Influence of NMP Concentration on Drug Release Behavior from PLGABased In-Situ Forming Implants

In this study, effect of N-methyl-2-pyrollidone (NMP) on Bupivacaine HCl release from PLGA- based in-situ forming implants have investigated. In many researches drug release from PLGA-502H is generally faster than PLGA-504H when all compositions are the same, and this is because of its lower molecular weight. But if polymer composition of system were unequal, results would change. The results were shown that the burst release and total drug release will be higher in PLGA- based system with higher Mw (504H) in compared with lower Mw (502H). In formulations, polymeric solution contained 30/58 (wt.%) and 55/33 (wt.%) 502H/NMP; and 30/58 (wt.%) and 48/40 (wt.%) 504H/NMP respectively. Burst release at first 24 hours was 81% and 10% for formulations with 502H; and 78% and 17% in formulations that have 504H. In addition, solvent removal results show that when NMP concentration is high, it will remove quicker; Consequently, Bupivacaine HCl will release faster