Development and characterization of emulsomes for sustained and targeted delivery of an antiviral agent to liver.

In this study we developed emulsomes, a novel lipoidal vesicular system with an internal solid fat core surrounded by a phospholipid bilayer. Plain emulsomal formulations composed of solid lipid (trilaurin or tristearin), cholesterol and soya phosphatidylcholine and stearylamine containing cationic emulsomes loaded with an antiviral drug (zidovudine) were prepared by a simple cast film method followed by sonication to produce emulsomes of nanometric size range. All different types of formulations were optimized for lipid ratios and characterized in-vitro for shape, morphology, size and in-vitro drug release profile. Emulsomal formulations displayed a sufficiently slow drug release profile (12-15% after 24 h). In-vivo organ distribution studies in rats demonstrated better uptake of emulsomal formulations by the liver cells. Further, a significantly higher (P < 0.05) liver concentration of drug was estimated over a period of 24 h for cationic emulsomes than for plain neutral emulsomes. We concluded that cationic emulsomes could fuse with the endosomal membrane due to charge-charge interaction and were released in the cytoplasm before lysosomal degradation and could sustain drug release over a prolonged period. The proposed cationic emulsome-based system showed excellent potential for intracellular hepatic targeting and the strategy could play a vital role in the effective treatment of life-threatening viral infections, such as hepatitis, HIV and Epstein-Barr virus infection.