5-Methylnicotinamide is primarily used in biochemical research to study cellular metabolism, particularly in the context of NAD+ biosynthesis and its role in cellular energy production. It serves as a precursor in the synthesis of NAD+ and is often employed to investigate the effects of NAD+ modulation on cellular processes such as aging, DNA repair, and stress responses. Additionally, it is utilized in studies exploring the therapeutic potential of targeting NAD+ pathways in metabolic disorders, neurodegenerative diseases, and cancer. Its application extends to in vitro and in vivo experiments to understand the mechanisms of NAD+-dependent enzymes like sirtuins and PARPs.