Basic Information
ID DDInter725 and DDInter2186
Interaction The bioavailability of orally administered iron may be reduced by concomitant administration of antacids or other agents with acid-neutralizing effects. The exact mechanism is unknown but may involve reduced iron solubility due to increase in gastric pH and/or reduced absorption due to complexation or precipitation of the iron.
Management To minimize the potential for interaction, it may be appropriate to administer oral iron preparations at least two hours apart from antacids or other agents with acid-neutralizing effects. . When coadministered with Suprep Bowel Prep (magnesium/potassium/sodium sulfates), the manufacturer recommends administering iron at least 2 hours before and not less than 6 hours after Suprep Bowel Prep to avoid chelation with magnesium.
References [1] O'Neil-Cutting MA, Crosby WH "The effect of antacids on the absorption of simultaneously ingested iron." JAMA 255 (1986): 1468-70 [2] Hall GJ, Davis AE "Inhibition of iron absorption by magnesium trisilicate." Med J Aust 2 (1969): 95-6 [3] Coste JF, de Bari VA, Keil LB, Needle MA "In-vitro interactions of oral hematinics." Curr Ther Res Clin Exp 22 (1977): 205-15 [4] Corby DG, McCullen AH, Chadwick EW, Decker WJ "Effect of orally administered magnesium hydroxide in experimental iron intoxication." J Toxicol Clin Toxicol 23 489-99 [5] Gugler R, Allgayer H "Effects of antacids on the clinical pharmacokinetics of drugs. An update." Clin Pharmacokinet 18 (1990): 210-9 [6] Rastogi SP, Padilla F, Boyd CM "Effect of aluminum hydroxide on iron absorption." Kidney Int 8 (1975): 417 [7] Ekenved G, Halvorsen L, Solvell L "Influence of a liquid antacid on the absorption of different iron salts." Scand J Haematol Suppl 28 (1976): 65-77 [8] Coste JF, De Barbi VA, Keil LB, Needle MA "In-vitro interactions of oral hemantics and antacid suspensions." Curr Ther Res Clin Exp 22 (1977): 205-16 [9] Snyder BK, Clark RF "Effect of magnesium hydroxide administration on iron absorption after a supratherapeutic dose of ferrous sulfate in human volunteers: A randomized controlled trial." Ann Emerg Med 33 (1999): 400-5 [10] Wallace KL, Curry SC, LoVecchio F, Raschke R "Effect of magnesium hydroxide on iron absorption after ferrous sulfate." Ann Emerg Med 34 (1999): 685-6 [11] Pruchnicki MC, Coyle JD, Hoshaw-Woodard S, Bay WH "Effect of phosphate binders on supplemental iron absorption in healthy subjects." J Clin Pharmacol 42 (2002): 1171-6 [12] "Product Information. Suprep Bowel Prep Kit (magnesium/potassium/sodium sulfates)." Braintree Laboratories (2010):
Alternative for Ferrous fumarate B03A
Iron sucrose Cyanocobalamin Folic acid Iron protein succinylate
Alternative for Aluminium (carbonate) -
Potential Metabolism Interactions
Substrate-Substrate Interaction：If more than one drug is metabolized by the same CYP, it is possible that its metabolism is inhibited because of the competition between the drugs. That means, it can be useful to lower the dosage of the drugs in the drug-cocktail because they remain longer in the organism than in monotherapy.
Inhibitor-Inhibitor Interaction：Combining two or more inhibitors of one CYP, should be compensated by lowering the dosage of these drugs because the metabolism is reduced and the drugs remain longer in the organism than in monotherapy. Not adapting the dosage bears the risk of even more side effects.
Inhibitor-Substrate Interaction：Combining drugs that have inhibitory effect and are substrates of one particular CYP, should be compensated by lowering the dosage. They rest longer in the organism than in monotherapy. Not adapting the dosage bears the risk of even more side effects.