Effect of poly(lactide-co-glycolide) molecular weight on the release of dexamethasone sodium phosphate from microparticles.
The objective of this study was to investigate the effect of poly(lactide-co-glycolide) (PLGA) molecular weight (Resomer RG 502H, RG 503H, and RG 504H) on the release behavior of dexamethasone sodium phosphate-loaded microparticles. The microparticles were prepared by three modifications of the solvent evaporation method (O/W-cosolvent, O/W-dispersion, and W/O/W-methods). The encapsulation efficiency of microparticles prepared by the cosolvent- and W/O/W-methods increased from approximately 50% to >90% upon addition of NaCl to the external aqueous phase, while the dispersion method resulted in lower encapsulation efficiencies. The release of dexamethasone sodium phosphate from PLGA microparticles (>50 microm) was biphasic. The initial burst release correlated well with the porosity of the microparticles, both of which increased with increasing polymer molecular weight (RG 504H > 503H > 502H). The burst was also dependent on the method of preparation and was in the order of dispersion method > WOW method > consolvent method. In contrast to the higher molecular weight PLGA microparticles, the release from RG 502H microparticles prepared by cosolvent method was not affected by volume of organic solvent (1.5-3.0 ml) and drug loading (4-13%). An initial burst of approximately 10% followed by a 5-week sustained release phase was obtained. Microparticles with a size <50 microm released in a triphasic manner; an initial burst was followed by a slow release phase and then by a second burst.
Jaraswekin
Saowanee
S
Faculty of Pharmacy, Mahidol University, Sri ayudthaya road, Bangkok 10400, Thailand. saowaneeja@gmail.com
Prakongpan
Sompol
S
Bodmeier
Roland
R
D003692:Delayed-Action Preparations; D003907:Dexamethasone / Q000031:analogs & derivatives* / Q000737:chemistry; D004339:Drug Compounding; D004655:Emulsions; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D010316:Particle Size; D011098:Polyglactin 910 / Q000737:chemistry* / Q000494:pharmacology; D012995:Solubility; D012996:Solutions; D012997:Solvents
D003692:Delayed-Action Preparations; D004655:Emulsions; D012996:Solutions; D012997:Solvents; C004180:dexamethasone 21-phosphate; D011098:Polyglactin 910; D003907:Dexamethasone