FIGURE 1.

The pharmacological mechanism of efaproxiral. Efaproxiral is an allosteric modifier of hemoglobin. It decreases oxygen affinity by stabilizing the central water cavity of the hemoglobin tetramer (Wireko et al., 1991). With the conformational structure changed, there will be an increase in whole-blood P50 (partial pressure of oxygen which results in 50% hemoglobin saturation) and an increase in the PO₂ (partial pressure of oxygen) in the tissue, expected to decrease the hypoxic fraction of brain metastasis and increase its sensitivity to RT (Suh, 2004).