Efaproxiral is an allosteric hemoglobin (Hb) modifier that reduces the affinity of Hb for oxygen, increasing the diffusion of oxygen from blood to tissue.
1 In isolated human whole blood, efaproxiral (1.75 mM) increases the partial pressure of oxygen at which Hb is 50% saturated (p50) from 26.75 to 38.63 mm Hg and decreases the percent oxyhemoglobin (Hb-O
2) saturation from 48 to 33.8% at a partial oxygen pressure (pO
2) of 26 mm Hg. Efaproxiral (150 mg/kg) increases tumor pO
2 from 5.2 to 13.1 mm Hg 30 minutes after administration in a RIF-1 mouse fibrosarcoma flank tumor model.
2 Efaproxiral (100 μM) enhances radiation-induced cytotoxicity in EMT6 mouse breast cancer cells grown under hypoxic conditions and increases radiosensitization and inhibits tumor growth in a hypoxic Lewis lung tumor mouse model when administered at a dose of 100 mg/kg.
3 It also increases the running capacity of normal mice and mice with left coronary artery (LCA) ligation-induced myocardial infarction (MI) when administered at a dose of 150 mg/kg.
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