Dual coating of swellable and rupturable polymers on glipizide loaded MCC pellets for pulsatile delivery: formulation design and in vitro evaluation.

This study is aimed to develop and evaluate time dependent rupturable multiparticulate pulsatile delivery system for Glipizide. Microcrystalline cellulose (MCC) based pellets containing Glipizide were prepared by extrusion-spheronization technique (Type I pellets). These were further coated with two consecutive layers, a swellable layer of hydroxypropylmethylcellulose (HPMC) and a rupturable layer of plasticized ethylcellulose (EC) with fluidized bed coating to yield Type II pellets. Drug release and water uptake studies were carried out on formulated pellets. SEM was used to monitor the pellets' morphology and change on exposure to dissolution medium. Both types of pellets were evaluated for particle size, flow, friability, dissolution and content uniformity. Immediate release pattern was optimized for Type I pellets to achieve more than 80% drug release within 30 min. Type II pellets displayed burst release and a lag period of 6-8 h. After selection of appropriate proportions of these pellets (Type I and Type II), drug release studies were performed which showed a pulsatile dissolution profile with a lag-time of 6-8 h. Multiparticulate approach with a blend of the two types of pellets was successfully used to develop a pulsatile release product for Glipizide.