Investigating the potential of essential oils as penetration enhancer for transdermal losartan delivery: Effectiveness and mechanism of action

Development and Characterization of Transdermal Patches Using Novel Thymoquinone-L-Arginine-Based Polyamide Nanocapsules for Potential Use in the Management of Psoriasis

Thymoquinone (TQ) is a phytochemical compound present in Nigella sativa and has potential benefits for treating dermatological conditions such as psoriasis. However, its clinical use is limited due to its restricted bioavailability, caused mainly by its low solubility and permeability. To overcome this, a new transdermal drug delivery system is required. Nanoparticles are known to enhance material solubility and permeability, and hence, this study aimed to synthesize TQ-loaded L-arginine-based polyamide (TQ/Arg PA) nanocapsules incorporated into transdermal patches for prolonged delivery of TQ. To achieve this, Eudragit E polymer, plasticizers, and aloe vera as penetration enhancer were used to develop the transdermal patch. Furthermore, novel TQ/Arg-PA was synthesized via interfacial polymerization, and the resultant nanocapsules (NCs) were incorporated into the matrix transdermal patch. The Arg-PA NCs' structure was confirmed via NMR and FTIR, and optimal TQ/Arg-PA NCs containing formulation showed high entrapment efficiency of TQ (99.60%). Molecular and thermal profiling of TQ/Arg-PA and the transdermal patch revealed the effective development of spherical NCs with an average particle size of 129.23 ± 18.22 nm. Using Franz diffusion cells and synthetic membrane (STRAT M®), the in vitro permeation profile of the prepared patches demonstrated an extended release of TQ over 24 h, with enhanced permeation by 42.64% when aloe vera was employed. In conclusion, the produced formulation has a potential substitute for corticosteroids and other drugs commonly used to treat psoriasis due to its effectiveness, safety, and lack of the side effects typically associated with other drugs.

Oxymatrine-fatty acid deep eutectic solvents as novel penetration enhancers for transdermal drug delivery: formation mechanism and enhancing effect

Transdermal delivery of drugs is commonly limited by low skin permeability. The aim of the study was to synthesize deep eutectic solvents (DESs) based on oxymatrine (OMT) and fatty acids with various alkyl chain lengths (LCFAs) as novel vehicles, to solubilize the water-insoluble drug and enhance percutaneous penetration. Quercetin (QUE) was selected as a model drug. Combining differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and molecular simulations demonstrated that the formation of DESs was mediated by charge-assisted hydrogen bonding. Physicochemical properties including stability, viscosity, and solubilization capacity were also studied. Subsequently, the effect of three stable DESs on drug release and skin permeability was evaluated. The results showed that QUE was solubilized well and presented a different sustained release behavior in DESs. Meanwhile, DESs enhanced the skin permeation of OMT and QUE, which was influenced by alkyl chain lengths of LCFAs, whereas DES consisting of lauric acid (LA) exhibited the highest enhancing effect. FTIR, DSC, and molecular docking further demonstrated consistency between micro molecular mechanism and macro penetration behavior. Additionally, HaCaT cells treated with DESs showed high cell viability, suggesting their good skin safety. Taken together, OMT-LCFA DESs would be a promising penetration enhancer for transdermal drug delivery, which also provides guidance for the design of new DESs.

Current Development of Chemical Penetration Enhancers for Transdermal Insulin Delivery

The use of the transdermal delivery system has recently gained ample recognition due to the ability to deliver drug molecules across the skin membrane, serving as an alternative to conventional oral or injectable routes. Subcutaneous insulin injection is the mainstay treatment for diabetes mellitus which often leads to non-compliance among patients, especially in younger patients. Apart from its invasiveness, the long-term consequences of insulin injection cause the development of physical trauma, which includes lipohypertrophy at the site of administration, scarring, infection, and sometimes nerve damage. Hence, there is a quest for a better alternative to drug delivery that is non-invasive and easily adaptable. One of the potential solutions is the transdermal delivery method. However, the stratum corneum (the top layer of skin) is the greatest barrier in transporting large molecules like insulin. Therefore, various chemical enhancers have been proposed to promote stratum corneum permeability, or they are designed to increase the permeability of the full epidermis, such as the use of ionic liquid, peptides, chemical pre-treatment as well as packaging insulin with carriers or nanoparticles. In this review, the recent progress in the development of chemical enhancers for transdermal insulin delivery is discussed along with the possible mechanistic of action and the potential outlook on the proposed permeation approaches in comparison to other therapeutical drugs

Amelioration of Full-Thickness Wound Using Hesperidin Loaded Dendrimer-Based Hydrogel Bandages

Wound healing is a complex biological phenomenon, having different but overlapping stages to obtained complete re-epithelization. The aim of the current study was to develop a dendrimer-based hydrogel bandage, to ameliorate full-thickness wounds. Hesperidin, a bioflavonoid found in vegetables and citrus fruits, is used for treatment of wounds; however, its therapeutic use is limited, due to poor water solubility and poor bioavailability. This issue was overcome by incorporating hesperidin in the inner core of a dendrimer. Hence, a dendrimer-based hydrogel bandage was prepared, and the wound healing activity was determined. A hemolysis study indicated that the hesperidin-loaded dendrimer was biocompatible and can be used for wound healing. The therapeutic efficacy of the prepared formulation was evaluated on a full-thickness wound, using an animal model. H&E staining of the control group showed degenerated neutrophils and eosinophils, while 10% of the formulation showed wound closure, formation of the epidermal layer, and remodeling. The MT staining of the 10% formulation showed better collagen synthesis compared to the control group. In vivo results showed that the preparation had better wound contraction activity compared to the control group; after 14 days, the control group had 79 ± 1.41, while the 10% of formulation had 98.9 ± 0.42. In a nutshell, Hsp-P-Hyd 10% showed the best overall performance in amelioration of full-thickness wounds.

Formulation Development and Ex-Vivo Permeability of Curcumin Hydrogels under the Influence of Natural Chemical Enhancers

Background: The aim of the present research was to formulate and evaluate curcumin hydrogel and to investigate the potential of natural essential oils as permeation enhancers. Methods: Curcumin 2% w/w hydrogel containing various concentrations of eucalyptus oil, aloe vera oil and clove oil was developed using carboxy methyl cellulose (CMC) as a gelling agent. Differential scanning calorimetry and Fourier Transform infrared spectroscopy were used to evaluate the compatibility between the drug and the excipients. In order to assess the efficacy of the formulation; rheological properties, skin irritation studies, in vitro release, ex vivo permeation and retention studies were conducted. Results: DSC and FTIR suggest no in-compatibility between curcumin and excipients. Studies proved that addition of suitable natural permeation enhancers to the hydrogels improved the in vitro release and ex vivo permeation and retention of curcumin. From the various natural essential oils, the aloe vera oil at a concentration of 3% w/w had the greatest effect on the permeability rate and skin retention of the Curcumin and produces the highest enhancement ratio amongst all the concentrations of essential oils examined. Conclusion: Aloe vera oil enhances the permeation of curcumin across the skin by altering the complex structure of the stratum corneum without itself undergoing any change. The developed curcumin hydrogels along with natural essential oils may present an effective choice regarding skin infection/wound healing.

Systematic Review on the Effectiveness of Essential and Carrier Oils as Skin Penetration Enhancers in Pharmaceutical Formulations

Oils, including essential oils and their constituents, are widely reported to have penetration enhancement activity and have been incorporated into a wide range of pharmaceutical formulations. This study sought to determine if there is an evidence base for the selection of appropriate oils for particular applications and compare their effectiveness across different formulation types. A systematic review of the data sources, consisting of Google Scholar, EMBASE, PubMed, Medline, and Scopus, was carried out and, following screening and quality assessment, 112 articles were included within the analysis. The research was classified according to the active pharmaceutical ingredient, dosage form, in vitro/in vivo study, carrier material(s), penetration enhancers as essential oils, and other chemical enhancers. The review identified four groups of oils used in the formulation of skin preparations; in order of popularity, these are terpene-type essential oils (63%), fatty acid-containing essential oils (29%) and, finally, 8% of essential oils comprising Vitamin E derivatives and miscellaneous essential oils. It was concluded that terpene essential oils may have benefits over the fatty acid-containing oils, and their incorporation into advanced pharmaceutical formulations such as nanoemulsions, microemulsions, vesicular systems, and transdermal patches makes them an attractive proposition to enhance drug permeation through the skin.

Synthesis and Characterization of Nanoporous Carbon Carriers for Losartan Potassium Delivery

Losartan potassium is most commonly used for the treatment of hypertension. In recent years, new applications of this drug have emerged, encouraging the design of novel nanoporous carriers for its adsorption and release. The purpose of this study was to synthesize ordered mesoporous carbon vehicles via a soft-templating method altered with the use of nitrogen precursors and via a hard-templating method followed by chitosan functionalization. As a result, the materials obtained differed in nitrogen content as well as in the number of total surface functional groups. The impact of the modification on the physicochemical properties of carbon carriers and their interaction with losartan potassium during adsorption and release processes was examined. The materials were characterized by various morphologies, specific surface areas (101–1180 m² g⁻¹), and the amount of acidic/basic oxygen-containing functional groups (1.26–4.27 mmol g⁻¹). These features, along with pore sizes and volumes, had a key effect on the sorption capacity of carbon carriers towards losartan potassium (59–161 mg g⁻¹). Moreover, they contributed to the differential release of the drug (18.56–90.46%). Losartan potassium adsorption onto the surface of carbonaceous materials was mainly based on the formation of hydrogen bonds and π–π interactions and followed the Langmuir type isotherm. It has been shown that the choice of the method of carbon carriers’ synthesis and their modification allows for the precise control of the kinetics of the losartan potassium release from their surface, resulting in rapid or sustained drug liberation.

Therapeutic benefits of natural oils along with permeation enhancing activity

The skin is the largest organ of the integumentary system with a multifunctional purpose to protect the body from heat and microbes, regulate body temperature, and act as a sensory organ. A topical dosage form applied on the skin will have to cross the stratum corneum, which would then allow the dosage form to traverse the subsequent layers of the skin. The drug with poor solubility and short half-life would serve as an ideal candidate for its delivery via the transdermal route. This review reports the role of natural oils in enhancing the permeation of drugs through skin as they possess different features like natural origin, favorable penetration enhancement, and partitioning action in the skin. Chemical penetration enhancers have been used widely but are associated with toxicities. Thus, more research should be channelized in the area of extraction of oils from natural sources, along with their active constituents, which can serve as therapeutic alternatives to various disorders and diseases. Natural oils are obtained from leaves, fruits, flowers, seeds, bark, and roots, which have a therapeutic potential as well as penetration enhancing activity. The demerits of oral drug delivery include degradation of drugs in the gastrointestinal tract, addition of taste masking, and coating of tablets, which can be overcome by delivering the drug via the transdermal route. Natural oil contains lipids, flavonoids, and terpenes, which play a significant role in anti-inflammatory and penetration enhancing activity.

The molecular design of drug-ionic liquids for transdermal drug delivery: Mechanistic study of counterions structure on complex formation and skin permeation

Though ionic liquids (ILs) as novel enhancers had garnered wide attention, detailed studies elucidating molecular design of drug-ILs were missing and mechanisms of their formation and skin permeation were still lacking. Herein, we systematically investigated effects of counterions structures on formation and skin permeation of drug-ILs. Firstly, effects of counterions on formation of drug-ILs were dependent on polarizability, molecular weight (M.W.) and polar surface area of counterions. It was caused by strong charge assisted hydrogen bond and van der Waals interactions revealed through FT-IR, X-ray photoelectron spectroscopy and molecular docking, which undermined ionic interactions and reduced total interaction strength, thereby produced lower lattice energy. Then, skin permeability of drug-ILs had a good parabola relationship with M.W., polarizability and log P of counterions. The underlying mechanism was the increased drug miscibility with stratum corneum, which caused conformational disorder and phase transition of lipid bilayers characterized by ATR-FTIR, DSC and confocal laser scanning microscopy. Finally, the drug-ILs proved to be non-irritating using in vivo skin erythema analysis. In conclusion, the quantitative structure-activity relationship models based on counterions structure to predict formation and skin permeation of drug-ILs were developed, which provided basic theory for design of drug-ILs with high permeation-enhancing efficiency.

Formulation, in-vitro and in-vivo pharmacokinetic evaluation of simvastatin nanostructured lipid carrier loaded transdermal drug delivery system

Background

A simvastatin nanostructured lipid carrier loaded transdermal patch was developed to enhance the bioavailability and therapeutic effect.

Methods

Simvastatin NLC preparation was prepared by optimized hot homogenization technique and were characterized by particle size in nanometer, polydispersity index, zeta potential in millivolt, scanning electron microscopy, and entrapment efficiency by applying Box Behnken design utilizing multiple linear regression method.

Results

Chosen optimized NLC F7 formulation has particle size of 125.4 ± 2.66 nm, zeta potential of − 33.6 ± 2.42 mV, and PI of 0.480 ± 0.24. The NLC was loaded in transdermal patch by solvent evaporation method and evaluated for physical characteristics, drug content, skin permeation studies, and in-vivo pharmacokinetic studies in male albino Wistar rat. In-vivo pharmacokinetic studies in NLC loaded transdermal patch show an increase in AUC0-α in mg/ml when compared to marketed oral dosage form, which confirms the enhancement of bioavailability of simvastatin by NLC loaded transdermal patch.

Conclusions

From the data, it was concluded that drug-loaded NLC transdermal patch will be a promising drug delivery system for poorly bioavailable drugs.

Commercial Essential Oil Combinations against Topical Fungal Pathogens

Essential oils are amongst the most popular natural products recommended for the treatment of topical fungal infections. This study investigated the antifungal activity of 128 essential oil combinations against fungal pathogen reference strains using the broth microdilution technique to determine the minimum inhibitory concentration (MIC). The essential oils were investigated at a volume of 100 μL and the combinations comprised of 50:50 μL. Each combination was tested in triplicate and the mean recorded. The fractional inhibitory concentration index was calculated for combinations, and synergistic interactions were investigated further at different ratios and plotted on isobolograms. The fungal pathogens were found to be highly susceptible to the essential oil combinations, with Trichophyton mentagrophytes being inhibited by all but one combination. The essential oil combinations containing Cinnamomum verum or Santalum austrocaledonicum were found to display the strongest inhibition with MIC values as low as 0.06 mg/mL. Potential combinations against fungal pathogens have been presented that could be studied in clinical settings with the goal of decreasing the need for systemic or prolonged antifungal treatments that may result in treatment failure or resistance.

Core/shell PLGA microspheres with controllable in vivo release profile via rational core phase design

Highly soluble drugs tend to release from preparations at high speeds, which make them need to be taken at frequent intervals. Additionally, some drugs need to be controlled to release in vivo at certain periods, so as to achieve therapeutic effects. Thus, the objective of this study is to design injectable microparticulate systems with controllable in vivo release profile. Biodegradable PLGA was used as the matrix material to fabricate microspheres using the traditional double emulsification-solvent evaporation method as well as improved techniques, with gel (5% gelatine or 25% F127) or LP powders as the inner phases. Their physicochemical properties were systemically investigated. Microspheres prepared by modified methods had an increase in drug loading (15.50, 16.72, 15.66%, respectively) and encapsulation efficiencies (73.46, 79.42, 74.40%, respectively) when compared with traditional methods (12.01 and 57.06%). The morphology of the particles was characterized by optical microscope (OM) and scanning electron microscopy (SEM), and the amorphous nature of the encapsulated drug was confirmed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. To evaluate their release behaviour, the in vitro degradation, in vitro release and in vivo pharmacodynamics were subsequently studied. Traditional microspheres prepared in this study with water as the inner phase had a relatively short release period within 16 d when compared with modified microspheres with 5% gelatine as the inner phase, which resulted in a smooth release profile and appropriate plasma LP concentrations over 21 d. Thus this type of modified microspheres can be better used in drugs requiring sustained release. The other two formulations containing 25% F127 and LP micropowders presented two-stage release profiles, resulting in fluctuant plasma LP concentrations which may be suitable for drugs requiring controlled release. All the results suggested that drug release rates from the microspheres prepared by various methods were mainly controlled by either the porosity inside the microspheres or the degradation of materials, which could, therefore, lead to different release behaviours. This results indicated great potential of the PLGA microsphere formulation as an injectable depot for controllable in vivo release profile via rational core phase design. Core/shell microspheres fabricated by modified double emulsification-solvent evaporation methods, with various inner phases, to obtain high loading drugs system, as well as appropriate release behaviours. Accordingly, control in vivo release profile via rational core phase design.

Efficient delivery of nanoparticles to deep skin layers using dissolvable microneedles with an extended-length design

Dissolvable microneedles with an extended-length design can efficiently deliver NPs to the deep skin layers and prolong the skin retention time of NPs up to 5 days.

The application of anethole, menthone, and eugenol in transdermal penetration of valsartan: Enhancement and mechanistic investigation

CONTEXT

The main barrier for transdermal delivery is the obstacle property of the stratum corneum. Many types of chemical penetration enhancers have been used to breach the skin barrier; among the penetration enhancers, terpenes are found as the most highly advanced, safe, and proven category.

OBJECTIVE

In the present investigation, the terpenes anethole, menthone, and eugenol were used to enhance the permeation of valsartan through rat skin in vitro and their enhancement mechanism was investigated.

MATERIALS AND METHODS

Skin permeation studies of valsartan across rat skin in the absence and the presence of terpenes at 1% w/v, 3% w/v, and 5% w/v in vehicle were carried out using the transdermal diffusion cell sampling system across rat skin and samples were withdrawn from the receptor compartment at 1, 2, 3, 4, 6, 8, 10, 12, and 24 h and analysed for drug content by the HPLC method. The mechanism of skin permeation enhancement of valsartan by terpenes treatment was evaluated by Fourier transform infrared spectroscopy (FTIR) analysis and differential scanning calorimetry (DSC).

RESULTS

All the investigated terpenes provided a significant (p < 0.01) enhancement in the valsartan flux at a concentration of 1%, and less so at 3% and 5%. The effectiveness of terpenes at 1% concentration was in the following order: anethole > menthone > eugenol with 4.4-, 4.0-, and 3.0-fold enhancement ratio over control, respectively. DSC study showed that the treatment of stratum corneum with anethole shifted endotherm down to lower melting point while FTIR studies revealed that anethole produced maximum decrease in peak height and area than other two terpenes.

CONCLUSION

The investigated terpenes can be successfully used as potential enhancers for the enhancement of skin permeation of lipophilic drug.

Novel perspectives in the tuberculosis treatment: Administration of isoniazid through the skin

Despite its high efficacy in anti-tuberculosis therapy, the oral administration of isoniazid (INH) may lead to poor patient compliance due to hepatotoxicity events. In this context, the transdermal administration of INH was evaluated, for the first time, since this route avoids hepatic first pass effect. INH was applied to porcine skin in Franz diffusion chambers alone and with 5% menthol, limonene or Transcutol(®). Infrared and DSC analyses were selected for mechanistic studies. The transdermal absorption of INH was sufficient to ensure a systemic therapeutic effect. Menthol was not able to improve the absorption of INH, but it increased the drug accumulation in skin compared to the control (1.4-fold). Transcutol(®) reduced permeation flux of INH (2.2-fold) and also increased the amount of drug retained in skin (1.7-fold). Limonene was the most effective excipient since it increased permeation flux of INH (1.5-fold) and lag time was greatly shortened (2.8-fold). DSC and FTIR analyses of limonene-treated skin suggest higher degree of disorder in lipid bilayers. Transdermal delivery of INH was positively correlated with logP of chemical enhancers. INH can be efficiently delivered by skin route and specific excipients may be selected depending on intended use.