ICI-118551 Hydrochloride is primarily used in research settings as a selective β2-adrenergic receptor antagonist. It is widely employed in pharmacological studies to investigate the role of β2-adrenergic receptors in various physiological and pathological processes. Researchers utilize it to block β2-adrenergic signaling, helping to understand its effects on cardiovascular function, bronchial smooth muscle relaxation, and metabolic regulation. Additionally, it is used in experimental models to study conditions such as asthma, hypertension, and heart failure, providing insights into potential therapeutic targets. Its high selectivity makes it a valuable tool for dissecting the specific contributions of β2-adrenergic receptors in complex biological systems.