Research paper
Polyglycerol fatty acid ester surfactant–based microemulsions for targeted delivery of ceramide AP into the stratum corneum: Formulation, characterisation, in vitro release and penetration investigation

https://doi.org/10.1016/j.ejpb.2012.05.017Get rights and content

Abstract

Ceramide AP (CER [AP]) is an integral component of the stratum corneum (SC) lipid matrix and is capable of forming tough and super stable lamellae. It may help to restore the barrier function in aged and affected skin. However, its effectiveness from conventional dosage forms is limited due to its poor solubility and penetration into the SC. Therefore, stable polyglycerol fatty acid ester surfactant (SAA)-based CER [AP] microemulsions (MEs) were formulated and characterised to enhance its solubilisation and penetration into the SC. TEGO® CARE PL 4 (TCPL4: polyglycerol-4-laurate), isopropyl palmitate (IPP) and water-1, 2 pentandiol (PeG) were used as amphiphilic, oily and hydrophilic components, respectively. The effects of HYDRIOL® PGMO.4 (HPGMO4: polyglyceryl-4-oleate) as a co-surfactant (co-SAA) and linoleic acid (Lin A) as part of the oil component on the stability and characteristics of the MEs were investigated. EPR results were used for the first time to reveal MEs nanostructures. The release and penetration behaviour of the MEs was assessed in vitro by using a multi-layer membrane model. The results obtained showed that HPGMO4 and Lin A increased stability and expanded the ME region considerably. The formulations were stable for 10 to >24 months. Dynamic light scattering (DLS) results showed that the droplets were bigger and asymmetric, which might be helpful to localise the CER into the upper layers of the epidermis. Release and penetration from the MEs was superior as compared to the hydrophilic cream (DAB). The rate and extent of CER [AP] released and penetrated from O/W MEs was better than W/O MEs.

Graphical abstract

The different nanostructures of CER [AP] MEs as characterised by EPR and other conventional techniques as well as their in vitro release and penetration profiles into the stratum corneum in comparison with a conventional hydrophilic cream.

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Introduction

Skin is the largest organ of the body and provides barrier against harmful environmental insults and loss of water and other essential components from body. The barrier function is solely founded on the SC (10–20 μm thick [1]) [2], which contains about 15 layers of corneocytes (flat dead cells filled with keratin filaments and water [3]) separated by a unique and complex mixture of highly ordered multi-lamellar lipid sheets [2], [4], [5]. The corneocytes are surrounded by a very dense corneocyte envelope, which is impermeable to most diffusing substances [6]. Thus, the main penetration pathway through the SC remains the intercellular lipid lamella [6], [7], and its main components are CERs, cholesterol and free fatty acids (FFAs), which exist nearly in equimolar amounts [2], [8].

CERs are sphingolipids that contain a sphingoid moiety (which can be sphingosine (S), dihydrosphingosine (D), phytosphingosine (P) or 6-hydroxy-sphingosine (H)), linked with a long-chain FFA moiety (which can be nonhydroxy (N), α-hydroxy (A) or ester-linked ω-hydroxy (EO)) through an amide bond [3], [9]. To date, 12 different classes of free CERs have been identified in human SC, which are named as “Ceramide XY” where “X” represents the type of FFA moiety and Y represents the type of sphingoid base [10], [11]. They play a major role in the water-retaining properties of the epidermis and are claimed to dramatically increase skin’s hydration level, repair the cutaneous barrier, prevent vital moisture loss, and contribute to reducing dry flaky skin and aged appearance [8], [10], [12]. They can also be used against some skin diseases such as atopic dermatitis [12] and psoriasis [3], [8]. Schröter et al. [13] indicated that CER [AP], with four hydroxyl groups on its head group, is capable of forming super stable membranes through formation of strong hydrogen bonds. It has also been shown to be antiproliferative and proapoptotic in numerous cancer cell types in vitro [14]. Therefore, administration of CER [AP] to the skin might help to restore the barrier function of aged and affected skin.

However, the effectiveness of CER [AP], like other CERs, is limited due to its inherent hydrophobicity and precipitation as fine lipid micellar suspensions when administered in hydrophilic formulations. From conventional dosage forms, CERs cannot penetrate the SC [14], [15] to reach the SC/SG interface, where the SC lipids are organised into meaningful lamellae [16], [17], [18], [19]. Therefore, to realise the therapeutic benefits of CER [AP], an appropriate drug delivery system that can enhance its solubility and penetration into the SC should be developed.

Microemulsions (MEs) are transparent, low-viscous, optically isotropic and thermodynamically stable colloidal dispersions of oil and water, which are stabilised by an interfacial film of a SAA, in most cases in combination with a co-SAA [20], [21]. In recent years, they have emerged as promising vehicles for dermal and transdermal delivery of drugs [22], [23], [24], [25], [26], [27], [28]. They possess large solubilisation capacity attributing to their immense interfacial area and the presence of various microdomains of different polarities [29], [30], [31], [32], [33]. They also significantly enhance penetration of hydrophilic, lipophilic and amphiphilic substances into and through biological membranes [23], [34], [35]. Besides, they are easy to formulate [29], [30], [31], [33], have relatively low viscosity [29], [30], [36] and have self-preserving property [37]. However, formulation of MEs might need high level of SAAs that might irritate the skin. Therefore, the objective of this work was to develop CER [AP] MEs that can enhance the permeability of the CER into the SC using safe and mild SAAs.

Section snippets

Materials

CER [AP] and TCPL4 were kindly donated by Evonik-Goldschmidt GmbH (Essen, Germany). HPGMO4 was a gift from Hydrior AG massgeschneiderte Tenside (Wettingen, Germany). PeG was kindly supplied by Symrise GmbH & Co KG (Holzminden, Germany). Lin A was purchased from Sigma-Aldrich Chemie GmbH (Taufkirchen, Germany). IPP and 4% collodion were obtained from Caesar & Loretz GmbH (Hilden, Germany). 14N HD-PMI (HD-PMI: 2-heptadecyl-2,3,4,5,5-pentamethyl-imidazoline-1-oxyl) was supplied by Institute of

Determination of solubility of CER [AP] in various solvents

As can be seen in Table 1, preceding development of CER [AP] MEs, the solubility of the lipid was determined in various solvents, oils and co-solvents at RT (21–23 °C) and 32 °C. The results in the table showed that solubility of CER [AP] increased considerably as the temperature increases. However, according to solubility classification, CER [AP] was practically insoluble in water, all the oils investigated and PG at both RT and 32 °C.

Formulation of CER [AP] MEs

A preliminary study was carried out to choose ME components

Acknowledgements

The authors would like to thank Manuela Woigk, Kerstin Schwarz and Adelheid Pötzsch for their excellent technical assistance. We are also grateful to Dr. Karsten Busse for his contribution during measurement and analysis of data Using PCS. Fitsum F. Sahle greatly acknowledges the financial support provided by the German Academic Exchange Service (DAAD).

References (75)

  • A. Schröter et al.

    Basic nanostructure of stratum corneum lipid matrices based on ceramides [EOS] and [AP]: a neutron diffraction study

    Biophys. J.

    (2009)
  • M. Loden

    The skin barrier and use of moisturizers in atopic dermatitis

    Clin. Dermatol.

    (2003)
  • J.A. Bouwstra et al.

    The skin barrier in healthy and diseased state

    Biochim. Biophys. Acta

    (2006)
  • X. Zhao et al.

    Enhancement of transdermal delivery of theophylline using microemulsion vehicle

    Int. J. Pharm.

    (2006)
  • L. Djekic et al.

    The influence of cosurfactants and oils on the formation of pharmaceutical microemulsions based on PEG-8 caprylic/capric glycerides

    Int. J. Pharm.

    (2008)
  • W. Zhu et al.

    Microemulsion-based hydrogel formulation of penciclovir for topical delivery

    Int. J. Pharm.

    (2009)
  • C.H. Liu et al.

    Terpene microemulsions for transdermal curcumin delivery: effects of terpenes and cosurfactants

    Colloids Surf. B: Biointerfaces

    (2011)
  • R.M. Hathout et al.

    Microemulsion formulations for the transdermal delivery of testosterone

    Eur. J. Pharm. Sci.

    (2010)
  • R.M. Hathout et al.

    Visualization, dermatopharmacokinetic analysis and monitoring the conformational effects of a microemulsion formulation in the skin stratum corneum

    J. Colloid Interface Sci.

    (2011)
  • J.S. Yuan et al.

    Linker-based lecithin microemulsions for transdermal delivery of lidocaine

    Int. J. Pharm.

    (2008)
  • W. Zhu et al.

    Formulation design of microemulsion for dermal delivery of penciclovir

    Int. J. Pharm.

    (2008)
  • G.M. El Maghraby

    Self-microemulsifying and microemulsion systems for transdermal delivery of indomethacin: effect of phase transition

    Colloids Surf. B: Biointerfaces

    (2010)
  • N. Pakpayat et al.

    Formulation of ascorbic acid microemulsions with alkyl polyglycosides

    Eur. J. Pharm. Biopharm.

    (2009)
  • M.J. Lawrence et al.

    Microemulsion-based media as novel drug delivery systems

    Adv. Drug Deliv. Rev.

    (2000)
  • W. Chaiyana et al.

    Characterization of potent anticholinesterase plant oil based microemulsion

    Int. J. Pharm.

    (2010)
  • J.S. Yuan et al.

    Effect of surfactant concentration on transdermal lidocaine delivery with linker microemulsions

    Int. J. Pharm.

    (2010)
  • X.Y. Zhao et al.

    Rheological properties and microstructures of gelatin-containing microemulsion-based organogels

    Colloids Surfaces A: Physicochem. Eng. Aspects

    (2006)
  • A.A. Date et al.

    Parenteral microemulsions: an overview

    Int. J. Pharm.

    (2008)
  • K. Raith et al.

    Profiling of human stratum corneum ceramides by liquid chromatography–electrospray mass spectrometry

    Anal. Chim. Acta

    (2000)
  • R. Neubert et al.

    A multilayer membrane system for modelling drug penetration into skin

    Int. J. Pharm.

    (1991)
  • F. Zhong et al.

    Formation and characterisation of mint oil/S and CS/water microemulsions

    Food Chem.

    (2009)
  • M. Fanun

    Formulation and characterization of microemulsions based on mixed nonionic surfactants and peppermint oil

    J. Colloid Interface Sci.

    (2010)
  • K. Margulis-Goshen et al.

    Formation of organic nanoparticles from volatile microemulsions

    J. Colloid Interface Sci.

    (2010)
  • O. Rojas et al.

    A new type of microemulsion consisting of two halogen-free ionic liquids and one oil component

    Colloids Surfaces A: Physicochem. Eng. Aspects

    (2010)
  • V. Castellino et al.

    The hydrophobicity of silicone-based oils and surfactants and their use in reactive microemulsions

    J. Colloid Interface Sci.

    (2011)
  • A. Graf et al.

    Protein delivery using nanoparticles based on microemulsions with different structure-types

    Eur. J. Pharm. Sci.

    (2008)
  • X. Fu et al.

    Conductivity study on the w/o microemulsion of a saponified mono(2-ethylhexyl) phosphoric acid extractant system

    Colloids Surfaces A: Physicochem. Eng. Aspects

    (1996)
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