A-205804 is primarily used in research settings for its potent inhibitory activity against the epithelial sodium channel (ENaC). This makes it a valuable tool in studies related to ion transport across epithelial tissues, particularly in the respiratory and renal systems. It has been investigated for potential therapeutic applications in conditions involving excessive fluid absorption, such as cystic fibrosis, where ENaC overactivity contributes to thickened mucus in the airways. By blocking ENaC, A-205804 helps restore airway surface hydration, improving mucociliary clearance in preclinical models. Its selectivity and potency also make it useful in pharmacological studies aimed at understanding sodium homeostasis and developing new treatments for hypertension and other fluid balance disorders.