Factors influencing the tissue distribution of coenzyme Q10 intravenously administered in an emulsion to rats: emulsifying agents and lipoprotein lipase activity.

The tissue distribution of coenzyme Q10 (CoQ10) administered intravenously in an emulsion prepared with egg yolk phosphatidylcholine (PC), egg yolk sphingomyelin (SPM) or a combination of PC and a polyoxyethylene derivative of hydrogenated castor oil (HCO-60) (PC + HCO-60) was investigated. The disappearance from the plasma of CoQ10 administered in three different emulsions of lipid particle size less than 0.5 micron varied with the particular emulsifier. Its disappearance occurred most rapidly from the PC emulsion; with the addition of HCO-60, its disappearance was much slower. In the reticuloendothelial system, the concentration of CoQ10 was higher in the spleen, for both the SPM and PC + HCO-60 emulsions than for the PC emulsion. HCO-60 reduced the CoQ10 distribution in the liver from the PC emulsion. Differences in disappearance rates from the plasma are thus considered to be due to the extent of CoQ10 distribution in the liver. CoQ10 concentration in the heart, a target organ, was greatest with the PC emulsion. Its distribution was related to lipoprotein lipase (LPL) activity in this organ. The effects caused by HCO-60, however, could not be explained by LPL activity alone. CoQ10 distribution in the adrenal gland and kidney can be explained partly by LPL activity but in the presence of HCO-60, the distribution mechanism apparently involves other factors.