Gastric antacids which cannot act as systemic alkalies

Abstract

The antacid most frequently used in the treatment of hyper-chlorhydria is sodium bicarbonate. But this is not only an antacid but an alkali, so that the contents of the stomach occasionally become alkaline. Moreover, the amount required to control the gastric symptoms is frequently sufficient to make the urine alkaline. Both these alkalinizations are regarded as unphysiological. Direct evidence of the occasional toxic action of therapeutic doses of sodium bicarbonate has recently become available. 1 2

The ideal gastric antacid would appear to be a substance which can neutralize hydrochloric acid but cannot make the stomach alkaline and which is excreted, unchanged, in the intestine and not in the urine. Such substances are found in the secondary and tertiary phosphates of calcium and magnesium. They are neutral substances, which dissolve in the hydrochloric acid of the stomach with the formation of the corresponding acid phosphates. An excess cannot quite alkalinize the stomach. The tertiary phosphates, as was shown by the work of Steel and Gies 1 and of Lothrop 2 for bone-ash, which is very nearly pure Ca₃(PO₄)₂, and by experiments of the author (see Table I) for Mg₃ (PO₄)₂, are precipitated in the intestine and eliminated in the stool. Dogs have received bone-ash, in many times the therapeutic dose, for years without apparent ill effect.