Review on strategies for analysis of some Structurally Related Pharmaceutical Compounds: Approach to forced degradation, degradation kinetics and impurity profiling of drugs

Structurally related compounds encounter a challenge in their determination due to similarity in chemical structure thus having very close chemical and/or physical properties. This work presented a review about some structurally related pharmaceutical compounds such as prodrugs in presence of active metabolite and/or inactive metabolite in addition to active pharmaceutical ingredients in existence of possible degradation compounds. This review also included simple approach to how to carry out forced degradation studies including hydrolysis and pH rate profiling of drugs, oxidative degradation, photo-degradation, and thermal degradation studies to develop stability indicating assay method (SIAM). The review discussed degradation kinetics including the determination of degradation reaction order, reaction rate, Half-life (t1/2), and shelf life (t 90%) in addition to applying Arrhenius equation to calculate the activation energy. The review also explained the Relative Response Factor (RRF) applied to study impurity profiling of drugs for analysis of pharmaceutical compounds in presence of its impurities.