The Effect of Pore-Formers and Plasticizers on the Release Kinetic of Diltiazem Hydrochloride from the Controlled Porosity Osmotic Pumps

Abstract

The aim of this study was to design a controlled porosity osmotic pump (CPOP) tablet of diltiazem hydrochloride (DLTZ) to deliver the drug according to the zero order kinetic model over 24 h. CPOPS were prepared by incorporating DLTZ in the tablet core followed by coating with cellulose acetate solution containing various types of pore-formers (PVP, PEG 2000, PEG 6000 and PEG 20000) and plasticizers (glycerol, castor oil and diethylphthalate). In vitro release study was conducted for the prepared formulations and the dissolution profiles were compared throughout four parameters, namely, D24 h (cumulative release in 24 h), tL (lag time), RSQzero (squared correlation coefficient of zero order kinetic) and MPDzero (mean percent deviation from zero order equation). Scanning electron microscopy showed formation of the pores in the semi-permeable membrane after coming in contact with dissolution medium. All formulations released more than 76% of contained drug during 24 h. Drug release rate and lag time were found to be directly proportional to the type and concentration of pore-formers as well as hydrophilicity of plasticizers. Our findings indicated that by optimizing formulation variables, CPOP tablets obeying zero order drug release kinetic could be obtained.