Micelles parenteral preparations

Apart from the already established formulations, researchers are trying to develop novel oil-based formulations to combat the poor solubility and bioavailablity of NCE. Shevachman et al. developed novel U-type microemulsions to improve the percutaneous permeability of diclofenac. Shah et al.2 2 used microwave heating for the preparation of solid lipid nanoparticles by microemulsion techniques, which resulted in improved particle characteristics. Ki et al. reported sustained-release liquid crystal of injectable leuprolide using sorbitan monooleate. Recently, various novel oil-based drug delivery technologies are reported, which includes tocol emulsions, solid lipid nanopar-ticles, nanosuspensions, Upid microbubbles, sterically stabilized phospholipid micelles, and environmentally responsive drug delivery systems for parenteral administration.25 259... 

Typical excipients used in parenteral suspensions include surfactants that are used to stabilise emulsions and suspensions as wetting agents (polysorbate 80, poloxamer), as micelle makers for the preparation of solubilisations and to influence the flocculation and deflocculation behaviour of a dispersed system (carmellose sodium, polyvidone). Paren-terally used surfactants in high concentrations are toxic and may cause venous irritation and occasional thrombophlebitis. However, these high concentrations are not necessary to formulate stable parenteral suspensions. 

Amphoteric surfactants possess both an anionic and a cationic function. In small-scale preparation they are little used but their role may increase in the future. Examples are long chain betains and phospholipids (e.g. lecithin). Phospholipids play an important role as emulsifiers and micelle formers for parenteral emulsions (see Sect. 13.5.7) and micellar solutions and also in liposome technology. 

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