Interaction between Oral Iron Preparations and Antacids
2002 Volume 28 Issue 6 Pages 559-563
Details
2002 Volume 28 Issue 6 Pages 559-563
The concomitant use of oral iron preparations and antacids causes iron to form macromolecular polymer thereby reducing its absorption as a result of a pH elevation in the stomach. We measured the Iron recovery after ultrafiltration to assess macromolecular polymer using sodium ferrous citrate (SFC) and ferrous sulfate (FS) preparations plus eight types of antacids Aluminum hydroxide (Al), Magnesium oxide (Mg), Calcium carbonate (Ca), and Sodium bicarbonate (NaHCO3) preparations and four combinations.
The samples were mixed under two conditions : (1) a mixture of the maximum single oral dose of each iron preparation and an antacid dissolved in a hydrochloric acid solution adjusted to various pH levels (4, 5, 6, 7, 8, and 9) (2) pH not adjusted. Iron recovery rate was measured using the O-phenanthroline method after ultrafiltration (fractions with a molecular weight of 10, 000).
As a result, we obtained the following results : (1) the iron recovery rate decreased according to elevation of pH. In addition, macromolecular polymer formation was pH dependent. The iron recovery rate of FS when mixed with all antacids except Mg was less than 60 % at a pH of 7. The iron recovery rate of SFC was not less than 60% at a pH of 7 with any antacid. (2) the iron recovery rate of FS when mixed with Ca, NaHCO3, the Al + Mg combination and Mg was less than 60%. The iron recovery rate of SFC was less than 60 % with only Mg.
FS formed macromolecular polymer in the presence of Ca, NaHCO3, the Al+Mg combination and Mg. As a result, the iron absorption was suggested to decrease when FS was administered with these antacids. SFC showed little formation of macromolecular polymer in the presence of antacids, and it was therefore suggested that the absorption would only be slightly influenced by the concomitant use of SFC with antacids. Therefore, the formation of macromolecular polymers differed between the two oral iron preparations, FS and SFC, when mixed with antacids. These findings suggest that iron absorption may differ between FS and SFC in concomitant use with antacids.
