Histamine receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

Histamine receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Histamine Receptors [75, 163]) are activated by the endogenous ligand histamine. Marked species differences exist between histamine receptor orthologues [75]. The human and rat H3 receptor genes are subject to significant splice variance [12]. The potency order of histamine at histamine receptor subtypes is H3 = H4 > H2 > H1 [163]. Some agonists at the human H3 receptor display significant ligand bias [171]. Antagonists of all 4 histamine receptors have clinical uses: H1 antagonists for allergies (e.g. cetirizine), H2 antagonists for acid-reflux diseases (e.g. ranitidine), H3 antagonists for narcolepsy (e.g. pitolisant/WAKIX; Registered) and H4 antagonists for atopic dermatitis (e.g. ZPL-3893787; Phase IIa) [163] and vestibular neuritis (AUV) (SENS-111 (Seliforant, previously UR-63325), entered and completed vestibular neuritis (AUV) Phase IIa efficacy and safety trials, respectively) [205, 8].