A physicochemical study of the morphology of progesterone-loaded microspheres fabricated from poly(D,L-lactide-co-glycolide).
Progesterone-loaded microspheres are fabricated by a solvent evaporation process from a poly(D,L-lactide-co-glycolide) (85/15 PLG) and from alpha-progesterone. Methylene chloride is used as solvent and polyvinyl alcohol and methylcellulose are used as surfactants. The microspheres are characterized by scanning electron microscopy, differential scanning calorimetry, and x-ray powder diagrams. Our study shows that the morphology and the thermal behavior of PLG microspheres can vary significantly with progesterone loading and sample thermal history. Below and at 16.5% loading the microspheres exhibit a smooth outer surface. Above 23% loading, the surface becomes rough, embedded by copolymer particles or well-defined crystals. Pores and cracks can also be observed. Below 35% the progesterone is molecularly dispersed. At 35% and above crystal domains of the steroid appear and two crystalline forms are found: alpha- and beta-progesterone. The physical state of progesterone and the nature of its crystal domains dispersed in the PLG matrix can change during storage. Also a progressive development of an endothermic peak at the Tg event of the copolymer is observed during storage. No well defined relationship of peak size to progesterone loading can be shown.
Rosilio
V
V
Laboratorie de Physico-Chimie des Surfaces et Innovation en Pharmacotechnie, URA CNRS 1218, Université Paris-Suid, Chatenay-Malabry, France.
Benoit
J P
JP
Deyme
M
M
Thies
C
C
Madelmont
G
G
D002152:Calorimetry, Differential Scanning; D002713:Chlorine / Q000032:analysis; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D011098:Polyglactin 910 / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D011374:Progesterone / Q000737:chemistry*; D013499:Surface Properties
D011108:Polymers; D011098:Polyglactin 910; D011374:Progesterone; D002713:Chlorine