NBI-75043

NBI-75043 is an orally active small molecule histamine H1 receptor antagonist that was developed by Neurocrine Biosciences for the treatment of insomnia. The drug functions by blocking the H1 receptor, thereby inhibiting the wake-promoting effects of histamine in the central nervous system to facilitate sleep onset and maintenance. During its pharmaceutical development, researchers transitioned from the crystalline free base and tartrate salt forms to a besylate salt formulation to overcome challenges related to low melting points and polymorphism, ensuring higher purity and stability for clinical use. Although it reached early clinical stages, it is no longer listed in Neurocrine's active development pipeline.