The binding of tacrolimus to blood components is an important factor in its pharmacokinetics 35. Tacrolimus is mainly found within erythrocytes (85–95%), only a small part being localized in lymphocytes (roughly 0.5%). In plasma, approximately 60% of tacrolimus is bound to the proteins albumin and α1‐acid glycoprotein (AGP), 30% to high‐density lipoprotein (HDL), 8% to low‐density lipoprotein (LDL) and 1% to very low‐density lipoprotein (VLDL). Only 0.3–2% of plasma tacrolimus is unbound