Fe: May reduce absorption w/ tea, coffee, wholegrain cereals, eggs, milk, Ca & Zn supplements; antacids, PPIs, & trientine. May impair absorption w/ bicarbonates, carbonates, oxalates, or phosphates. Reduced absorption of fluoroquinolones, tetracyclines, levodopa, carbidopa, entacapone, penicillamine, & cefdinir; eltrombopag. Folic acid: May reduce effect w/ trimethoprim or sulfonamides, alone or in combination as co-trimoxazole. Reduced plasma levels of anticonvulsants, particularly phenytoin, phenobarb & primidone. May interfere w/ the microbiological assay for serum & erythrocyte folic acid conc w/ antibiotics.