A-331440 is described here instead of A-331440 dihydrochloride. A-331440 is an antagonist of non-imidazole histamine H3 receptor with an IC50 value of 22.7 nM for human cortex histamine H3 [1].

Histamine, as a neurotransmitter, is important in homeostasis and physiology. In the CNS, histamine released has the potential to interact with H1, H2, H3 and possibly H4 receptors. All the receptors are G-protein coupled receptors [2].

In HEK 293 cells stably transfected with rat or human histamine H3 receptors, A-331440 was tested for its ability to antagonize increasing calcium mobilization in response to (R)-α-methylhistamine and showed pKb ± S.E.M. values of 7.38 ± 0.10 and 7.37 ± 0.29 for rat histamine H3 and human histamine H3, respectively [1].

In mice, treatment with A-331440 at a dose of 100 mg/kg resulted in piloerection and hypoactivity in the first 2 h, but diminished thereafter. In naive male CD-1 mice, administration with comparable doses of A-331440 i.p. also produced similar data. By day 28, mice treated with A-331440 at the intermediate dose weighed 35.7 ± 0.93 g with an average weight loss of 5.3 ± 0.99 g. The high dose of A-331440 (15 mg/kg, p.o., b.i.d.) produced a marked and sustained weight loss [1].

References:
[1].  Hancock AA, Bennani YL, Bush EN, et al. Antiobesity effects of A-331440, a novel non-imidazole histamine H3 receptor antagonist. European journal of pharmacology, 2004, 487(1): 183-197.
[2].  Hancock AA, Diehl MS, Faghih R, et al. In vitro Optimization of Structure Activity Relationships of Analogues of A-331440 Combining Radioligand Receptor Binding Assays and Micronucleus Assays of Potential Antiobesity Histamine H3 Receptor Antagonists. Basic & clinical pharmacology & toxicology, 2004, 95(3): 144-152.