The i.v. iron drugs should be formulated to avoid its release iron into plasma.Following administration, macrophages from thereticulo endothelial system clear the iron carbohydrate complex from plasma and break it down.Thus, a linear relation between the i.v. drug dose and the maximal after dosing drug concentration would be expected.In a follow-up publication where dose-related pharmacokinetics of ferric bepectate was evaluated, it was proved that a second compartment of distribution appeared at the highest administered dose.The fraction of labile iron released from the iron drug at the time of administration and the short-term stability of the iron drug in plasma, as labile iron has well-known direct toxic effects and may influence pharmacokinetics and body distribution.EMA does not recommend a simple methodol. to characterize early after dosing stability of i.v. iron drugs.Whether recommended dose regimens for all marketed i.v. irons are designed to avoid capillary leak episodes with extravasation of iron and other plasma constituents is unknown.As for ferumoxytol, an i.v. iron drug marketed outside EU, iron extravasation as a secondary volume of distribution has been demonstrated.We, therefore, urge the Marketing Authorisation Holders to perform the two-step procedure described above especially for i.v. irons dose regimens used repeatedly (e.g., in CKD).Our suspicion of a deleterious effect of frequently repeated doses of i.v. iron in CKD patients could be clarified in a pharmacoepidemiol. study.CKD patients exposed to frequently repeated doses of i.v. iron should be compared with a group of CKD patients receiving a few yearly injections with respect to cardiovascular events.