MW: 966.21. Purity ~98% by HPLC. Zotarolimus (also known as ABT-578) is an analogue of rapamycin (sirolimus) that was designed to have a shorter in vivo half-life than rapamycin. Zotarolimus was found to be comparable in potency for inhibiting in vitro proliferation of both rat and human T cells and mechanistically similar to sirolimus in having high-affinity binding to the immunophilin FKBP12. Zotarolimus is a semi-synthetic derivative of rapamycin. It was designed for use in stents with phosph