The chemical is a derivative of propanoic acid. 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.[4][5][6] No benefit was seen for efaproxiral in phase III clinical trials.[7] The increased oxygenation of tissues could theoretically also produce enhanced exercise capacity in feline, rat and canine models for approximately 100 min. immediately after a high dosage 45 min. intravenous infusion.[8]
This has led World Anti-Doping Agency to categorise efaproxiral under a prohibited method to artificially enhance the uptake, transport or delivery of oxygen.[9] There is no existing evidence that efaproxiral can effectively enhance performance in humans.[10] Efaproxiral can be absorbed via transdermal, rectal, inhalation and gastrointestinal routes, though not at plasma concentrations great enough to alter the oxygen-haemoglobin dissociation curve.[11]
Efaproxiral is explicitly excluded from the 2012 World Anti-Doping Agency list of Prohibited Substances and is explicitly included in the Prohibited Methods section M1 as a forbidden procedure to alter the oxygen-haemoglobin dissociation curve in order to allosterically modify haemoglobin.[12]
^US 5731454, Abraham DJ, Joshi G, Randad R, Panikker J, "Allosteric modifiers of hemoglobin useful for decreasing oxygen affinity and preserving oxygen carrying capability of stored blood", issued 24 March 1998, assigned to Virginia Commonwealth University (Richmond, VA).
^Kunert MP, Liard JF, Abraham DJ (August 1996). "RSR-13, an allosteric effector of hemoglobin, increases systemic and iliac vascular resistance in rats". The American Journal of Physiology. 271 (2 Pt 2): H602–H613. doi:10.1152/ajpheart.1996.271.2.H602. PMID8770102.
^Donnelly ET, Liu Y, Rockwell S (March 2006). "Efaproxiral (RSR13) plus oxygen breathing increases the therapeutic ratio of carboplatin in EMT6 mouse mammary tumors". Experimental Biology and Medicine. 231 (3): 317–321. doi:10.1177/153537020623100312. PMID16514179. S2CID19475480.
^Scott C, Suh J, Stea B, Nabid A, Hackman J (December 2007). "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". American Journal of Clinical Oncology. 30 (6): 580–587. doi:10.1097/COC.0b013e3180653c0d. PMID18091051. S2CID42750048.
^Campanini B, Raboni M (January 2003). "Oxygen Delivery by Allosteric Effectors of Hemoglobin, Blood Substitutes, and Plasma Expanders". Burger's Medicinal Chemistry, Drug Discovery and Development. pp. 385–441. doi:10.1002/0471266949.bmc048. ISBN978-0471266945.