BL-1020 Mesylate is a novel oral antipsychotic agent that interacts with multiple receptors. It exhibits high affinity for dopamine and serotonin receptors, as well as moderate affinity for GABA-A receptors. Key inhibition constants (Ki) are as follows:
Dopamine D2L (human): Ki = 0.066 nM
Dopamine D2S (human): Ki = 0.062 nM
Dopamine D3 (human): Ki = 0.048 nM
Serotonin 5-HT2A (human): Ki = 0.211 nM
Serotonin 5-HT2B (human): Ki = 0.026 nM
Serotonin 5-HT7 (human): Ki = 0.051 nM
Histamine H1 (human): Ki = 0.473 nM
Adrenergic α1 (rat): Ki = 1.77 nM
Sigma 1 (human): Ki = 55 nM
GABA-A agonist site (rat): Ki = 3.74 μM [1].

Acute Antipsychotic Efficacy (Amphetamine-Induced Hyperactivity): In male Wistar rats, oral administration of BL-1020 Mesylate (6.6 mg/kg, equimolar to 3.2 mg/kg perphenazine) significantly antagonized amphetamine (3.0 mg/kg ip)-induced hyperactivity. It reduced the number of head movements (HM) by 68% and completely blocked wall climbing attempts (WC) to levels not significantly different from vehicle-treated controls, measured 90 minutes after amphetamine administration [1].
Subchronic Antipsychotic Efficacy (Amphetamine-Induced Hyperlocomotion): After 17 days of daily oral administration to rats, BL-1020 Mesylate dose-dependently reduced amphetamine-induced hyperlocomotion. At doses of 3.31, 6.63, and 13.26 mg/kg, the cumulative number of crossings was reduced by 24%, 58%, and 54%, respectively, compared to the amphetamine-only group. The reductions at the two higher doses were statistically significant (p < 0.01) [1].
Acute Catalepsy: In the acute amphetamine-induced hyperactivity model, BL-1020 Mesylate (6.6 mg/kg) did not induce any cataleptic effect as measured by the bar test 4 hours after drug administration, which was significantly different from the long-lasting cataleptic effect observed with an equimolar dose of perphenazine (3.2 mg/kg) [1].
Subchronic Catalepsy: In the 17-day study, BL-1020 Mesylate showed significantly lower global catalepsy scores compared to equimolar doses of perphenazine after a single dose and after 8 days of daily administration at doses of 3.31 and 6.63 mg/kg. At the highest dose of 13.26 mg/kg, the anti-cataleptic effect was reduced [1].
Effect on Prolactin Levels: In male Wistar rats, oral administration of BL-1020 Mesylate at doses equimolar to perphenazine (4.5 and 9.0 mg/kg) significantly and equally increased plasma prolactin levels at 120 and 180 minutes compared to baseline. This effect was similar to that of perphenazine itself [1].
Effect on Neurotransmitter Efflux (Microdialysis): Subcutaneous administration of BL-1020 Mesylate (1.0, 3.0, and 10 mg/kg) significantly and dose-dependently increased dopamine (DA) efflux in the rat medial prefrontal cortex (mPFC) and hippocampus (HIP). No significant increases in acetylcholine (ACh) efflux were observed in these brain regions at any of the doses tested [1].
Behavioral and Physiological Effects (Irwin Test): In an Irwin test, single oral doses of BL-1020 Mesylate up to 20 mg/kg produced no adverse side effects in rats. At 30 mg/kg, slight to moderate sedation, abnormal gait, and decreased reactivity to touch were observed [1].

Acute Amphetamine-Induced Hyperactivity:** Male Wistar rats (250-300 g) were administered orally with either perphenazine (3.2 mg/kg) or an equimolar dose of BL-1020 Mesylate (6.6 mg/kg), dissolved in 1% lactic acid/water. A control group received vehicle. Ninety minutes later, amphetamine (3.0 mg/kg) was administered intraperitoneally. A naive group received only amphetamine. Animals were then placed in individual barrels for 60 minutes, and head movements (HM) and wall climbing attempts (WC) were recorded every 15 minutes for a 120-second duration per measurement. Catalepsy was assessed 240 minutes after neuroleptic treatment using a bar test, measuring the latency for the animal to descend from a bar (5.5 cm height) [1].
* **Subchronic Amphetamine-Induced Hyperlocomotion:** Male Wistar rats received daily oral doses of perphenazine (1.6, 3.2, 6.4 mg/kg) or equimolar doses of BL-1020 Mesylate (3.3, 6.6, 13.3 mg/kg) for 17 days. Control animals received vehicle. On day 17, 2 hours after the last dose, all groups except controls received amphetamine (3.0 mg/kg ip). Rats were placed in activity meter cages, and the number of photocell crossings was recorded by computer at 10-minute intervals for 90 minutes. Catalepsy was evaluated using a four-point scale based on several parameters, observed for up to 8 hours on days 1, 8, and 15 [1].
* **Microdialysis for DA and ACh Efflux:** Male Sprague-Dawley rats (250-300 g) were anesthetized and stereotaxically implanted with guide cannulas in the medial prefrontal cortex (mPFC) and hippocampus (HIP). Concentric dialysis probes were implanted 3-5 days later. After overnight perfusion, dialysate samples were collected every 30 minutes. After stable baseline values were obtained, BL-1020 Mesylate (0.3, 1.0, 3.0, 10 mg/kg) or vehicle was administered subcutaneously through an implanted catheter, and sampling continued for 180 minutes. DA and ACh concentrations in dialysates were analyzed by HPLC with electrochemical detection [1].
* **Prolactin Level Measurement:** Male Wistar rats (250-300 g) were orally administered perphenazine (4.5, 9.0 mg/kg), equimolar doses of BL-1020 Mesylate, or vehicle, dissolved in 1% lactate solution. Blood samples were collected from the suborbital vein prior to dosing and at 120 and 180 minutes post-dose. Plasma was separated and prolactin levels were measured using a rat prolactin immunoassay kit [1].
* **Irwin Test:** Adult male Wistar rats (4 per group) were administered single increasing oral doses (3, 6, 10, 13, 20, 30 mg/kg) of BL-1020 Mesylate. The control group received vehicle. Behavioral and physiological responses, including convulsions, tremor, sedation, abnormal gait, changes in tone, piloerection, and autonomic reactions, were assessed using an Irwin test panel [1].

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Acute Amphetamine-Induced Hyperactivity: Male Wistar rats (250-300 g) were administered orally with either perphenazine (3.2 mg/kg) or an equimolar dose of BL-1020 Mesylate (6.6 mg/kg), dissolved in 1% lactic acid/water. A control group received vehicle. Ninety minutes later, amphetamine (3.0 mg/kg) was administered intraperitoneally. A naive group received only amphetamine. Animals were then placed in individual barrels for 60 minutes, and head movements (HM) and wall climbing attempts (WC) were recorded every 15 minutes for a 120-second duration per measurement. Catalepsy was assessed 240 minutes after neuroleptic treatment using a bar test, measuring the latency for the animal to descend from a bar (5.5 cm height) [1].
Subchronic Amphetamine-Induced Hyperlocomotion: Male Wistar rats received daily oral doses of perphenazine (1.6, 3.2, 6.4 mg/kg) or equimolar doses of BL-1020 Mesylate (3.3, 6.6, 13.3 mg/kg) for 17 days. Control animals received vehicle. On day 17, 2 hours after the last dose, all groups except controls received amphetamine (3.0 mg/kg ip). Rats were placed in activity meter cages, and the number of photocell crossings was recorded by computer at 10-minute intervals for 90 minutes. Catalepsy was evaluated using a four-point scale based on several parameters, observed for up to 8 hours on days 1, 8, and 15 [1].
Microdialysis for DA and ACh Efflux: Male Sprague-Dawley rats (250-300 g) were anesthetized and stereotaxically implanted with guide cannulas in the medial prefrontal cortex (mPFC) and hippocampus (HIP). Concentric dialysis probes were implanted 3-5 days later. After overnight perfusion, dialysate samples were collected every 30 minutes. After stable baseline values were obtained, BL-1020 Mesylate (0.3, 1.0, 3.0, 10 mg/kg) or vehicle was administered subcutaneously through an implanted catheter, and sampling continued for 180 minutes. DA and ACh concentrations in dialysates were analyzed by HPLC with electrochemical detection [1].
Prolactin Level Measurement: Male Wistar rats (250-300 g) were orally administered perphenazine (4.5, 9.0 mg/kg), equimolar doses of BL-1020 Mesylate, or vehicle, dissolved in 1% lactate solution. Blood samples were collected from the suborbital vein prior to dosing and at 120 and 180 minutes post-dose. Plasma was separated and prolactin levels were measured using a rat prolactin immunoassay kit [1].
Irwin Test: Adult male Wistar rats (4 per group) were administered single increasing oral doses (3, 6, 10, 13, 20, 30 mg/kg) of BL-1020 Mesylate. The control group received vehicle. Behavioral and physiological responses, including convulsions, tremor, sedation, abnormal gait, changes in tone, piloerection, and autonomic reactions, were assessed using an Irwin test panel [1].

Absorption and Bioavailability: Following a single oral dose of 5 mg/kg [14C]-BL-1020 Mesylate to rats, radioactivity was rapidly detected in blood, plasma, and brain, with peak levels reached at 1 hour. After 24 hours, 63.7 ± 6.1% of the administered radioactivity was recovered, with 35.9 ± 2.8% in urine and 19.4 ± 1.6% in feces, indicating extensive metabolism and good bioavailability [1].
Plasma Pharmacokinetics: The terminal half-life (T1/2) in rat plasma was 8.55 hours. The maximal plasma concentration (Cmax) following a 5 mg/kg oral dose was 1.4 μg/g [1].
Brain Distribution and Metabolism: BL-1020 Mesylate crosses the blood-brain barrier intact. HPLC radio-chromatography of brain homogenates after oral administration showed the presence of both intact BL-1020 and a larger peak of [14C]-GABA, confirming its hydrolysis in the brain. Intact BL-1020 was detected up to 30 minutes post-dose, while GABA was present for at least 4 hours [1].
Tissue Distribution: After oral administration, [14C]-BL-1020-derived radioactivity was distributed to the brain, heart, lungs, and kidneys. Autoradioluminography confirmed its presence in specific brain regions including the nucleus accumbens, hypothalamus, dorsal raphe, and area postrema [1].

Acute Behavioral Toxicity (Irwin Test): In rats, single oral doses of BL-1020 Mesylate up to 20 mg/kg were well tolerated with no observable adverse effects. At the highest dose tested (30 mg/kg), slight to moderate sedation, abnormal gait (rolling), and decreased reactivity to touch were observed, starting from 180 minutes and persisting up to 48 hours post-dose. Sporadic defecation/diarrhea and myosis were also noted at this dose [1].

[1]. BL-1020: a novel antipsychotic drug with GABAergic activity and low catalepsy, is efficacious in a rat model of schizophrenia. Eur Neuropsychopharmacol. 2009 Jan;19(1):1-13.

BL-1020 Mesylate (4-amino-butyric acid 2-[4-[3-2-chloro-phenothiazine-10-yl propyl]piperazine-1-yl]-ethyl ester, trimaleate salt) is a novel chemical entity designed as an ester prodrug of the first-generation antipsychotic perphenazine and the inhibitory neurotransmitter GABA. The rationale for its development is to address both the dopaminergic hyperactivity and GABAergic deficit implicated in schizophrenia. By crossing the blood-brain barrier intact and then being hydrolyzed by esterases to release perphenazine and GABA, BL-1020 provides a multimodal therapeutic approach. It combines potent dopamine D2 and serotonin 5-HT2A receptor antagonism (typical of first- and second-generation antipsychotics) with GABA-A receptor agonism. Preclinical studies demonstrate its antipsychotic-like efficacy in animal models comparable to perphenazine but with a significantly reduced propensity to induce catalepsy, a predictor of extrapyramidal side effects (EPS). This improved EPS profile is attributed to the GABAergic component. BL-1020 also enhances dopamine release in the prefrontal cortex and hippocampus, regions associated with cognition and mood, without affecting acetylcholine levels, suggesting potential benefits for cognitive symptoms and mood stabilization. Phase IIa clinical trial results mentioned in the article reported high efficacy, low EPS, and high compliance [1].

C26H37CLN4O5S2

585.18

584.189

916898-61-8

751477-01-7;916898-61-8 (mesylate);

154701740

Typically exists as solid at room temperature

2

10

11

38

700

0

LOSZUFJASRVQGR-UHFFFAOYSA-N

InChI=1S/C25H33ClN4O2S.CH4O3S/c26-20-8-9-24-22(19-20)30(21-5-1-2-6-23(21)33-24)12-4-11-28-13-15-29(16-14-28)17-18-32-25(31)7-3-10-27;1-5(2,3)4/h1-2,5-6,8-9,19H,3-4,7,10-18,27H2;1H3,(H,2,3,4)

2-[4-[3-(2-chlorophenothiazin-10-yl)propyl]piperazin-1-yl]ethyl 4-aminobutanoate;methanesulfonic acid

Perphenazine gamma-aminobutyrate mesylate BL-1020 Mesylate AN-168 Perphenazine GABA ester Perphenazine-4-aminobutyrate BL 1020 BL1020 CYP-1020

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.)