Kinetic mechanisms of covalent inhibition

The recent clinical and commercial success of covalent drugs has prompted a renewed interest in covalent inhibitors as therapeutic agents. With this has come an increased understanding of both the benefits and limitations of covalent inhibition and the techniques required to fully characterize covalent inhibitors. As covalent inhibition is time-dependent, it requires careful kinetic characterization to ensure the correct interpretation of compound SAR through the generation of kinact/KI values rather than the IC50 values which have been traditionally employed to determine the SAR of rapidly reversible non-covalent inhibitors. This chapter discusses the mechanisms of covalent inhibition that are typically encountered in drug discovery programs, along with the numerous experimental and analytical techniques that may be used to evaluate covalent inhibitors. One aspect of covalent inhibition that is often overlooked is the applicability and limitations of the various kinetic analysis techniques that may be used to characterize covalent inhibitors and so in addition to outlining the various methods of covalent analysis, this chapter also discusses the strengths and limitations of each technique.