HPMC 1 Itopride HCl 1 Release kinetics 1 Response surface methodology 1 article 1 bulk density 1 drug formulation 1 drug granule 1 drug half life 1 drug solubility 1 filler 1 high performance liquid chromatography 1 hydroxypropylmethylcellulose 1 in vitro study 1 itopride lactose 1 mathematical model 1 matrix tablet 1 porosity 1 process optimization 1 pyrrolidine derivative 1 response surface method 1 scanning electron microscopy 1 sustained drug release 1 tablet compression 1