«Preformed Microspheres for the Controlled Delivery of Progesterone»

RODOLFO N. MARIANO; LUDMILA N. TURINO; MARÍA I. CABRERA; RICARDO J. A. GRAU

Rio Grande del Sur (Brasil)

Congreso; COLAOB 2010, 6to Congreso Latinoamericano de Biomateriales y Organos Artificiales; 2010

SLABO

The use of biodegradable microspheres as drug delivery systems offers important advantages such as: (a) the possibility to accurately control the release rate of an incorporated drug; (b) easy administration; and (c) no need of surgical removal. Biocompatible poly(lactic-co-glycolic acid) (PLGA) is widely used for this purpose. A variety of preparation methods based on two phases are well documented. In the current art, the use of halogenated alkanes, such as dichloromethane and chloroform, is very common. However, it is not desirable from the viewpoints of environmental and human safety, so they are not recommended for clean manufacturing process. In recognition of this issue, a number of investigations have sought safer solvents. Among them, Ethyl Acetate (EA) is considered one of the most preferred solvents. The present study relates to a process of entrapping progesterone (PRG) in PLGA michospheres, using the emulsion solvent extraction technique. More particularly, we report here the results from the process based on using EA as solvent containing about 20% w/v of PLGA 50:50 (Resomer) and about 10% w/v of progesterone emulsified (1:3) with an aqueous solution of PVA 1%. After stirring at 4000 rpm, distilled water is added to dilute the EA and, consequently, precipitates PLGA. Microscopic characterization showed that the obtained PLGA microparticles containing entrapped PRG are spherical and non-aggregated. The microparticle system is characterized by a Gaussian size distribution (19.4 ± 7.6 ìm; n=144) (Mean±SD). When compared with the characterization of PLGA microspheres without entrapped PRG, it was statistically determined that the presence of the PRG has effect on the particles sizes (14.5 ± 3.9 ìm; n=145). UV spectrophotometer analysis showed a PRG entrapping efficiency of about 35%. From these promising results for preparing PLGA microspheres for PRG controlled delivery, studies for improving the entrapping efficiency are ongoing at the time of this writing.