Hemoglobin oxygen-affinity modifier

ITPP is a synthetic phosphate derivative of inositol that gets inside red blood cells and makes hemoglobin let go of its oxygen more readily, so more oxygen reaches tissue that is short of it. It was developed as a cancer drug, to relieve tumor hypoxia, and has been through one phase Ib trial in 28 patients that established a maximum tolerated intravenous dose. Its reputation as a performance drug rests on a single 2009 mouse study in which it raised maximal exercise capacity by up to 57%; nothing like that has been tested in people, and anti-doping laboratories screen urine for it.