ABT-239 is a selective, nonimidazole H3 receptor antagonist/inverse agonist, which was investigated by Abbott laboratory as a potential drug for treatment of a variety of cognitive disorders including attention deficit/hyperactivity disorder, Alzheimer's disease, and schizophrenia.

Thioperamide is an antihistamine at H3 and H4 receptors. Thioperamide behaves as both antagonist and inverse agonist.Thioperamide is under preclinical development with Glaxo Wellcome (UK) for the treatment of short-term memory impairment. It has also demonstrated antiarrhythmic effects in preclinical trials. Active development of thioperamide appears to have been discontinued.

1-Methylhistamine also known as tele-methylhistamine can be found primarily in most biofluids, including cerebrospinal fluid (CSF), urine, feces, and blood, as well as in human bone marrow, brain, and mast cell tissues; it is involved in histidine metabolism. This endogenous compound can be a marker of the inflammatory bowel disease because during the development of the disease it concentration is enhanced. Besides, experiments on dogs have revealed, that 1-methylhistamine can be used as a marker of intestinal inflammation in chronic gastrointestinal disease.

1-[(5-chloro-1H-indol-2-yl)carbonyl]-4-methylpiperazine (JNJ 7777120) is the first selective antagonist of the histamine H4 receptor. Johnson & Johnson Pharmaceutical Research and Development is developing JNJ 7777120 for the treatment of inflammatory disorders. JNJ 7777120 demonstrates efficacy as anti-inflammatory agents in vivo. JNJ 7777120 have shown promising activity in down-regulating immune responses in a range of animal disease models including acute inflammation, hapten-mediated colitis, allergic airway inflammation (e.g. allergic rhinitis), colitis, allergic pruritis and atopic dermatitis.