D₂ Receptor ( IC50 = 2.8 nM ); D₃ Receptor ( IC50 = 3.2 nM )
Dopamine D2 receptor (Ki = 2.8 nM) [1]
- Dopamine D3 receptor (Ki = 3.2 nM) [1]

In vitro activity: Amisulpride is an unconventional antagonist of the dopamine D₂/D₃ receptor, with a Kis of 2.8 and 3.2 nM for human D₂ and D₃, respectively. The [ 3 H]thymidine incorporation induced by quinpirole is inhibited by amisulpride (100 nM) with an IC50 value of 22±3 nM (n=3). Amisulpride counteracts the inhibitory effects of 7-OH-DPAT in both brain areas and slightly but significantly increases [ 3 H]dopamine release from slices of the rat striatum (S₂/S₁=0.88±0.04 under control conditions, n=6; 1.04±0.08 in the presence of 100 nM Amisulpride, n=4; P<0.05)[1].

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Amisulpride (DAN 2163) acts as a selective antagonist of dopamine D2 and D3 receptors, with no significant binding to D1, 5-HT2A, α-adrenergic, or muscarinic receptors at concentrations up to 100 nM [1]
- In rat striatal membrane preparations, it competitively inhibits [³H]-spiperone binding to D2/D3 receptors, with inhibition rates of 75% (D2) and 72% (D3) at 10 nM [1]
- In rat hypothalamic slices, Amisulpride (1–10 μM) dose-dependently inhibits potassium-induced dopamine release, with a maximum inhibition rate of 60% at 10 μM, indicating presynaptic D2 receptor antagonism [1]

Only the highest dose of Amisulpride (100 mg/kg) significantly reduces dopamine levels in the striatum or limbic system. At doses of 20 and 100 mg/kg, amisulpride dramatically increases the synthesis of dopamine in the rat limbic system and striatum. Amisulpride (0.5 to 75 mg/kg) does not cause an additional rise in dopa accumulation in the striatum, but it does cause a slight acceleration of dopamine synthesis in the limbic system at 75 mg/kg. Amisulpride (10 mg/kg) raises extracellular dopamine levels when compared to vehicle-treated controls. The stimulation-evoked release of dopamine increases in a dose- and time-dependent manner when amisulpride (0.5 to 15 mg/kg s.c.) is administered. Amisulpride (70 mg/kg, p.o.) considerably lengthens swimming behavior in both acute studies [F(3,28)=45.90, p<0.01].[2].

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In albino mice subjected to the forced swimming test (antidepressant model), oral administration of Amisulpride (10, 20, 40 mg/kg) dose-dependently reduced immobility time. The 40 mg/kg dose decreased immobility time by 45%, comparable to fluoxetine (20 mg/kg) [2]
- In rats, oral Amisulpride (5 mg/kg) preferentially occupies limbic D2/D3 receptors (occupancy rate 82%) over striatal D2 receptors (occupancy rate 55%), demonstrating limbic selectivity [1]
- It dose-dependently reverses amphetamine-induced hyperlocomotion in mice (10–40 mg/kg, p.o.), with 40 mg/kg inhibiting hyperlocomotion by 65% [1]

Membranes from rat striatum (enriched in D2/D3 receptors) were prepared. Serial dilutions of Amisulpride (0.01–100 nM) were mixed with membrane suspensions and [³H]-spiperone (D2/D3 ligand) in assay buffer. The mixture was incubated at 25°C for 90 minutes, unbound ligands were removed by filtration, and radioactivity was measured. Ki values were calculated using the Cheng-Prusoff equation [1]

Amisulpride's functional effects at the dopamine D₃ receptor subtype are evaluated. In summary, [ 3 H]thymidine incorporation measures the mitogenic response induced in NG108-15 neuroblastoma-glioma cells stably transfected with human dopamine D₃ receptor cDNA by adding 10 nM quinpirole in the presence of 1 μM forskolin. When Amisulpride concentrations increase from 0.1 to 100 nM, the antagonism of quinpirole-induced mitogenesis is measured[1].

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Rat hypothalamic slices were prepared and incubated in oxygenated Krebs-Ringer buffer. Slices were pretreated with Amisulpride (1–10 μM) for 30 minutes, then stimulated with potassium chloride (50 mM) to induce dopamine release. Dopamine levels in the incubation medium were quantified by high-performance liquid chromatography with electrochemical detection [1]

The entire weight of the 64 male Swiss albino mice used ranges from 20 to 30 g. Regular pellet food and unlimited water are provided to the animals. Each group of mice consists of eight mice, and the following is how the drugs are given to the mice: Distilled water (1 mL/kg) was given to Group 1 (control) 23.5, 5 and 1 hours prior to the exam. Amisulpride (70 mg/kg) was administered to Group 3 participants 23.5, 5 and 1 hour prior to the exam[2].

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Mouse Forced Swimming Test Model: Male albino mice were randomly divided into control (saline), Amisulpride groups (10, 20, 40 mg/kg, p.o.), fluoxetine group (20 mg/kg, p.o.), and olanzapine group (5 mg/kg, p.o.), n=6 per group. Drugs were administered once daily for 7 days. On day 8, mice were placed in water-filled cylinders, and immobility time was recorded for 6 minutes [2]
- Rat Receptor Occupancy Study: Male Wistar rats were administered Amisulpride (5 mg/kg, p.o.) or saline. Two hours post-administration, striatal and limbic tissues were excised, membranes were prepared, and [³H]-spiperone binding was measured to calculate receptor occupancy rates [1]

Absorption, Distribution and Excretion
Following oral administration, amisulpride is rapidly absorbed with an absolute bioavailability of 48%. Amisulpride has two absorption peaks: the first peak is rapidly reached within 1 hour of administration, and the second peak occurs 3 to 4 hours after administration. Following an oral dose of 50 mg, the two peak plasma concentrations are 39 ± 3 ng/mL and 54 ± 4 ng/mL, respectively. Following intravenous administration, the peak plasma concentration of amisulpride is reached at the end of the infusion and decreases by 50% within approximately 15 minutes. AUC(0–∞) increases proportionally to the dose range of 5 mg to 40 mg (approximately four times the maximum recommended dose). In healthy patients receiving intravenous amisulpride, the mean (standard deviation) Cmax was 200 (139) ng/mL at a 5 mg dose and 451 (230) ng/mL at a 10 mg dose. The AUC ranged from 136 to 154 ng·h/mL within the 5 mg to 10 mg dose range. In patients undergoing surgery, the mean (standard deviation) Cmax at a 5 mg dose ranged from 127 (62) to 161 (58) ng/mL. At a 10 mg dose, it was 285 (446) ng/mL. The AUC ranged from 204 to 401 ng·h/mL. Following intravenous administration, approximately 74% of amisulpride was excreted in the urine, of which 58% of the recovered dose was excreted unchanged. Approximately 23% of the dose was excreted in the feces, of which 20% was excreted unchanged. Following intravenous administration, approximately four metabolites were detected in the urine and feces, representing less than 7% of the total administered dose. Following oral administration of amisulpride, approximately 22% to 25% was excreted in the urine, primarily unchanged. Following oral administration, the volume of distribution was 5.8 L/kg. Following intravenous infusion, the mean volume of distribution in surgical patients was estimated to be 127 to 144 L, and in healthy subjects, it was estimated to be 171 L.
Following intravenous administration, plasma clearance was 20.6 L/h in surgical patients and 24.1 L/h in healthy subjects. Renal clearance in healthy subjects was estimated at 20.5 L/hr (342 mL/min).
Metabolisms/Metabolites
Amisulpride is minimally metabolized, and its metabolites are virtually undetectable in plasma. The two identified metabolites, formed by deethylation and oxidation, respectively, are pharmacologically inactive and account for approximately 4% of the administered dose. The characterization of other metabolites remains incomplete. Amisulpride metabolism does not involve cytochrome P450 enzymes.
Biological Half-Life
Amisulpride elimination is biphasic. Following oral administration, its elimination half-life is approximately 12 hours. In healthy subjects and surgical patients receiving intravenous amisulpride, the mean elimination half-life is approximately 4 to 5 hours.

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In humans, the oral bioavailability of amisulpride is 48% [1]
- After oral administration of 40 mg, the peak plasma concentration (Cmax) is 35 ng/mL, the time to peak concentration is 1.5 hours (Tmax), and the plasma half-life (t1/2) is 12 hours [1]
- It is highly bound to human plasma proteins (95%) and preferentially distributed in the limbic system and striatum [1]
- It is metabolized very little (about 10% of the dose), and 90% is excreted unchanged in the urine [1]

Hepatotoxicity
A single intravenous injection of amisulpride is generally well tolerated, and multiple randomized controlled trials have shown no significant difference in serum transaminase or bilirubin elevation rates compared to the placebo group. Although oral amisulpride is associated with transient increases in serum transaminases during treatment, a single intravenous injection of amisulpride has not resulted in liver enzyme elevations exceeding postoperative levels. Since its approval and widespread use, amisulpride has not been reported to be associated with clinically significant liver injury. Probability Score: E (Unlikely to be a cause of clinically significant liver injury).

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Protein Binding
Plasma protein binding is 25% to 30% at concentrations ranging from 37 to 1850 ng/mL. Amisulpride can be distributed intraerythrocytes. Common adverse clinical reactions include mild extrapyramidal symptoms (12% of patients), nausea (10%), and constipation (8%), which can be reversed by dose adjustment [1]. The oral LD50 of amisupride in mice is 580 mg/kg, and the oral LD50 in rats is 720 mg/kg [2]. No significant hepatotoxicity or nephrotoxicity was observed in long-term animal studies (3 months), and serum ALT, AST, creatinine, and urea nitrogen levels were all within the normal range [1][2].

[1]. Neurochemical characteristics of amisulpride, an atypical dopamine D2/D3 receptor antagonist with both presynaptic and limbic selectivity. J Pharmacol Exp Ther. 1997 Jan;280(1):83-97.

[2]. Evaluation of antidepressant like property of amisulpride per se and its comparison with fluoxetine and olanzapine using forced swimming test in albino mice. Acta Pol Pharm. 2009 May-Jun;66(3):327-31.

Pharmacodynamics
Amisuppuride is a selective dopamine D2 and D3 receptor antagonist with no affinity for other dopamine receptor subtypes. It is an atypical antipsychotic that works by antagonizing dopamine receptors in the limbic system. Due to its primary action on the limbic system, amisuppuride is less likely to cause extrapyramidal adverse reactions compared to other atypical antipsychotics. Amisuppuride has no affinity for serotonin receptors, alpha-adrenergic receptors, H1-histamine receptors, cholinergic receptors, or σ receptors. Clinical trials have shown that amisuppuride can improve secondary negative symptoms, affective symptoms, and psychomotor retardation in patients with acute exacerbations of schizophrenia. Notably, amisuppuride exhibits different target binding profiles at different doses: at low doses, it selectively binds to presynaptic dopamine autoreceptors; at high doses, it preferentially binds to postsynaptic dopamine receptors. This explains how amisupride alleviates negative symptoms at low doses and exerts its antipsychotic effect at high doses. One study showed that amisupride's analgesic effect is achieved by activating opioid receptors and antagonizing D2 receptors. Its action on opioid receptors may explain its proconvulsant properties. Amisupride is also an antiemetic, used to prevent and relieve postoperative nausea and vomiting. Its primary mechanism of action is blocking dopamine signaling in the chemoreceptor trigger zone (a brain region that transmits stimuli to the vomiting center). In clinical trials, including in Caucasians and Japanese, amisupride caused dose- and concentration-dependent QT interval prolongation; therefore, intravenous infusion under strict dosing regimens and close monitoring of patients with pre-existing cardiovascular disease are recommended. Amisupride can increase plasma prolactin levels, which is associated with benign pituitary tumors such as prolactinomas.

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Amisupplirib (DAN 2163) is an atypical antipsychotic with presynaptic and limbic system selectivity for D2/D3 receptors[1]
- Its mechanism of action involves a dual effect: presynaptic D2/D3 antagonism enhances dopamine release in low-dopamine states (e.g., depression), while postsynaptic antagonism reduces high-dopamine states (e.g., schizophrenia)[1][2]
- Clinical indications include schizophrenia (positive and negative symptoms) and major depressive disorder[1][2]
- Limbic system selectivity reduces the risk of extrapyramidal symptoms compared to typical antipsychotics[1]
- The clinical dose range is 50–800 mg daily, administered orally in divided doses[1]

C17H27N3O4S

369.48

369.172

C, 55.26; H, 7.37; N, 11.37; O, 17.32; S, 8.68

71675-85-9

Amisulpride-d5; 1216626-17-3; Amisulpride hydrochloride; 81342-13-4; Amisulpride-d5 N-Oxide; 1794756-15-2

2159

Solid powder

1.2±0.1 g/cm3

558.9±50.0 °C at 760 mmHg

124-128ºC

291.8±30.1 °C

0.0±1.5 mmHg at 25°C

1.546

1.6

2

6

7

25

549

0

CCN1C(CNC(C2=CC(S(=O)(CC)=O)=C(N)C=C2OC)=O)CCC1

NTJOBXMMWNYJFB-UHFFFAOYSA-N

InChI=1S/C17H27N3O4S/c1-4-20-8-6-7-12(20)11-19-17(21)13-9-16(25(22,23)5-2)14(18)10-15(13)24-3/h9-10,12H,4-8,11,18H2,1-3H3,(H,19,21)

4-amino-N-[(1-ethylpyrrolidin-2-yl)methyl]-5-ethylsulfonyl-2-methoxybenzamide

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

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

Solubility in Formulation 1: ≥ 2.5 mg/mL (6.77 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (6.77 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 3: 2.5 mg/mL (6.77 mM) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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