USE OF SURFACTANTS IN POLYLACTIC ACID PROTEIN MICROSPHERES

This paper describes the effect on the in vitro release profile of pol y(D,L-lactic) acid (DL-PLA), and poly(D,L-lactic-co-glycolic) acid (D, L-PLGA), microspheres containing BSA as a model protein prepared by th e double emulsion technique, due to the addition of surfactant agents in the first emulsion (W/O) made using two type of homogenizer. In the first stage D L-PLA microspheres were prepared with a mixture of Span -40(R) and Tween-80(R) to get HLB 6 and 7, W/O ratio in the first emul sion 1:3 and two types of homogenizers (High pressure homogenizer and Sonicator) against microspheres without surfactants. The microspheres made with high pressure homogenizer presented less BSA trapping effici ency and higher burst effect than those made with sonicator which show ed a very slow release rate. In the second stage D,L-PLA and D,L-PLGA microspheres with and without surfactant agents and using sonicator we re compared. The BSA release from D,L-PLGA microspheres was continuous , but batches with HLB 6 and without surfactant presented a initial re lease of 55 % of the incorporated BSA while batch with HLB 7 showed le ss burst effect and slower release rate. The D,L-PLA microspheres rele ased a percentage of incorporated drug at the beginning of the in vitr o assay and then stopped.