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Identification
NameSitaxentan
Accession NumberDB06268
TypeSmall Molecule
GroupsApproved, Investigational, Withdrawn
Description

Sitaxentan is a medication for the treatment of pulmonary arterial hypertension (PAH). It was marketed as Thelin by Encysive Pharmaceuticals until Pfizer purchased Encysive in February 2008. In 2010, Pfizer voluntarily removed sitaxentan from the market due to concerns about liver toxicity.

Structure
Thumb
Synonyms
Sitaxsentan
External Identifiers
  • IPI-1040
  • TBC-11251
Approved Prescription Products
NameDosageStrengthRouteLabellerMarketing StartMarketing End
Thelintablet100 mgoralPfizer Canada Inc2007-06-192011-04-30Canada
Approved Generic Prescription ProductsNot Available
Approved Over the Counter ProductsNot Available
Unapproved/Other Products Not Available
International BrandsNot Available
Brand mixturesNot Available
Salts
Name/CASStructureProperties
Sitaxentan sodium
210421-74-2
Thumb
  • InChI Key: MDTNUYUCUYPIHE-UHFFFAOYSA-N
  • Monoisotopic Mass: 475.9879505
  • Average Mass: 476.88
DBSALT001120
Categories
UNIIJ9QH779MEM
CAS number184036-34-8
WeightAverage: 454.905
Monoisotopic: 454.006005309
Chemical FormulaC18H15ClN2O6S2
InChI KeyInChIKey=PHWXUGHIIBDVKD-UHFFFAOYSA-N
InChI
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
IUPAC Name
N-(4-chloro-3-methyl-1,2-oxazol-5-yl)-2-[2-(6-methyl-2H-1,3-benzodioxol-5-yl)acetyl]thiophene-3-sulfonamide
SMILES
CC1=NOC(NS(=O)(=O)C2=C(SC=C2)C(=O)CC2=CC3=C(OCO3)C=C2C)=C1Cl
Taxonomy
DescriptionThis compound belongs to the class of organic compounds known as benzodioxoles. These are organic compounds containing a benzene ring fused to either isomers of dioxole. Dioxole is a five-membered unsaturated ring of two oxygen atoms and three carbon atoms.
KingdomOrganic compounds
Super ClassOrganoheterocyclic compounds
ClassBenzodioxoles
Sub ClassNot Available
Direct ParentBenzodioxoles
Alternative Parents
Substituents
  • Benzodioxole
  • Aryl alkyl ketone
  • Aryl ketone
  • Benzenoid
  • Aryl halide
  • Aryl chloride
  • Heteroaromatic compound
  • Aminosulfonyl compound
  • Thiophene
  • Sulfonyl
  • Sulfonic acid derivative
  • Sulfonamide
  • Oxazole
  • Isoxazole
  • Azole
  • Ketone
  • Oxacycle
  • Azacycle
  • Acetal
  • Hydrocarbon derivative
  • Organosulfur compound
  • Organooxygen compound
  • Organonitrogen compound
  • Organochloride
  • Organohalogen compound
  • Carbonyl group
  • Aromatic heteropolycyclic compound
Molecular FrameworkAromatic heteropolycyclic compounds
External DescriptorsNot Available
Pharmacology
IndicationInvestigated for use/treatment in pulmonary hypertension, connective tissue diseases, hypertension, and congestive heart failure.
PharmacodynamicsSitaxentan 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.
Mechanism of actionSitaxentan 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.
Related Articles
Absorption70-100%
Volume of distributionNot Available
Protein binding99% +
Metabolism

Hepatic (CYP2C9- and CYP3A4-mediated)

Route of eliminationRenal (50 to 60%) Fecal (40 to 50%)
Half life10 hours
ClearanceNot Available
ToxicityNot Available
Affected organisms
  • Humans and other mammals
PathwaysNot Available
SNP Mediated EffectsNot Available
SNP Mediated Adverse Drug ReactionsNot Available
ADMET
Predicted ADMET features
PropertyValueProbability
Human Intestinal Absorption+0.9811
Blood Brain Barrier+0.511
Caco-2 permeable-0.5662
P-glycoprotein substrateNon-substrate0.8285
P-glycoprotein inhibitor INon-inhibitor0.8519
P-glycoprotein inhibitor IINon-inhibitor0.8682
Renal organic cation transporterNon-inhibitor0.9158
CYP450 2C9 substrateNon-substrate0.8057
CYP450 2D6 substrateNon-substrate0.8266
CYP450 3A4 substrateNon-substrate0.5263
CYP450 1A2 substrateNon-inhibitor0.6693
CYP450 2C9 inhibitorInhibitor0.7225
CYP450 2D6 inhibitorNon-inhibitor0.8052
CYP450 2C19 inhibitorNon-inhibitor0.5
CYP450 3A4 inhibitorInhibitor0.925
CYP450 inhibitory promiscuityHigh CYP Inhibitory Promiscuity0.9157
Ames testNon AMES toxic0.634
CarcinogenicityNon-carcinogens0.5575
BiodegradationNot ready biodegradable0.9958
Rat acute toxicity2.5528 LD50, mol/kg Not applicable
hERG inhibition (predictor I)Weak inhibitor0.9901
hERG inhibition (predictor II)Non-inhibitor0.9051
ADMET data is predicted using admetSAR, a free tool for evaluating chemical ADMET properties. (23092397 )
Pharmacoeconomics
ManufacturersNot Available
PackagersNot Available
Dosage forms
FormRouteStrength
Tabletoral100 mg
PricesNot Available
Patents
Patent NumberPediatric ExtensionApprovedExpires (estimated)
CA2161346 No2004-11-232014-05-20Canada
CA2281090 No2005-06-072018-04-02Canada
Properties
StateSolid
Experimental PropertiesNot Available
Predicted Properties
PropertyValueSource
Water Solubility0.0181 mg/mLALOGPS
logP3.35ALOGPS
logP3.09ChemAxon
logS-4.4ALOGPS
pKa (Strongest Acidic)6.89ChemAxon
pKa (Strongest Basic)0.75ChemAxon
Physiological Charge-1ChemAxon
Hydrogen Acceptor Count6ChemAxon
Hydrogen Donor Count1ChemAxon
Polar Surface Area107.73 Å2ChemAxon
Rotatable Bond Count5ChemAxon
Refractivity105.8 m3·mol-1ChemAxon
Polarizability43.12 Å3ChemAxon
Number of Rings4ChemAxon
Bioavailability1ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Spectra
Mass Spec (NIST)Not Available
Spectra
Spectrum TypeDescriptionSplash Key
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, NegativeNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, NegativeNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, NegativeNot Available
References
Synthesis ReferenceNot Available
General ReferencesNot Available
External Links
ATC CodesC02KX03
AHFS CodesNot Available
PDB EntriesNot Available
FDA labelNot Available
MSDSNot Available
Interactions
Drug Interactions
Drug
CyclosporineThe serum concentration of Sitaxentan can be increased when it is combined with Cyclosporine.
TofacitinibThe serum concentration of Tofacitinib can be increased when it is combined with Sitaxentan.
WarfarinThe serum concentration of Warfarin can be increased when it is combined with Sitaxentan.
Food Interactions
  • Take without regard to meals

Targets

Kind
Protein
Organism
Human
Pharmacological action
yes
Actions
antagonist
General Function:
Phosphatidylinositol phospholipase c activity
Specific Function:
Receptor for endothelin-1. Mediates its action by association with G proteins that activate a phosphatidylinositol-calcium second messenger system. The rank order of binding affinities for ET-A is: ET1 > ET2 >> ET3.
Gene Name:
EDNRA
Uniprot ID:
P25101
Molecular Weight:
48721.76 Da
References
  1. Girgis RE, Frost AE, Hill NS, Horn EM, Langleben D, McLaughlin VV, Oudiz RJ, Robbins IM, Seibold JR, Shapiro S, Tapson VF, Barst RJ: Selective endothelin A receptor antagonism with sitaxsentan for pulmonary arterial hypertension associated with connective tissue disease. Ann Rheum Dis. 2007 Nov;66(11):1467-72. Epub 2007 May 1. [PubMed:17472992 ]
  2. Albertini M, Lafortuna CL, Ciminaghi B, Mazzola S, Clement MG: Endothelin involvement in respiratory centre activity. Prostaglandins Leukot Essent Fatty Acids. 2001 Sep;65(3):157-63. [PubMed:11728166 ]
  3. Chen X, Ji ZL, Chen YZ: TTD: Therapeutic Target Database. Nucleic Acids Res. 2002 Jan 1;30(1):412-5. [PubMed:11752352 ]
  4. Kiowski W, Sutsch G, Oechslin E, Bertel O: Hemodynamic effects of bosentan in patients with chronic heart failure. Heart Fail Rev. 2001 Dec;6(4):325-34. [PubMed:11447307 ]
  5. Kramp R, Fourmanoir P, Caron N: Endothelin resets renal blood flow autoregulatory efficiency during acute blockade of NO in the rat. Am J Physiol Renal Physiol. 2001 Dec;281(6):F1132-40. [PubMed:11704565 ]
  6. Martin C, Held HD, Uhlig S: Differential effects of the mixed ET(A)/ET(B)-receptor antagonist bosentan on endothelin-induced bronchoconstriction, vasoconstriction and prostacyclin release. Naunyn Schmiedebergs Arch Pharmacol. 2000 Aug;362(2):128-36. [PubMed:10961375 ]
  7. Sihvola RK, Pulkkinen VP, Koskinen PK, Lemstrom KB: Crosstalk of endothelin-1 and platelet-derived growth factor in cardiac allograft arteriosclerosis. J Am Coll Cardiol. 2002 Feb 20;39(4):710-7. [PubMed:11849873 ]
Kind
Protein
Organism
Human
Pharmacological action
unknown
Actions
antagonist
General Function:
Peptide hormone binding
Specific Function:
Non-specific receptor for endothelin 1, 2, and 3. Mediates its action by association with G proteins that activate a phosphatidylinositol-calcium second messenger system.
Gene Name:
EDNRB
Uniprot ID:
P24530
Molecular Weight:
49643.255 Da
References
  1. Girgis RE, Frost AE, Hill NS, Horn EM, Langleben D, McLaughlin VV, Oudiz RJ, Robbins IM, Seibold JR, Shapiro S, Tapson VF, Barst RJ: Selective endothelin A receptor antagonism with sitaxsentan for pulmonary arterial hypertension associated with connective tissue disease. Ann Rheum Dis. 2007 Nov;66(11):1467-72. Epub 2007 May 1. [PubMed:17472992 ]
  2. Chen X, Ji ZL, Chen YZ: TTD: Therapeutic Target Database. Nucleic Acids Res. 2002 Jan 1;30(1):412-5. [PubMed:11752352 ]
  3. Gardiner SM, Kemp PA, March JE, Bennett T: Effects of bosentan (Ro 47-0203), an ETA-, ETB-receptor antagonist, on regional haemodynamic responses to endothelins in conscious rats. Br J Pharmacol. 1994 Jul;112(3):823-30. [PubMed:7921608 ]
  4. Gupta SK, Saxena A, Singh U, Arya DS: Bosentan, the mixed ETA-ETB endothelin receptor antagonist, attenuated oxidative stress after experimental myocardial ischemia and reperfusion. Mol Cell Biochem. 2005 Jul;275(1-2):67-74. [PubMed:16335785 ]
  5. Marano G, Palazzesi S, Bernucci P, Grigioni M, Formigari R, Ballerini L: ET(A)/ET(B) receptor antagonist bosentan inhibits neointimal development in collared carotid arteries of rabbits. Life Sci. 1998;63(18):PL259-66. [PubMed:9806221 ]
  6. Richard V, Kaeffer N, Hogie M, Tron C, Blanc T, Thuillez C: Role of endogenous endothelin in myocardial and coronary endothelial injury after ischaemia and reperfusion in rats: studies with bosentan, a mixed ETA-ETB antagonist. Br J Pharmacol. 1994 Nov;113(3):869-76. [PubMed:7858879 ]
  7. Said SA, Ammar el SM, Suddek GM: Effect of bosentan (ETA/ETB receptor antagonist) on metabolic changes during stress and diabetes. Pharmacol Res. 2005 Feb;51(2):107-15. [PubMed:15629255 ]

Enzymes

Kind
Protein
Organism
Human
Pharmacological action
unknown
Actions
inhibitor
General Function:
Steroid hydroxylase activity
Specific Function:
Responsible for the metabolism of a number of therapeutic agents such as the anticonvulsant drug S-mephenytoin, omeprazole, proguanil, certain barbiturates, diazepam, propranolol, citalopram and imipramine.
Gene Name:
CYP2C19
Uniprot ID:
P33261
Molecular Weight:
55930.545 Da
References
  1. Barst RJ, Rich S, Widlitz A, Horn EM, McLaughlin V, McFarlin J: Clinical efficacy of sitaxsentan, an endothelin-A receptor antagonist, in patients with pulmonary arterial hypertension: open-label pilot study. Chest. 2002 Jun;121(6):1860-8. [PubMed:12065350 ]
Kind
Protein
Organism
Human
Pharmacological action
unknown
Actions
substrateinhibitor
General Function:
Steroid hydroxylase activity
Specific Function:
Cytochromes P450 are a group of heme-thiolate monooxygenases. In liver microsomes, this enzyme is involved in an NADPH-dependent electron transport pathway. It oxidizes a variety of structurally unrelated compounds, including steroids, fatty acids, and xenobiotics. This enzyme contributes to the wide pharmacokinetics variability of the metabolism of drugs such as S-warfarin, diclofenac, phenyto...
Gene Name:
CYP2C9
Uniprot ID:
P11712
Molecular Weight:
55627.365 Da
References
  1. Pulido T, Sandoval J, Roquet I, Gutierrez R, Rueda T, Pena H, Santos E, Miranda MT, Lupi E: Interaction of acenocoumarol and sitaxentan in pulmonary arterial hypertension. Eur J Clin Invest. 2009 Jun;39 Suppl 2:14-8. doi: 10.1111/j.1365-2362.2009.02116.x. [PubMed:19335742 ]
  2. Opitz CF, Ewert R, Kirch W, Pittrow D: Inhibition of endothelin receptors in the treatment of pulmonary arterial hypertension: does selectivity matter? Eur Heart J. 2008 Aug;29(16):1936-48. doi: 10.1093/eurheartj/ehn234. Epub 2008 Jun 17. [PubMed:18562303 ]
  3. Barst RJ, Rich S, Widlitz A, Horn EM, McLaughlin V, McFarlin J: Clinical efficacy of sitaxsentan, an endothelin-A receptor antagonist, in patients with pulmonary arterial hypertension: open-label pilot study. Chest. 2002 Jun;121(6):1860-8. [PubMed:12065350 ]
Kind
Protein
Organism
Human
Pharmacological action
unknown
Actions
inhibitor
General Function:
Vitamin d3 25-hydroxylase activity
Specific Function:
Cytochromes P450 are a group of heme-thiolate monooxygenases. In liver microsomes, this enzyme is involved in an NADPH-dependent electron transport pathway. It performs a variety of oxidation reactions (e.g. caffeine 8-oxidation, omeprazole sulphoxidation, midazolam 1'-hydroxylation and midazolam 4-hydroxylation) of structurally unrelated compounds, including steroids, fatty acids, and xenobiot...
Gene Name:
CYP3A4
Uniprot ID:
P08684
Molecular Weight:
57342.67 Da
References
  1. Stavros F, Kramer WG, Wilkins MR: The effects of sitaxentan on sildenafil pharmacokinetics and pharmacodynamics in healthy subjects. Br J Clin Pharmacol. 2010 Jan;69(1):23-6. doi: 10.1111/j.1365-2125.2009.03541.x. [PubMed:20078609 ]
  2. Barst RJ, Rich S, Widlitz A, Horn EM, McLaughlin V, McFarlin J: Clinical efficacy of sitaxsentan, an endothelin-A receptor antagonist, in patients with pulmonary arterial hypertension: open-label pilot study. Chest. 2002 Jun;121(6):1860-8. [PubMed:12065350 ]
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Drug created on March 19, 2008 10:20 / Updated on August 17, 2016 12:24