New developments around histamine H(3) receptor antagonists/inverse agonists: a patent review (2010 - present).

INTRODUCTION: Histamine H3 receptor (H3R) is involved in the central and peripheral regulation of levels of histamine and other neurotransmitters (e.g., acetylcholine, noradrenaline, dopamine or serotonin). H3R antagonists/inverse agonists constitute attractive targets in the search for new drugs. Preclinical data indicate their potential utility in the treatment of various central nervous system (CNS), metabolic, pain and allergic disorders. So far, many structurally diverse H3R ligands have been synthesized and pharmacologically evaluated. Certain compounds have reached clinical trials. The first results from these studies have appeared. AREAS COVERED: The literature covering patent applications (2010 through June 2013) found in the Espacenet database will be reported. EXPERT OPINION: In comparison with previous years, recently the number of patent applications concerning H3R antagonists/inverse agonists has decreased. The utility of compounds is still being verified in pharmacological studies. The first published results from clinical trials have shown not only positive effects but also emerging drawbacks. So far, BF2.649 is the most advanced in human trials (tiprolisant; Phase III trials). New ligands are being intensively tested in preclinical tests. Thus, it is expected that they will soon undergo clinical trials.