Characterization and Reverse Engineering of Pharmaceuticals: Role of Thermoanalytical Techniques

Abstract

During pharmaceutical or biopharmaceutical drug product development, one of the most important steps to be followed is characterization and reverse engineering of the drug product. Out of so many characterization tools and orthogonal reverse engineering techniques, thermoanalytical methods are the most useful techniques. Different thermoanalytical techniques are used to identify, quantify and understand the interaction between different polymorphic forms of drug substances and excipients. These techniques are also used to monitor the physical form (amorphous or crystalline) of the drug substance in drug product throughout its manufacturing processes and helps in identifying, omitting or modifying the steps or processes responsible for change in physical or polymorphic form of the drug substance in the finished drug product. Thermoanalytical techniques are not only useful for characterization of small molecules but also extensively applied in analysis of biological samples and nano-formulations. In current scenario, pharmaceutical development specifically during generic drug development the most useful step is the reverse engineering. When reverse engineering of drug product is concerned, thermoanalytical techniques are the best tools to be used to prove the similarity of physico-chemical properties or same state of matter or arrangement of matter between test and reference products. However, in earlier days these techniques were not used as frequently as the other techniques like spectroscopy and chromatography. Various reasons for limited use of thermoanalytical techniques were unavailability of software or compatible hardware, manual sampling process and a tedious process of manual calculation which consumes lots of time. Now a day, due to advancement of technology, automation, use of robotics, and better understanding, and the thermal analysis not only become a powerful tool but also increase the throughput. The present review focuses on some of the most commonly used Thermoanalytical techniques e.g. Differential Scanning Calorimeter (DSC), Thermogravimetric Analysis (TGA), Solution Calorimeter (SC), Thermo Mechanical Analysis (TMA) and Isothermal Titration Calorimeter (ITC) for characterization and reverse engineering of different dosage forms like solid oral dosage forms, injectable formulation, inhalation formulation, ophthalmic formulation, and biosimilar formulation products such as peptides and proteins using specific case studies.