Sitaxentan sodium

Catalog No.S3034 Synonyms: TBC-11251

Sitaxentan sodium Chemical Structure

Molecular Weight(MW): 476.89

Sitaxentan sodium is a selective endothelin A receptor (ETA) antagonist with IC50 and Ki of 1.4 nM and 0.43 nM, respectively, exhibits 7000-fold selectivity over ETB. Phase 3.

Size Price Stock Quantity  
In DMSO USD 400 In stock
USD 210 In stock
USD 270 In stock
USD 970 In stock
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Biological Activity

Description Sitaxentan sodium is a selective endothelin A receptor (ETA) antagonist with IC50 and Ki of 1.4 nM and 0.43 nM, respectively, exhibits 7000-fold selectivity over ETB. Phase 3.
ET-A [1] ET-A [1]
0.43 nM(Ki) 1.4 nM
In vitro

Sitaxentan sodium inhibits ET-1-induced stimulation of phosphoinositide turnover with a Ki of 0.69 nM and a pA2 of 8.0. [1]

In vivo Sitaxentan sodium has a serum half-life in the rat and the dog of 6 hours - 7 hours and 60−100% oral bioavailability. Orally administered Sitaxentan sodium is rapidly absorbed in both the rat and the dog with a t1/2(abs) of 0.7 hours and 0.3 hours, respectively. Peak plasma concentrations occurred between 2 hours and 3 hours postdosing in the rat and between 45 minutes and 90 minutes in the dog. [1] The pulmonary vasoconstrictor response to acute hypoxia (10% O2 for 90 minutes) is prevented with Sitaxentan sodium (5 mg/kg infused i.v. 10 minutes prior to the onset of hypoxia). Sitaxentan sodium delivered i.v. 50 minutes after the onset of hypoxia reverses the established pulmonary vasoconstriction. Sitaxsentan blocks increased plasma endothelin levels. Sitaxsentan dose dependently (10 mg/kg and 50 mg/kg per day in the drinking water) attenuates right ventricular systolic pressure, right heart hypertrophy, and pulmonary vascular remodeling observed 3 weeks after a single subcutaneous injection of monocrotaline. [2] Systemic administration of the ETA receptor antagonist Sitaxentan sodium significantly attenuates cerebral vasospasm after subarachnoid hemorrhage (SAH). [3] Sitaxentan sodium reduces the development of hypoxic pulmonary vasoconstriction (HPV) in the pig. In addition, bolus injection of Sitaxentan sodium reverses already established HPV. [4]


Kinase Assay:[1]
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Ligand binding studies:

Binding studies are performed in a 30 mM HEPES buffer, pH 7.4, containing 150 mM NaCl, 5 mM MgCl2, and 0.05% bacitracin using 2 mg/tube (ETA) or 0.75 mg/tube (ETB) membrane. Sitaxentan sodium is dissolved in DMSO and diluted with the assay buffer to give a final concentration of 0.25% DMSO. Competitive inhibition experiments are performed in triplicate in a final volume of 200 μL containing 4 pM [125I]ET-1 (1.6 nCi). Nonspecific binding is determined in the presence of 100 nM ET-1. Samples are incubated for 16 hours−18 hours at 24 °C. One milliliter of PBS is then added and the assay centrifuged at 2000 g for 25 minutes at 4 °C. The supernatant is decanted and the membrane bound radioactivity counted on a Genesys gamma counter.
Cell Research:[1]
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  • Cell lines: TE 671 or transfected COS 7 cells
  • Concentrations: 0 μM -10 μM
  • Incubation Time: 45 minutes
  • Method: TE 671 or transfected COS 7 cells are grown to confluence in six-well plates. Sixteen hours prior to use, the media in each well is replaced with 2 mL of inositol-free RPMI-164 (IF-RPMI) media containing 10% inositol-free FCS and 2 mCi [3H]myoinositol and incubated at 37 °C in the presence of 6% CO2. The media is aspirated, and the cells are washed twice with PBS. Cells are preincubated for 10 minutes in 1 mL of lithium buffer (15 μM HEPES, pH 7.4, 145 μM NaCl, 5.4 μM KCl, 1.8 μM CaCl2, 0.8 μM MgSO4, 1.0 μM NaH2PO4, 11.2 μM glucose, 20 μM LiCl) with or without Sitaxentan sodium prior to the addition of 100 μM of ET-1 at different concentrations. Cells are then incubated for an additional 45 minutes. The buffer is discarded, and the accumulated inositol phosphates are extracted with ice cold methanol. The total cell protein in each well is measured using the BCA assay after solubilizing the cells in 0.1 M NaOH.
    (Only for Reference)

Solubility (25°C)

In vitro DMSO 40 mg/mL (83.87 mM)
Ethanol 20 mg/mL (41.93 mM)
Water Insoluble

* Please note that Selleck tests the solubility of all compounds in-house, and the actual solubility may differ slightly from published values. This is normal and is due to slight batch-to-batch variations.

Chemical Information

Molecular Weight 476.89


CAS No. 210421-74-2
Storage powder
Synonyms TBC-11251

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Clinical Trial Information

NCT Number Recruitment Conditions Sponsor/Collaborators Start Date Phases
NCT01251848 Withdrawn Pulmonary Arterial Hypertension Pfizer January 2011 Phase 1
NCT01210443 Terminated Hypertension, Pulmonary Pfizer November 2010 Phase 3
NCT01244620 Terminated Pulmonary Arterial Hypertension Pfizer November 2010 Phase 1
NCT01204853 Terminated Hypertension, Pulmonary Pfizer August 2010 Phase 3
NCT00995566 Terminated Pulmonary Arterial Hypertension Pfizer April 2010 --
NCT01445873 Completed Pulmonary Arterial Hypertension Pfizer December 2009 --

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Endothelin Receptor Signaling Pathway Map

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Cell Lines Assay Type Concentration Incubation Time Formulation Activity Description PMID