Preparation and Evaluation of Gelatin-Acacia Microcapsules of Sulfamethoxazole

Sulfamethoxazole particles were microencapsulated using the gelatin-acacia complex coacervation method. Micromeritic properties and dissolution characteristics of the microcapsules were studied. The particle size distribution followed log-normal form. As the hardening time increased, the particle size and wall thickness increased ($45.3-52.0\;{\mu}m$, $2.02-5.12\;{\mu}m$, respectively). This is considered to be due to the cross-linked wall structure of formalized microcapsules which prevents shrinking of gelatin during the dehydration and drying processes. An increase of hardening time clearly delayed the release rate. The in vitro 50% dissolution time $(t_{50})$ for unencapsulated sulfamethoxazole powder was less than 3 min.; for microcapsules hardened for 30 min, the $t_{50}$ was 20.1 min.; for those hardened for 60 min. the $t_{50}$ was 25.0 min.; for those hardened for 120 min., the $t_{50}$ was 35.8 min. The surface of the unhardened microcapsules was smooth and had no cracking or pore penetration. However, the surface of the hardened microcapsules was folded and invaginated.