Fe: Administration w/ food may further impair Fe salts absorption. Compd containing Ca & Mg, including antacids & mineral supplements, & bicarbonates, carbonates, oxalates, or phosphates, may also impair absorption of Fe by formation of insoluble complexes. Absorption of both Fe salts & tetracyclines is diminished when taken concomitantly PO. A suitable interval is advised if Fe supplement is required in patients receiving trientine. Zn salts may decrease absorption of Fe. Ascorbic acid & citric acid may increase absorption of Fe. Delayed response to Fe in patients receiving systemic chloramphenicol. Folic acid: Folate deficiency states may be produced by antiepileptics, OCs, antituberculous drugs, alcohol, & folic acid antagonists eg, aminopterin, MTX, pyrimethamine, trimethoprim & sulfonamides. Decreased serum-phenytoin conc & possibility that same effect could also occur w/ barbiturate antiepileptics.