Objective: To investigate the pharmacokinetics and tissue distribution characteristics of the 5F oral microemulsion in mouse. Method: An Hypersil C18(4.6 mm×250 mm

5 μm)was adopted with the mobile phase of methanol and 0.5% acetic acid(55: 45)at the flow rate of 0.8 mL·min-1.The column room temperature was set at 35 ℃ and the injection volume was 20 μL. KM mice were orally administrated with 5F microemulsion at the dose of 20 mg·kg-1. At the setting time intervals

blood were collected from the ocular artery directly from the mice after eyeball removal; serum was immediately separated by centrifugation. The heart

liver

spleen

lungs and kidneys of each mouse was rapidly collected following blood collections

and immediately washed

wiped with filter paper

weighed and homogenized with normal saline to 10%. The serum and homogenates were extracted and then HPLC analysis. Result: The pharmacokinetics after oral administrations of 5F microemulsion were AUC0→t 12.202 μg·L-1·h-1

Cmax.3.434 μg·L-1

Tmax 1.048 h

MRT0→t 2.451 h. The relative bioavailability was 616.15% higher for microemulsion than that for the control. Conclusion: The average drug retention time was prolonged

and the relative bioavailability improved. 5F microemulsion has sustained-release characteristic.