Prolongation of effect of asparaginase by implantation in polyacrylamide in rats.

Asparaginase was immobilized in spherical polyacrylamide microparticles, which were inserted in polyacrylamide gel for implantation in rats. Intraperitoneal implantation of this gel depressed systemic L-asparagine for the same duration as was achieved with microparticles, i.e., 8-10 days. The duration of the effect was prolonged up to about 25 days when the gel with the enzyme was implanted subcutaneously on the back of the rat. In both cases, a collagenous capsule formed around the gel, eventually preventing contact with the circulation. The effect of a second implantation was of the same magnitude as the first one.