[Pharmacokinetics and relative bioavailability of iron and folic acid in healthy volunteers].

The pharmacokinetics and the relative bioavailability of iron and of folic acid was investigated in a randomized, balanced 2-way cross-over study with 14 healthy male participants. The drugs were given in a combined preparation dragée (Ferro-Folsan) containing 100 mg of ferrous-II-sulfate x 1.5 H2O (CAS 13463-43-9) and 0.85 mg of folic acid (CAS 59-30-3). Other established preparations were used as reference drugs. All subjects had a normal iron body level and were brought to a saturated folic acid level prior to the investigation. After administration of 2 dragées of the test medication and determination of serum iron level until 9 h p.a., a relative bioavailability of 64%, compared to an equal dose of a ferrous-II-sulfate-ascorbic acid reference solution, was calculated. From the serum folate AUC (0-9 h) the relative bioavailability was evaluated with 97% for the oral formulation compared to the i.m. administration. The ratio of the cumulative renal folate excretion in the 0-9 h interval amounted to 76% for the oral compared to the i.m. administration. However, in order to understand this differing result it should be kept in mind that during the first hours following parenteral administration a greater amount of the unchanged compound is renally excreted than after oral dosing. This is presumably based upon the different rate of absorption following both administrations with a steeper absorption phase following the parenteral dose.