Senicapoc (ICA-17043) is a potent and selective Gardos channel (Ca²⁺-activated K⁺ channel; KCa3.1) blocker with an IC₅₀ of 11 nM. Senicapoc blocks Ca²⁺-induced rubidium flux from human RBCs with an IC₅₀ value of 11 nM and inhibits RBC dehydration with IC₅₀ of 30 nM^[1]. IC50 & Target: IC50: 11 nM (Gardos channel)^[1] In Vitro: ICA-17043 is shown to block the Gardos channel of mouse (C57 Black) RBCs with an IC₅₀ of 50±6 nM. ICA-17043 blocks this increase in cellular hemoglobin concentration in human RBCs in a concentration-dependent fashion^[1]. In Vivo: ICA-17043 (10 mg/kg, p.o.) administration produces a significant decrease in Gardos channel activity measured at day 11 and 21 and is associated with a corresponding increase in red cell K⁺ content without changes in Na⁺ content. ICA-17043 (10 mg/kg, twice a day) induces a significant increase in Hct after 11 days of dosing in the SAD mouse^[1]. Senicapoc (30 mg/kg, p.o.) reduces airway hyperresponsiveness, eosinophil numbers in bronchoalveolar lavage taken 48 hours post-allergen challenge, and vascular remodelling in the sheep^[2].