Preparation of a colon-specific sustained-release capsule with curcumin-loaded SMEDDS alginate beads

A colon-specific capsule with alginate beads containing a self-microemulsifying drug delivery system (SMEDDS) was developed and evaluated. The SMEDDS technique was used to improve the solubility of curcumin (Cur). After encapsulating the Cur-loaded SMEDDS, the alginate beads were placed inside an impermeable capsule body. A konjac glucomannan/lactose/hydroxypropyl methylcellulose (KG/Lac/ HPMC) plug tablet was then prepared and placed in the mouth of the capsule. The capsule demonstrated a pulsatile drug-release profile with a specific lag time and subsequent sustained-release phase. The lag time was modified by changing the type of HPMC and the ratio of KG/Lac/HPMC. In addition, 0.5% b-mannase solution and 5% rat cecal solution were used to simulate the colon fluid, significantly decreasing the lag time of the capsule. The results show that the capsule has potential for use in colon-specific drug delivery and exhibits a sustained-release characteristic.