in patients treated concurrently with theophylline and enoxacin, concentrations of the methylxanthine in plasma arise due to a reduced metabolic clearance of theophylline. Ranitidine, sucralfate, antacids containing magnesium or aluminum, supplements containing calcium, iron, or zinc: co-administration with these substances can lead to therapeutic failure of the antibiotic due to decreased absorption by the intestinal tract. For example, magnesium or aluminum antacids turn enoxacin into insoluble salts that are not readily absorbed by the gastroenteric tract. Notes References Further reading . External links Medline entry CYP1A2 inhibitors Fluoroquinolone antibiotics Withdrawn drugs Naphthyridines Piperazines Carboxylic acids