Sitaxsentan (IPI 1040; TBC-11251) 184036-34-8_New Products_Signaling Pathways_Products

Sitaxsentan (IPI 1040; TBC-11251) is a novel and potent endothelin A receptor (ETA) antagonist is an orally bioavailable endothelin A receptor (ETA) antagonist with anti-hypertensive activity. It inhibits ETA with IC50 and Ki of 1.4 nM and 0.43 nM, respectively. Sitaxentanis an approved medication for the treatment of pulmonary arterial hypertension (PAH).

Physicochemical Properties

Molecular Formula	C₁₈H₁₅CLN₂O₆S₂
Molecular Weight	454.90
Exact Mass	454.006
CAS #	184036-34-8
Related CAS #	Sitaxsentan sodium;210421-74-2
PubChem CID	216235
Appearance	Typically exists as solid at room temperature
Density	1.6g/cm3
Boiling Point	600.4ºC at 760 mmHg
Flash Point	316.9ºC
Vapour Pressure	2.25E-14mmHg at 25°C
Index of Refraction	1.687
LogP	5.115
Hydrogen Bond Donor Count	1
Hydrogen Bond Acceptor Count	9
Rotatable Bond Count	6
Heavy Atom Count	29
Complexity	720
Defined Atom Stereocenter Count	0
SMILES	O=S(C1=C(C(CC2=CC3=C(C=C2C)OCO3)=O)SC=C1)(NC4=C(C(C)=NO4)Cl)=O
InChi Key	PHWXUGHIIBDVKD-UHFFFAOYSA-N
InChi Code	InChI=1S/C18H15ClN2O6S2/c1-9-5-13-14(26-8-25-13)7-11(9)6-12(22)17-15(3-4-28-17)29(23,24)21-18-16(19)10(2)20-27-18/h3-5,7,21H,6,8H2,1-2H3
Chemical Name	N-(4-chloro-3-methyl-1,2-oxazol-5-yl)-2-[2-(6-methyl-1,3-benzodioxol-5-yl)acetyl]thiophene-3-sulfonamide
Synonyms	IPI-1040Thelin Sitaxentan sodiumIPI-1040 TBC11251IPI1040TBC-11251 IPI 1040TBC 11251 TBC-11251 sodium salt, Sitaxsentan
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

ln Vitro

In vitro activity: Sitaxentan sodium inhibits ET-1-induced stimulation of phosphoinositide turnover with a Ki of 0.69 nM and a pA2 of 8.0.

Kinase Assay: 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 Assay: 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.

ln 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. 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. Systemic administration of the ETA receptor antagonist Sitaxentan sodium significantly attenuates cerebral vasospasm after subarachnoid hemorrhage (SAH). Sitaxentan sodium reduces the development of hypoxic pulmonary vasoconstriction (HPV) in the pig. In addition, bolus injection of Sitaxentan sodium reverses already established HPV.

Animal Protocol

5 mg/kg infused i.v.; 10 mg/kg and 50 mg/kg

Rats, dogs, pigs

ADME/Pharmacokinetics

Absorption, Distribution and Excretion
70-100%
Renal (50 to 60%) Fecal (40 to 50%)

Metabolism / Metabolites
Hepatic (CYP2C9- and CYP3A4-mediated)

Biological Half-Life
10 hours

Toxicity/Toxicokinetics

Protein Binding
99% +

References

J Med Chem.1997;40(11):1690-7;Pulm Pharmacol Ther.2000;13(2):87-97;Neurosurgery.1998;43(6):1409-17.

Additional Infomation

Sitaxentan is a member of benzodioxoles.
Sitaxentan was marketed under the trade name Thelin for the treatment of pulmonary arterial hypertension (PAH) by Encysive Pharmaceuticals until Pfizer purchased Encysive in February 2008. In 2010, Pfizer voluntarily removed sitaxentan from the market over concerns of hepatotoxicity.

Drug Indication
Investigated for use/treatment in pulmonary hypertension, connective tissue diseases, hypertension, and congestive heart failure.

Mechanism of Action
Sitaxentan is a competitive antagonist of endothelin-1 at the endothelin-A (ET-A) and endothelin-B (ET-B) receptors. Under normal conditions, endothelin-1 binding of ET-A or ET-B receptors causes pulmonary vasoconstriction. By blocking this interaction, Sitaxentan decreases pulmonary vascular resistance. Sitaxentan has a higher affinity for ET-A than ET-B.

Pharmacodynamics
Sitaxentan belongs to a class of drugs known as endothelin receptor antagonists (ERAs). Patients with PAH have elevated levels of endothelin, a potent blood vessel constrictor, in their plasma and lung tissue. Sitaxentan blocks the binding of endothelin to its receptors, thereby negating endothelin's deleterious effects.

Solubility Data

Solubility (In Vitro)

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

Solubility (In Vivo)

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.

Injection Formulations
(e.g. IP/IV/IM/SC) 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).
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)

Oral Formulations 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).
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

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.

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

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	2.1983 mL	10.9914 mL	21.9829 mL
	5 mM	0.4397 mL	2.1983 mL	4.3966 mL
	10 mM	0.2198 mL	1.0991 mL	2.1983 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.

PeptideDB

Sitaxsentan (IPI 1040; TBC-11251) 184036-34-8

CAS No.: 184036-34-8

Physicochemical Properties

Biological Activity

Solubility Data