Design, development and optimization of a novel time and pH-dependent colon targeted drug delivery system.

The aim of present study was to develop a time- and pH-dependent system for delivering mesalamine to the colon. The system consists of the core tablet of mesalamine which is compression coated with hydroxypropyl methylcellulose (HPMC K4M) (time-dependent factor). This is then coated with pH-dependent polymer Eudragit L100. The simplex lattice design was adopted to optimize the independent variables i.e. amount of HPMC (X1), dextrose (X2) and polyvinyl pyrollidone (PVP) (X3) and to study their effect on the dependent variables i.e. lag time and time for 50% drug dissolution (t50). The results of the linear interactive model and graphical representation revealed that as the amount of HPMC increases, the lag time and t50 value also increases and as the amount of dextrose and PVP were increased the lag time and t50 value decreases.