Application of electrostatic dry powder coating technology on capsules to achieve sustained release

This study introduces an electrostatic dry powder coating process to coat hard gelatin capsules and hydroxypropyl methylcellulose capsules directly in a coating pan to achieve sustained release. The process overcomes many difficulties in the capsule liquid coating process, such as stickiness and poor adhesion. According to the results of SEM, the coating process required more polymer powder to seal the weakest area of the capsule, the joint of the body and the cap. The dissolution test showed that various release rates were achieved successfully by adjusting the formulations of coating materials and the weight gain of capsules. The capsule shell would also influence the drug release rate due to the dissolubility of capsule materials. This study demonstrates that electrostatic dry powder coating technology can be applied on hard HPMC capsules and gelatin capsules to achieve sustained release of the capsules. Aspirin and caffeine were used as the active pharmaceutical ingredients.