Zotarolimus is a semi-synthetic macrocyclic lactone prepared from rapamycin by preparation of the 42-triflate ester, followed by displacement with tetrazole and purification of the two isomeric products. This structural change affords a less bioavailable product, a preferred profile for some applications. Like all tacrolimus analogues, zotarolimus binds to a receptor protein (FKBP12). The complex then binds to mTOR preventing it from interacting with target proteins. Zotarolimus is extensively cited in the literature with over 200 citations.