Evaluation of formulation related parameters on the release of gliclazide from controlled porosity osmotic pump system

Osmotic drug delivery systems have many advantages over traditional dosage forms including: constant release rate, longer duration of action and higher patient compliance. The aim of this study was the design and formulation of a CPOP system of gliclazide as a model of water-insoluble drugs by using solubility enhancing agent in the core formulation. Central cores were made using simple mixing of ingredients and direct compression technique with concave punches under 150 g/cm2 pressure. Dip coating technique was used for coating of core tablets by a semipermeable membrane and the drug concentrations in the samples were analyzed by UV/visible spectrophotometer. Cellulose acetate was used as semipermeable membrane. Polyethylenglycol 200, 300 and 6000 were used as hydrophilic plasticizers. Diethylphtalate and castor oil were used as hydrophobic plasticizers. Tween 80 and sodium lauryl sulphate (SLS) also used as channeling agent and solubility enhancer respectively. Three comparative parameters including D24h (total amounts of the release after 24 hours), %Devzero (mean deviation percents of the drug release from zero order equation) and RSQzero (RSQ of linear regression of release data) were used for the comparison of the prepared formulations. The best D2 h was seen in formulation containing 30mg SLS (7.5%w/w) in core formulation. Semipermeable membranes containing Tween 80 showed higher mechanical resistance than others. Increasing of SLS from 0 to 30mg (optimum amount) was enhanced D24h and improved kinetic related parameters (%Devzero and RSQzero) significantly. This effect probably aroused from solubilization of the drug in medium by solubility enhancer after exposing of the system to dissolution medium.