Solution space of pharmacokinetics and its application on mice brain with 18F-FECNT / 中华核医学杂志

ABSTRACT

Objective To forward the concept of solution space of pharmacokinetics for studying radiophannaceutical distributions in animal models. Methods On the basis of special solutions of differential equations of pharmacokinetics, the solution space was established using the characteristics of linearly independent particular solutions and used to express the pharmacokinetics of pharmaceuticals in vivo. 0. 2 ml (7.4 MBq) 2β-carbomethoxy-3β- (4-corophenyl)-8-(2-18F-fluoroethyl) nortropane (18F-FECNT) was injected through tail vein into normal mice. The mice were sacrificed by decapitation at 5, 15, 30, 60, 120 and 180 min post-injection. Brain tissues were removed and weighed, and radioactivity was counted with the γ-counter. The solution space theory was used to study pharmacokinetics of 18F-FECNT in brain tissues of mice. Results The result showed that all solutions of pharmacokinetics models, based on differential equations, were included in the solution space. The solution of any organ or tissue could be linearly expressed by bases of the solution space. When the dimension number of the solution space was no more than 3, the solution could be directly expressed with coordinate picture. By this rule in our theory, the quantity of 18F-FECNT in brain tissues of mice changed with time, which was accorded with the experiment. The coordinates of striatum, frontal cortex, temporal cortex, occipital cortex, parietal cortex, hippocampus and cerebellum in the solution space were ( 10.13, 1.49), (4.27, 0. 84), (4.48, 0.81 ), (2.89, 0.98), (3.65, 0. 83),(3.55, 0. 98) and (2.03, 1.25 ), respectively. Conclusion The theory of solution space could be used to study pharmacokinetics of 18 F-FECNT in mice brain.