Effect of Antibacterial Drugs on Hydrolytic Degradation of Aliphatic Polyesters

— Supercritical fluid encapsulation of gentamicin, levofloxacin and tetracycline into bioresorbable poly(lactic-co-glycolic)acid (PLGA) scaffolds at 20 wt % was performed by PLGA plasticization in supercritical carbon dioxide with its subsequent foaming. The effect of incorporated antibiotics on the rate of PLGA hydrolytic degradation, determined by weekly measurements of the polymer molecular weight and decrease in gravitational masses during 6 weeks of incubation of scaffolds in a phosphate-buffered saline (PBS) solution, was studied. Measurements of pH of PBS containing scaffolds were carried out in the same way. The rate constants of PLGA hydrolysis for different scaffolds comprising various drugs were determined. It was shown that tetracycline significantly reduced the rate of PLGA degradation compared to the rate of degradation of control (pure polymer) scaffolds. At the same time, the presence of gentamicin and levofloxacin in the scaffolds had no visible effect on their degradation. These results enhance the predicting potential for the kinetics of release of the considered antibiotics from bioresorbable polymer carriers into bioactive media, which is necessary for the development of highly efficient sustained-release dosage forms.