Microemulsions parenteral delivery

Park K-M, Kim C-K. Preparation and evaluation of flurbiprofen-loaded microemulsion for parenteral delivery. International Journal of Pharmaceutics. 1999 181(2) 173-179. 

Micellar solutions and microemulsions are also used for parenteral delivery of hydrophobic drugs. They are usually stabilized by large amounts of hydrophilic surfactants, such as bile salts and polysorbates. Owing to their small size, micelles are less readily recognized by the immune system, resulting in prolonged circulation [36]. An example of micellar formulation is Taxol , in which the active antitumor agent paclitaxel is solubilized in micelles of polyoxyl castor oil. 

Date, A. A., M.S. Nagarsenker. 2010. Design and evaluation of microemulsions for improved parenteral delivery of propofol. AAPS PharmSciTech 9(1) 138-145. 

Microemulsions, and Lipid-Based Drug Delivery Systems for Drug Solubilization and Delivery—Part I Parenteral Applications... 

The phenomenon of microemulsification is mainly governed by factors such as (1) nature and concentration of the oil, surfactant, co-surfactant and aqueous phase, (2) oil/surfactant and surfactant/co-surfactant ratio, (3) temperature, (4) pH of the environment and (5) physicochemical properties of the API such as hydrophilicity/lipophilicity, plformulating microemulsions. From a pharmaceutical perspective, one of the most important factors to be considered is acceptability of the oil, surfactant and co-surfactant for the desired route of administration. This factor is very important while developing micro emulsions for parenteral and ocular delivery as there is only limited number of excipients which are approved for the parenteral and ocular route. In Chapter 3 of this book a more general overview of formulating microemulsions is given and formulation considerations with respect to the components of microemulsions used in pharmaceutical applications are discussed below. 

The production of microemulsions is comparatively simple and cost-effective, and thus, they have attracted a great interest as drug-delivery vehicles. Microemulsions have the capability of transporting lipophilic substances through an aqueous medium, and can also carry hydrophilic substances across lipoidal medium. Based on this attribute, potential of microemulsions has been explored for oral, transdermal, parenteral, topical, and pulmonary administration of lipophilic and hydrophilic drugs. In the last decade, microemulsions have also been explored for their potential as vehicles for topical ocular drug delivery."- ... 

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... 

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