THE PREPARATION AND EVALUATION OF SALBUTAMOL SULFATE-CONTAINING POLY(LACTIC ACID-CO-GLYCOLIC ACID) MICROSPHERES WITH FACTORIAL DESIGN-BASEDSTUDIES

Microspheres of salbutamol sulphate (SS) with poly(lactic acid-co-glyc olic acid) (PLGA 85115) were prepared by the modified solvent evaporat ion method using a double emulsion. In the preparation of the formulat ions, we used a 2(3) factorial design based on three independent varia bles: drug loading, amount of gelatin and concentration of PVA. The de pendent variables are particle size of the microspheres and entrapment ratio % in the microspheres. The effect of the three independent vari ables on the particle size and entrapment ratio % were evaluated with analysis of variance and response surface graphs. The in vitro release studies were carried out by shaking in isotonic phosphate buffer solu tion: pH 7.4. The particle sizes of microspheres were determined by in frared particle size apparatus (IPS). The interaction between PLGA and drug was investigated by DSC and FT-IR analysis. Extended release was obtained for 96 h with F8 formulation microspheres. The best release profile (F8 formulation) fitted the dissolution model proposed by Bake r and Lonsdale. In vitro degradation of the best formulation was inves tigated using scanning electron microscopy. The pore size increased wi th time and then degraded becoming empty holes.