I1421 is an activator of the cystic fibrosis transmembrane conductance regulator (CFTR), with an EC50 of 64 nM for WTCFTR currents. It also allosterically activates various CF-causing mutants, demonstrating good in vivo efficacy with an oral bioavailability of 60% in mice and a corresponding half-life of 75 minutes. I1421 works synergistically with Elexacaftor to enhance CFTR currents.

I1421, administered as a single dose at 10 mg/kg via intraperitoneal (ip), oral (po), and subcutaneous (sc) routes in C57BL/6 mice, is rapidly absorbed. Maximum plasma concentrations (C max) after intraperitoneal and oral administration were observed at 15 minutes, reaching 7.4 μM and 3.4 μM, respectively, with higher plasma levels following intraperitoneal injection compared to the other methods. When given as a single dose at 3 mg/kg intravenously (iv) and orally (po), the compound demonstrated a bioavailability of 60% in mice, though the oral half-life (T 1/2) was relatively short at 75 minutes.