Effect of injection volume on the pharmacokinetics of oil particles and incorporated menatetrenone after intravenous injection as O/W lipid emulsionsin rats

Oil-in-water lipid emulsions are promising drug carriers for lipophilic dru gs, however, the pharmacokinetics after entering the circulation should be clarified at clinical injection volume in order to utilize them in a clinic al situation. In the present study, the standard lipid emulsions, consistin g of soybean oil, egg yolk phosphatides and menatetrenone with diameters of about 150 nm, were prepared using a microfluidizer system. The pharmacokin etics of menatetrenone and the oil particles after intravenous injection as standard lipid emulsions at various injection volumes, from the clinical i njection volume (0.1 ml/kg) to the experimental injection volume (3.0 ml/kg ), were examined in rats. The plasma concentrations of menatetrenone and the oil particles were simil ar after administration, showing that menatetrenone was not released even a fter entering the circulation. Menatetrenone was delivered to the liver and spleen at the clinical injection volume, and more menatetrenone was delive red to the liver at clinical injection volume compared with the experimenta l volume. Moreover, additional information on injection volume-dependency w as also obtained from these findings. These results at various injection vo lumes suggested that the standard lipid emulsions can be utilized as a usef ul drug delivery system at the clinical injection volume, especially for li ver and spleen targeting.