PREPARATION AND SUBSEQUENT DEGRADATION OF POLY(L-LACTIC ACID) MICROSPHERES SUITABLE FOR AEROSOLISATION - A PHYSICOCHEMICAL STUDY

The encapsulation of nedocromil sodium and beclomethasone dipropionate with microspheres of poly(L-lactic acid) has been studied and prepara tion conditions optimised for entrapment efficiency and microsphere si ze suitable for inhalation. DSC was used to characterise the microsphe res both in terms of drug/polymer interaction and influence of anneali ng conditions on the T-g and degree of crystallinity. The absence of m olecular interaction was confirmed by FTIR. Incubation of the microsph eres in phosphate buffer at 37 degrees C for 8 days demonstrated no ch emical degradation of the polymer as evidenced by IR spectral analysis and estimates of percentage crystallinity. Surface morphology (SEM) a nd internal structure (TEM) were consistent with a homogeneous degrada tion pattern. (C) 1997 Elsevier Science B.V.