Sintering Technique: A Novel Approach for Enhancing Mechanical Strength of Tablets; Formulation Development and Optimization of Process Variables

The aim of the study is enhancement of mechanical strength of tablets prepared by direct compression, by sintering technique and optimization of process variables. In the present work metronidazole tablets, containing varying concentration of poly ethylene glycol as sintering polymer, were prepared by direct compression and subjected to sintering at high temperature (60 +/- 5 degrees C). Prior to compression, powder blend for all the formulations was evaluated for official parameters related to flow while compressed tablets were subjected to various official and un-official tests. Mechanical strength of the tablets was estimated on the basis of crushing strength, specific crushing strength, tensile strength, and friability. Optimization of the process variables was carried out by response surface methodology, using Design Expert software (Design Expert, version 9.0.5.1), and applying two factors, three level, study design. Quantity of polymer and sintering time were taken as process variables while crushing strength of the tablets was taken as response variable. Results showed that increase in sintering time has significant effect on mechanical strength of the tablets. Due to water soluble nature of PEG, disintegration time of the tablets remained within the official limits. PEG has solubility enhancing effect so in vitro drug release from all the formulations was above 90 % . It is concluded from the study that sintering technique can be applied for increasing mechanical strength of the tablets. It is more useful than the other techniques as it requires no scale up and can be applied at commercial level.