This book describes the UV-visible, fluorescence quenching, fluorescence enhancement, resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) methods of analysis of drugs and their interaction with metal ions. In some cases the drug has also been analysed in pharmaceutical formulations by its ion-association reaction with metal ions. The sensitivity of these methods has also been compared with trivial analytical techniques. The stability constant and molar ratio of drug to metal has been determined by UV and fluorescence spectrophotometery.