Surface drug removal from ibuprofen-loaded PLA microspheres

The preparation. characterisation and drug release behaviour of ibuprofen l oaded poly(D,L-lactic acid) (PLA) microspheres are described. Depending on the gelatin concentration in the aqueous external solution (1, 0.5, 0.1% w/ v), microspheres with three different sizes (2.2. 4.1, 7.5 mu m) were obtai ned. The properties or. microspheres washed with water (Untreated microsphe res) (Un-Ms) were compared to those of the microspheres washed with a sodiu m carbonate solution in order to remove the surface drug (treated microsphe res) (T-Ms). The results indicate that the removal of the surface drug did not induce any change in the size of the microspheres whereas the morpholog y Of the smallest T-Ms appeared to be modified. The release profiles of bot h Un-Ms and T-Ms resulted in biphasic patterns. The initial burst effect (f irst release phase) of the T-Ms was lower than that of the Un-Ms. The rate of the second release phase did not change for the microspheres with the bi ggest size but increased for the smallest microspheres probably owing to th e modification of the matrix porosity. (C) 2000 Published by Elsevier Scien ce B.V. All rights reserved.