Rho-associated protein kinas/ROCK; norepinephrine transporter/NET

Animal efficacy study found that the topical treatment of netarsudil was able to affect both proximal (trabecular meshwork and Schlemms Canal) and distal portions (intrascleral vessels) of the mouse conventional outflow tract.

A total of 23 ROCK structures were found in the PDB. The maximum and minimum resolutions were 3.4 Å and 2.93 Å, respectively. Seven ROCK-I and two ROCK-II non-redundant structures were selected for the binding assay. Out of 46 compounds tested (20 isoquinolines, 15 aminofurazan, 6 benzodiazepine, 4 indazoles, and 1 amide), 34 presented a significantly higher docking score for ROCK-1, when compared to Y-27632 (p < 0.0001). All ROCKi classes presented a stronger mean docking score than Y-27632 (p < 0.0001). The frequency of compounds presenting highest docking score was higher in the isoquinoline, aminofurazan, and benzodiazepine classes for ROCK-I; and in isoquinolines and amides for ROCK-II (Supplementary Figure S2A). The top ten compounds that presented the highest mean docking scores for ROCK-I and II are shown in Supplementary Figure S2B. The isoquinoline class represented 70% of the drugs within the top ten highest docking scores, with three compounds presenting a docking score stronger than 􀀀12. There were no significant differences among ROCK inhibitors other than Y-27632. Interestingly, in silico molecular docking simulation showed that the majority of the molecules evaluated, specifically fromthe isoquinoline, benzodiazepine, and amide classes, had higher binding strength for ROCK-1 and ROCK-2 than Y-27632 (Supplementary Figure S2B). In silico molecular docking simulation was performed, coupling isoforms found for AR-13324 and Y-27632 inhibitors in the PDB to high-resolution ROCK proteins. All of the AR-13324 molecules tested had a higher docking score for ROCK-1 and -2 than Y-27632. In addition, PDB molecules from the isoquinoline, benzodiazepine, and amide classes also showed superior mean docking scores than Y-27632 isoforms (Supplementary Figure S2B)[3].

The proliferation rates of primary CECs were assessed using the EdU incorporation Click-iT cell proliferation assay as per the manufacturer’s instructions. Two ROCK inhibitors, AR-13324 and AR-13503, were assessed for their capacity to enhance proliferation of CECs, with two concentrations (100 nM or 1 M for AR-13324 and 1 M or 10 M for AR-13503). Donor-matched CECs with no ROCKi added served as negative control, whereas CECs with Y-27632 added served as positive control. Briefly, cultured CECs, passaged using TS, were seeded onto FNC-coated glass slides at a density of 5  103 cells per cm2 and maintained in M5-Endo for 24 h (Day 1). On the second day (Day 2), the medium was switched to each respective condition, and cells were cultured for another 24 h. On the third day, cells were incubated in M4-F99 containing 10mMof EdU for 24 h. Subsequently, samples were rinsed once with PBS before they were fixed in freshly prepared 4% PFA for 15 min at room temperature. Next, Samples were rinsed twice with 3% BSA in PBS and were incubated in 0.5% Triton X-100 in PBS for 20 min at room temperature for blocking and permeabilization. Incorporated EdU was detected by fluorescent-azide-coupling Click-iT reaction where samples were incubated for 30 min in the dark with a reaction mixture containing Click-iT EdU reaction buffer, CuSO4, azide-conjugated Alexa Fluor 488 dye, and reaction buffer additive. Following that, samples were rinsed with 3% BSA before incubating in 5 g/mL Hoechst 33,342 for 10 min at room temperature in the dark. Finally, samples were washed twice in PBS and mounted in Vectashield containing 4,6-diamidino-2-phenylindole (DAPI). Labelled proliferative cells were examined under a Zeiss Axioplan 2 fluorescence microscope. At least 250 nuclei were analyzed for each experimental condition[3].

Visual impairment due to glaucoma currently impacts 70 million people worldwide. While disease progression can be slowed or stopped with effective lowering of intraocular pressure, current medical treatments are often inadequate. Fortunately, three new classes of therapeutics that target the diseased conventional outflow tissue responsible for ocular hypertension are in the final stages of human testing. The rho kinase inhibitors have proven particularly efficacious and additive to current therapies. Unfortunately, non-contact technology that monitors the health of outflow tissue and its response to conventional outflow therapy is not available clinically. Using optical coherence tomographic (OCT) imaging and novel segmentation software, we present the first demonstration of drug effects on conventional outflow tissues in living eyes. Topical netarsudil (formerly AR-13324), a rho kinase/ norepinephrine transporter inhibitor, affected both proximal (trabecular meshwork and Schlemm's Canal) and distal portions (intrascleral vessels) of the mouse conventional outflow tract. Hence, increased perfusion of outflow tissues was reliably resolved by OCT as widening of the trabecular meshwork and significant increases in cross-sectional area of Schlemm's canal following netarsudil treatment. These changes occurred in conjunction with increased outflow facility, increased speckle variance intensity of outflow vessels, increased tracer deposition in conventional outflow tissues and decreased intraocular pressure. This is the first report using live imaging to show real-time drug effects on conventional outflow tissues and specifically the mechanism of action of netarsudil in mouse eyes. Advancements here pave the way for development of a clinic-friendly OCT platform for monitoring glaucoma therapy.[1]

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Paired human eyes (n = 5) were perfused with either 0.3 μM netarsudil-M1 or vehicle solution at constant pressure (15 mm Hg). After 3 hours, fluorescent microspheres were added to perfusion media to trace the outflow patterns before perfusion-fixation. The percentage effective filtration length (PEFL) was calculated from the measured lengths of tracer distribution in the trabecular meshwork (TM), episcleral veins (ESVs), and along the inner wall (IW) of Schlemm's canal after global and confocal imaging. Morphologic changes along the trabecular outflow pathway were investigated by confocal, light, and electron microscopy. Results: Perfusion with netarsudil-M1 significantly increased C when compared to baseline (51%, P < 0.01) and to paired controls (102%, P < 0.01), as well as significantly increased PEFL in both IW (P < 0.05) and ESVs (P < 0.01). In treated eyes, PEFL was significantly higher in ESVs than in the IW (P < 0.01) and was associated with increased cross-sectional area of ESVs (P < 0.01). Percentage effective filtration length in ESVs positively correlated with the percentage change in C (R2 = 0.58, P = 0.01). A significant increase in juxtacanalicular connective tissue (JCT) thickness (P < 0.05) was found in treated eyes compared to controls.[2]

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Topical application

Mice with elevated intraocular pressure (IOP)

Absorption, Distribution and Excretion
The systemic exposure of netarsudil and its active metabolite, AR-13503, after topical ocular administration of netarsudil opthalmic solution 0.02% once daily (one drop bilaterally in the morning) for eight days in 18 healthy subjects demonstrated no quantifiable plasma concentrations of netarsudil (lower limit of quantitation [LLOQ] 0.100 ng/mL) post dose on Day 1 and Day 8. Only one plasma concentration at 0.11 ng/mL for the active metabolite was observed for one subject on Day 8 at 8 hours post dose.
Clinical studies assessing the *in vitro* metabolism of netarsudil using corneal tissue from humans, human plasma, and human liver microsomes and microsomal S9 fractions demonstrated that netarsudil metabolism occurs through esterase activity. Subsequent metabolism of netarsudil's esterase metabolite, AR-13503, was not detectable. In fact, esterase metabolism in human plasma was not detected during a 3 hour incubation.
As netarsudil and its active metabolite demonstrate a high degree of protein binding, it is expected to exhibit a low volume of distribution.
The clearance of netarsudil is strongly influenced by its low plasma concetrations following topical administration and absorption and high protein binding in human plasma inn.

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Metabolism / Metabolites
After topical ocular dosing, netarsudil is metabolized by esterases in the eye to its active metabolite, netarsudil-M1 (or AR-13503).

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Biological Half-Life
The half-life of netarsudil incubated *in vitro
with human corneal tissue is 175 minutes.

Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
No information is available on the use of netarsudil during breastfeeding. Because netarsudil poorly absorbed by the mother after administration to the eye, it is unlikely to adversely affect the breastfed infant. Until more data become available, netarsudil should be used with caution during breastfeeding, especially while nursing a newborn or preterm infant. To decrease the amount of drug that reaches the breastmilk after using eye drops, place pressure over the tear duct by the corner of the eye for 1 minute or more, then remove the excess solution with an absorbent tissue.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
The active metabolite of netarsudil, AR-13503 is highly protein bound in plasma, at approximately 60% bound. As AR-13503 is considered to bind less extensively to plasma proteins as its parent netarsudil, the % protein binding of netarsudil may be at least 60% or higher.

[1]. Eur J Pharmacol.2016 Sep 15;787:20-31.
[2]. Invest Ophthalmol Vis Sci.2016 Nov1;57(14):6197-6209.
[3]. Cells . 2023 May 3;12(9):1307.

Pharmacodynamics
Aqueous humour flows out of the eye via two pathways: 1) the conventional trabecular pathway and 2) the unconventional uveoscleral pathway. And, although it has been shown that the conventional trabecular pathway accounts for most aqueous outflow due to various pathologies, most medications available for treating glaucoma target the uveoscleral pathway for treatment and leave the diseased trabecular pathway untreated and unhindered in its progressive deterioration and dysfunction. Netarsudil is subsequently a novel glaucoma medication that is both a rho kinase and norepinephrine transport (NATs)s inhibitor that specifically targets and inhibits rho kinase and NATS found in the conventional trabecular pathway while many of its contemporaries offer therapy that focuses on cell and muscle tissue remodelling

C28H27N3O3

453.54

453.205

C, 74.15; H, 6.00; N, 9.27; O, 10.58

1254032-66-0

1422144-42-0 (mesylate);1254032-66-0;1253952-02-1 (HCl);

66599893

Typically exists as solid at room temperature

1.3±0.1 g/cm3

711.9±60.0 °C at 760 mmHg

384.3±32.9 °C

0.0±2.3 mmHg at 25°C

1.667

3.53

2

5

8

34

678

1

O(C(C1C=CC(C)=CC=1C)=O)CC1C=CC(=CC=1)[C@H](C(NC1C=CC2C=NC=CC=2C=1)=O)CN

OURRXQUGYQRVML-AREMUKBSSA-N

InChI=1S/C28H27N3O3/c1-18-3-10-25(19(2)13-18)28(33)34-17-20-4-6-21(7-5-20)26(15-29)27(32)31-24-9-8-23-16-30-12-11-22(23)14-24/h3-14,16,26H,15,17,29H2,1-2H3,(H,31,32)/t26-/m1/s1

Benzoic acid, 2,4-dimethyl-, (4-((1S)-1-(aminomethyl)-2-(6-isoquinolinylamino)-2-oxoethyl)phenyl)methyl ester

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)

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.)