Histamine H3 antagonists as wake-promoting and pro-cognitive agents.

The histamine H3 receptor is a pre-synaptic auto- and hetero-receptor that controls the release of histamine and a variety of other neurotransmitters in the brain. As such, modulation of the histamine H(3) receptor is expected to affect wake via control of the release of histamine and to affect cognition via regulation of several other neurotransmitters including acetylcholine and norepinephrine. Over the last several years numerous pre-clinical studies have shown that histamine H3 antagonists promote wakefulness, improve cognition, and in some cases affect food intake. Based on the interest level generated from these early pharmacology studies, and following the cloning and expression of the human histamine H3 receptor, many pharmaceutical companies began drug discovery programs aimed at the identification of histamine H3 antagonists suitable for human clinical trials. These efforts have led to many new chemotypes, and several promising compounds have recently entered the clinic for a variety of conditions, including ADHD, Narcolepsy, EDS associated with Narcolepsy, Cognitive disorders and Schizophrenia. Recent efforts towards the identification and pharmacological characterization of novel histamine H3 antagonists will be discussed.