Progress in the development of histamine H3 receptor antagonists/inverse agonists: a patent review (2013-2017).

INTRODUCTION: Since years, ligands blocking histamine H3 receptor (H3R) activity (antagonists/inverse agonists) are interesting targets in the search for new cures for CNS disorders. Intensive works done by academic and pharmaceutical company researchers have led to many potent and selective H3R antagonists/inverse agonists. Some of them have reached to clinical trials. AREAS COVERED: Patent applications from January 2013 to September 2017 and the most important topics connected with H3R field are analysed. Espacenet, Patentscope, Pubmed, GoogleScholar or Cochrane Library online databases were principially used to collect all the materials. EXPERT OPINION: The research interest in histamine H3R field is still high although the number of patent applications has decreased during the past 4 years (around 20 publications). Complexity of histamine H3R biology e.g. many isoforms, constitutive activity, heteromerization with other receptors (dopamine D2, D1, adenosine A2A) and pharmacology make not easy realization and evaluation of therapeutic potential of anti-H3R ligands. First results from clinical trials have verified potential utility of histamine H3R antagonist/inverse agonists in some diseases. However, more studies are necessary for better understanding of an involvement of the histaminergic system in CNS-related disorders and helping more ligands approach to clinical trials and the market. Lists of abbreviations: hAChEI - human acetylcholinesterase inhibitor; hBuChEI - human butyrylcholinesterase inhibitor; hMAO - human monoamine oxidase; MAO - monoamine oxidase.