CGS-21680 hydrochloride hydrate is primarily used in research settings to study adenosine receptor activity, particularly the A2A subtype. It acts as a selective agonist, making it valuable for investigating the role of adenosine receptors in various physiological processes, such as cardiovascular function, inflammation, and neurotransmission. In neuroscience, it helps explore its effects on dopamine signaling, which is relevant to conditions like Parkinson's disease and addiction. Additionally, it is utilized in studies focusing on immune modulation, as A2A receptors play a role in regulating immune responses. This compound is also employed in preclinical models to assess its potential therapeutic applications in treating ischemia, inflammation, and neurodegenerative disorders.