RELATIONSHIPS BETWEEN MANUFACTURING PARAMETERS AND PHARMACEUTICAL-TECHNOLOGICAL REQUIREMENTS ON BIODEGRADABLE MICROPARTICLES .5. RELATIONSHIPS BETWEEN MANUFACTURING PARAMETERS, SURFACE-PROPERTIES AND DEGRADATION CHARACTERISTICS

Cinchocain containing biodegradable microspheres are prepared using a modified solvent-evaporation process and a spray-drying technique. Scanning electron micrographs show that changes in the microparticle porosity are achieved by increasing the pH of the continuous phase and by combining low with high molecular weight polymers. Determinations of the specific surface area by the BET-methode are in good agreement with the microscopic results. Combining low with high molecular weight polymers increases the specific surface area from 0.4 to 0.9 m2/g mirospheres with a mean particle diameter of 30-mu-m. Spray products are characterized by a specific surface area of 5 m2/g. Surface degradation of microspheres is slower than erosion of the inner matrix. In vitro degradation increases with increasaing drug loading and decreasing molecular weight.