FAT EMULSIONS BASED ON STRUCTURED LIPIDS (1,3-SPECIFIC TRIGLYCERIDES)- AN INVESTIGATION OF THE IN-VIVO FATE

Purpose. Structured lipids(1,3-specific triglycerides) are new chemica l entities made by enzymatic transesterification of the fatty acids in the 1,3 positions of the triglyceride. The purpose of this study is t o characterize structured lipids with either short chain fatty acids o r medium chain fatty acids in the 1,3 positions with regard to their h ydrophobicity, and investigate the in vivo fate in order to evaluate t he potential of structured lipids as core material in fat emulsions us ed as parenteral drug delivery system. Methods. The lipids were charac terized by employing reversed phase high performance liquid chromatogr aphy. The biodistribution of radioactively labeled emulsions was studi ed in rats. Results. By employing high performance liquid chromatograp hy a rank order of the hydrophobicities of the lipids could be given, with the triglycerides containing long chain fatty acids being the mos t hydrophobic and the structured lipid with short chain fatty acids in the 1,3 positions the least. When formulated as fat emulsions, the em ulsion based on structured lipids with short fatty acids in the 1,3 po sitions was removed slower from the general blood circulation compared to emulsions based on lipids with long chain fatty acids in the 1,3 p ositions. Conclusions. The type of core material influences the in viv o circulation time of fat emulsions.