32P-磷酸铬-聚 L-乳酸缓释粒子的制备及其放射性释出和生物分布

Objective The aim of this study was to prepare the 32P-chromic phosphate-poly(L-lac-tide) (32P-CP-PLLA) particles with different ratio of the materials and further examine their performance in-dex in vivo and in vitro and their intracorporeal distribution. Methods The erosion, degrading rates, de-layed release velocity and radioactivity self-absorption coefficient (RSAC) of 32P-CP-PLLA particles made from different materials were investigated and compared. After the implantation of 32P-CP-PLLA particles and the injection of 32P-CP colloids in the muscular tissues, the weight loss rate and the radioactivity release rate (RRR) of the particles were calculated. The intracorporeal distribution, radioactive half-life and bio-logical effect of 32P in the targeting sites were further studied. Statistical analysis was performed with SPSS 12.0, and one-way analysis of variance and t-test were used. Results 32P-CP-PLLA particles were of green cylinder, with regular shape and radionuclide distribution. The RSAC of the particles was of little re-lation with molecular weight of PLLA and proportional to the ratio of PLLA to CP. The extracorporeal release rate increased with the reduction of molecular weight of PLLA and with the increase of the ratio of PLLA to CP. The RRR reached peak when PLLA was 3 times of CP. The 32P-CP, released with the degradation and corrosion of the particle distributed mainly in the surrounding muscles of the particle. And the peak of per-centage activity of injection dose per gram of tissue (% ID/g) in liver, spleen and bone were 1. 7887, 1. 6401 and 1. 9470 respectively, much lower than that in the 32P-CP group (4.7523, 3.9712 and 4.3174 ; all t > 2.7, all P < 0.05). The % ID/g in other organs was much less. The radioactivity effective half-life in the targeting sites increased to about 13 d. There was widespread necrosis around the particles with no ex-istence of normal tissues among them. And no abnormality in spleen and liver was found. Conclusion As a better dosage form of pure β-particle emitter, 32P-CP-PLLA, which can increase the targeting radioactive dosage and effective half-life in the implanting sites, can be served as an potential implanting agent for onco-therapy with a better perspective.

Preliminary study on preparation, release velocity and intracorporcal physical distribution of 32P-chromic phosphate-poly (L-lactide) delayed release panicles