FORMULATION, DEVELOPMENT AND OPTIMIZATION OF CONTROLLED POROSITY OSMOTIC PUMP TABLETS OF TRAMADOL HYDROCHLORIDE

The aim of the present study was the formulation, development, and optimization of controlled porosity osmotic pump tablets of Tramadol hydrochloride. Cellulose acetate was used as the semi-permeable membrane. The porous osmotic pump contains pore-forming water-soluble additive (PEG-8000) in the coating membrane, which after coming in contact with water, dissolves, resulting in an in-situ formation of microporous structure. The dosage regimen of Tramadol hydrochloride is a 50-mg tablet at every 6 h. The plasma half-life ranges from 5.5 to 6 h. Hence, Tramadol hydrochloride was chosen as a model drug with an aim to develop a controlled release system for 24 h. The effect of different formulation variables, namely ratio of drug to osmogent, membrane weight gain, and concentration of pore former on the in-vitro release, was studied using 2³ factorial design. The effect of pH and agitation on drug release was also studied. Drug-excipients compatibility was studied by Differential Scanning Calorimetry (DSC). The microporous structure of the coating membrane of optimized formulation was determined by Scanning Electron Microscope (SEM). The optimized formulation was subjected to stability study for one month period. It was found that drug release rate increased with the amount of osmogent because of increased water uptake and hence increased driving force for drug release. Drug release was inversely proportional to membrane weight gain: however, it is directly related to the concentration of pore former in the membrane. Optimized formulation was found to deliver above 98% of drug (Tramadol hydrochloride) at a zero-order rate for 24 h.