5-HT2A Receptor (IC50 = 5.8 nM); 5-HT2C Receptor (IC50 = 120 nM)
Eplivanserin targets the serotonin 5-HT2A receptor, where it acts as an inverse agonist. It is a potent and selective antagonist of the 5-HT2 receptor, with an IC50 of 5.8 nM in rat cortical membranes and a Kd for the 5-HT2 receptor. Some sources also describe it as a selective antagonist of melatonin receptors MT1 and MT2. However, its primary pharmacological activity is as a 5-HT2A receptor inverse agonist. By binding to this receptor, it reduces the constitutive activity of the receptor.

Other 5-HT kinases are weakly inhibited by eplivanserin hemifumarate (SR 46349B), with IC50 values of 0.12 μM for pig cortical 5-HT1C, 14 μM for rat hippocampus 5-HT1A, and 16 μM for rat stnatum 5-HT1B, Ox) caudate nucleus 5-HT1D. With IC50 values of 3.4 μM, 1.0 μM, 5.0 μM, and 39 μM, respectively, eplivanserin also inhibits rat cortical epinephrine α1 and α2, rat whole brain histamine H1, Na+ channels, and rat striatum dopamine D1 and D2. , 9 μM, and 28 μM, in that order [1].

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In vitro, eplivanserin is a potent and selective 5-HT2 receptor antagonist with an IC50 of 5.8 nM in rat cortical membranes and a Kd for the 5-HT2 receptor. It acts as an inverse agonist at the serotonin 5-HT2A receptor, meaning it not only blocks agonist binding but also reduces the receptor's basal activity. This mechanism is thought to contribute to its effects on sleep architecture. In cell-based assays, eplivanserin can inhibit 5-HT2A receptor-mediated signaling, such as phospholipase C activation and calcium mobilization.

Eplivanserin halffumarate (SR 46349B) has an ED50 of 0.087 mg/kg following intraperitoneal injection and 0.097 mg/kg following oral administration in mice [1]. It inhibits the 5-HT2 receptor binding of [3H]ketanserin. After multiple cocaine treatments, SR 46349B (0.25–1 mg/kg; i.p.) prevents rats from becoming hyperactive due to cocaine [2].

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In vivo, eplivanserin was developed as a potential treatment for insomnia. It is orally bioactive, indicating good oral bioavailability. By antagonizing 5-HT2A receptors, it promotes sleep and alters sleep architecture. It was studied in clinical trials for insomnia but was not approved for marketing. It may also have effects on mood and anxiety due to its action on the serotonergic system.

A new potent, selective and p.o. active serotonergic [5-hydroxytryptamine (5-HT2)] receptor antagonist, Eplivanserin (SR-46349) [trans, 4-([3Z)3-(2-dimethylaminoethyl)oxyimino-3(2-flurophenyl++ +)propen-1-yl]phenol hemifumarate) has been characterized by a series of "in vitro" and "in vivo" methods. Based upon binding studies with 5-HT2 receptors in rat brain cortical membranes and blockade of 5-HT-induced contractions in isolated tissues (rabbit thoracic aorta, rat jugular vein, rat caudal artery, rat uterus and guinea pig trachea), Eplivanserin (SR-46349) showed high affinity for 5-HT2 receptors. Furthermore, Eplivanserin (SR-46349) displayed moderate affinity for the 5-HT1C receptor and had no affinity for the other 5-HT1 subclass (5-HT1A, 5-HT1B or 5-HT1D), dopamine (D1 or D2), "alpha" adrenergic (alpha-1 or alpha-2), sodium and calcium channel and histamine (H1) receptors. It did not interact with histamine (H1), alpha-1 adrenergic and 5-HT3 receptors in smooth muscle preparations. No inhibition of the uptake of norepinephrine, dopamine or 5-HT was seen. Based upon blockade of pressor responses to 5-HT in pithed rats and in vivo binding studies in mice, SR 46349B was found to be a potent and p.o. active 5-HT2 receptor antagonist with a relatively long duration of action. Behavioral experiments, including mescaline- and 5-hydroxytryptophan-induced head twitches and learned helplessness, as well as sleep-waking cycle and EEG spectral parameter studies, indicated that SR 46349B has a classical 5-HT2 psychopharmacological antagonist profile.[1]

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Non-cellular in vitro assays for eplivanserin involve receptor binding studies. A standard protocol uses membrane preparations from rat cortical tissue or cells expressing recombinant human 5-HT2A receptors. The membranes are incubated with a radiolabeled ligand, such as [³H]ketanserin, and varying concentrations of eplivanserin. Non-specific binding is determined in the presence of an excess of unlabeled ketanserin. After incubation, the reaction is terminated by rapid filtration, and the radioactivity bound to the membranes is measured. The IC50 or Ki values are calculated from the competition curves.

Cellular assays for eplivanserin are performed using cell lines expressing 5-HT2A receptors, such as HEK293 cells stably transfected with the receptor. Cells are pre-incubated with eplivanserin at various concentrations and then stimulated with a 5-HT2A agonist (e.g., DOI). The inhibition of agonist-stimulated signaling is measured. This can include the inhibition of intracellular calcium mobilization, measured using a calcium-sensitive fluorescent dye, or the inhibition of downstream signaling pathways such as phospholipase C activation.

The 5-HT2AR antagonist Eplivanserin (SR-46349) also blocked cocaine-evoked hyperactivity following repeated cocaine treatment, whereas the other 5-HT2R ligands were ineffective. When any of the 5-HT2R ligands was coadministered with cocaine during the treatment regimen (10 mg/kg/day for 5 days), the development of sensitization was unchanged as measured by the level of cocaine-evoked hyperactivity upon challenge 5 days after termination of the treatment. The present study implies that 5-HT2AR and 5-HT2CR exert oppositional influence upon hyperactivity evoked by acute administration of cocaine; this balance is altered following repeated cocaine administration.

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In vivo animal studies for eplivanserin were conducted in rodent models of sleep. Rats or mice were administered eplivanserin orally or intraperitoneally at doses such as 1-10 mg/kg. Sleep architecture was assessed by electroencephalography (EEG) and electromyography (EMG) recordings. The compound's effects on sleep duration, sleep latency, and the proportion of REM and non-REM sleep were measured. Eplivanserin was shown to promote sleep and increase non-REM sleep duration in these models.

Eplivanserin fumarate has a molecular weight of 444.45 and a molecular formula of C23H25FN2O6. It is orally bioactive, indicating good oral bioavailability. The compound is soluble in DMSO. For in vivo studies, it can be formulated in vehicles such as 10% DMSO, 40% PEG300, 5% Tween-80, and 45% saline. Detailed pharmacokinetic parameters, such as half-life, Cmax, and AUC, have not been fully reported in the available literature.

Detailed toxicological data for eplivanserin have not been extensively reported. As a research chemical, it is not intended for human use and is strictly for preclinical research purposes. Standard safety precautions should be followed when handling eplivanserin, including the use of personal protective equipment. No specific toxicity data, such as LD50 values, are available in the provided literature.

[1]. Biochemical and pharmacological properties of SR 46349B, a new potent and selective 5-hydroxytryptamine2 receptor antagonist. J Pharmacol Exp Ther. 1992 Aug;262(2):759-68.

[2]. Contribution of serotonin (5-hydroxytryptamine; 5-HT) 5-HT2 receptor subtypes to the hyperlocomotor effects of cocaine: acute and chronic pharmacological analyses. J Pharmacol Exp Ther. 2004 Sep;310(3):1246-54.

Drug Indication
This study compared the roles of serotonin (5-hydroxytryptamine; 5-HT) 5-HT2 receptor subtypes (5-HT2AR, 5-HT2BR, and 5-HT2CR) in acute cocaine-induced hyperactivity and their contribution to the development and expression of motor sensitization in male Wistar rats after repeated, intermittent cocaine treatment (10 mg/kg/day for 5 days). Pretreatment with the preferred 5-HT2AR agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) and the 5-HT2CR antagonist SDZ SER-082 [(+)-cis-4,5,7a,8,9,10,11,11a-octahydro-7H-10-methylindolo(1,7-BC)(2,6)naphthyldimethylfumarate] significantly enhanced cocaine-induced hyperactivity. The 5-HT2AR antagonist SR 46349B [1(Z)-[2-(dimethylamino)ethoxyimino]-1(2-fluorophenyl)-3-(4-hydroxyphenyl)-2(E)-propene] and the preferred 5-HT2CR agonist MK 212 [6-chloro-2-(1-piperazinyl)pyrazine hydrochloride] (2 mg/kg) significantly attenuated cocaine-induced acute ADHD; however, lower doses of MK 212 (0.3 mg/kg) enhanced cocaine-induced ADHD. The 5-HT2BR agonist BW 723C86 (1-[5-(2-thiophenemethoxy)-1H-3-indolyl]propyl-2-amine hydrochloride) and the 5-HT2BR antagonist SB 204741 [N-(1-methyl-5-indolyl)-N'-(3-methyl-5-isothiazolyl)urea] had no effect on cocaine-induced hyperactivity. Hyperactivity increased two-fold upon re-exposure to cocaine after repeated cocaine treatment alone, 5 days after cessation of cocaine treatment. The 5-HT2AR antagonist SR 46349B also blocked hyperactivity induced by repeated cocaine treatment, while other 5-HT2R ligands were ineffective. During the treatment regimen (10 mg/kg/day for 5 days), if any 5-HT2R ligand was administered concurrently with cocaine, the degree of hyperactivity induced by cocaine was not changed after a second administration of cocaine 5 days after the end of treatment, indicating that the development of sensitization was not altered. This study shows that 5-HT2AR and 5-HT2CR have an antagonistic effect on hyperactivity induced by acute cocaine administration; this balance is altered after repeated administration of cocaine. [2]

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Eplivanserin (SR-46349) is a potent, selective, and orally bioactive 5-HT2 receptor antagonist/inverse agonist. It was originally developed as a potential treatment for insomnia. The compound acts primarily at the 5-HT2A receptor, where it reduces receptor activity. It was evaluated in clinical trials but was not approved for marketing. Eplivanserin remains a valuable research tool for studying the role of 5-HT2A receptors in sleep, mood, and other physiological processes.

C23H25FN2O6

444.4594

444.17

C, 62.15; H, 5.67; F, 4.27; N, 6.30; O, 21.60

130580-02-8

Eplivanserin (mixture);130581-13-4;Eplivanserin;130579-75-8

135456189

Typically exists as solid at room temperature

456.3ºC at 760mmHg

229.8ºC

1.63E-08mmHg at 25°C

3.238

4

14

16

56

537

0

OC(/C=C/C(=O)O)=O.CN(CCON/C(/C1=CC=CC=C1F)=C/C=C1/C=CC(=O)C=C/1)C.CN(CCON/C(/C1=CC=CC=C1F)=C/C=C1/C=CC(=O)C=C/1)C

RNLKLYQQDLHHBH-ABDBJYMXSA-N

InChI=1S/2C19H21FN2O2.C4H4O4/c2*1-22(2)13-14-24-21-19(17-5-3-4-6-18(17)20)12-9-15-7-10-16(23)11-8-15;5-3(6)1-2-4(7)8/h2*3-12,23H,13-14H2,1-2H3;1-2H,(H,5,6)(H,7,8)/b2*12-9+,21-19-;2-1+

(E)-but-2-enedioic acid;4-[(E,3Z)-3-[2-(dimethylamino)ethoxyimino]-3-(2-fluorophenyl)prop-1-enyl]phenol

Eplivanserin fumarate; Eplivanserin fumarate; Eplivanserin hemifumarate; SR-46349B; 130580-02-8; BT8UYC46KA; Eplivanserin fumarate [USAN]; SR46349B; SR 46349B; SR-46349 fumarate

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~25 mg/mL (~64.69 mM)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)