Parametric release was the first subset of real time release testing (RTRT), applied to terminally sterilised injectable drug products. The objective was to offer the industry an alternative to the time and money consuming sterility testing, without compromising the sterility of the products. The rationale was that quality cannot be tested into products, instead it must be planned (the principle of quality by design, QbD). This can be implemented by setting appropriate in-process controls supported on process analytical technologies (PAT). Two of the most versatile and promising PAT tools are the near infrared spectroscopy (NIRS) and the Raman spectroscopy. However, their application to injectable drug product development and manufacturing has been scarce. This review has the objective to provide a framework for the practical implementation of the QbD approach to injectable formulations, including application of diverse risk assessment and factorial design tools. Finally, the actual application of PAT, namely NIRS and Raman spectroscopy, to injectable drug product analysis is addressed.