Pharmacokinetics of iron salts and ferric hydroxide-carbohydrate complexes

Pharmacokinetic measurements of ferrous sulphate and ferric hydroxide-polymaltose complex on anaemic and non-anaemic rats have shown different postabsorption serum iron levels, invasion and elimination constants and distribution volumes for the two preparations. But nevertheless the absorption and utilization ratios of iron from both preparations are equal. It is therefore not justified to calculate utilization ratios for chemically different iron preparations on the basis of postabsorption serum iron measurements. Similar pharmacokinetic differences of these two iron preparations could also be found in clinical trials, which means that different serum iron increase results in an equal utilization ratio for both preparations. It is clear that ferrous sulphate and ferric hydroxide-polymaltose complex must have a different absorption mechanism. The postulated absorption mechanism is in agreement with all the facts known today and does explain the pharmacokinetic difference between the investigated preparations.