Terpenes in propylene glycol as skin-penetration enhancers: permeation and partition of haloperidol, Fourier transform infrared spectroscopy, and differential scanning calorimetry

Evidence of the protective role of Carvacrol in a retinal degeneration animal model

Neurodegenerative pathologies affecting the posterior segment of the eye, are characterized by being devastating and responsible for the majority of visual dysfunctions worldwide. These diseases are primarily degenerative, progressing chronically, and can inflict gradual harm to the optic nerve, retinal ganglion cells (RGC), photoreceptors, and other retinal cells. This retinal damage leads to a progressive loss of vision, marking these conditions as a significant health concern worldwide. The intravitreal administration of the phytochemical Carvacrol (CAR) is expected to demonstrate a neuroprotective and antiapoptotic effect on retinal cells, with a specific focus on RGC. This effect will be observed in a retinal degeneration model (RDM) in rabbits induced by cytotoxic and oxidative agents, namely glutamate (GLUT) and L-buthionine-S, R-sulfoximine (BSO). An in vivo study was conducted using New Zealand rabbits in which retinal damage was created to evaluate the effectiveness of CAR. The effectiveness of CAR on the functionality of retinal neuronal cells in RDM was evaluated using pupillary light reflection (PLR). Furthermore, the phytotherapeutic's influence on cell viability was determined through flow cytometry analysis. Finally, the neuroprotective and antiapoptotic capabilities of CAR were specifically scrutinized in RGC through histological studies, quantifying cell survival, and employing immunohistochemical assays to detect the apoptotic index (%) using the TUNEL technique. Our results demonstrated that CAR promoted the recovery of the pupillary contraction profile over time, maintaining the functionality of retinal cells as healthy controls. Additionally, it showed increased cell viability under oxidative and cytotoxic conditions given by GLUT-BSO agents. Finally, we found that CAR protects the survival of RGC and decreases the percentage of apoptotic cells when compared to RDM. CAR demonstrated to have positive effects on the functionality of photoreceptive nerve cells by restoring pupillary contraction. Likewise, it was shown to have neuroprotective and antiapoptotic effects when evaluated in a general and specific way on retinal nerve cells.

Glycols: The ubiquitous solvent for dermal formulations

Glycols stand out as one of the most commonly employed safe and effective excipients for pharmaceutical and cosmeceutical products. Their widespread adoption can be attributed to their exceptional solvency characteristics and their ability to interact effectively with skin lipids and keratin for permeation enhancement. Notably, propylene glycol enjoys significant popularity in this regard. Ongoing research endeavours have been dedicated to scrutinising the impact of glycols on dermal drug delivery and shedding light on the intricate mechanisms by which glycols enhance skin permeation. This review aims to mitigate the discordance within the existing literature, assemble a holistic understanding of the impact of glycols on the percutaneous absorption of active compounds and furnish the reader with a profound comprehension of the foundational facets pertaining to their skin permeation enhancement mechanisms, while simultaneously delving deeper into the intricacies of these processes.

The Fate of 1,8-cineole as a Chemical Penetrant: A Review

The stratum corneum continues to pose the biggest obstacle to transdermal drug delivery. Chemical penetrant, the first generation of transdermal drug delivery system, offers a lot of potential. In order to fully examine the permeation mechanism of 1,8-cineole, a natural monoterpene, this review summarizes the effects of permeation-enhancing medications on drugs that are lipophilic and hydrophilic as well as the toxicity of this substance on the skin and other tissues. For lower lipophilic drugs, 1,8-cineole appears to have a stronger osmotic-enhancing impact. An efficient and secure tactic would be to combine enhancers and dose forms. 1,8-cineole is anticipated to be further developed in the transdermal drug delivery system and even become a candidate drug for brain transport due to its permeability and low toxicity.

A Comprehensive Review on Potential Chemical and Herbal Permeation Enhancers Used in Transdermal Drug Delivery Systems

Using skin patches to deliver drugs is dependable and doesn't have the same issues as permeation enhancers, which help drugs get through the skin but struggle because of the skin's natural barrier. Strategies are required to increase topical bioavailability to enhance drug absorption. Natural compounds offer a promising solution by temporarily reducing skin barrier resistance and improving drug absorption. Natural substances allow a wider variety of medications to be distributed through the stratum corneum, offering a dependable approach to enhancing transdermal drug delivery. Natural substances have distinct advantages as permeability enhancers. They are pharmacologically effective and safe, inactive, non-allergenic, and non-irritating. These characteristics ensure their suitability for use without causing adverse effects. Natural compounds are readily available and well tolerated by the body. Studies investigating the structure-activity relationship of natural chemicals have demonstrated significant enhancer effects. By understanding the connection between chemical composition and enhancer activity, researchers can identify effective natural compounds for improving drug penetration. In conclusion, current research focuses on utilizing natural compounds as permeability enhancers in transdermal therapy systems. These substances offer safety, non-toxicity, pharmacological inactivity, and non-irritation. Through structure-activity relationship investigations, promising advancements have been made in enhancing drug delivery. Using natural compounds holds enormous potential for improving the penetration of trans-dermally delivered medications.

Enhancement of antifungal activity and transdermal delivery of 5-flucytosine via tailored spanlastic nanovesicles: statistical optimization, in-vitro characterization, and in-vivo biodistribution study

Aim and background: This current study aimed to load 5-flucytosine (5-FCY) into spanlastic nanovesicles (SPLNs) to make the drug more efficient as an antifungal and also to load the 5-FCY into a hydrogel that would allow for enhanced transdermal permeation and improved patient compliance. Methods: The preparation of 5-FCY-SPLNs was optimized by using a central composite design that considered Span 60 (X1) and the edge activator Tween 80 (X2) as process variables in achieving the desired particle size and entrapment efficiency. A formulation containing 295.79 mg of Span 60 and 120.00 mg of Tween 80 was found to meet the prerequisites of the desirability method. The optimized 5-FCY-SPLN formulation was further formulated into a spanlastics gel (SPG) so that the 5-FCY-SPLNs could be delivered topically and characterized in terms of various parameters. Results: As required, the SPG had the desired elasticity, which can be credited to the physical characteristics of SPLNs. An ex-vivo permeation study showed that the greatest amount of 5-FCY penetrated per unit area (Q) (mg/cm2) over time and the average flux (J) (mg/cm2/h) was at the end of 24 h. Drug release studies showed that the drug continued to be released until the end of 24 h and that the pattern was correlated with an ex-vivo permeation and distribution study. The biodistribution study showed that the 99mTc-labeled SFG that permeated the skin had a steadier release pattern, a longer duration of circulation with pulsatile behavior in the blood, and higher levels in the bloodstream than the oral 99mTc-SPNLs. Therefore, a 5-FCY transdermal hydrogel could possibly be a long-acting formula for maintenance treatment that could be given in smaller doses and less often than the oral formula.

Hydrogel forming microneedle-mediated transdermal delivery of sildenafil citrate from polyethylene glycol reservoir: An ex vivo proof of concept study

Erectile dysfunction (ED) is a disorder that often occurs in men worldwide. One of the drugs used as the first-line therapy for erectile dysfunction is sildenafil citrate (SC). Unfortunately, SC was commonly found in oral, injection, and transdermal dosage forms with some limitations, mainly related to low oral bioavailability caused by the occurrence of first-pass metabolism in the liver, and poor patient comfort and compliance. Therefore, it was essential to develop dosage forms to overcome these limitations. We developed hydrogel-forming microneedles (HFM) that can facilitate transdermal delivery of SC by penetrating the stratum corneum. HFM was made using polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) as polymers and several variations of tartaric acid as crosslinking agents. The evaluation of swelling properties, mechanical resistance, and penetration ability showed that the HFM produced had good insertion properties and swelling capabilities ranging from 300% to 700%. This HFM was designed to be integrated with a polyethylene glycol (PEG) reservoir prepared using several types of PEG with different molecular weights. The ex vivo permeation study showed that up to 80% of SC (equivalent to 20.2 ± 0.29 mg/mL) was delivered transdermally from this combined dosage form. For the first time, SC has been successfully developed into an HFM that was integrated with a PEG reservoir which was non-irritating, safe, and painless. It also had promising results for increasing the effectiveness of ED therapy.

Biomimetic Stratum Corneum Liposome Models: Lamellar Organization and Permeability Studies

The stratum corneum (SC), the outer layer of the skin, plays a crucial role as a barrier protecting the underlying cells from external stress. The SC comprises three key components: ceramide (CER), free fatty acid (FFA), and cholesterol, along with small fractions of cholesterol sulfate and cholesterol ester. In order to gain a deeper understanding about the interdependence of the two major components, CER and FFA, on the organizational, structural, and functional properties of the SC layer, a library of SC lipid liposome (SCLL) models was developed by mixing CER (phytosphingosine or sphingosine), FFA (oleic acid, palmitic acid, or stearic acid), cholesterol, and cholesterol sulfate. Self-assembly of the SC lipids into lamellar phases was first confirmed by small-angle X-ray scattering. Short periodicity and long periodicity phases were identified for SCLLs containing phytosphingosines and sphingosine CERs, respectively. Furthermore, unsaturation in the CER acyl and FFA chains reduced the lipid conformational ordering and packing density of the liposomal bilayer, which were measured by differential scanning calorimetry and Fourier transform infrared spectroscopy. The introduction of unsaturation in the CER and/or FFA chains also impacted the lamellar integrity and permeability. This extensive library of SCLL models exhibiting physiologically relevant lamellar phases with defined structural and functional properties may potentially be used as a model system for screening pharmaceuticals or cosmetic agents.

Altered Skin Permeation of Finasteride Using Clove Oil, Urea, and Lyophilized Powder of Grape Seed Extract

Purpose: Finasteride is a 5-alpha reductase inhibitor used to treat hair loss and acne. The skin permeation of finasteride is one of the main challenges associated with dermal drug delivery. One way to overcome the skin barrier is to use penetration enhancers. The purpose of this study was to investigate the effect of some penetration enhancers on finasteride permeability on the skin, as well as the effect of pretreatment time on their efficacy. Methods: In order to determine the effect of penetration enhancers on the skin permeability of finasteride, the skin was exposed to clove oil, urea, and lyophilized powder of grape seed extract (LPGSE) at different pretreatment times (2, 4 h), and then the permeability parameters were determined by passing the drug through the skin. Results: The results of this study showed that clove oil, urea, and LPGSE increased the transfer of finasteride from the skin. The highest rate of permeation was observed with clove oil (4 h), and the least permeability was observed with urea (4 h). Conclusion: Increasing the pretreatment time with clove oil and LPGSE increases the permeability of finasteride. Meanwhile, the increase in pretreatment time with urea reduces the penetration of finasteride from the skin due to reversible effects.

A comprehensive review on invasomal carriers incorporating natural terpenes for augmented transdermal delivery

Background

Transdermal drug delivery is one of the most widely used drug administration routes, which offer several advantages over other routes of drug delivery. The apical layer of the skin called the stratum corneum is the most dominant obstacle in the transdermal drug delivery, which restricts the passage of drugs across the skin. Considerable strategies have been applied to enhance the rate of permeation across the epithelial cells; however, the most widely used strategy is the use of sorption boosters, also known as permeation enhancers.

Main body

Terpenes were considered as efficient skin permeation enhancers and are generally recognized as safe as per Food and Drug Administration. Terpenes improve the permeability of drugs either by destructing the stratum corneum’s tightly packed lipid framework, excessive diffusivity of drug in cell membrane or by rampant drug partitioning into epithelial cells. Various vesicular systems have been developed and utilized for the transdermal delivery of many drugs. Invasomes are one such novel vesicular system developed which are composed of phospholipids, ethanol and terpenes. The combined presence of ethanol and terpenes provides exceptional flexibility to the vesicles and improves the permeation across the barrier offered due to the stratum corneum as both ethanol and terpenes act as permeation enhancers. Therefore, utilization of invasomes as carriers to facilitate higher rate of drug permeation through the skin can be a very useful approach to improve transdermal drug delivery of a drug.

Conclusion

The paper focuses on a broad updated view of terpenes as effective permeation enhancers and invasomes along with their applications in the pharmaceutical formulations.

Collaborative permeation of drug and excipients in transdermal formulations. In vitro scrutiny for ethanol:limonene combinations

Enhancement of skin permeation of drugs is affected by the simultaneous co-permeation of excipients that hinder the predictivity of in vitro tests. The collaborative effects of two permeation enhancers (ethanol and d-limonene) of a lipophilic drug (alprazolam) have been simultaneously assessed in human skin under different in vitro conditions: integrated setups of diffusion cell experiments with selective concentration gradients of permeants (asymmetric) or without (symmetric) have been combined with coadministration dosages (all-in-one) at different concentrations or short-time skin pretreatment to scrutiny this mutual performance. Findings: Drug permeation is increased under moderated supersaturation but reaches a stationary level above 33 % of its solubility. Ethanol in absence of a concentration gradient increases ca.5 times basal drug permeation. Limonene until 20 % permeates human skin proportionally to its donor concentration but its effect does not depend on ethanol in symmetric conditions and is based on skin imbibition rather than on a carry-on effect. Simultaneous permeation of ethanol and limonene reaches a stationary state after 1.5 h, enough time to achieve maximal enhancement of alprazolam permeation. Additive enhancement is based on ethanol solubilisation maximized by skin saturation of terpene. Complementary analyses of skin disruption published in the literature are in line with these assessments and consolidate them.

Medicated Lacquer For Application On Adornments To Treat Affections In Aesthetic Perforations

Aesthetic perforations are often associated with health issues, such as itching, inflammation, or microbial infection. Accordingly, this work proposed a lacquer to be applied on the adornment accessory forming a film from which a proper drug is released. For this, lacquers were formulated containing three different permeation enhancers (limonene - LIM, propylene glycol - PG, and oleic acid - AO) combined according to a mixture design with a model anti-inflammatory natural drug (naringenin) and a soluble film-former polymer (polyvinyl alcohol). Formulations were characterized by physicochemical tests and in vitro and in vivo skin permeation studies. The lacquers were stable and provided a vectorized drug release. LIM, combined with one of the other permeation enhancers, showed a synergic effect, enhancing topical skin penetration in vitro by 53% while preventing permeation to the receptor medium. The in vivo evaluation of lacquers in rodent models showed these systems could provide higher levels of drug retention in the ear (166.4 ± 14.9 µg per ear for F4 and 174.9 ± 29.3 µg per ear for F5) compared to the control (109.2 ± 16.3 µg) without allowing its permeation into the bloodstream, confirming the local drug delivery. Moreover, the anti-inflammatory activity was achieved in the animal model developed for lacquer application on the earring, obtaining inhibition of ear swelling up to 40.8% ± 2.3 compared to the untreated ear. Thus, such an innovative lacquer proved a promising vehicle for treating affections caused by adornments, enhancing skin permeation while avoiding a systemic effect.

Thermal analysis of mammalian stratum corneum using differential scanning calorimetry for advancing skin research and drug delivery

For effective topical and transdermal drug delivery, it is necessary for most actives to penetrate and permeate through the stratum corneum (SC). Extensive investigation of the thermal behaviour of mammalian SC has been performed to understand the barrier function of the skin. However, little attention has been paid to the related experimental variables in thermal analysis of the SC using differential scanning calorimetry that may influence the results obtained from such studies. In this review, we provide a comprehensive overview of the thermal transitions of the SC of both porcine and human skin. More importantly, the selection and impact of the experimental and instrumental parameters used in thermal analysis of the SC are critically evaluated. New opportunities for the use of thermal analysis of mammalian SC in advancing skin research, particularly for elucidation of the actions of excipients employed in topical and transdermal formulations on the skin are also highlighted.

Neomenthol prevents the proliferation of skin cancer cells by restraining tubulin polymerization and hyaluronidase activity

Introduction

Neomenthol, a cyclic monoterpenoid, is a stereoisomer of menthol present in the essential oil of Mentha spp. It is used in food as a flavoring agent, in cosmetics and medicines because of its cooling effects. However, neomenthol has not been much explored for its anticancer potential. Additionally, targeting hyaluronidase, Cathepsin-D, and ODC by phytochemicals is amongst the efficient approach for cancer prevention and/or treatment.

Objectives

To investigate the molecular and cell target-based antiproliferative potential of neomenthol on human cancer (A431, PC-3, K562, A549, FaDu, MDA-MB-231, COLO-205, MCF-7, and WRL-68) and normal (HEK-293) cell lines.

Methods

The potency of neomenthol was evaluated on human cancer and normal cell line using SRB, NRU and MTT assays. The molecular target based study of neomenthol was carried out in cell-free and cell-based test systems. Further, the potency of neomenthol was confirmed by quantitative real-time PCR analysis and molecular docking studies. The in vivo anticancer potential of neomenthol was performed on mice EAC model and the toxicity examination was accomplished through in silico, ex vivo and in vivo approaches.

Results

Neomenthol exhibits a promising activity (IC₅₀ 17.3 ± 6.49 μM) against human epidermoid carcinoma (A431) cells by arresting the G2/M phase and increasing the number of sub-diploid cells. It significantly inhibits hyaluronidase activity (IC₅₀ 12.81 ± 0.01 μM) and affects the tubulin polymerization. The expression analysis and molecular docking studies support the in vitro molecular and cell target based results. Neomenthol prevents EAC tumor formation by 58.84% and inhibits hyaluronidase activity up to 10% at 75 mg/kg bw, i.p. dose. The oral dose of 1000 mg/kg bw was found safe in acute oral toxicity studies.

Conclusion

Neomenthol delayed the growth of skin carcinoma cells by inhibiting the tubulin polymerization and hyaluronidase activity, which are responsible for tumor growth, metastasis, and angiogenesis.

The enhancing effect and promoting mechanisms of the stereoisomeric monoterpene alcohol esters as enhancers for drugs with different physicochemical properties

To explore the structure-activity connections of amphiphilic permeation enhancers containing the length of the hydrophobic chains as well as the properties of the polar head, O-acylgeraniol and O-acylnerol derivatives were synthesized from geraniol/nerol (cis-isomer of geraniol) and pharmaceutical excipient acids in this research. Their promotion of the percutaneous absorption of three drugs as the model, flurbiprofen (FP), isosorbide dinitrate (ISDN) and donepezil (DNP), which were selected based on their physicochemical properties, was tested by in vitro skin penetration and in vivo. Molecular simulation, ATR-FTIR, CLSM and histological observation were implement to evaluate the mode of action of the enhancers. The results indicated that (E)-3,7-dimethyl-2,6-octadien-1-yl tetradecanoate (GER-C14, trans-) achieved the highest enhancement ability for the three drugs; additionally, the in vivo results obtained were in good correlation with the in vitro data. Molecular docking results suggested that enhancers loosen the hydrogen bonds between ceramides, and the results of molecular simulation indicated that GER-C14, NER-C14 could insert into the middle of the lipid bilayer to form an independent phase. According to ATR-FTIR and histological evaluation, the enhancers extracted lipids and influenced the protein region, thereby disturbing the skin array. In addition, CLSM described the dynamic effects of enhancers on lipids between stratum corneum (SC) cells. In conclusion, GER-C14 had a better penetration promotion effect, which broadened our understanding of stereoisomeric penetration enhancers.

Current Status of Amino Acid-Based Permeation Enhancers in Transdermal Drug Delivery

Transdermal drug delivery (TDD) presents many advantages compared to other conventional routes of drug administration, yet its full potential has not been achieved. The administration of drugs through the skin is hampered by the natural barrier properties of the skin, which results in poor permeation of most drugs. Several methods have been developed to overcome this limitation. One of the approaches to increase drug permeation and thus to enable TDD for a wider range of drugs consists in the use of chemical permeation enhancers (CPEs), compounds that interact with skin to ultimately increase drug flux. Amino acid derivatives show great potential as permeation enhancers, as they exhibit high biodegradability and low toxicity. Here we present an overview of amino acid derivatives investigated so far as CPEs for the delivery of hydrophilic and lipophilic drugs across the skin, focusing on the structural features which promote their enhancement capacity.

HPLC method development/validation and skin diffusion study of caffeine, methyl paraben and butyl paraben as skin-diffusing model drugs

The focus of this research was to develop and validate a suitable HPLC method, which allows simultaneous determination of three proposed skin model penetrants to investigate the percutaneous diffusion behavior of their combination: caffeine, methyl paraben and butyl paraben. These penetrants were selected because they represent a wide range of lipophilicities. This model highlights the effect of combining penetrants of different molecular properties on their diffusion behavior through skin. The proposed method employed a gradient system that was systematically optimized for separation and quantification of the penetrants. The effect of the stationary phase (C18, C4 and cyano (CN)) was assessed with CN proven to be superior in terms of peak shape, retentivity and dynamic linear range. Significant differences in retention time, peak broadening, and quantifiability between different stationary phases could be demonstrated. The method was validated as per ICH guidelines Q2 (R1) with a satisfactory outcome. The method was successfully applied for real diffusion experiments, and revealed notable differences between the individual penetrants and their ternary mixture on transdermal permeation. The method could potentially be extended to determine these analytes in other related skin permeation investigations.

Permeability coefficients and vapour pressure determination for fragrance materials

OBJECTIVE

This study aims to correlate new experimental data relevant to the description of the combined evaporation/permeation process of a perfume applied onto the skin.

METHODS

The vapour pressure data were measured by thermogravimetric analysis (TG-DTA). The Antoine constants and the Clarke and Glew parameters were determined for the same set of fragrance molecules to describe its low vapour pressures at new temperature ranges. The permeability coefficient of a set of 14 fragrance molecules in ethanolic solution was determined by Franz diffusion cell experiments, using porcine skin. The samples were analysed by gas chromatography with a flame ionization detector (GC/FID) and high-performance liquid chromatography with UV visible detector (HPLC/UV). A QSAR model was proposed to correlate the experimental data.

RESULTS

The Antoine constants were determined and presented low standard deviations. The Clarke and Glew physically significant parameters were obtained along with its statistical analysis. The fitting is good since the magnitude order is in accordance with the literature, associated with the low correlation between the estimated parameters and low standard deviations. The presented correlation, based on a mixture using only ethanol as solvent, showed better results than previous QSAR models with a standard relative deviation ( σ r ) of 0.190, a standard error (SE) of 0.397 and a determination coefficient (R² ) of 0.7786.

CONCLUSION

The dataset is still small compared to larger and more general QSAR models; however, it is much more specific as to the type of solvent and class of materials studied. This work represents an advance for the modelling of the perfume diffusion process since it specifies important properties that until then had been treated in a more general way.

Hair Growth is Promoted in Mouse Dorsal Skin by a Mixture of Platycladus orientalis (L.) Franco Leaf Extract and Alpha-Terpineol by Increasing Growth Factors and wnt3/β-Catenin

In this study, we investigated the effect of a mixture of Platycladus orientalis (L.) Franco leaf extract and α-terpineol, a natural monoterpene alcohol (PEaT), on hair growth and its mechanisms. C57/BL6 mice (total n = 14) in the telogen phase of hair growth were used. Either distilled water as vehicle or PEaT was topically applied to the dorsal skin for 17 days. Chronological hair growth change was examined by hair growth-promoting scores. In addition, to find out mechanisms of PEaT on hair growth, insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor (VEGF), Ki-67, wnt3, and β-catenin expressions were investigated by using immunohistochemistry. We found that PEaT remarkably promoted hair growth by inducing early anagen transition compared with the control group. In addition, treatment with PEaT significantly increased numbers of Ki-67-positive cells and expressions of IGF-1, VEGF, wnt3, and β-catenin in the outer root sheath. These results indicate that PEaT used in this study might be a good hair growth promoter, showing that PEaT treatment increased growth factors and cell proliferation through upregulation of wnt3 and β-catenin expressions.

Odoriferous Therapy: A Review Identifying Essential Oils against Pathogens of the Respiratory Tract

This review explores the body of scientific information available on the antimicrobial properties of essential oils against pathogens responsible for respiratory infections and critically compares this to what is recommended in the Layman's aroma-therapeutic literature. Essential oils are predominantly indicated for the treatment of respiratory infections caused by bacteria or viruses (total 79.0 %), the efficacy of which has not been confirmed through clinical trials. When used in combination, they are often blended for presumed holistic synergistic effects. Of the essential oils recommended, all show some degree of antioxidant activity, 50.0 % demonstrate anti-inflammatory effects and 83.3 % of the essential oils showed antihistaminic activity. Of the essential oils reviewed, 43.8 % are considered non-toxic while the remaining essential oils are considered slightly to moderately toxic (43.7 %) or the toxicity is unknown (12.5 %). Recommendations are made for further research into essential oil combinations.

Anti-echinococcal activity of menthol and a novel prodrug, menthol-pentanol, against Echinococcus multilocularis

Alveolar echinococcosis is one of the most dangerous parasitic zoonoses. This disease, widely distributed in the northern hemisphere, is caused by the metacestode stage of the tapeworm Echinococcus multilocularis. All surgical and non-surgical patients should perform chemotherapy with benzimidazoles, mainly with albendazole. However, the efficacy of albendazole is variable due to its deficient pharmacokinetic properties. Therefore, the need to find new therapeutic alternatives for the treatment of alveolar echinococcosis is evident. Menthol is a natural compound of low toxicity, used in industries such as cosmetics and gastronomy and generally recognized as safe by the Food and Drug Administration. In addition, menthol has important pharmacological effects and is effective against a wide variety of organisms. The development of prodrugs allows improving the pharmacokinetic properties of the parental drug. To improve lipophilicity and therefore the bioavailability of menthol, a novel prodrug called menthol-pentanol was developed by masking the functional polar group of menthol by linking n-pentanol by a carbonate bond. The aim of the current work was to evaluate the in vitro and in vivo efficacy of menthol and menthol-pentanol against E. multilocularis. Menthol-pentanol had a greater protoscolicidal effect than menthol. In addition, the prodrug demonstrated a similar clinical efficacy to albendazole. The increase in lipophilicity of the prodrug with respect to menthol was reflected in an increase in its antiparasitic activity against E. multilocularis. Thus, menthol-pentanol appears as a promising candidate for further evaluation as a potential alternative for the treatment of alveolar echinococcosis.

Esters of terpene alcohols as highly potent, reversible, and low toxic skin penetration enhancers

Skin penetration/permeation enhancers are compounds that improve (trans)dermal drug delivery. We designed hybrid terpene-amino acid enhancers by conjugating natural terpenes (citronellol, geraniol, nerol, farnesol, linalool, perillyl alcohol, menthol, borneol, carveol) or cinnamyl alcohol with 6-(dimethylamino)hexanoic acid through a biodegradable ester linker. The compounds were screened for their ability to increase the delivery of theophylline and hydrocortisone through and into human skin ex vivo. The citronellyl, bornyl and cinnamyl esters showed exceptional permeation-enhancing properties (enhancement ratios up to 82) while having low cellular toxicities. The barrier function of enhancer-treated skin (assessed by transepidermal water loss and electrical impedance) recovered within 24 h. Infrared spectroscopy suggested that these esters fluidized the stratum corneum lipids. Furthermore, the citronellyl ester increased the epidermal concentration of topically applied cidofovir, which is a potent antiviral and anticancer drug, by 15-fold. In conclusion, citronellyl 6-(dimethylamino)hexanoate is an outstanding enhancer with an advantageous combination of properties, which may improve the delivery of drugs that have a limited ability to cross biological barriers.

Biochemical Responses of Wheat Seedlings on the Introduction of Selected Chiral Ionic Liquids to the Soils

In this study, new chiral ionic liquids (CILs) were obtained from the natural-origin material (1 R,2 S,5 R)-(-)-menthol. The physicochemical characteristics of the studied imidazolium salts were investigated. The obtained 3-ethyl-1-[(1 R,2 S,5 R)-(-)-menthoxy-methyl]imidazolium salts are nonvolatile, nonflammable, and stable in air, in contact with water, and in commonly used organic solvents. The influences of the obtained chiral salts on physiological and biochemical parameters were determined for wheat ( Triticum aestivum L.) seedlings. Both salts led to changes in plant metabolism, which resulted in decreased assimilation pigments, decreased fresh weight, and increased dry weight and proline in wheat seedlings. Moreover, the growth of the above-ground parts and roots was inhibited. Additionally, there was a drop in the potential and germination capacity of wheat seeds after using the highest concentrations of the ionic liquids. The salts caused oxidative stress in wheat seedlings, which was demonstrated by increased malondialdehyde content. In response, the plants engaged their defensive system against free oxygen radicals, which resulted in increased catalase and peroxidase activity and decreased H₂O₂ levels in the plants. There were no changes in the activity of superoxide dismutase. All of the changes observed in the levels of determined biomarkers of oxidative stress in the plants were linearly correlated with the increase in the concentrations of the chiral ionic liquids in the soil. The salt with hexafluorphosphate anion exhibited slightly higher toxicity toward wheat seedlings than the other salt. The CILs led to premature aging of plants, which was demonstrated by the increase in peroxidase activity and a decrease of chlorophyll in the seedlings. The experiment also showed good correlation between the increase in peroxidase activity and the decrease in chlorophyll level, which proves that the decrease in chlorophyll content resulted from not only the increase in CILs concentration in the soil but also the increased POD activity, which leads to the damage of chlorophyll particles.

Fisetin loaded binary ethosomes for management of skin cancer by dermal application on UV exposed mice

Fisetin loaded binary ethosomes were prepared and optimized using Box-Behnken design for dermal application to alleviate skin cancer. The prepared formulations were evaluated for vesicle size, entrapment efficiency and flux of fisetin. Additionally, the optimized formulation was further evaluated by transmission electron microscopy, confocal laser microscopy, vesicles-skin interaction, dermatokinetic study and DPPH (2, 2-diphenyl-1-picryl-hydrazyl) assay. The in vivo study was carried out for the evaluation of tumor incidence, pro-inflammatory cytokines such as TNF-α and IL-1α, lipid peroxidation values, glutathione content and catalase activity in mice. The optimized binary ethosomes formulation presented sealed unilamellar shaped vesicles, with vesicles size, entrapment efficiency and flux of 99.89 ± 3.24 nm, 89.23 ± 2.13% and 1.01 ± 0.03 µg/cm²/h respectively. The confocal images of rat skin clearly illustrated the deeper penetration of rhodamine B loaded binary ethosomes formulation. Further, the binary ethosomes gel treated rat skin showed substantial increase in C_{Skin max} and AUC_0-8 in comparison to rat skin treated with conventional gel. In vivo study revealed that the mice pre-treated with fisetin binary ethosomes gel caused marked decrease in the levels of TNF-α and IL-1α as compared to the mice exposed to UV only. Further the binary ethosomes gel treated mice group had demonstrated less percentage of tumour incidences (49%) as compared to mice treated with UV only (96% tumour incidence). The novelty of the work lies in successful optimization of formulation using Box-Behnken design and characterization of binary ethosomes carrier of fisetin and demonstration of improved dermal delivery of the same. The overall data suggest that the fisetin loaded binary ethosomes formulation is a potential dermal delivery system for the management of skin cancer.

Enhancement of Transdermal Delivery of Haloperidol via Spanlastic Dispersions: Entrapment Efficiency vs. Particle Size

Haloperidol (Hal) is a well-known typical antipsychotic. Hepatic first pass metabolism leads to its limited oral bioavailability. This study aimed at enhancing transdermal delivery of Hal via spanlastic formulae. Hal-loaded spanlastics of Span®60 and an edge activator (EA) were successfully prepared by ethanol injection method according to a 3¹.4¹ full factorial design. In this design, independent variables were X₁, EA type, and X₂, Span®60 to EA ratio. Y₁, percentage entrapment efficiency (EE%); Y₂, particle size (PS); Y₃, deformability index (DI); and Y₄, percentage drug released after 4h (Q4h), were chosen as dependent variables. The Fourier-transform infrared spectral analysis showed no considerable chemical interaction between Hal and the used excipients. Both factors affected significantly all the responses except DI. Desirability of each prepared formula was calculated based on maximizing EE% and Q4h and minimizing PS. Formula F6, with X₁, Tween®80, and X₂, 8:2, had the highest desirability value followed by F7, with X₁, Tween®80, and X₂, 6:4, and both were chosen as selected formulae (SF) for further investigation. F6 (having more entrapped Hal), F7 (of smaller PS), and Hal solution in propylene glycol were subjected to ex vivo permeation test through newborn rat skin. Both formulae showed marked enhancement in drug permeation compared with drug solution. The significantly higher Q_36h and J_36h of F7 from F6 may indicate that the smaller particle size aided more than higher entrapment in achieving a higher permeation for Hal of 3.5±0.2μg/cm².h. These results are promising for further investigation of this formula.

Cationic Moieties in Polystyrene Gels Swollen with d-Limonene Improved Transdermal Delivery System

d-limonene, a terpene and natural compound, has been found to be an excellent penetration enhancer for transdermal drug delivery (TDD). It hence has been incorporated within various transdermal formulations. Herein, we report the application of polystyrene gel swollen with d-limonene and its derivatives for TDD. Poly(styrene-co-divinylbenzene) (PS gel), poly(styrene-co-divinylbenzene-co-4-vinylpyridine) (PS-4VP) gel and poly(styrene-co-divinylbenzene-co-(vinylbenzyl) trimethylammonium chloride) (PS-VBAC gel) were employed as chemical gels to improve the stability of the TDD substrates. The drug permeation properties from the PS gels swollen in limonene were examined, regarding the effect of its network density as well as their rheological properties. The lowest density of the network showed the highest steady flux of the permeation at 43.7 ± 0.3 μg/cm². FT-IR spectra were confirmed for PS-4VP and PS-VBAC, bearing cationic moieties and they could control the release of ibuprofen by the electrostatic interaction at the interface of organogel and skin. The steady state flux of skin permeation got low values from 55.2 ± 0.8 to 11.6 ± 2.0 μg/cm², when the cationic moieties were increased. Moreover, the chemical network of PS gel swollen in limonene showed high mechanical stability illustrated by elastic modulus (G') of about 98 kPa for 10% cross-linked PS gel. The developed PS gels swollen in limonene show highly promising results, suggesting their possible application in TDD.

Germacrone and sesquiterpene-enriched extracts from Curcuma aeruginosa Roxb. increase skin penetration of minoxidil, a hair growth promoter

Minoxidil is approved for topical treatment of androgenic alopecia but hampered by poor cutaneous absorption. Recently, the randomized control trial showed that hair loss treatment of minoxidil was improved by co-application of the anti-androgen, Curcuma aeruginosa Roxb. extract. Here, we aimed to show that the apparent synergism arises from improved cutaneous penetration of minoxidil by bioactive compound, germacrone or C. aeruginosa (as an n-hexane extract, or essential oil). The partition coefficient of germacrone was determined by HPLC. Skin penetration was measured ex vivo on Franz diffusion cells using full thickness human foreskin as membranes. The receiver solution was sampled hourly for 8 h after which the skin was removed, the stratum corneum separated, and minoxidil assayed in this and in the remaining viable skin layer by HPLC. Skin penetration of minoxidil with 0.2 and 2% extract was increased ~ 4-fold (accumulated amount in receiver + skin viable layer after 8 h). Furthermore, germacrone enhanced minoxidil flux by ~ 10-fold and C. aeruginosa essential oil by ~ 20-fold. This work suggests three clinical consequences: (i) minoxidil efficacy is promoted, (ii) lower doses of minoxidil suffice, and (iii) C. aeruginosa extract/essential oil or germacrone can supplement treatment outcomes by acting as anti-androgen, thereby introducing a more effective topical treatment strategy for androgenic alopecia.

Third-Generation Transdermal Delivery Systems Containing Zidovudine: Effect of the Combination of Different Chemical Enhancers and a Microemulsion System

This study aimed to examine the influence of the combination of chemical enhancers and a microemulsion on the transdermal permeation of zidovudine (AZT). Ethanol, 1,8-cineole, and geraniol were incorporated in a microemulsion. The droplet size, zeta potential, rheology, and SAXS analysis were performed. The permeation enhancer effect was evaluated using pig ear skin. Snake skin (Boa constrictor) treated with the formulations was also used as a stratum corneum model and studied by attenuated total reflectance-infrared spectroscopy. As a result, it was observed that the incorporation of the chemical enhancers promoted a decrease of the droplet size and some rheological modifications. The 1,8-cineole associated with the microemulsion significantly increased the permeated amount of AZT. Conversely, ethanol significantly increased the quantity of the drug retained in the skin. The probable mechanism for the cineole and ethanol effects was respectively: fluidization and increasing of the diffusion coefficient, and increasing of the partition coefficient. Surprising, geraniol + microemulsion drastically decreased both the permeated and the retained amount of AZT into the skin. Thus, the adequate association of microemulsion and chemical enhancers showed to be a crucial step to enable the topical or transdermal use of drugs.

Penetration enhancer-containing spanlastics (PECSs) for transdermal delivery of haloperidol: in vitro characterization, ex vivo permeation and in vivo biodistribution studies

Haloperidol (Hal) is one of the widely used antipsychotic drugs. When orally administered, it suffers from low bioavailability due to hepatic first pass metabolism. This study aimed at developing Hal-loaded penetration enhancer-containing spanlastics (PECSs) to increase transdermal permeation of Hal with sustained release. PECSs were successfully prepared using ethanol injection method showing reasonable values of percentage entrapment efficiency, particle size, polydispersity index and zeta potential. The statistical analysis of the ex vivo permeation parameters led to the choice of F1L – made of Span^® 60 and Tween^® 80 at the weight ratio of 4:1 along with 1% w/v Labrasol^® – as the selected formula (SF). SF was formulated into a hydrogel by using 2.5% w/v of HPMC K4M. The hydrogel exhibited good in vitro characteristics. Also, it retained its physical and chemical stability for one month in the refrigerator. The radiolabeling of SF showed a maximum yield by mixing of 100 µl of diluted formula with 50 µl saline having 200 MBq of ^99mTc and containing 13.6 mg of reducing agent (NaBH₄) and volume completed to 300 µl by saline at pH 10 for 10 min as reaction time. The biodistribution study showed that the transdermal ^99mTc-SF hydrogel exhibited a more sustained release pattern and longer circulation duration with pulsatile behavior in the blood and higher brain levels than the oral ^99mTc-SF dispersion. So, transdermal hydrogel of SF may be considered a promising sustained release formula for Hal maintenance therapy with reduced dose size and less frequent administration than oral formula.

α-Terpineol, a natural monoterpene: A review of its biological properties

Terpineols are monocyclic monoterpene tertiary alcohols which are naturally present in plant species. There are five common isomers of terpineols, alpha-, beta-, gamma-, delta- and terpinen-4-ol, of which α-terpineol and its isomer terpinen-4-ol are the most common terpineols found in nature. α-Terpineol plays an important role in the industrial field. It has a pleasant odor similar to lilacs and it is a common ingredient in perfumes, cosmetics, and aromatic scents.

In addition, α-terpineol attracts a great interest as it has a wide range of biological applications as an antioxidant, anticancer, anticonvulsant, antiulcer, antihypertensive, anti-nociceptive compound. It is also used to enhance skin penetration, and also has insecticidal properties. This study reviews the relevance of α-terpineol based on scientific findings on Google Scholar, Pubmed, Web of Science, Scopus and Chemical Abstracts.

Collectively, the use of α-terpineol in medicine and in the pharmaceutical industry plays an important role in therapeutic applications. This review will, therefore, support future research in the utilization of α-terpineol.

Copaiba oil enhances in vitro/in vivo cutaneous permeability and in vivo anti-inflammatory effect of celecoxib

OBJECTIVES

The aim of this article was to use copaiba oil (C.O) to improve skin permeability and topical anti-inflammatory activity of celecoxib (Cxb).

METHODS

Formulations containing C.O (1-50%) were associated with Cxb (2%). In vitro skin permeability studies were conducted using porcine ear skin. Histological analysis of the hairless mice skin samples after application of formulations was achieved with the routine haematoxylin/eosin technique. The anti-inflammatory activity was assessed using the AA-induced ear oedema mice model.

KEY FINDINGS

The formulation containing 25% C.O promoted the highest levels of in vitro Cxb permeation through pig ear skin, retention in the stratum corneum (SC) and epidermis/dermis of pig ear skin in vitro (~5-fold) and hairless mice skin in vivo (~2.0-fold), as compared with the control formulation. At 25%, C.O caused SC disorganization and increased cell infiltration and induced angiogenesis without clear signs of skin irritation. The formulation added to 25% C.O as adjuvant inhibited ear oedema and protein extravasation by 77.51 and 89.7%, respectively, and that it was, respectively, 2.0- and 3.4-fold more efficient than the commercial diethylammonium diclofenac cream gel to suppress these inflammatory parameters.

CONCLUSIONS

25% C.O is a potential penetration enhancer for lipophilic drugs like Cxb that can improve cutaneous drug penetration and its anti-inflammatory activity.

A red-emitting indolium fluorescence probe for membranes - flavonoids interactions

The red-emitting indolium derivative compound (E)-2-(4-(diphenylamino)styryl)-1,3,3-trimethyl-3H-indol-1-ium iodide (H3) was demonstrated as a sensitive membrane fluorescence probe. The probe located at the interface of liposomes when mixed showed much fluorescence enhancement by inhibiting the twisted intramolecular charge transfer state. After ultrasonic treatment, it penetrated into lipid bilayers with the emissions leveling off and a rather large encapsulation efficiency (71.4%) in liposomes. The ζ-potential and particle size measurement confirmed that the charged indolium group was embedded deeply into lipid bilayers. The probe was then used to monitor the affinities of antioxidant flavonoids for membranes. It was verified that quercetin easily interacted with liposomes and dissociated the probe from the internal lipid within 60 s under the condition of simply mixing. The assessment of binding affinities of six flavonoids and the coincident results with their antioxidation activities indicated that it was a promising membrane probe for the study of drug bio-affinities.

Elucidation of penetration enhancement mechanism of Emu oil using FTIR microspectroscopy at EMIRA laboratory of SESAME synchrotron

It has been proposed that Emu oil possesses skin permeation-enhancing effect. This study aimed to address its possible penetration enhancement mechanism(s) using IR microscopy, in accordance with LPP theory. The penetration of Emu oil through the layers of human skin was accomplished by monitoring oil-IR characteristic feature at 3006cm^-1. The unsaturated components of Emu oil accumulated at about 270μm depth of skin surface. The interaction of Emu oil with lipid and protein constituents of SC was investigated in comparison with a commonly used enhancer, IPM. Inter-sample spectral differences were identified using PCA and linked with possible enhancement mechanisms. Emu oil treatment caused a change in the slope of the right contour of amide I band of the protein spectral range. This was also clear in the second derivative spectra where the emergence of a new shoulder at higher frequency was evident, suggesting disorganization of keratin α-helix structure. This effect could be a result of disruption of some hydrogen bonds in which amide CO and NH groups of keratin are involved. The low intensity of the emerged shoulder is also in agreement with formation of weaker hydrogen bonds. IPM did not affect the protein component. No conclusions regarding the effect of penetration enhancers on the SC lipids were obtained. This was due to the overlap of the endogenous (skin) and exogenous (oil) CH stretching and scissoring frequencies. The SC carbonyl stretching peak disappeared as a result of IPM treatment which may reflect some degree of lipid extraction.

Enhancing blood donor skin disinfection using natural oils

BACKGROUND

Effective donor skin disinfection is essential in preventing bacterial contamination of blood components with skin flora bacteria like Staphylococcus epidermidis. Cell aggregates of S. epidermidis (biofilms) are found on the skin and are resistant to the commonly used donor skin disinfectants chlorhexidine-gluconate and isopropyl alcohol. It has been demonstrated that essential oils synergistically enhance the antibacterial activity of chlorhexidine-gluconate. The objective of this study was to test plant-extracted essential oils in combination with chlorhexidine-gluconate or chlorhexidine-gluconate plus isopropyl alcohol for their ability to eliminate S. epidermidis biofilms.

STUDY DESIGN AND METHODS

The composition of oils extracted from Artemisia herba-alba, Lavandula multifida, Origanum marjoram, Rosmarinus officinalis, and Thymus capitatus was analyzed using gas chromatography-mass spectrometry. A rabbit model was used to assess skin irritation caused by the oils. In addition, the anti-biofilm activity of the oils used alone or in combination with chlorhexidine-gluconate or chlorhexidine-gluconate plus isopropyl alcohol was tested against S. epidermidis biofilms.

RESULTS

Essential oil concentrations 10%, 20%, and 30% were chosen for anti-biofilm assays, because skin irritation was observed at concentrations greater than 30%. All oils except for O. marjoram had anti-biofilm activity at these three concentrations. L. multifida synergistically enhanced the anti-biofilm activity of chlorhexidine-gluconate and resulted in the highest anti-biofilm activity observed when combined with chlorhexidine-gluconate plus isopropyl alcohol. Gas chromatography-mass spectrometry revealed that the main component contributing to the activity of L. multifida oil was a natural terpene alcohol called linalool.

CONCLUSION

The anti-biofilm activity of chlorhexidine-gluconate plus isopropyl alcohol can be greatly enhanced by L. multifida oil or linalool. Therefore, these components could potentially be used to improve blood donor skin disinfection.

Cutaneous Penetration-Enhancing Effect of Menthol: Calcium Involvement

Menthol is a naturally occurring terpene used as a penetration enhancer in topical and transdermal formulations. Literature shows a growing interest in menthol's interactions with the transient receptor potential melastatin 8. A decrease in extracellular Ca²⁺ due to the activation of the transient receptor potential melastatin 8 receptor produces inhibition of E-cadherin expression that is responsible for cell-cell adhesion. Because calcium is present in the entire epidermis, the purpose of this study is to evaluate whether the aforementioned properties of menthol are also related to its penetration-enhancing effects. We formulated 16 gels: (i) drug-alone (diphenhydramine or lidocaine), (ii) drug with menthol, (iii) drug, menthol, and calcium channel blocker (CCB; verapamil or diltiazem), and (iv) drug and CCB. In vitro studies showed no effect of the CCB on the release of the drugs either with or without menthol. In vivo experiments were performed for each drug/menthol/CCB combination gel by applying 4 formulations on a shaved rabbit's dorsum on the same day. Dermis concentration profiles were assessed with microdialysis. The gels containing menthol showed higher penetration of drugs than those without whereas the addition of the CCB consistently inhibited the penetration-enhancing effects of menthol. In summary, these findings strongly support the involvement of calcium in the penetration-enhancing effect of menthol.

Enhanced acyclovir delivery using w/o type microemulsion: preclinical assessment of antiviral activity using murine model of zosteriform cutaneous HSV-1 infection

The present study was aimed to develop and evaluate a microemulsion-based dermal drug delivery of an antiviral agent, acyclovir. A water-in-oil microemulsion was prepared using isopropyl myristate, Tween 20, Span 20, water and dimethylsulphoxide. It was characterized for drug content, stability, globule size, pH, viscosity and ex vivo permeation through mice skin. In vivo antiviral efficacy of optimized formulation was assessed in female Balb/c mice against herpes simplex virus-I (HSV-I)-induced infection. It was observed that optimized formulation when applied 24-h post-infection could completely inhibit the development of cutaneous herpetic lesions vis-à-vis marketed cream.

Intranasal haloperidol-loaded miniemulsions for brain targeting: Evaluation of locomotor suppression and in-vivo biodistribution

Haloperidol is a commonly prescribed antipsychotic drug currently administered as oral and injectable preparations. This study aimed to prepare haloperidol intranasal miniemulsion helpful for psychiatric emergencies and exhibiting lower systemic exposure and side effects associated with non-target site delivery. Haloperidol miniemulsions were successfully prepared by spontaneous emulsification adopting 2(3) factorial design. The effect of three independent variables at two levels each namely; oil type (Capmul®-Capryol™90), lipophilic emulsifier type (Span 20-Span 80) and HLB value (12-14) on globule size, PDI and percent locomotor activity inhibition in mice was evaluated. The optimized formula (F4, Capmul®, Tween 80/Span 20, HLB 14) showed globule size of 209.5±0.98nm, PDI of 0.402±0.03 and locomotor inhibition of 83.89±9.15% with desirability of 0.907. Biodistribution study following intranasal and intravenous administration of the radiolabeled (99m)Tc mucoadhesive F4 revealed that intranasal administration achieved 1.72-fold higher and 6 times faster peak brain levels compared with intravenous administration. Drug targeting efficiency percent and brain/blood exposure ratios remained above 100% and 1 respectively after intranasal instillation compared to a maximum brain/blood exposure ratio of 0.8 post intravenous route. Results suggested the CNS delivery of major fraction of haloperidol via direct transnasal to brain pathway that can be a promising alternative to oral and parenteral routes in chronic and acute situations. Haloperidol concentration of 275.6ng/g brain 8h post intranasal instillation, higher than therapeutic concentration range of haloperidol (0.8 to 5.15ng/ml), suggests possible sustained delivery of the drug through nasal route.

The Effect of Various Vehicles on the Naproxen Permeability through Rat Skin: A Mechanistic Study by DSC and FT-IR Techniques

PURPOSE

The purpose of the present investigation was to evaluate the effectiveness of different vehicles on drug permeability and microstructure of intercellular or lipids in SC layer of skin.

METHODS

Pre-treated skin of rat using some vehicles including Labarac PG ,Transcutol P, tween 80, span 80 and propylene glycol (PG), were mounted on specialized design franz-diffusion cell was used to assess naproxen permeation and parameters such as permeability coefficients and state flux (Jss) were evaluated. Any differences in peak position and also change in symmetric and asymmetric stretching of C-H bond, lipid ester carbonyl stretching in SC, C=O stretching (Amide I) and C-N stretching of keratin (Amide II) absorbance using Fourier transform infrared spectroscopy (FTIR) were considered to investigate the enhancing mechanism. DSC method was utilized to compare their mean transition temperature (Tm) and enthalpies (ΔH).

RESULTS

Steady-state flux (Jss), permeability coefficient (Kp) and diffusion coefficient (D) were significantly (p<0.05) increased by using their span80 showed the biggest enhancement ratio (ERflux) and Transcutol P, Labrafac PG, Tween 80 and Propylene glycol were at the next levels. In comprised to hydrated rat skin the maximum increase in diffusion coefficient was for Tween 80(p<0.05), Lipid fluidization, lipid disruption structure and the irreversible denaturation of proteins in the SC layer of skin by span 80, Tween 80, Labrafac PG, Transcutol P and propylene glycol, were indicated by FT-IR and DSC techniques.

CONCLUSION

It is concluded that naproxen permeation through rat skin may be facilitated by utilizing the vehicle systems. Lipid fluidization and lipid extraction are among suggested mechanisms.

The Effect of Various Vehicles on the Naproxen Permeability through Rat Skin: A Mechanistic Study by DSC and FT-IR Techniques

PURPOSE

The purpose of the present investigation was to evaluate the effectiveness of different vehicles on drug permeability and microstructure of intercellular or lipids in SC layer of skin.

METHODS

Pre-treated skin of rat using some vehicles including Labarac PG ,Transcutol P, tween 80, span 80 and propylene glycol (PG), were mounted on specialized design franz-diffusion cell was used to assess naproxen permeation and parameters such as permeability coefficients and state flux (Jss) were evaluated. Any differences in peak position and also change in symmetric and asymmetric stretching of C-H bond, lipid ester carbonyl stretching in SC, C=O stretching (Amide I) and C-N stretching of keratin (Amide II) absorbance using Fourier transform infrared spectroscopy (FTIR) were considered to investigate the enhancing mechanism. DSC method was utilized to compare their mean transition temperature (Tm) and enthalpies (ΔH).

RESULTS

Steady-state flux (Jss), permeability coefficient (Kp) and diffusion coefficient (D) were significantly (p<0.05) increased by using their span80 showed the biggest enhancement ratio (ERflux) and Transcutol P, Labrafac PG, Tween 80 and Propylene glycol were at the next levels. In comprised to hydrated rat skin the maximum increase in diffusion coefficient was for Tween 80(p<0.05), Lipid fluidization, lipid disruption structure and the irreversible denaturation of proteins in the SC layer of skin by span 80, Tween 80, Labrafac PG, Transcutol P and propylene glycol, were indicated by FT-IR and DSC techniques.

CONCLUSION

It is concluded that naproxen permeation through rat skin may be facilitated by utilizing the vehicle systems. Lipid fluidization and lipid extraction are among suggested mechanisms.

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.