Isothipendyl (AY 56012), an azaphenothiazine derivative, is a potent histamine 1 (H1) receptor antagonist. Isothipendyl is a primary metabolite.

Tecastemizole (Norastemizole), a major metabolite of Astemizole, is a potent and selective H1 receptor antagonist. Tecastemizole shows anti-inflammatory activities.

(R)-(+)-Dimethindene maleate is an orally active H1-receptor blocker with antihistaminic properties in pigs.

INCB38579 is an orally active, highly brain penetrable, and selective histamine H4 receptor (HH4R) antagonist (hH4R IC50=4.8 nM, mH4R IC50=42 nM, rH4R IC50=32 nM). INCB38579 shows anti-inflammatory pain and anti-pruritic activities.

Cimetidine (SKF-92334) hydrochloride is an orally active and inverse histamine H2 receptor antagonist with a Ki of 0.6 μM. Cimetidine hydrochloride is a gastric acid reducer, and can be used for duodenal and gastric ulcers research. Cimetidine hydrochloride has anti-cancer and anti-inflammatory activity.

Izuforant (JW1601) (Compound 24) is an orally active histamine H4 receptor (H4R) antagonist with an IC50 of 36 nM against human H4R. Izuforant also shows binding affinity of human serotonin 3 receptor (h5-HT3R) with an IC50 of 9.1 μM. Izuforant exhibits strong anti-pruritic and anti-inflammatory efficacies.

Dexchlorpheniramine is an potent and blood-brain barrier (BBB) penetrant histamine 1 (H1) receptor antagonist with anticholinergic properties. Dexchlorpheniramine can be used for researching allergies.

Cetirizine Impurity C dihydrochloride is an impurity of Cetirizine. Cetirizine, a second-generation antihistamine and the carboxylated metabolite of hydroxyzine, is a specific, orally active and long-acting histamine H1-receptor antagonist[1][2].

ROS 234 is a potent H3 antagonist, with a pKB of 9.46 for Guinea-pig ileum H3-receptor, a pKi of 8.90 for Rat cerebral cortex H3-receptor, and a ED50 of 19.12 mg/kg (ip) in ex vivo of Rat cerebral cortex. ROS 234 diaplays poor central access.

Cyclizine is a piperazine first-generation antagonist of histamine 1 receptor.

S 38093 is a novel brain-penetrant antagonist/inverse agonist of H3 receptors.

VUF10460 is a non-imidazole histamine H4 receptor agonist; binds to rat H4 receptor with a pKi of 7.46.

TASP0410461 is a potent, selective histamine H3 receptor antagonist/inverse agonist.

Enerisant hydrochloride (TS091 hydrochloride) is a potent, selective histamine H3 receptor antagonist/inverse agonist with IC50 of 2.89 and 14.5 nM against hH3R and rH3R, respectively.Enerisant inhibited R-α-methylhistamine–stimulated [35S]GTPγS binding to human histamine H3 receptor and rat histamine H3 receptor with IC50 values of 1.06 and 10.05 nM, respectively, inhibited basal [35S]GTPγS binding to human histamine H3 receptor with an EC50 value of 0.357 nM.Enerisant displays negligible effects on binding to human histamine H1, H2, and H4 receptor subtypes, as well as negligible affinities for 66 other receptors, transporters, and ion channels at 1-10 uM.Oral administration of enerisant hydrochloride attenuated the dipsogenia response on R-α-methylhistamine–induced dipsogenia in rats, the intraperitoneal administration of enerisant hydrochloride increased the total extracellular acetylcholine levels in the mPFC.Enerisant hydrochloride significantly decreased slow-wave deep sleep at doses of 1-10 mg/kg (P < 0.01-0.05). Enerisant hydrochloride (1, 3 and 10 mg/kg, p.o.) did not affect the accumulated locomotor activity time at up to 7 hours after administration.

Enerisant (S091,TS-091) is a potent, selective histamine H3 receptor antagonist/inverse agonist with IC50 of 2.89 and 14.5 nM against hH3R and rH3R, respectively.Enerisant inhibited R-α-methylhistamine–stimulated [35S]GTPγS binding to human histamine H3 receptor and rat histamine H3 receptor with IC50 values of 1.06 and 10.05 nM, respectively, inhibited basal [35S]GTPγS binding to human histamine H3 receptor with an EC50 value of 0.357 nM.Enerisant displays negligible effects on binding to human histamine H1, H2, and H4 receptor subtypes, as well as negligible affinities for 66 other receptors, transporters, and ion channels at 1-10 uM.Oral administration of enerisant hydrochloride attenuated the dipsogenia response on R-α-methylhistamine–induced dipsogenia in rats, the intraperitoneal administration of enerisant hydrochloride increased the total extracellular acetylcholine levels in the mPFC.Enerisant hydrochloride significantly decreased slow-wave deep sleep at doses of 1-10 mg/kg (P < 0.01-0.05). Enerisant hydrochloride (1, 3 and 10 mg/kg, p.o.) did not affect the accumulated locomotor activity time at up to 7 hours after administration.

GSK189254A (GSK189254) is a novel, potent and selective histamine H3 receptor antagonist with pKi values of 9.59-9.90 and 8.51-9.17 for human and rat H3, respectively.

Roxatidine is an active metabolite of Roxatidine acetate hydrochloride, is a histamine H2-receptor antagonist. Roxatidine, an anti-ulcer agent, suppresses histamine release (thus inhibiting proton secretion) and inhibits the production of VEGF-1, an important marker of inflammation and angiogenesis. Anti-allergic inflammatory effect.

JNJ-5207852 is a selective and potent histamine H3 receptor (H3R) antagonist, with pKis of 8.9, 9.24 for rat and human H3R, respectively.

(R)-(-)-α-Methylhistamine dihydrochloride is a potent, selective and brain-penetrant agonist of H3 histamine receptor, with a Kd of 50.3 nM. (R)-(-)-α-Methylhistamine dihydrochloride can enhance memory retention, attenuates memory impairment in rats.

4-Methylhistamine (dihydrochloride) is the potent agonist of histamine 4 receptor (H4R). 4-Methylhistamine (dihydrochloride) has the potential for the research of immune-related diseases such as cancer and autoimmune disorders.

Sequifenadine is a H1-antihistamine. Sequifenadine has the potential for the research of inflammatory eye disease with allergic symptoms.

Dioxopromethazine is an orally active antihistamine. Dioxopromethazine inhibits asthmatic symptoms.

Bilastine is a selective histamine H1 receptor antagonist used for treatment of allergic rhinoconjunctivitis and urticaria.

Epinastine(WAL801) is an antihistamine and mast cell stabilizer that is used in eye drops to treat allergic conjunctivitis.

JNJ-7777120 is a selective H4R antagonist with Ki of 4 ±1 nM, exhibits >1000-fold selectivity over the other histamin receptors.

Imetit dihydrobromide (VUF 8325 dihydrobromide) is a high affinity and potent agonist of histamine H3 and H4 receptors, with Ki values of 0.3 and 2.7 nM, respectively. Imetit mimics histamine effect in triggering a shape change in eosinophils (EC50=25 nM).

Betahistine is a strong affinity histamine H3 receptor antagonist and weak affinity agonist of histamine H1 receptors.

Ciproxifan maleate(FUB-359 maleate) is a highly potent and selective histamin H3-receptor antagonist with IC50 of 9.2 nM, with low apparent affinity at other receptor subtypes.

Cinnarizine is a medication derivative of piperazine, and characterized as an antihistamine and a calcium channel blocker.

Cipralisant (GT-2331) (maleate) is an orally active, low-toxicity, potent, selective, high affinity histamine H3 receptor full antagonist in vivo, and an agonist in vitro, with a pKi of 9.9 for histamine H3 receptor and a Ki of 0.47 nM for rat histamine H3 receptor. Cipralisant (maleate) has the potential for attention-deficit hyperactivity disorder research.