SB-399885 HCl is primarily used in research settings to study the role of 5-HT6 receptors in the central nervous system. It acts as a selective antagonist for these receptors, making it a valuable tool for investigating their function in cognitive processes, memory, and learning. Researchers utilize this compound to explore potential therapeutic applications for neurological and psychiatric disorders, such as Alzheimer's disease, schizophrenia, and depression. Its high selectivity allows for precise modulation of 5-HT6 receptor activity, aiding in the development of targeted treatments for these conditions. Additionally, SB-399885 HCl is employed in preclinical studies to better understand the neurochemical pathways involved in behavior and cognition.