Drug compounds have included stable heavy isotopes of carbon, hydrogen, and other elements, mostly as quantitative tracers while the drugs were being developed. Because deuteration may have an effect on a drug's pharmacokinetics and metabolic properties, it is a cause for concern [1].

Absorption, Distribution and Excretion
After a single-dose administration, the Tmax was four hours and the absolute oral bioavailability was 95%. Brexpiprazole steady-state concentrations were attained within 10 to 12 days of dosing. After single and multiple once-daily dose administration, the Cmax and AUC increased dose-proportionally. A high-fat meal did not significantly affect the Cmax or AUC of brexpiprazole.
Following a single oral dose of radiolabeled brexpiprazole, approximately 25% and 46% of radioactivity was recovered in the urine and feces, respectively. Less than 1% of unchanged brexpiprazole was excreted in the urine, and approximately 14% of the oral dose was recovered unchanged in the feces.
The volume of distribution of brexpiprazole following intravenous administration is 1.56 ± 0.42 L/kg, indicating extravascular distribution.
Apparent oral clearance of brexpiprazole after once-daily administration is 19.8 (±11.4) mL/h/kg.

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Metabolism / Metabolites
According to _in vitro_ studies, brexpiprazole is mainly metabolized by CYP3A4 and CYP2D6. Brexpiprazole and its major metabolite, DM-3411, were the predominant drug moieties in the systemic circulation following single and multiple dose administration. At steady-state, DM-3411 represented 23% to 48% of brexpiprazole exposure (AUC) in plasma. DM-3411 is considered not to be pharmacologically active.

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Biological Half-Life
After multiple once-daily administrations, the terminal elimination half-lives of brexpiprazole and its major metabolite, DM-3411, were 91 hours and 86 hours, respectively.

Hepatotoxicity
Liver test abnormalities were reported to occur in ~1% of patients on long term therapy with brexpiprazole, but similar rates occurred in patients on placebo or with comparator agents. There have been no published reports of clinically apparent acute liver injury due to brexpiprazole and only rare instances have been reported with the much more frequently used aripiprazole. Thus, liver injury due to brexpiprazole must be rare, if it occurs at all.
Likelihood score: E (unlikely cause of clinically apparent liver injury).

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
No information is available on the excretion of brexpiprazole in breastmilk. A single case report implicated brexpiprazole as a cause of decreased lactation. A review of case reports found lactation disorders and breast secretion reported as side effects, but details are lacking. Until more data are available, an alternate drug may be preferred.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
A woman was taking brexpiprazole 2 mg daily during the third trimester of pregnancy for bipolar disorder. Her newborn infant was hospitalized in the NICU for hypoxic ischemic encephalopathy for 18 days. While her infant was in the NICU, she reduced her brexpiprazole dose to 2 mg every 2 days because of a shortage of medication. The mother, who had successfully breastfed 2 previous infants, pumped milk 10 times daily and was able to pump 120 mL daily by one week postpartum. After her infant was discharged, she increased the dose back to 2 mg daily. At a follow-up clinic visit, she could only pump 30 mL daily. She then stopped brexpiprazole and began a short course of metoclopramide. Within 10 days of stopping brexpiprazole, her milk supply increased, and she could almost exclusively breastfeed her infant who gained weight normally. Her serum prolactin level also increased to normal.
A review of case reports of adverse reactions reported in the US Food and Drug Administration’s Adverse Event Reporting System from 2015 to 2023 found 6 reports of “lactation disorder” and 10 cases of “breast discharge” reported with brexpiprazole. Other details were lacking.

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Protein Binding
_In vitro_, brexpiprazole was 99% bound to plasma proteins, mainly serum albumin and α1-acid glycoprotein.

[1]. Impact of Deuterium Substitution on the Pharmacokinetics of Pharmaceuticals. Ann Pharmacother. 2019 Feb;53(2):211-216.

[2]. Potentiation of neurite outgrowth by brexpiprazole, a novel serotonin-dopamine activity modulator: a role for serotonin 5-HT1A and 5-HT2A receptors. Eur Neuropsychopharmacol. 2015 Apr;25(4):505-11.

[3]. Improvement of dizocilpine-induced social recognition deficits in mice by brexpiprazole, a novel serotonin-dopamine activity modulator. Eur Neuropsychopharmacol. 2015 Mar;25(3):356-64.

Brexpiprazole is a N-arylpiperazine.
Brexpiprazole is an atypical antipsychotic and a novel D2 dopamine and serotonin 1A partial agonist called serotonin-dopamine activity modulator (SDAM). It has a high affinity for serotonin, dopamine and alpha (α)-adrenergic receptors. Although it is structurally similar to [aripiprazole], brexpiprazole has different binding affinities for dopamine and serotonin receptors. Compared to aripiprazole, brexpiprazole has less potential for partial agonist-mediated adverse effects such as extrapyramidal symptoms, which is attributed to lower intrinsic activity at the D2 receptor. It also displays stronger antagonism at the 5-HT1A and 5-HT2A receptors. Brexpiprazole was first approved by the FDA on July 10, 2015. Currently approved for the treatment of depression, schizophrenia, and agitation associated with dementia due to Alzheimer’s disease, brexpiprazole has also been investigated in other psychiatric disorders, such as post-traumatic stress disorder.
Brexpiprazole is an Atypical Antipsychotic.
Brexpiprazole is an atypical antipsychotic used in the treatment of schizophrenia and major depressive disorders. Brexpiprazole has been associated with a low rate of serum aminotransferase elevations during therapy but has not been linked to instances of clinically apparent acute liver injury.

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Drug Indication
Brexpiprazole is indicated as adjunctive therapy to antidepressants for the treatment of major depressive disorder in adults. It is also indicated for the treatment of schizophrenia in patients 13 years of age and older. Brexpiprazole is also indicated for the treatment of agitation associated with dementia due to Alzheimer’s disease; however, it is not indicated as an as-needed (“prn”) treatment for this condition.
Treatment of schizophrenia.
Treatment of schizophrenia

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Mechanism of Action
Although the exact mechanism of action of brexpiprazole in psychiatric disorders has not been fully elucidated, the efficacy of brexpiprazole may be attributed to combined partial agonist activity at 5-HT_1A and dopamine D2 receptors, and antagonist activity at 5-HT_2A receptors. Brexpiprazole binds to these receptors with subnanomolar affinities. These therapeutic targets have been implicated in psychiatric conditions such as schizophrenia and depression. Partial D2 receptor agonism allows the drug to stimulate D2 receptors under low dopamine conditions, while attenuating their activation when dopamine levels are high. Partial agonism at 5-HT_1A receptors may be tied to improved memory function and cognitive performance. Antagonism at α-adrenergic receptors has also been implicated in schizophrenia and depression.

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Pharmacodynamics
Brexpiprazole is an atypical antipsychotic agent used to ameliorate the symptoms of psychiatric conditions, such as cognitive deficits and affective symptoms. Brexpiprazole has affinity (expressed as Ki) for multiple monoaminergic receptors including serotonin 5-HT_1A (0.12 nM), 5-HT_2A (0.47 nM), 5-HT_2B (1.9 nM), 5-HT₇ (3.7 nM), dopamine D2 (0.30 nM), D3 (1.1 nM), and noradrenergic α_1A (3.8 nM), α_1B (0.17 nM), α_1D (2.6 nM), and α_2C (0.59 nM) receptors. Brexpiprazole acts as a partial agonist at the 5-HT_1A, D2, and D3 receptors and as an antagonist at 5-HT_2A, 5-HT_2B, 5-HT₇, α_1A, α_1B, α_1D, and α_2C receptors. Brexpiprazole also exhibits affinity for histamine H1 receptor (19 nM) and for muscarinic M1 receptor (67% inhibition at 10 µM).

C25H27N3O2S

441.615078210831

433.182

1427049-19-1

Brexpiprazole;913611-97-9

11978813

Off-white to light yellow solid powder

4.7

1

5

7

31

636

0

S1C=CC2=C1C=CC=C2N1C([2H])([2H])C([2H])([2H])N(CCCCOC2=CC=C3C=CC(NC3=C2)=O)C([2H])([2H])C1([2H])[2H]

ZKIAIYBUSXZPLP-UHFFFAOYSA-N

InChI=1S/C25H27N3O2S/c29-25-9-7-19-6-8-20(18-22(19)26-25)30-16-2-1-11-27-12-14-28(15-13-27)23-4-3-5-24-21(23)10-17-31-24/h3-10,17-18H,1-2,11-16H2,(H,26,29)

7-[4-[4-(1-benzothiophen-4-yl)piperazin-1-yl]butoxy]-1H-quinolin-2-one

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)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

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.)