Microemulsion Systems and Their Potential as Drug Carriers

Alany, Raid G.; Maghraby, Gamal M. El; Krauel-Goellner, Karen; Graf, Anja

doi:10.1201/9781420089608.ch9

Cited by 5 publications

(7 citation statements)

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“…In this way, it is suggested that the structuring of the formulation is dependent on the oil/surfactant ratio. The higher the surfactant concentration, the more liquid crystal domains are formed, making the formulation more organized [19].…”

Section: Resultsmentioning

confidence: 99%

Bioadhesive Surfactant Systems for Methotrexate Skin Delivery

et al. 2016

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Methotrexate (MTX) is an immunosuppressive drug for systemic use in the treatment of skin diseases, however, MTX presents a number of side effects, such as hepatotoxicity. To overcome this limitation, this study developed skin MTX delivery surfactant systems, such as a microemulsion (ME) and a liquid crystalline system (LCS), consisting of a glycol copolymer-based silicone fluid (SFGC) as oil phase, polyether functional siloxane (PFS) as surfactant, and carbomer homopolymer type A (C971) dispersion at 0.5% (wt/wt) as aqueous phase. Polarized light microscopy and small-angle X-ray scattering evidenced the presence of hexagonal and lamellar LCSs, and also a ME. Texture profile and in vitro bioadhesion assays showed that these formulations are suitable for topical application, showing interesting hardness, adhesiveness and compressibility values. Rheology analysis confirmed the Newtonian behaviour of the ME, whereas lamellar and hexagonal LCSs behave as pseudoplastic and dilatant non-Newtonian fluids, respectively. In vitro release profiles indicated that MTX could be released in a controlled manner from all the systems, and the Weibull model showed the highest adjusted coefficient of determination. Finally, the formulations were not cytotoxic to the immortalized human keratinocyte line HaCaT. Therefore, these bioadhesive surfactant systems established with PFS and C971 have great potential as skin delivery systems.

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Section: Resultsmentioning

confidence: 99%

Bioadhesive Surfactant Systems for Methotrexate Skin Delivery

et al. 2016

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“…True colloids obey Einstein equation (hϭh · (1ϩ2.5j)). 5) Below 20% (w/w) the attractive interaction and molecular reorganization of droplets at the interface will dominate. Above 20% (w/w) the viscosity changes are gradual, which is characteristic for bicontinuous systems.…”

Section: )mentioning

confidence: 99%

“…In general microemulsions display Newtonian flow with low viscosity whilst liquid crystals exhibit non-Newtonian flow and are of relatively high viscosity. 5) Furthermore viscosity can also be used to study the microstructure of microemulsions. [6][7][8] Normally o/w microemulsions have a lower viscosity compared to w/o microemulsions in which the more viscous oil forms the external phase.…”

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confidence: 99%

“…Moreover microemulsions are known to have different microstructures namely oil in water (o/w), water in oil (w/o) and bicontinuous. 5) Elucidating the internal structure of microemulsions is of a great interest as the phase behaviour of these systems can influence drug solubility, stability and in vitro release. Phase behaviour of microemulsions can be monitored through visual inspection, measuring electrical conductivity, viscosity, droplets size, density determination, surface tension measurements, and diffusion coefficient measurements.…”

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Formulation and Physicochemical Characterization of Imwitor 308 Based Self Microemulsifying Drug Delivery Systems

Zargar‐Shoshtari

Wen

Alany

2010

CHEMICAL & PHARMACEUTICAL BULLETIN

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Microemulsions are thermodynamically stable, transparent, isotropic systems, consisting of oil, water and surfactant with or without a cosurfactant. They are considered ideal for drug delivery due to their low viscosity, ease of preparation, improved drug stability and solubility, small droplet size, surfactant provoked permeability and protection against enzymatic degradation.1) The later characteristics are responsible for improved permeability of the drug across biological membranes including the skin. Although the oil and surfactant constituents are known to enhance the solubility of lipophilic drugs, at higher weight fraction of water (j), their solubility may be greatly compromised. To overcome this effect microemulsions containing cyclodexterine have been investigated. Incorporation of cyclodexterines has been shown to improve the solubility of the model steroid drug progesterone in selected microemulsions by 3300 folds.2) Self Microemulsifying Drug Delivery Systems (SMEDDS) can be considered a novel alternative to conventional transdermal delivery systems.3) SMEDDS are preconcentrated (waterfree) microemulsions, made up of oils and surfactants. Upon dilution with an aqueous medium and gentle agitation, these systems can form microemulsions. 4) Enhanced solubility and improved bioavailability are amongst the main advantages of SMEDDS.Before SMEDDS can be used as drug delivery systems it is necessary to characterize the internal structure of the resulting microemulsion. This is highly critical as multiple colloidal and coarse dispersions may coexist. Amongst these are microemulsions, coarse emulsions, various liquid crystalline systems (hexagonal, reverse hexagonal, lamellar, cubic) and gels. These can form upon mixing oils, surfactants and water. Moreover microemulsions are known to have different microstructures namely oil in water (o/w), water in oil (w/o) and bicontinuous. 5) Elucidating the internal structure of microemulsions is of a great interest as the phase behaviour of these systems can influence drug solubility, stability and in vitro release. Phase behaviour of microemulsions can be monitored through visual inspection, measuring electrical conductivity, viscosity, droplets size, density determination, surface tension measurements, and diffusion coefficient measurements. Visual observation is one of the first and foremost techniques used to establish the phase boundaries and distinguish microemulsions from coarse emulsions, liquid crystals and gels. To further differentiate microemulsions form lamellar liquid crystals one can take advantage of other experimental techniques such as polarized light microscopy and viscosity measurements. In general microemulsions display Newtonian flow with low viscosity whilst liquid crystals exhibit non-Newtonian flow and are of relatively high viscosity.5) Furthermore viscosity can also be used to study the microstructure of microemulsions. [6][7][8] Normally o/w microemulsions have a lower viscosity compared to w/o microemulsions in which the more viscous oil ...

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“…Микроэмульсии обладают значительно большим по сравнению с мицеллярными системами внутренним объемом капель, что обеспечивает большую солюбилизационную емкость таких систем. Таким образом, микроэмульсии сочетают в себе ряд преимуществ традиционных эмульсий и мицеллярных систем [6][7][8][9][10].…”

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