[Comparative study on pharmacokinetics and tissue distribution of a novel microemulsion based on the paclitaxel/L-OH...

The pharmacokinetics and tissue distributions of the novel paclitaxel microemulsion based on the L-OH lipid complex made in our laboratory were studied in this article with the commercial paclitaxel injection in cremophor as reference preparation by injected intravenously with single dose of 5 mg x kg(-1) in rats. LC-MS/MS method was used to determine the drug concentration in plasma and calculate the pharmacokinetic parameters. [3H]-paclitaxel was used to reveal the tissue distributions of different organs in 0.5 h, 3 h, 24 h and 120 h. The results indicated that the AUC of the emulsion group descended to 42.55%, with the CLz and Vz increased by 2.27 times and 3.81 times respectively. Tissue distribution results revealed that the emulsion showed a significantly increase in liver and spleen with a peak concentration up to 5 times; a slightly increase was observed in lung with no statistical differences; a significantly decrease in heart, kidney, gastrointestinal tract, bone marrow, aorta, thymus, pancreas, fat, muscle, skin, seminal vesicle, reproductive organs and brain with a drop of 40%-80%. These results indicated that paclitaxel microemulsion based on L-OH lipid complexes can remarkably reduced the blood exposure, accelerate plasma clearance rate and increase distribution volume. The fact that paclitaxel microemulsion tended to be uptake by reticuloendothelial system (RES) contributed to the target in liver, spleen and lung, and help to reduce the toxicity in blood, heart, kidney and gastrointestinal tract.