In vitro duodenal lipolysis of lipid-based drug delivery systems studied by HPLC-UV and HPLC-MS.

Oral drug delivery systems based on lipids are biodegraded in a process called lipolysis to release free fatty acids and monoglycerides. The rate of this lipolysis is usually measured by pH titration. Nevertheless, this technique has some limitations, such as not providing any information about the actual composition of the lipolytic products. In this study, we propose a method to analyze these products during and after lipolysis using HPLC. For the first time, HPLC-UV and HPLC-MS have been used to investigate in vitro duodenal lipolysis of long- and medium-chain triglycerides nanoemulsions. These results have been compared with pH titration, revealing the complementarity of both techniques. The main free fatty acids and monoglycerides produced were effectively identified and quantified as they were formed and after the lipolysis experiment and subsequent ultracentrifugation. The release of fatty acids during lipolysis was qualitatively similar between the compared techniques, although a partial precipitation of medium chain fatty acids could be revealed with HPLC-MS. In addition, the release of two hydrophobic compounds with health benefits, oleoylethanolamide and carnosic acid, was investigated. In conclusion, this study may serve as a starting point for subsequent investigations regarding biodegradation and absorption of lipid-based drug delivery systems using HPLC.