Spray drying production of trypsin containing microparticles

This paper describes the production by the spray-drying technique of empty and trypsin-containing Eudragit RL microparticles. The effects \nof different air drying (heating) temperatures, namely 85, 95, 105 and 135°C, were evaluated. Both empty and trypsin-containing microparticles, \ncharacterized by optical and electron microscopy, exhibited the same morphological characteristics. Microparticles demonstrated particle recovery \nof between 38 and 67% and a size of between 5 and 11 μm. Microparticle recovery, morphological characteristics and mean diameters were \nnot particularly infl uenced by heating. Indeed, in all cases, microparticles maintained a spherical shape, a slight increase in dimensions and no \naggregation phenomena. However, an increase in air drying temperature caused a drastic reduction in terms of trypsin activity (assayed by UV \ndetermination) with respect to the free enzyme. Indeed, trypsin activity fell from more than 90 to 4.05% in the case of microspheres produced at 95 \nand 135°C, respectively. Nevertheless, using either suspended or solubilized polymer as the feeding material, the activity profi les of trypsin indicate \nthat the enzyme maintained its activity almost quantitatively (93%) when particles are produced at 95°C. Taken together, these results suggest that \nspray-drying could represent an interesting technique for the production of microparticles intended for the administration of enzymes.