In vivo ESR studies on pharmacokinetics and metabolism of parenteral lipid emulsion in living mice.

PURPOSE

We applied non-invasive and real-time method with in vivo ESR spectroscopy to determining pharmacokinetics and metabolism of lipid emulsion as a drug carrier in living mice.

METHODS

A spin-labeled triglyceride (SL-TG) was newly synthesized and lipid emulsion containing SL-TG was prepared. In vivo ESR spectra in mice were observed after intravenous administration of the lipid emulsion.

RESULTS

In vivo ESR spectra consisted of three components, coinciding with the in vitro spectra of SL-TG particles, free and immobilized fatty acids. The amount of the components depended on both the observing domain and the period after administration. In the chest, all three components were observed, while SL-TG particle was lacking in the abdomen. The half-life of the lipid particles in the chest was 2 hr.

CONCLUSIONS

Non-invasive and real-time analysis of drug carriers in living animal is successfully accomplished using an in vivo ESR method.