconazole across the rat's skin in a slow control release manner. The NPs containing SLS, T80, and PG exhibited the best penetration and skin retention profile. In addition, the formulation exhibited a potential antifungal effect against C. albicans. It was concluded that the development of chitosan NPs has a great potential for the topical delivery of voriconazole against fungal infection.

Olive Oil Based Methotrexate Loaded Topical Nanoemulsion Gel for the Treatment of Imiquimod Induced Psoriasis-like Skin Inflammation in an Animal Model

Simple Summary

Psoriasis, being chronic inflammatory illness, provoked by genetic and environmental factors is linked to several other life-threatening diseases. Methotrexate is regarded as gold standard for the management of psoriasis, so an attempt was made to incorporate this drug into nanoemulsion gel. Thus olive oil based formulation was fabricated to target animal model induced psoriasis- like skin inflammation. The optimized methotrexate nanoemulsion gel formulation produced a psoriasis area and severity Index (PASI) decrease that was similar or better than the 91% reduction seen in the methotrexate tablet group. The results of this study revealed effectiveness of methotrexate nanoemulsion gel formulation to treat psoriasis and reduce the remission of psoriasis-like symptoms.

Abstract

Psoriasis, a chronic inflammatory illness, is on the rise and is linked to several other life-threatening diseases. The primary goal of this study was to create a nanoemulsion gel loaded with methotrexate and olive oil (MTX NEG). The formulation was evaluated for physicochemical characterization, entrapment efficiency, drug release kinetics, skin permeation studies and stability tests. In addition, the efficacy of MTX NEG against psoriasis was tested using imiquimod-induced psoriasis in a rat model. The final optimized MTX NEG was developed with a particle size of 202.6 ± 11.59 nm and a PDI of 0.233 ± 0.01, with a 76.57 ± 2.48% average entrapment efficiency. After 20 h, the release kinetics predicted a 72.47% drug release at pH 5.5. FTIR findings demonstrated that the optimized MTX NEG formulation effectively fluidized both the epidermis and dermis of the skin, potentially increasing drug permeability and retention. The application of Tween 80 and PEG 400, on the other hand, significantly enhanced these effects, as these are well known penetration enhancers. After 24 h, an average of 70.78 ± 5.8 μg/cm² of methotrexate was permeated from the nanoemulsion gel with a flux value of 2.078 ± 0.42 μg/cm²/h, according to permeation measurements. Finally, in vivo experiments on rabbit skin revealed that the increased skin penetration of methotrexate-loaded nanoemulsion gel was not due to structural alterations in intercellular lipid layers in the stratum corneum. In vivo antipsoriatic studies on rats revealed that MTX NEG produced a PASI decrease that was extremely similar and even better than the 91% reduction seen in the MTX tablet group. According to the pharmacokinetic profile, Cmax was 8.5 μg/mL, Tmax was 12 h, and t1/2 was 15.5 ± 2.37 h. These findings reinforce that MTX-NEG based on olive oil could be a possible treatment for psoriasis and could decrease the remission of psoriasis-like symptoms.

Development and optimisation of biopharmaceutical properties of a new microemulgel of cannabidiol for locally-acting dermatological delivery

Cannabidiol (CBD) is a pleiotropic phytocannabinoid, recently investigated to treat many skin diseases. This study aimed to develop a CBD-loaded O/A microemulsion (CBD-ME) formulated as microemulgel (CBD-MEgel), suitable for local administration. The developed CBD-ME consisted of Solutol HS 15 (20%, surfactant), Transcutol P (9%, cosolvent), isopropyl myristate (5%, oil phase), water (66%) and 1% w/w CBD. Globules had polydispersity index less than 0.23 ± 0.02 and size of 35 ± 2 nm; these values did not change after loading CBD and gelling the formulation with Sepigel 305 obtaining a clear and homogeneous formulation with a pH of 6.56 ± 0.20, suitable for cutaneous application. Viscosity properties were investigated by the rotational digital viscometer, at both 21 ± 2 °C and 35 ± 2 °C. Viscosities of CBD-MEgel were 439,000 ± 4,243 mPa·s and 391,000 ± 1,414 mPa·s respectively. The release studies displayed that 90 ± 24 μg/cm² of CBD were released in 24 h. The CBD permeability, evaluated using Franz diffusion cells and rabbit ear skin, was 3 ± 1 μg/cm². Skin-PAMPA^TM gave a CBD effective permeability of (1.67 ± 0.16) ·10^-7 cm/s and an absorbed dose of 115.30 ± 16.99 µg/cm² after 24 h. Lastly, physical and chemical stability of both CBD-ME and CBD-MEgel were evaluated over a period of 3 months, showing optimal shelf-life at the storage conditions.

Microemulsion for Prolonged Release of Fenretinide in the Mammary Tissue and Prevention of Breast Cancer Development

The need of pharmacological strategies to preclude breast cancer development motivated us to develop a non-aqueous microemulsion (ME) capable of forming a depot after administration in the mammary tissue and uptake of interstitial fluids for prolonged release of the retinoid fenretinide. The selected ME was composed of phosphatidylcholine/tricaprylin/propylene glycol (45:5:50, w/w/w) and presented a droplet diameter of 175.3 ± 8.9 nm. Upon water uptake, the ME transformed successively into a lamellar phase, gel, and a lamellar phase-containing emulsion in vitro as the water content increased and released 30% of fenretinide in vitro after 9 days. Consistent with the slow release, the ME formed a depot in cell cultures and increased fenretinide IC₅₀ values by 68.3- and 13.2-fold in MCF-7 and T-47D cells compared to a solution, respectively. At non-cytotoxic concentrations, the ME reduced T-47D cell migration by 75.9% and spheroid growth, resulting in ∼30% smaller structures. The depot formed in vivo prolonged a fluorochrome release for 30 days without producing any sings of local irritation. In a preclinical model of chemically induced carcinogenesis, ME administration every 3 weeks for 3 months significantly reduced (4.7-fold) the incidence of breast tumors and increased type II collagen expression, which might contribute to limit spreading. These promising results support the potential ME applicability as a preventive therapy of breast cancer.

Nanosystems in Cosmetic Products: A Brief Overview of Functional, Market, Regulatory and Safety Concerns

Nanosystems exhibit various innovative physico-chemical properties as well as a range of cosmetic functions, including increased skin retention for loaded compounds. The worldwide nano-market has therefore been consistently extensive in recent decades. This review summarizes the most important properties of nanosystems that are employed in cosmetics, including composition, functions and interactions with skin, with particular attention being paid to marketed products. Moreover, the worldwide regulatory landscape of nanomaterials used as cosmetic ingredients is considered, and the main safety concerns are indicated. In general, advanced physico-chemical characterization is preliminarily needed to assess the safety of nanomaterials for human health and the environment. However, there is currently a shortfall in global legislation as a universally accepted and unambiguous definition of a nanomaterial is still lacking. Therefore, each country follows its own regulations. Anyhow, the main safety concerns arise from the European context, which is the most restrictive. Accordingly, the poor dermal permeation of nanomaterials generally limits their potential toxic effects, which should be mainly ascribed to unwanted or accidental exposure routes.

Are lipid nanoparticles really superior? A holistic proof of concept study

Lipid nanoparticles are a successful carrier system for dermal drug delivery. They possess various beneficial properties, i.e., increased chemical stability for chemically labile compounds, increased dermal penetration of active compounds, or skin carrying properties after dermal application due to the formation of a so-called "invisible patch." Despite manifold studies showing these properties individually, a study that investigates if one lipid nanoparticle formulation can really combine all the above-mentioned benefits at once is not yet available. In the present study, lipid nanoparticles (NLC) were produced and characterized regarding their physico-chemical properties. The chemical stability of the incorporated active ingredient (AI) was determined, as well as the dermal penetration efficacy of the AI, and the skin carrying properties of the NLC after dermal penetration. The properties of the NLC were compared to classical formulations, i.e., AI dissolved in pure oil, an o/w cream base and a nanoemulsion. All formulations contained similar lipids and emulsifiers, which allowed for a direct comparison of the different properties. NLC were shown to provide most efficient chemical stabilization and most efficient dermal penetration for the AI. The formation of the invisible patch was shown for the NLC but not for the other formulations. Skin hydration and skin carrying properties were also most pronounced for the NLC. Results provide evidence that NLC can combine all beneficial effects that were previously described in one formulation. Thus, providing evidence that NLC are a holistically superior formulation principle when compared to other formulation principles.

Fabrication, optimisation and evaluation of cisplatin-loaded nanostructured carriers for improved urothelium permeability for intravesical administration

AIM

To design microemulsions as carriers to improve cisplatin permeation capability for intravesical administration.

METHOD

The response surface methodology with factorial design was used to investigate and optimise the influence of the compositions e.g. capryol 90 and 5-pentanediol/transcutol mixture on the permeation accumulation amount and tissue deposition amount of cisplatin-loaded microemulsions. The in vitro permeation study and in vivo intravesical test were conducted to prove the effect of microemulsions.

RESULTS

The droplet size and the viscosity of all drug-loaded formulations ranged 235.8-309.3 nm and 550.8-861.7 cps, respectively. The permeation accumulation amounts significantly increased about 26-fold, by used microemulsion as carriers. In vivo study, the cisplatin deposition amount in bladder tissue significantly increased 4.1-fold (p < 0.05) and the penetration depth increased from 60 μm up 120 μm. The nanocarrier showed considerable thermodynamic stability.

CONCLUSION

The designed nanocarrier was considered to be a promising delivery system for cisplatin intravesical administration.

Topical transdermal chemoprevention of breast cancer: where will nanomedical approaches deliver us?

Despite the high incidence of breast cancer, there are few pharmacological prevention strategies for the high-risk population and those that are available have low adherence. Strategies that deliver drugs directly to the breasts may increase drug local concentrations, improving efficacy, safety and acceptance. The skin of the breast has been proposed as an administration route for local transdermal therapy, which may improve drug levels in the mammary tissue, due to both deep local penetration and percutaneous absorption. In this review, we discuss the application of nanotechnology-based strategies for the delivery of well established and new agents as well as drug repurposing using the topical transdermal route to improve the outcomes of preventive therapy for breast cancer.

Melittin exerts opposing effects on short- and long-range dynamics in bicontinuous microemulsions

Bicontinuous microemulsions (BμEs) are a promising biomembrane mimetic system for investigating the behavior of antimicrobial peptides (AMPs) and their delivery to open wounds to combat antibiotic-resistant microorganisms. The properties of the BμE host are in turn affected by the guest AMP and can deviate from those of the unperturbed BμEs, especially at higher AMP concentrations. Here we report the effect of an archetypal AMP, melittin, over a wide range of concentrations, on the nanoscopic dynamics of BμEs formed by water/sodium dodecyl sulfate (SDS)/1-pentanol/dodecane, investigated using quasi-elastic neutron scattering (QENS). Two distinct motions are observed, namely, (i) the lateral motion of the surfactant on the surface of the oil channels and (ii) the internal motion of the surfactants. It is found that melittin restricts both the lateral and the internal motion, thereby acting as a stiffening agent. The lateral motion is more strongly affected, at low concentration of melittin. The lateral diffusion coefficient decreased sharply, approaching a constant value at higher melittin concentration. These results are in sharp contrast with the recent dynamic light scattering and neutron spin echo results which showed that at the length and time scales longer than those probed in the current work, melittin enhanced the long-range collective and local undulation motions of BμEs. Considered together, our results indicate that incorporation of melittin modulates the dynamics differently depending on the spatial and temporal regimes, in which the dynamics are being probed. The addition of melittin at low concentrations increased the magnitude of the zeta potential, but further increase of the melittin concentration decreased it. This suggests that addition of melittin at low concentrations led to increase in the surfactant concentration, but did not affect the negative charge per surfactant molecule, while further addition of melittin led to ion pairing of melittin with the oppositely charged surfactant. This study therefore demonstrates how the addition of melittin hinders the lateral motion of surfactants as a result of the strong association between melittin and SDS, suggesting that the release of AMPs from BμE-based delivery vehicles may be hindered.

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.

Preclinical Assessment Addressing Intravenous Administration of a [68Ga]Ga-PSMA-617 Microemulsion: Acute In Vivo Toxicity, Tolerability, PET Imaging, and Biodistribution

It has been herein presented that a microemulsion, known to be an effective and safe drug delivery system following intravenous administration, can be loaded with traces of [⁶⁸Ga]Ga-PSMA-617 without losing its properties or causing toxicity. Following tolerated IV injections the capability of the microemulsion in altering [⁶⁸Ga]Ga-PSMA-617 distribution was presented at 120 min post injection based on its ex vivo biodistribution results.

Development and Evaluation of Topical Delivery of Microemulsions Containing Adapalene (MEs-Ap) for Acne

The main objective of the study was to prepare the microemulsions containing adapalene (MEs-Ap) to enhance epidermal penetration, dermal retention, and local bioavailability compared with the commercial preparation. The optimal formulations were selected by solubility experiments, pseudo-ternary phase diagram, and percutaneous permeation experiments and the physiochemical properties were also investigated. Then, the study of permeability, retention, safety, pharmacodynamics, and pharmacokinetics in the skin for MEs-Ap compared with the commercial preparation were researched. The optimized formulation was developed as follows: the ratio of AP, isopropyl myristate, polyoxyethylene hydrogenated castor oil, ethanol, and water was 0.01:1:1.25:3.75:4 (w/w). The globule size and average viscosity of the optimized MEs-Ap were 99.34 nm and 1.7 mPa·s, respectively, which was oil-in-water microemulsion without serious irritation or allergy for skin. The J_s, Q_n, and Q_retention of MEs-Ap (0.81 ± 0.19 μg/cm²/h, 24.73 ± 4.24 μg/cm², 2.08 ± 0.18 μg/cm²) were apparently higher than Differin® (0.022 ± 0.009 μg/cm²/h, 0.536 ± 0.103 μg/cm², and 0.523 ± 0.130 μg/cm²) respectively. The local bioavailability study showed that the AUC_{0 → 36h} of the MEs-Ap in the dermal (19.6 ± 1.22 μg/cm²) was significantly improved comparing to Differin® (13.9 ± 1.73 μg/cm²) (p < 0.01). The pharmacodynamics study showed that the therapeutic effect of MEs-Ap was better than that of Differin® in the acne model of rabbit auricle. These results suggested that the MEs-Ap could be considered as a having higher epidermal penetrability, dermal retention, local bioavailability, efficacy, and safety topical preparations for acne. Graphical abstract.

Microemulsion-Based Media in Nose-to-Brain Drug Delivery

Nose-to-brain drug delivery has recently attracted enormous attention as an alternative to other delivery routes, including the most popular oral one. Due to the unique anatomical features of the nasal cavity, drugs administered intranasally can be delivered directly to the central nervous system. The most important advantage of this approach is the ability to avoid the blood-brain barrier surrounding the brain and blocking the entry of exogenous substances to the central nervous system. Moreover, selective brain targeting could possibly avoid peripheral side effects of pharmacotherapy. The challenges associated with nose-to-brain drug delivery are mostly due to the small volume of the nasal cavity and insufficient drug absorption from nasal mucosa. These issues could be minimized by using a properly designed drug carrier. Microemulsions as potential drug delivery systems offer good solubilizing properties and the ability to enhance drug permeation through biological membranes. The aim of this review is to summarize the current status of the research focused on microemulsion-based systems for nose-to-brain delivery with special attention to the most extensively investigated neurological and psychiatric conditions, such as neurodegenerative diseases, epilepsy, and schizophrenia.

Biological Evaluation of Oil-in-Water Microemulsions as Carriers of Benzothiophene Analogues for Dermal Applications

During the last decade, many studies have been reported on the design and formulation of novel drug delivery systems proposed for dermal or transdermal administration. The efforts focus on the development of biocompatible nanodispersions that can be delivered to the skin and treat severe skin disorders, including cancer. In this context, oil-in-water (O/W) microemulsions have been developed to encapsulate and deliver lipophilic bioactive molecules for dermal application. An O/W biocompatible microemulsion composed of PBS buffer, Tween 80, and triacetin was assessed for its efficacy as a drug carrier of DPS-2, a lead compound, initially designed in-house to inhibit BRAF^V600E oncogenic kinase. The system was evaluated through both in vitro and ex vivo approaches. The cytotoxic effect, in the presence and absence of DPS-2, was examined through the thiazolyl blue tetrazolium bromide (MTT) cell proliferation assay using various cell lines. Further investigation through Western blotting revealed that cells died of necrosis. Porcine ear skin was used as a skin model to evaluate the degree of permeation of DPS-2 through skin and assess its retention. Through the ex vivo experiments, it was clarified that encapsulated DPS-2 was distributed within the full thickness of the stratum corneum (SC) and had a high affinity to hair follicles.

Comparative evaluation of intranasally delivered quetiapine loaded mucoadhesive microemulsion and polymeric nanoparticles for brain targeting: pharmacokinetic and gamma scintigraphy studies

Background

Treatment in neurological disorders like schizophrenia requires continuous presence of drug in the brain for a prolonged period of time to achieve an effective therapeutic response. Delivery of antipsychotic drug quetiapine in the form of conventional delivery systems suffers from low oral bioavailability, first-pass metabolism, and frequent dosing. In addition to that biological obstacles present at the brain interface also hinders the transport of quetiapine across the brain. In the present study, nasal delivery of quetiapine loaded nanoparticles and microemulsion formulation were designed to evaluate their individual in vivo potential to achieve brain targeting. Chitosan-based polymeric nanoparticles and mucoadhesive microemulsion systems were developed through ionic gelation and water titration method respectively.

Results

Microemulsion showed globule size lower than 50 nm with 95% drug loading while, nanoparticles exhibited 65% drug loading with particle size of 131 nm. Nasal diffusion study showed highest diffusion with chitosan-based mucoadhesive microemulsion over nanoparticles suggesting permeation-enhancing effects of chitosan. Due to the overall hydrophilic nature, quetiapine-loaded nanoparticles could not diffuse superiorly across nasal mucosa, hence, showed 1.3 times lesser diffusion compared to mucoadhesive microemulsion. Pharmacokinetics in rats showed highest brain concentration and 1.9-folds higher nasal bioavailability with mucoadhesive microemulsion over nanoparticles suggesting direct brain transport through olfactory route bypassing blood-brain barrier.

Conclusion

Higher quetiapine transport with mucoadhesive microemulsion suggested that synergistic effects like tight junction modulation by chitosan and unique composition facilitating smaller globule size could be responsible for higher brain transport. Imaging study by gamma scintigraphy also supported pharmacokinetic outcomes and concluded that mucoadhesive microemulsion could be a promising nanocarrier approach for non-invasive nose to brain delivery.

Graphical abstract

Effect of nanoemulsion modification with chitosan and sodium alginate on the topical delivery and efficacy of the cytotoxic agent piplartine in 2D and 3D skin cancer models

Due to the limited options for topical management of skin cancer, this study aimed at developing and evaluating nanoemulsions (NE) for topical delivery of the cytotoxic agent piplartine (piperlongumine). NEs were modified with chitosan or sodium alginate, and the effects on the physicochemical properties, piplartine delivery and formulation efficacy were evaluated. The nanoemulsion droplets displayed similar size (96-112 nm), but opposite charge; the polysaccharides improved piplartine penetration into and across the skin (1.3-1.9-fold) in a similar manner, increasing the ratio "drug in the skin/receptor phase" by 1.4-1.5-fold compared to the plain NE and highlighting their relevance for cutaneous localization. Oleic acid addition to the chitosan-containing NE further increased drug penetration (~1.9-2.0-fold), as did increases in drug content from 0.5 to 1%. The cytotoxicity of piplartine was ~2.8-fold higher when the drug was incorporated in the chitosan-containing NE compared to its solution (IC50 = 14.6 μM) against melanoma cells. The effects of this nanocarrier on 3D melanoma tissues were concentration-related; at 1%, piplartine elicited marked epidermis destruction. These results support the potential applicability of the chitosan-modified nanoemulsion containing piplartine as a new strategy for local management of skin cancer.

Hydroxysafflor Yellow A: A Systematical Review on Botanical Resources, Physicochemical Properties, Drug Delivery System, Pharmacokinetics, and Pharmacological Effects

Hydroxysafflower yellow A (HSYA), as a principal natural ingredient extracted from safflower (Carthamus tinctorius L.), has significant pharmacological activities, such as antioxidant, anti-inflammatory, anticoagulant, and anticancer effects. However, chemical instability and low bioavailability have been severely hampering the clinical applications of HSYA during the treatment of cardiovascular and cerebrovascular disease. Therefore, this present review systematically summarized the materials about HSYA, including acquisition methods, extraction and detection methods, pharmacokinetics, pharmacological effects and molecular mechanism, especially focus on the possible causes and resolutions about the chemical instability and low bioavailability of HSYA, in order to provide relatively comprehensive basic data for the related research of HSYA.

Foray into Concepts of Design and Evaluation of Microemulsions as a Modern Approach for Topical Applications in Acne Pathology

With a fascinating complexity, governed by multiple physiological processes, the skin is considered a mantle with protective functions which during lifetime are frequently impaired, triggering dermatologic disorders. As one of the most prevalent dermatologic conditions worldwide, characterized by a complex pathogenesis and a high recurrence, acne can affect the patient's quality of life. Smart topical vehicles represent a good option in the treatment of a versatile skin condition. By surpassing the stratum corneum known for diffusional resistance, a superior topical bioavailability can be obtained at the affected place. In this direction, the literature study presents microemulsions as a part of a condensed group of modern formulations. Microemulsions are appreciated for their superior profile in matters of drug delivery, especially for challenging substances with hydrophilic or lipophilic structures. Formulated as transparent and thermodynamically stable systems, using simplified methods of preparation, microemulsions have a simple and clear appearance. Their unique structures can be explained as a function of the formulation parameters which were found to be the mainstay of a targeted therapy.

Development of Microemulsions Containing Glochidion wallichianum Leaf Extract and Potential for Transdermal and Topical Skin Delivery of Gallic Acid

Glochidion wallichianum (GW) is a good source of antioxidants, including gallic acid, promoting its development as a microemulsion. We constructed five pseudo-ternary phase diagrams comprising isopropyl myristate (IPM), water, and surfactant mixture (Smix)—i.e., Labrasol®:HCO-40® (1:1) with Transcutol® (1:1, 2:1, 3:1), and Tween80:Span80 (3:2) with Transcutol® or propylene glycol:ethanol (1:1). Additionally, blank and GW extract-loaded microemulsions were prepared at an IPM:Water:Smix ratio of 10:30:60 (high water content) and 30:10:60 (high oil content) from each Smix. The physical characteristics, skin permeation, and disposition were evaluated. The formulations with high water content and conductivities provided higher gallic acid permeation and disposition than those with high oil content. The Smix of Labrasol®:HCO-40® (1:1) and Transcutol® (1:1) promoted the highest gallic acid permeation (enhancement ratio 1.78 ± 0.12) and was suitable for transdermal delivery. However, the 1% hydroxypropyl methylcellulose control gel, the microemulsion with Smix of Labrasol®:HCO-40® (1:1) with Transcutol® (2:1), and Smix of Tween80:Span80 (3:2) with propylene glycol:ethanol (1:1) could provide higher skin accumulation of gallic acid than that with other formulations. The microstructures, ratio of surfactant:cosurfactant, and compositions of microemulsions were found to affect the skin permeation and disposition of gallic acid and require optimization to act as transdermal or topical delivery carriers.

Determination of efficacy and toxicity of diclofenac microemulsion formulation for musculoskeletal pain: an observational study

OBJECTIVE

Musculoskeletal pain is often caused by injury to the bones, muscles, tendons, ligaments or nerves. Symptoms can be localized or generalized. Mild-moderate symptoms are treated with topical/oral over the counter drugs. Microemulsion delivery formulations are thermodynamically stable, have superior bioavailability and better penetration of lipophilic and hydrophilic drug into the dermis. A prospective observational study in patients: 18 years or older, with mild-moderate musculoskeletal pain; with severe pain without adequate pain control; with severe pain and could not tolerate oral agents; with renal impairment were invited to try diclofenac 2% in microemulsion foam. They were followed up at 2 and 4 weeks. A 50% reduction on a visual analog pain scale was considered success. Adverse events were defined as irritation, gastrointestinal upset/bleed, rectal bleed, and hematemesis. The objective was to determine the efficacy and toxicity of diclofenac 2% in microemulsion foam.

RESULTS

Thirteen consecutive patients with musculoskeletal pain consented to participate. Two patients were lost to follow up. Two of the 11 patients reported minimal improvement, while nine patients reported minimum 50% reduction. No adverse effects were reported. Diclofenac 2% in microemulsion foam is effective in the treatment of mild to moderate musculoskeletal pain and well tolerated.

In Vitro Skin Permeation and Antifungal Activity of Naftifine Microemulsions

Objectives

Microemulsions are fluid, isotropic, colloidal systems that have been widely studied as drug delivery systems. The percutaneous transport of active agents can be enhanced by their microemulsion formulation when compared to conventional formulations. The purpose of this study was to evaluate naftifine-loaded microemulsions with the objective of improving the skin permeation of the drug.

Materials and Methods

Microemulsions comprising oleic acid (oil phase), Kolliphor EL or Kolliphor RH40 (surfactant), Transcutol (co-surfactant), and water were prepared and physicochemical characterization was performed. In vitro skin permeation of naftifine from microemulsions was investigated and compared with that of its conventional commercial formulation. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used to evaluate the interaction between the microemulsions and the stratum corneum lipids. Candida albicans American Type Culture Collection (ATCC) 10231 and Candida parapsilosis were used to evaluate the antifungal susceptibility of the naftifine-loaded microemulsions.

Results

The microemulsion formulation containing Kolliphor RH40 as co-surfactant increased naftifine permeation through pig skin significantly when compared with the commercial topical formulation (p<0.05). ATR-FTIR spectroscopy showed that microemulsions increased the fluidity of the stratum corneum lipid bilayers. Drug-loaded microemulsions possessed superior antifungal activity against Candida albicans ATCC 10231 and Candida parapsilosis.

Conclusion

This study demonstrated that microemulsions could be suggested as an alternative topical carrier with potential for enhanced skin delivery of naftifine.