| Abstract: | The neurotransmitter histamine exerts its action through four distinct histamine receptors. The histamine H1 and H2 receptor are well established drug targets, whereas the histamine H4 receptor is undergoing rigorous characterisation at present. The histamine H3 receptor (H3R) is a Gi/o-protein coupled receptor and is mostly expressed in the CNS. A remarkably large and different array of therapeutic areas, in which ligands for the H3R may prove useful, has been identified and a massive research undertaking is underway to substantiate the high expectations for H3R ligands. At present, several ligands for the H3R are being evaluated in clinical studies. In this review, the many potential therapeutic areas for H3R antagonists, inverse agonists and agonists is discussed. Promising medicinal chemistry and toxicological developments, as well as the advancement of several H3R ligands into the clinic, will be highlighted. This review also describes the problems that have been overcome and the questions that remain in developing H3R-related drugs. Considering the tremendous efforts by industry, it can be expected that the first H3R drugs will reach the market soon. |
