A novel plug-controlled colon-specific pulsatile capsule with tablet of curcumin-loaded SMEDDS

This study developed and evaluated a colon-specific pulsatile capsule with tablet of self-microemulsifying drug delivery system (SMEDDS). This system is based on an impermeable capsule containing a rapid-disintegrating curcumin-loaded SMEDDS tablet inside it, and a highly methoxylated pectin (H-pectin)/lactose tablet plugged in the capsule mouth. The SMEDDS tablet enhanced the solubility of curcumin, a water-insoluble drug. An in vitro release study of the pulsatile capsule showed a typical pulsatile release profile with a specific lag time. The lag time, which determines the efficiency of colon-specific delivery, could be regulated by varying the H-pectin/lactose ratio. Pectinase and rat cecal contents added to the release medium significantly shortened the erosion time, which proved that the H-pectin plug is sensitive to enzyme degradation. These results show that the pulsatile capsule with SMEDDS tablet has potential for the colon-specific delivery of water-insoluble drugs.