The objective of this works is to develop electrochemical and instrumental techniques used in the analysis of some pharmaceutical drugs containing the carbonyl and/or substituted amine groups. - An electrochemical method based on modified polymeric membranes was applied for the determination of solifenacin succinate. For the first time, molecular modeling and docking techniques were used to study the nature of the binding between the drug and ionophore molecules. Also, to assist the interpretation of the obtained results and to compare the performance of different sensors. - A first derivative synchronous spectrofluorimetric method was developed and optimized for the simultaneous determination of amlodipine and celecoxib in bulk powder, pharmaceutical preparation and spiked human plasma. Using SDS, an enhancement in the fluorescence intensity was obtained by complex formation between each drug and the surfactant which was confirmed by molecular dynamic simulations using molecular modeling techniques. - A high performance thin layer chromatographic method was developed and optimized for the simultaneous determination of amlodipine and celecoxibe in presence of process related impurity using molecular docking and modeling techniques to elucidate the health hazards of the process related impurity. The chromatographic conditions were optimized using experimental design techniques as response surface methodology based on a central composite design and a validated model was obtained to predict the best conditions that achieve the desired method outcomes regarding resolution and overall run time. - UV spectrophotometric methods were applied for the simultaneous determination of numerous drugs in their pharmaceutical mixtures. Due to simplicity, accuracy and low cost of these methods made it possible to be involved in quality control routine analysis. Several methods were applied some were classical and well known as Dual-wavelength, Derivative methods, ratio difference, ratio derivative and mean centering. Other newly developed smart methods were also applied as Induced dual-wavelength, absorption correction factor, absorptivity factor and Fourier self deconvolution methods.