Controlling gastric acid.

Abstract

Leading Articles MEDIC&L JOURNAL cyclines were given orally the plasma levels of antibiotic reached only 10-50% of the level expected. Because iron and tetracyclines bind in equimolecular ratios, the reduction in the amount of tetracycline absorbed was relatively greater for those with a low recommended dose than for those with a high one. From this work it can be predicted that only insignificant amounts of antibiotic would be absorbed if 200 mg. of ferrous sulphate and 250 mg. of any tetracycline were given simultaneously by mouth. Patients requiring both iron and tetracyclines for their treatment are commonly seen. Moreover, iron is a constituent of popular tonics and beverages freely available to the public. Thus the interaction between iron and tetracycline, as a result of which neither is absorbed, is likely to be common and could lead to failure of antibiotic therapy. Clearly iron by mouth must not be prescribed while a patient is receiving a tetracycline.