Efaproxiral free acid

    WARNING: This product is for research use only, not for human or veterinary use.

MedKoo CAT#: 201180

CAS#: 131179-95-8 (free acid)

Description: Efaproxiral, also known as RSR13, is an analogue of the cholesterol drug bezafibrate developed for the treatment of depression, traumatic brain injury, ischemia, stroke, myocardial infarction, diabetes, hypoxia, sickle cell disease, hypercholesterolemia and as a radio sensitiser. One use for efaproxiral is to increase the efficacy of certain chemotherapy drugs which have reduced efficacy against hypoxic tumours, and can thus be made more effective by increased offloading of oxygen into the tumour tissues

Chemical Structure

Efaproxiral free acid
CAS# 131179-95-8 (free acid)

Theoretical Analysis

MedKoo Cat#: 201180
Name: Efaproxiral free acid
CAS#: 131179-95-8 (free acid)
Chemical Formula: C20H23NO4
Exact Mass: 341.16271
Molecular Weight: 341.4
Elemental Analysis: C, 70.36; H, 6.79; N, 4.10; O, 18.75

Size Price Shipping out time Quantity
100mg USD 250 2 weeks
200mg USD 450 2 weeks
500mg USD 650 2 weeks
1g USD 850 2 weeks
2g USD 1550 2 weeks
5g USD 2450 2 weeks
Inquire bulk and customized quantity

Pricing updated 2021-03-03. Prices are subject to change without notice.

Efaproxiral, purity > 98%, is in stock. Current shipping out time is about 2 weeks after order is received. CoA, QC data and MSDS documents are available in one week after order is received.

Related CAS #: 170787-99-2 (sodium)   131179-95-8 (free acid)    

Synonym: NSC722758; NSC-722758; NSC 722758; RSR13; RSR-13; RSR 13; Efaproxiral; Efaproxyn;

IUPAC/Chemical Name: 2-[4-[2-[(3,5-dimethylphenyl)amino]-2-oxoethyl]phenoxy]-2-methylpropanoic acid.


InChi Code: InChI=1S/C20H23NO4/c1-13-9-14(2)11-16(10-13)21-18(22)12-15-5-7-17(8-6-15)25-20(3,4)19(23)24/h5-11H,12H2,1-4H3,(H,21,22)(H,23,24)

SMILES Code: CC(C)(OC1=CC=C(CC(NC2=CC(C)=CC(C)=C2)=O)C=C1)C(O)=O

Solid powder

>98% (or refer to the Certificate of Analysis)

Shipping Condition:
Shipped under ambient temperature as non-hazardous chemical. This product is stable enough for a few weeks during ordinary shipping and time spent in Customs.

Storage Condition:
Dry, dark and at 0 - 4 C for short term (days to weeks) or -20 C for long term (months to years).

Soluble in DMSO, not in water

Shelf Life:
>2 years if stored properly

Drug Formulation:
This drug may be formulated in DMSO

Stock Solution Storage:
0 - 4 C for short term (days to weeks), or -20 C for long term (months).

HS Tariff Code:

Handling Instructions:

Preparing Stock Solutions

The following data is based on the product molecular weight 341.4 Batch specific molecular weights may vary from batch to batch due to the degree of hydration, which will affect the solvent volumes required to prepare stock solutions.

Select a batch to recalculate based on the batch molecular weight:
Concentration / Solvent Volume / Mass 1 mg 5 mg 10 mg
1 mM 1.15 mL 5.76 mL 11.51 mL
5 mM 0.23 mL 1.15 mL 2.3 mL
10 mM 0.12 mL 0.58 mL 1.15 mL
50 mM 0.02 mL 0.12 mL 0.23 mL

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1: Watanabe A, Poole DC, Kano Y. The effects of RSR13 on microvascular Po(2) kinetics and muscle contractile performance in the rat arterial ligation model of peripheral arterial disease. J Appl Physiol (1985). 2017 Oct 1;123(4):764-772. doi: 10.1152/japplphysiol.00257.2017. Epub 2017 Jun 15. PubMed PMID: 28620055.

2: Srinivasan AJ, Morkane C, Martin DS, Welsby IJ. Should modulation of p50 be a therapeutic target in the critically ill? Expert Rev Hematol. 2017 May;10(5):449-458. doi: 10.1080/17474086.2017.1313699. Epub 2017 Apr 12. Review. PubMed PMID: 28402148.

3: Xu GG, Deshpande TM, Ghatge MS, Mehta AY, Omar AS, Ahmed MH, Venitz J, Abdulmalik O, Zhang Y, Safo MK. Design, Synthesis, and Investigation of Novel Nitric Oxide (NO)-Releasing Prodrugs as Drug Candidates for the Treatment of Ischemic Disorders: Insights into NO-Releasing Prodrug Biotransformation and Hemoglobin-NO Biochemistry. Biochemistry. 2015 Dec 15;54(49):7178-92. doi: 10.1021/acs.biochem.5b01074. Epub 2015 Dec 3. PubMed PMID: 26582149; PubMed Central PMCID: PMC5453643.

4: Görgens C, Guddat S, Schänzer W, Thevis M. Screening and confirmation of myo-inositol trispyrophosphate (ITPP) in human urine by hydrophilic interaction liquid chromatography high resolution / high accuracy mass spectrometry for doping control purposes. Drug Test Anal. 2014 Nov-Dec;6(11-12):1102-7. doi: 10.1002/dta.1700. Epub 2014 Jul 28. PubMed PMID: 25070041.

5: Yi R, Sandhu J, Zhao S, Lam G, Loganathan D, Morrissey B. Detection of efaproxiral (RSR13) and its metabolites in equine by liquid chromatography tandem mass spectrometry. J Mass Spectrom. 2014 Jan;49(1):57-67. doi: 10.1002/jms.3304. PubMed PMID: 24446264.

6: Mohindra P, Sinha RN, Andrews RJ, Khuntia D. Non-cytotoxic radiosensitizers in brain radiotherapy: journey till the first decade of this millennium. Curr Cancer Drug Targets. 2012 Mar;12(3):260-78. Review. PubMed PMID: 22268387.

7: Olson JJ, Paleologos NA, Gaspar LE, Robinson PD, Morris RE, Ammirati M, Andrews DW, Asher AL, Burri SH, Cobbs CS, Kondziolka D, Linskey ME, Loeffler JS, McDermott M, Mehta MP, Mikkelsen T, Patchell RA, Ryken TC, Kalkanis SN. The role of emerging and investigational therapies for metastatic brain tumors: a systematic review and evidence-based clinical practice guideline of selected topics. J Neurooncol. 2010 Jan;96(1):115-42. doi: 10.1007/s11060-009-0058-3. Epub 2009 Dec 3. PubMed PMID: 19957013; PubMed Central PMCID: PMC2808529.

8: Viani GA, Manta GB, Fonseca EC, De Fendi LI, Afonso SL, Stefano EJ. Whole brain radiotherapy with radiosensitizer for brain metastases. J Exp Clin Cancer Res. 2009 Jan 6;28:1. doi: 10.1186/1756-9966-28-1. PubMed PMID: 19126230; PubMed Central PMCID: PMC2648943.

9: Watanabe T, Takeda T, Omiya S, Hikoso S, Yamaguchi O, Nakano Y, Higuchi Y, Nakai A, Abe Y, Aki-Jin Y, Taniike M, Mizote I, Matsumura Y, Shimizu T, Nishida K, Imai K, Hori M, Shirasawa T, Otsu K. Reduction in hemoglobin-oxygen affinity results in the improvement of exercise capacity in mice with chronic heart failure. J Am Coll Cardiol. 2008 Aug 26;52(9):779-86. doi: 10.1016/j.jacc.2008.06.003. PubMed PMID: 18718428.

10: Borrione P, Mastrone A, Salvo RA, Spaccamiglio A, Grasso L, Angeli A. Oxygen delivery enhancers: past, present, and future. J Endocrinol Invest. 2008 Feb;31(2):185-92. Review. PubMed PMID: 18362513.

11: Gustafsson T, Pontén F, Seeberger PH. Trimethylaluminium mediated amide bond formation in a continuous flow microreactor as key to the synthesis of rimonabant and efaproxiral. Chem Commun (Camb). 2008 Mar 7;(9):1100-2. doi: 10.1039/b719603b. Epub 2008 Feb 1. PubMed PMID: 18292903.

12: Scott C, Suh J, Stea B, Nabid A, Hackman J. Improved survival, quality of life, and quality-adjusted survival in breast cancer patients treated with efaproxiral (Efaproxyn) plus whole-brain radiation therapy for brain metastases. Am J Clin Oncol. 2007 Dec;30(6):580-7. PubMed PMID: 18091051.

13: Hou H, Khan N, Grinberg OY, Yu H, Grinberg SA, Lu S, Demidenko E, Steffen RP, Swartz HM. The effects of Efaproxyn (efaproxiral) on subcutaneous RIF-1 tumor oxygenation and enhancement of radiotherapy-mediated inhibition of tumor growth in mice. Radiat Res. 2007 Aug;168(2):218-25. PubMed PMID: 17638413.

14: Kaal EC, Vecht CJ. CNS complications of breast cancer: current and emerging treatment options. CNS Drugs. 2007;21(7):559-79. Review. PubMed PMID: 17579499.

15: Bayés M, Rabasseda X, Prous JR. Gateways to clinical trials. Methods Find Exp Clin Pharmacol. 2006 Oct;28(8):533-91. PubMed PMID: 17136234.

16: Venitz J. Using exposure-response and biomarkers to streamline early drug development. Ernst Schering Res Found Workshop. 2007;(59):47-63. Review. PubMed PMID: 17117714.

17: Peacock KH, Lesser GJ. Current therapeutic approaches in patients with brain metastases. Curr Treat Options Oncol. 2006 Nov;7(6):479-89. Review. PubMed PMID: 17032560.

18: Cavaliere R, Schiff D. Cerebral metastases--a therapeutic update. Nat Clin Pract Neurol. 2006 Aug;2(8):426-36. Review. PubMed PMID: 16932601.

19: Stea B, Shaw E, Pintér T, Hackman J, Craig M, May J, Steffen RP, Suh JH. Efaproxiral red blood cell concentration predicts efficacy in patients with brain metastases. Br J Cancer. 2006 Jun 19;94(12):1777-84. PubMed PMID: 16773073; PubMed Central PMCID: PMC2361352.

20: Bayes M, Rabasseda X, Prous JR. Gateways to clinical trials. Methods Find Exp Clin Pharmacol. 2006 Mar;28(2):121-42. PubMed PMID: 16636723.

Additional Information

According to Drugs R D. 2005;6(3):178-85. Efaproxiral  is a synthetic, small-molecule, radiation-sensitising agent being developed by Allos Therapeutics primarily for the treatment of cancer. It works by binding and allosterically stabilising deoxyhaemoglobin in hypoxic regions of tumour tissue. This increases oxygen uptake of the tumour tissue and restores its sensitivity to radiation therapy, making therapy potentially more successful. This first-of-its-class compound is particularly applicable for the treatment of certain tumour types that lack oxygen, such as brain metastases. In contrast to conventional chemotherapeutic agents or radiation sensitisers, there is no requirement for efaproxiral to be administered directly into tumours or to cross the blood-brain barrier for it to display efficacy.  Efaproxiral is under review for approval in the US and EU as an adjunct to whole-brain radiation therapy (WBRT) for the treatment of brain metastases originating from breast cancer. It is also under clinical evaluation for a variety of other cancers, including glioblastoma, non-small cell lung cancer (NSCLC) and cervical cancer.
According to wikipedia.com, Efaproxiral (INN) is an analog of the cholesterol drug bezafibrate developed for the treatment of depression, traumatic brain injury, ischemia, stroke, myocardial infarction, diabetes, hypoxia, sickle cell disease, hypercholesterolemia and as a radio sensitizer. The chemical is a propanoic acid in the class of amphipathic carboxylic acids. Most propanoic acid produced is consumed as a preservative for both animal feed and food for human consumption. One use for efaproxiral is to increase the efficacy of certain chemotherapy drugs which have reduced efficacy against hypoxic tumours, and can thus be made more effective by increased offloading of oxygen into the tumour tissues. No benefit was seen for efaproxiral in phase III clinical trials. (source: http://en.wikipedia.org/wiki/Efaproxiral).