The evaluation of stress relaxation of lactose and calcium hydrogen phosphate mixtures intended for the preparation of tablets with theophylline.

Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical technology Consultant: Mgr. Petra Svačinová, PhD. Student: Le Thanh Tra Title of Thesis: Evaluation of stress relaxation of mixtures of lactosum and calcii hydrogenphosphate for preparation tablets with theophylline This thesis studies viscoelastic behavior of fillers and tensile strength of tablets with theophylline. Used material are described in theoretical part: Laktosum SpheroLac 100, microcrystalline cellulose Comprecel 102, calcium hydrogenophosphate anhydrate Di-Cafos A150, calcium hydrogenophosphate dihydrate Di-Cafos D160, theophylline and magnesium stearate. Thesis also describes the stress relaxation test, methods of evaluation and it's application. Experimental part evaluates viscoelastic behavior and tensile strength through the test of stress relaxation with maximal compression force 10 kN and dwell time 180 s. The tensile strength of tablets is also evaluated. Experimental part evaluates parameters of elasticity Ai and plasticity Pi, which were obtained from the test of stress relaxation. It evaluates effect of different fillers on these parameters. The highest values were measured at mixtures E (Spherolac 100 a Comprecel 102), further at mixtures D (Spherolac 100 a Di-Cafos A150) and..