Self-emulsifying

OU- and water-resistant treatments have been reported which iavolve blends of fluoropolymers and alkoxysUane or alkoxysUoxane materials, dehvered as 100% actives (90) or from solvent or emulsion (91), fluotinated alkoxysUoxane emulsions (92), and self-emulsifying fluotinated alkoxysUane-based concentrates (93). 

The preemulsified carriers contain water. These products usually require homogenization through colloidal mills or similar equipment to reduce the particle size and ultimately stabilize the product. The preemulsified as well as the clear self-emulsifying products require the use of a solvent when the carrier-active material is a soHd. 

Tackifiers to produce pressure-sensitive adhesives were also prepared as a latex. Self-emulsifying resin or rosin composition, useful as tackifiers for ad-... 

Lipid systems such as oils/emulsions/microemulsions/self-emulsifying systems in capsules... 

This list illustrates the numerous pharmaceutical possibilities available to handle bioavailability problems caused by low solubility. This is a continuously developing area exemplified by more recent developments, such as self-emulsifying lipid systems and nanopartides. 

Microgels by Emulsion Copolymerization of Self-Emulsifying Unsaturated Polyesters and Comonomers... 

By emulsion copolymerization (ECP) of self-emulsifying unsaturated polyesters (EUP) and bifunctional monomers, such as styrene (S), microgels may be prepared which have a rather uniform diameter [109]. This uniformity of size is due to a special mechanism of particle formation involved in using EUP as comonomers. 

Unsaturated polyesters that are terminated by carboxylic acid groups at both ends of the chain after neutralization are efficient emulsifiers for lipophilic monomers [110] and thus act as self-emulsifying crosslinking agents in the ECP of these systems. Normal emulsions of EUP and comonomers have a white, milky appearance. With an appropriate structure and molar mass of the EUP and within a certain range of EUP/comonomer ratios, however, microemulsions are... 

Unsaturated Polyesters as Self-Emulsifying Components of Copolymerization... 

Fig. 12. Preparation of different emulsions of self-emulsifying unsaturated polyesters (EUP) and comonomers.

The parameters which influence the particle size of microgels have been studied during self-emulsifying, seeded emulsion copolymerization of an unsaturated polyester and butyl acrylate [134]. 

Microgels which have been prepared in emulsions or microemulsion have a more compact structure than those obtained by polymerization in solution. For microemulsion copolymerization, preferentially self-emulsifying comonomers, such as unsaturated polyesters, are used as polymerizable surfactants, because no emulsifier must be removed after the reaction. By choosing suitable monomer combinations the composition, size and structure of microgels can be widely varied, thus adjusting these macromolecules to special applications. 

Araya H, Tomita M, Hayashi M (2006) The novel formulation design of self-emulsifying drug delivery systems (SEDDS) type O/W microemulsion III The permeation mechanism of a poorly water soluble drug entrapped O/W microemulsion in rat isolated intestinal membrane by the Ussing chamber method. Drug Metab Pharmacokinet 21 45-53. 

Methods. Initially a range of different nonlonlc surfactant-oil mixtures containing 30 w/w surfactant were screened for their ability to self-emulsify in water at 25 and 37°C. Gentle agitation was provided by a glass stirrer as described by Pouton (liL). The efficiency of self-emulslflcatlon was assessed subjectively on a scale of 1 to 5 (bad to excellent) by visual observation. 

Table I, Qualitative Screening of Surfactant-Oil Mixtures for Self-Emulsifying Behaviour at 25 and 37°C. (S) Denotes Suspended Material in Binary Mixture.

Phase Behaviour. The differences in the self-emulsifying behaviour of Tagat TO - Miglyol 812 binary mixtures can, in part, be explained from considerations of their phase behaviour. Figures 4a-4d show the representative equilibrium phase diagrams obtained when binary mixtures containing 10,25,30 and 40J surfactant were sequentially diluted with water. The phase notation used is based on that of Mitchell et ai (li). 

The concept of interfacial mesophases promoting spontaneous emulsification (21.22) can be applied to the Tagat TO - Miglyol 812 system, where stable liquid crystalline dispersion phases are adequate to promote the process of self-emulsification. The stability of the resulting emulsion systems can also be accounted for by liquid crystalline interface stabilisation (23.24). Phase separation of material as observed above 55f surfactant, in conjuction with the increased viscosities of such systems, will inhibit the dynamics of the self-emulsification process and hence the quality of self-emulsified systems declines when the surfactant concentration is increased above 55. ... 

The self-emulsifying behaviour of a binary nonlonlc surfactant vegetable oil mixture has been shown to be dependant on both temperature and surfactant concentration. The quality of the resulting emulsions as assessed by particle size analysis showed that manipulation of these parameters can result In emulsion formulations of controlled droplet size and hence surface area. Such considerations are Important when the partition of lipophilic drugs Into aqueous phases and drug release rates are considered. 

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