Statistical optimization of mesalamine pulsatile release pH dependent coated pellets for possible ileo-cecal targeting

Abstract

The present study is an attempt to design and optimize mesalamine loaded pulsatile release pH sensitive coated pellets for ileo-cecal targeted pulsatile drug delivery. The novelty of this formulation is to release drug specifically and instantly in ileo-cecal region without being released in upper gastrointestinal tract. Preliminary experimental batches are studied for micromeritic properties and in vitro drug release. Formulation showed desirable lag time and dissolution profile was further optimized by applying 32 full factorial design to study the effect of extent of coating (% w/w). Eudragit S100 and Croscarmellose sodium over drug layered pellets were selected as independent variables X1 and X2 respectively and two responses as lag time of 5 hours and 90% of drug release within 90 minutes after lag time as Y1 and Y2, respectively. Various kinetic models such as Zero order, First order, Higuchi Matrix, Korsmeyer-Peppas were applied to the all optimized batches. The regression equation generated for Q300 (lag time of 5 hours, Y1) was +5.72 - 31.97*X1 + 0.82*X2 - 0.49*X1*X2 + 26.36*X12 - 0.15*X22 and that for Q390 (90% of drug release at pH 7.2 within 90 minutes after lag time, Y2) was +84.63 - 40.09*X1 + 4.62*X2. The drug release data of optimized formulation was close to that predicted by the model. The formulation containing 35.22% w/w Eudragit S100 and 4.00% w/w Croscarmellose sodium was found to be optimum. Formulation of barium sulphate layered and optimized coated pellets studied for radio imaging study showed significant lag time of 5 hours and barium sulphate released successfully in ileo-cecal region. The present study demonstrates that the mesalamine enteric coated pellets could be successfully targeted at ileo-cecal region.