Imetit (hydrobromide)

Imetit is a histamine H₃ and H₄ receptor agonist (K_is = 0.3 and 2.7 nM, respectively, in radioligand binding assays).¹ It is selective for histamine H₃ and H₄ receptors over H₁ and H₂ receptors at concentrations up to 100 µM, as well as the serotonin (5-HT) receptor subtype 5-HT₃ (K_i = 240 nM).^2,3 Imetit reduces potassium-induced increases in histamine levels in isolated rat cerebral cortex slices (EC₅₀ = 2.8 nM).⁴ It increases scratching in mice (ED₅₀ = 0.9 µmol), an effect that is reduced by the H₃ receptor antagonist thioperamide (Item No. 10011127).⁵

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1. Liu, C., Ma, X., Jiang, X., et al. Cloning and pharmacological characterization of a fourth histamine receptor (H4) expressed in bone marrow. Mol. Pharmacol. 59(3), 420-426 (2001).

2. Howson, W., Michael, E., Parsons, P.R., et al. Two novel, potent and selective histamine H3 receptor agonists. Bioorg. Med. Chem. Lett. 2(1), 77-78 (1992).

3. Leurs, R., Tulo, M.T., Menge, W.M., et al. Evaluation of the receptor selectivity of the H3 receptor antagonists, iodophenpropit and thioperamide: an interaction with the 5-HT₃ receptor revealed. Br. J. Pharmacol. 116(4), 2315-2321 (1995).

4. Garbarg, M., Arrang, J.M., Rouleau, A., et al. S-[2-(4-imidazolyl)ethyl]isothiourea, a highly specific and potent histamine H3 receptor agonist. J. Pharmacol. Exp. Ther. 263(1), 304-310 (1992).

5. Bell, J.K., McQueen, D.S., and Rees, J.L. Involvement of histamine H4 and H1 receptors in scratching induced by histamine receptor agonists in BalbC mice. Br. J. Pharmacol. 142(2), 374-380 (2004).