Oil-in-water microemulsions stabilized by 3-( N , N - dimethylalkylammonio)propanesulfonate surfactants of varying alkyl chain length: Solubilisation of testos-terone propionate (original) (raw)
Journal of Colloid and Interface Science, 1986
Phase diagrams have been determined showing the extent of the inverse micellar or microemulsion region for systems consisting of water-surfactant-cosurfactant or water-surfactant-hydrocarbon cosurfactant mixture with three surfactants and four cosurfactants. The surfactants are sodium dodecyl sulfate, sodium laurate, and tetradecyltrimethylammonium bromide while the cosurfactants are pentanol, hexanol, pentylamine, and hexylamine. Hexylamine is found to be a very effective cosurfactant giving rise to very good water solubilizing capacity at extremely low surfactant concentrations and very low eosurfactant levels at rather high initial hydrocarbon levels.
Journal of Colloid and Interface Science, 2012
The present study is focused on the evaluation of the interfacial composition, thermodynamic properties, and structural parameters of water-in-oil mixed surfactant microemulsions [(cetylpyridinium chloride, CPC + polyoxyethylene (20) cetyl ether, Brij-58 or polyoxyethylene (20) stearyl ether, Brij-78)/ 1-pentanol/n-heptane, or n-decane] under various physicochemical environments by the Schulman method of cosurfactant titration of the oil/water interface. The estimation of the number of moles of 1-pentanol at the interface ðn i a Þ and bulk oil ðn o a Þ and its distribution between these two domains at the threshold level of stability have been emphasized. The thermodynamics of transfer of 1-pentanol from the continuous oil phase to the interface have been evaluated. n i a ; n i a , standard Gibbs free energy ðDG 0 t Þ, standard enthalpy ðDH 0 t Þ, and standard entropy ðDG 0 t Þ of transfer process have been found to be dependent on the molar ratio of water to surfactant (x), type of nonionic surfactant and its content (X Brij-58 or Brij-78 ), oil and temperature. A correlation between ðDH 0 t Þ and ðDS 0 t Þ is examined at different experimental temperatures. Bulk surfactant composition dependent temperature insensitive microemulsions have been reported. Associated structural parameters, such as droplet dimensions and aggregation number of surfactant and cosurfactant at the droplet interface have been evaluated using a mathematical model after suitable modifications for mixed surfactant systems. In light of these parameters, the prospect of using these microemulsion systems for the synthesis of nanoparticles and the modulation of enzyme activity has been discussed. Correlations of the results in terms of the evaluated physicochemical parameters have been attempted.
Surfactants for microemulsions
Current Opinion in Colloid & Interface Science, 1997
Research effort in past years has focused on the •development of microemulsions with specific properties, namely, high solubilizing power and temperature insensitivity. Phase behavior studies have provided the foundations for this development. On the basis of mass balance analysis and the geometry of three-phase tie triangles, the composition of the surfactant films separating micro-water and oil domains in bicontinuous type microemulsions has been determined. This information allows a beller comparison of the solubilizing power .of surfactants. In addition, decisive progress has been made in the development of surfactant systems for the preparation of biocompatible microemulsions.
Journal of Pharmaceutical Sciences, 1998
The level of solubilization of the drug testosterone propionate into 2% w/w oil-in-water (o/w) microemulsions, stabilized by the nonionic surfactant polyoxyethylene 10-oleyl ether (Brij 96) and containing a range of oils, has been determined. Although testosterone propionate was readily soluble in the ethyl esters ethyl oleate, ethyl caprylate, and ethyl butyrate, and the triglycerides soybean oil, Miglyol 812, and tributryin, and the alkene 1-heptene, only microemulsions containing the ethyl esters and the triglyceride oils exhibited a significant increase in solubilization over the corresponding micellar solution (i.e., surfactant solution in the absence of oil). Furthermore, the increase in drug solubility observed in the microemulsion systems was not related to the solubility of the drug in the bulk oil. That is, while the smaller molecular volume oils, such as ethyl butyrate, exhibited a greater capacity for the drug, microemulsions containing these oils were only marginally better at solubilizing the drug than the corresponding micellar solution. In contrast, microemulsions containing the larger molecular volume oil, Miglyol 812, gave levels of drug solubilization almost three times those containing ethyl butyrate, yet the bulk capacity for drug in this oil was less than half that of ethyl butyrate. Light scattering and phase inversion temperature studies suggested that the structure of the microemulsion was sensitive to the oil being used, in that, at the low oil concentrations used in this study, the smaller molecular volume oils generally penetrated the interfacial surfactant monolayer in much the same way as a cosurfactant, causing an alteration, presumably a dilution, of the relatively concentrated polyoxyethylene region close to the hydrophobic core, thereby destroying one of the main loci of drug solubilization and counteracting any advantages encountered due to the high solubility of the drug in the bulk oil.
Study on the Effect of Oil Phase and Co-Surfactant on Microemulsion Systems
Malaysian Journal of Analytical Science, 2017
The purpose of the present study was to investigate the effect of different oil and chain lengths of co-surfactant on microemulsion region. Oleic acid and isopropyl myristate were used as the oil phase, transcutol, polyethylene glycol 400 (PEG 400) and propylene glycol as co-surfactant and Brij 97 as a surfactant. From the ternary phase diagrams, isopropyl myristate based system is more feasible oil phase to formulate microemulsion compared to oleic acid based system. Moreover, transcutol (medium chain length) is the most suitable co-surfactant to blend with a single-chain surfactant, Brij 97 in order to have a high stability and a large area of microemulsion region.
Microemulsion systems containing bioactive natural oils: an overview on the state of the art
Drug Development and Industrial Pharmacy, 2016
Natural oils are extremely complex mixtures containing compounds of different chemical nature. Some of them have physiological or therapeutic activities that may act either alone or in synergy. Therefore, they are used in the pharmaceutical, agronomic, food, sanitary, and cosmetic industries. Today, the interest in bioactive natural oils is growing due to their immense potential to prevent and treat numerous human diseases. Formulation in microemulsions (MEs) containing natural oils appeared suitable to improve pharmaceutical and biopharmaceutical properties of bioactive compounds derivate from these oils. ME systems are thermodynamically stable, transparent, and isotropic dispersions consisting of oil and water stabilized by an interfacial film of surfactants, typically in combination with a cosurfactant. They can protect labile compounds from premature degradation, control release, increase solubility, and hence enhance the bioavailability of poorly bioavailable compounds. The aim of this work was to review the various advantages of bioactive compounds presented in natural oil loaded ME systems to be used as delivery systems. Firstly, the state of the art of the parameters involved in the ME formation, including the basic concepts of the physicochemical formulation of the ME systems, and the main aspects of production and the energy responsible for their formation were reported. The second section describes the use of ME systems and reviews the recent applications of natural oil-loaded in the ME systems as the bioactive compound in the formulation.
Uses and applications of microemulsions
Since the discovery of microemulsion s, they have attained increasing significance both in basic r e- search and in industry. Due to their unique proper- ties, namely, ultralow interfacial tension, large interfacial area, thermodynamic stability and the ability to solubilize otherwise immiscible liquids, uses and applications of microemulsion s have been numerous. The objective of this review is to present briefly the possible applications of the novel co m- partmentallized systems of microemulsions. IT is well established that large amounts of two immi s- cible liquids (e.g. water and oil) can be brought into a single phase (macroscopically homogeneous but micro- scopically heterogeneous) by addition of an appropriate surfactant or a surfactant mi xture. This unique class of optically clear, thermodynamically stable and usually low viscous solutions, called 'microemulsions' 1 , have been the subject of extensive research over the last two decades primarily because of thei...
Pharmaceutical Research, 2016
Purpose: Aim was to formulate oil-in-water (O/W) microemulsion with a high-volume ratio of complex natural oil, i.e., copaiba oil and low surfactant content. The strategy of formulation was based on (i) the selection of surfactants based on predictive calculations of chemical compatibility between their hydrophobic moiety and oil components and (ii) matching the HLB of the surfactants with the required HLB of the oil. Method: Solubility parameters of the hydrophobic moiety of the surfactants and of the main components found in the oil were calculated and compared. In turn, required HLB of oils were calculated. Selection of surfactants was achieved matching their solubility parameters with those of oil components. Blends of surfactants were prepared with HLB matching the required HLB of the oils. Oil/water mixtures (15/85 and 25/75) were the titrated with surfactant blends until a microemulsion was formed. Results: Two surfactant blends were identified from the predictive calculation approach. Microemulsions containing up to 19.6 % and 13.7% of selected surfactant blends were obtained. Conclusion: O/W microemulsions with a high-volume fraction of complex natural oil and a reasonable surfactant concentration were formulated. These microemulsions can be proposed as delivery systems for the oral administration of poorly soluble drugs.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2002
The improved water and oil solubilization in the presence of polyols (propylene glycol, PG, and glycerol, Gly) and short-chain alcohol (ethanol) in U-type nonionic W/O and O/W food microemulsions was investigated. The phase behavior of systems based on Tweens (ethoxylated sorbitan esters) was compared with non-food-grade systems based on C 18:1 E 10 (Brij 96v). Short-chain alcohol (ethanol in food-grade systems) together with polyols (glycerol and propylene glycol) when added to a three component system (oil-surfactant-water) induce the formation of both water-in-oil (W/O) and oil-in-water (O/W) microemulsions. Alcohols and polyols destabilize the liquid crystalline phase and extend the isotropic region to higher surfactant concentrations. The total monophasic area, A T , at R( + )-limonene/ethanol of 1/1 (w/w) and aqueous phase of water/PG of 1/1 (w/w), was 73 and 64% of the total area of the phase diagram for Brij 96v and Tween 60, respectively. The transition from a W/O microemulsion into an O/W microemulsion happens gradually, and continuously without any phase separation. The total monophasic area depends also on the type of the oil, on the composition of the polar and apolar phases, and on the nature of the polyol. The results are discussed in terms of BSO equation, spontaneous curvature, H 0 , film flexibility, s and s , surfactant oil and surfactant cosolvent compatibility and the participation of the polyol at the interface. The difference in temperature sensitivity of PG-based microemulsions vs. temperature sensitivity of Gly-based is demonstrated and explained.