The objective of this thesis was the development of floating controlled release drug delivery systems and their extensive in vitro characterisation. Coated, gas-generating, balloon-like bilayer tablets were found to be the optimal formulation for soluble model drug Metformin-HCl showing short floating lag times, high floating strength values, a long floating duration, a robust drug release, storage stability over 12 months and industrial feasibility. Model drug Cefdinir shows low, pH dependent solubility. Floating matrix tablets were found to be the optimal formulation for this challenging drug showing very short floating lag times, high floating strength, a floating duration above 8 h and an almost pH independent drug release over 20 hours. In conclusion, optimized floating tablets for Metformin-HCl and Cefdinir were developed. It was possible to predict and optimize release rates of drugs showing pH dependent solubility by determination of microenvironmental pH. Furthermore, the dissolution stress test analysis is able to characterize the robustness of formulation principles towards mechanical stresses of bio-relevant intensity. In vivo trials have to be carried out to decide about future applications of developed floating drug delivery systems.