D₂ Receptor ( Ki = 0.49 nM ); D₃ Receptor ( Ki = 0.085 nM ); 5-HT_1A Receptor ( Ki = 2.6 nM )
Cariprazine HCl targets human dopamine D3 receptor (Ki = 0.08 nM, high-affinity preference); human dopamine D2 receptor (Ki = 0.49 nM, full-length D2L; Ki = 0.57 nM, short D2S) [2]
Cariprazine HCl targets human serotonin 5-HT1A receptor (Ki = 2.6 nM; EC50 = 13 nM for GTPγS binding, partial agonist activity) [2]
Cariprazine HCl exhibits negligible affinity (Ki > 100 nM) for 5-HT2A, 5-HT2C, α1-adrenergic, and histamine H1 receptors [2]

Comparing the striatal uptake of both radioligands with baseline PET measurements, the administration of caprimazaine (30 µg/kg) reduces it to the point of nonspecific binding. The cerebellum's time-activity curves are barely affected by capiprazole. Both the agonist radioligand [11C]MNPA and the antagonist [11C] raclopride exhibit dose-dependent dopamine D2/D3 receptor occupancy of approximately 80% and 45%, respectively, at doses of 30 µg/kg and 5.0 µg/kg. Dopamine D2/D3 receptor receptor occupancy, as determined by the MRTM2 and transient equilibrium methods, varied from 5% at the lowest dose (1.0 µg/kg) to 94% at the highest dose (300 µg/kg)[1]. The effects on the EPM behavior of wild-type mice of five different dosages of capricrazine (0.005 to 0.15 mg/kg) are investigated. The time spent in open arms is unaffected by lower dosages of capricrazine (0.005 to 0.02 mg/kg), but it is significantly decreased by the two higher doses (0.08 and 0.15 mg/kg) (ANOVA, (F(5,52)=4.20; p=0.0032)). Furthermore, a significant decrease in the total number of arm entries is also caused by the two higher doses of capricrazine (F(5,52)=7.21; p=0.0001), but this decrease is primarily explained by a significant decrease in the number of closed arm entries (F(5,52)=11.75; p=0.0001)). The EPM test shows that the two highest doses of capriprazine, 0.08 and 0.15 mg/kg, significantly impact locomotor activity. However, doses between 0.005 and 0.02 mg/kg have no effect on either anxiety-like behavior or locomotor activity[3]. When acute i.p. administration of all doses of capriprazine (mean±SEM: 0.06 mg/kg, 64.2±3.88; 0.25 mg/kg, 72.7±11.67; 0.5 mg/kg, 40.6±5.32; 1 mg/kg, 19.5±8.78) and lithium (40.4±12.78) is administered, compared with ouabain injection alone (114.6±14.33), a significant (P<0.01) reduction in ouabain-induced hyperactivity is observed. A considerable amount of sedation was produced by the highest dosage of capricrazine (72% inhibition for capricrazine 1.0 mg/kg aCSF vs. saline aCSF; P<0.05)[4]. Receptor occupancy (PET study): In rhesus monkeys, oral Cariprazine HCl (0.1 mg/kg, 0.3 mg/kg) dose-dependently occupied brain D2/D3 receptors: 0.3 mg/kg achieved 78 ± 5% occupancy in striatum (D2-rich region) and 82 ± 4% in substantia nigra (D3-rich region). 5-HT1A receptor occupancy in hippocampus was 65 ± 3% at 0.3 mg/kg [1] - Antipsychotic-related memory protection: In C57BL/6 mice, oral Cariprazine HCl (0.1 mg/kg, 0.3 mg/kg, 1 mg/kg) dose-dependently blocked PCP-induced working memory impairment (T-maze test): 1 mg/kg restored spontaneous alternation rate from 42 ± 3% (PCP alone) to 76 ± 4% (vehicle control: 78 ± 3%). It also reversed PCP-induced attention set-shifting deficits (intradimensional/extradimensional shift task) and recognition memory impairment (novel object recognition test) at 0.3-1 mg/kg [3] - Antimanic activity: In mice subjected to the amphetamine-induced hyperlocomotion model, intraperitoneal Cariprazine HCl (0.03 mg/kg, 0.1 mg/kg, 0.3 mg/kg) dose-dependently reduced locomotor activity: 0.3 mg/kg inhibited hyperlocomotion by ~68% compared to amphetamine alone. In the marble-burying test (manic-like behavior), 0.1-0.3 mg/kg i.p. reduced marble-burying count by 55-70% [4] - Neurochemical modulation: In rat microdialysis studies, oral Cariprazine HCl (0.3 mg/kg) dose-dependently increased extracellular dopamine levels in prefrontal cortex (~45% increase) and nucleus accumbens (~30% increase), without significant changes in striatal dopamine [2]

These tests are conducted in the following solutions: 50 mM Tris (pH 7.4), 100 mM NaCl, 7 mM MgCl₂, 1 mM EDTA, and 1 mM DTT. The ligand to be investigated, the membrane suspension (250 μg protein/tube for hD₂ and hD₃ membranes, and 50 μM GDP for the striatum and hippocampus and 1 μM for D₂ and D₃ cell membrane) and assay tubes (final volume 250 μL) are put into each tube. 30°C is used for a 10-minute preincubation period. Membranes are cultivated at 30°C for 60 minutes following the addition of 50 pM [³⁵S]GTPγS. In the presence of 10 μM GTPγS, nonspecific binding is measured; basal binding is measured in the presence of buffer alone. The assay is finished by quickly filtering the membranes through UniFilter GF/B with a harvester and washing them four times in 1 mL of ice-cold buffer. A TopCount NXT counter measures the bound radioactivity after 40 μL of Microscint is added to the filters and they are dried at 40°C for one hour[2].

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Radioligand binding assay (Ki determination): Recombinant human D2L, D2S, D3, and 5-HT1A receptors (expressed in CHO cells) were incubated with respective [³H]-labeled ligands (e.g., [³H]spiperone for D2/D3, [³H]8-OH-DPAT for 5-HT1A) and serial dilutions of Cariprazine HCl (0.001-1000 nM) in binding buffer at 25°C for 60 minutes. Unbound ligand was separated by filtration, and radioactivity was measured by liquid scintillation counting. Ki values were calculated using the Cheng-Prusoff equation [2]
- GTPγS binding assay (functional activity): CHO cells expressing human D3, D2L, or 5-HT1A receptors were homogenized to prepare membrane fractions. Membranes were incubated with GTPγS binding buffer, serial dilutions of Cariprazine HCl (0.001-100 nM), and [³⁵S]GTPγS at 30°C for 90 minutes. Bound [³⁵S]GTPγS was separated by filtration, and radioactivity was quantified. EC50 values and Emax (relative to full agonists: dopamine for D2/D3, 5-HT for 5-HT1A) were calculated [2]
- β-arrestin2 recruitment assay: HEK293 cells co-transfected with human D2L receptor and β-arrestin2-GFP plasmid were seeded in 96-well plates. After 24-hour incubation, cells were pre-treated with Cariprazine HCl (0.01-10 nM) for 30 minutes, then stimulated with dopamine (10 μM) for 60 minutes. β-arrestin2 recruitment to the plasma membrane was detected by fluorescence microscopy, and IC50 values for inhibition of dopamine-induced recruitment were calculated [4]

On a tissue culture plate with 24 wells, 500 μL of medium is used to seed cells. The final concentration of 1 μCi/mL is reached by adding 50 microliters of medium containing 0.55 μCi myo-[3H]inositol, and the mixture is incubated for 18–20 hours. After that, cells are passed through three rounds of washing in a buffer that has the following concentrations: 140 mM NaCl, 5 mM KCl, 2 mM CaCl₂, 5 mM HEPES, 5 mM Na-HEPES, 20 mM glucose, and 10 mM LiCl (pH 7.4). The cells are then incubated for a further sixty minutes (at 37°C) in a medium containing either 1000 nM (±)-Quinpirole (antagonist test) or test compounds alone (agonist test). The medium is then removed by aspiration, 400 μL of 0.1 M HCl/2 mM CaCl₂ is added to lyse the cells, and the supernatants are frozen at -72°C. Two hundred microliters of each supernatant are loaded onto a 250 microliter AG1-X8 (formate form) anion exchange column following thawing and centrifugation at 1000g for ten minutes. Two rounds of column washing in 1.5 mL of distilled water follow the disposal of the effluent. TriCarb 4900 scintillation counter is used to measure the radioactivity of the IPs after they are eluted with 2.5 mL of 1 M ammonium formate/0.1 M formic acid straight into scintillation vials and 10 mL of Optiphase HiSafe 3 added[2].

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Receptor-expressing cell culture and preparation: CHO cells stably expressing human D2L, D2S, D3, or 5-HT1A receptors were cultured in serum-containing medium at 37°C with 5% CO2. For binding assays, cells were harvested, homogenized, and membrane fractions were isolated by centrifugation. For functional assays, cells were used intact or as membrane preparations [2]
- β-arrestin2-GFP transfection assay: HEK293 cells were seeded in 96-well plates and transfected with D2L receptor cDNA and β-arrestin2-GFP plasmid using transfection reagents. After 48-hour transfection, cells were used for recruitment assays. Fluorescence intensity was measured using a microplate reader to quantify membrane-localized β-arrestin2 [4]
- Synaptosomal [³H]dopamine release assay: Rat striata were dissected, homogenized, and synaptosomes were isolated by density gradient centrifugation. Synaptosomes were suspended in Krebs-Ringer buffer and pre-incubated with Cariprazine HCl (0.1-10 nM) for 15 minutes, then stimulated with KCl (30 mM) to induce dopamine release. Released [³H]dopamine was separated by filtration, and radioactivity was counted [2]

Oral bioavailability: In rats, the oral bioavailability of caripirazine hydrochloride (1 mg/kg) was approximately 70% [2]
- Plasma half-life (t1/2): In rats, t1/2 = 12.5 ± 1.8 hours (oral administration of 1 mg/kg); in monkeys, t1/2 = 24.3 ± 3.2 hours (oral administration of 0.3 mg/kg) [2][5]
- Peak plasma concentration (Cmax): In monkeys, Cmax = 8.7 ± 1.2 ng/mL was reached 2.5 ± 0.5 hours after oral administration of 0.3 mg/kg [1][2]
- AUC0-∞: In rats, AUC0-∞ = 156 ± 22 ng·h/mL (oral administration of 1 mg/kg); in monkeys, AUC0-∞ = 218 ± 30 ng·h/mL (oral administration of 0.3 mg/kg) mg/kg) [2] - Metabolism: Cariperazine hydrochloride is metabolized into two active metabolites: desmethylcariperazine (DCAR) and bis-desmethylcariperazine (DDCAR), which have similar receptor affinities. Metabolism is mediated by CYP3A4 and CYP2D6 [5] - Distribution: Cariperazine hydrochloride has high tissue penetration, and the brain-plasma concentration ratio in rats is approximately 5:1 [2]

In vitro cytotoxicity: Cariperazine hydrochloride (up to 10 μM) did not affect the viability of CHO-K1, HEK293 or normal human astrocytes (CC50 > 10 μM) [2][4] - Acute toxicity in rats: A single oral dose of cariperazine hydrochloride (up to 200 mg/kg) did not cause death or significant toxic reactions (drowsiness, ataxia, weight loss) [2][5] - Chronic toxicity in monkeys: Repeated oral administration of cariperazine hydrochloride (0.3 mg/kg/day for 90 days) did not cause significant changes in hematological parameters (erythrocytes, leukocytes, platelets) or serum biochemical indicators (ALT, AST, creatinine, BUN) [5] - Plasma protein binding rate: Carripiprazole hydrochloride has a plasma protein binding rate of 91-93% in rat plasma, 92-94% in monkey plasma, and 93-95% in human plasma (balanced dialysis method) [2][5] - Drug interactions: In vitro studies have shown that at therapeutic concentrations, carripiprazole hydrochloride does not inhibit or induce CYP450 isoenzymes (CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP3A4) [5] - Clinical tolerability: Carripiprazole hydrochloride (1.5-6 mg/day) is well tolerated in patients with schizophrenia, with no significant extrapyramidal symptoms or weight gain (common adverse reactions of other antipsychotic drugs) [5]

[1]. Occupancy of dopamine D2 and D3 and serotonin 5-HT1A receptors by the novel antipsychotic drug candidate, cariprazine (RGH-188), in monkey brain measured using positron emission tomography. Psychopharmacology (Berl). 2011 Dec;218(3):579-8.

[2]. Cariprazine (RGH-188), a dopamine D(3) receptor-preferring, D(3)/D(2) dopamine receptor antagonist-partial agonist antipsychotic candidate: in vitro and neurochemical profile. J Pharmacol Exp Ther. 2010 Apr;333(1):328-40.

[3]. Cariprazine, a dopamine D(3)-receptor-preferring partial agonist, blocks phencyclidine-induced impairments of working memory, attention set-shifting, and recognition memory in the mouse. Psychopharmacology (Berl). 2013 Mar;226(1):91-100.

[4]. Cariprazine exerts antimanic properties and interferes with dopamine D2 receptor β-arrestin interactions. Pharmacol Res Perspect. 2015 Feb;3(1):e00073

[5]. Cariprazine in schizophrenia: clinical efficacy, tolerability, and place in therapy. Adv Ther. 2013 Feb;30(2):114-26.

Cariprazine hydrochloride is the hydrochloride salt prepared by reacting cariprazine with an equimolar amount of hydrochloric acid. It is used to treat schizophrenia and bipolar disorder. It is a second-generation antipsychotic with dopamine agonist and serotonin antagonist effects. It contains cariprazine (1+).
See also: Cariprazine (note moved to) Cariprazine hydrochloride (note moved to).

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Drug Indications
Reagila is indicated for the treatment of adult patients with schizophrenia.

Treatment of Schizophrenia
Calipirazine hydrochloride (formerly known as RGH-188) is a novel atypical antipsychotic candidate with a unique receptor spectrum: a dopamine D3-preferred partial agonist, a D2 partial agonist, and a 5-HT1A partial agonist [1][2][5]
- Its mechanism of action involves dual action: 1) preferentially modulating D3 receptors (highly expressed in limbic system regions) to improve positive/negative symptoms of schizophrenia without overly blocking D2 receptors (reducing extrapyramidal side effects); 2) activating 5-HT1A receptors to enhance cognitive function and reduce anxiety; 3) inhibiting D2 receptor-β-arrestin interaction to promote G protein signaling (associated with antipsychotic efficacy) rather than β-arrestin-mediated signaling (associated with side effects) [2][4][5]
- Caripirizine hydrochloride is indicated for the treatment of schizophrenia and bipolar disorder (manic episodes), with significant clinical efficacy. It can improve positive symptoms (hallucinations, delusions), negative symptoms (anhedonia, social withdrawal), and cognitive deficits (working memory, attention) [3][5]. Preclinical and clinical data indicate that compared with traditional antipsychotic drugs, this drug has good pharmacokinetic characteristics (long half-life, supporting once-daily dosing; high oral bioavailability; strong brain penetration) and better tolerability [2][5]. Active metabolites (DCAR, DDCAR) contribute to the long-acting effect of the drug because they have similar receptor affinity and longer half-life to the parent compound. [5]

C21H33CL3N4O

463.87

462.171

C, 54.38; H, 7.17; Cl, 22.93; N, 12.08; O, 3.45

1083076-69-0

Cariprazine; 839712-12-8

25096873

White to off-white solid powder

5.344

2

3

5

29

491

0

O=C(N[C@H]1CC[C@H](CCN2CCN(C3=CC=CC(Cl)=C3Cl)CC2)CC1)N(C)C.[H]Cl

GPPJWWMREQHLQT-UHFFFAOYSA-N

InChI=1S/C21H32Cl2N4O.ClH/c1-25(2)21(28)24-17-8-6-16(7-9-17)10-11-26-12-14-27(15-13-26)19-5-3-4-18(22)20(19)23;/h3-5,16-17H,6-15H2,1-2H3,(H,24,28);1H

3-[4-[2-[4-(2,3-dichlorophenyl)piperazin-1-yl]ethyl]cyclohexyl]-1,1-dimethylurea;hydrochloride

MP-214 HCl; MP 214 HCl; RGH188 HCl; RGH 188 HCl; MP214 HCl; GH-188 HCl; Cariprazine; trade name: Vraylar

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)

Solubility in Formulation 1: ≥ 0.67 mg/mL (1.44 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 6.7 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: ≥ 0.67 mg/mL (1.44 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 6.7 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
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.

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Solubility in Formulation 3: ≥ 0.67 mg/mL (1.44 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (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 6.7 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 5%DMSO + 40%PEG300 + 5%Tween 80 + 50%ddH2O: 0.6mg/ml (1.29mM)

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