This hypothesis is that patients with anorexia nervosa (AN) demonstrate derangement in the histamine central nervous system. It might be possible to ameliorate these by careful use of histamine receptor antagonists targeting Histamine 1, 2, or 3 receptors. Histamine 3 receptors are exclusively present in the brain. Pitolisant is the only one agent currently available that targets these receptors. Pitolisant (brand name Wakix) was approved in the European Union, as a treatment for narcolepsy in March 2016.