STELARA 130 mg STELARA contains Ustekinumab, a human IgG1kappa monoclonal antibody that binds specifically to the shared p40 protein subunit of interleukin-12 (IL-12) and interleukin-23 (IL-23) cytokines. By preventing IL-12 and IL-23 from binding to the IL-12Rβ1 receptor complex expressed on the surface of immune cells, ustekinumab interrupts downstream cytokine signaling, cell activation, and cytokine cascade, thereby suppressing chronic mucosal and systemic inflammation. This intravenous formulation is specifically indicated as an induction dose for the treatment of moderately to severely active Crohn's disease and ulcerative colitis in adult patients.