The quantitative analysis of bulk materials, drug formulations, drug products, impurities, and biological products containing pharmaceuticals and their metabolites is challenging in the field of pharmaceutical research. It is also complicated to choose the best method. Pharmacokinetic studies frequently make use of quantitative or qualitative studies of a drug and its metabolite. Developing a generic product with quantitative equivalence, which increases regulatory flexibility, seems to be the ultimate aim. Knowing the exact components of reference items and their concentrations is extremely helpful when developing generic formulations. The quantitative composition of the dosage forms is kept secret by the innovators. In such a situation, the quantitative formula of the dosage form is being decoded by generic manufacturers through reverse engineering. To quantify them, we need reliable, non-destructive analytical tools. In this article, we covered excipient quantification techniques, analytical data reports, challenges, and applications.