“…1b). It is well known that the release of drugs from chemically stable polymer systems occurs via the dif fusion mechanism [37][38][39], whereas biodegradable polyesters with unstable chemical bonds (even in the absence of enzymes) can experience hydrolysis in aqueous solutions, specifically via the mechanism of end group autocatalysis [40]. The characteristic signs of hydrolysis are a loss in the total weight of the sam ple; a decrease in its viscosity average molecular mass; and, after prolonged hydrolysis, a change in the degree dr 0 0 a c of crystallinity (as was shown for PHB, its copolymer with 3 oxyvalerate, polylactides, and PHB-polylac tide mixtures [19,41]).…”