Effect of prednisolone and salicyclic acid on ionic fluxes across the human stomach.

We compared ionic fluxes across human gastric mucosa after instillation of test solutions of isotonic hydrochloric acid alone or containing salicylic acid, or prednisolone or both. Prednisolone produced no alteration in fluxes of H+ and Na+ ions compared with controls. Salicyclic acid induced a significant net loss of H+ ions and gain of Na+ ions indicating alteration of the gastric mucosal barrier. Combined salicyclic acid plus prednisolone produced no increase in permeability of gastric mucosa to H+ and Na+ ions or to salicylic acid itself. Prednisolone was not appreciably absorbed from the stomach while salicylic acid was well absorbed. Combination of salicylic acid and prednisolone did not increase absorption of either drug. Neither salicylic acid nor prednisolone solutions alone or combined caused an increase in pepsin output over that due to 160 mM HCl. Salicylic acid resulted in a significant fall in potential difference compared to control while prednisolone produced no change in the one subject studied. In acute studies in man prednisolone is not absorbed from the stomach, does not itself affect the gastric mucosal barrier nor pepsin output nor does it enhance the absorption of or effect of salicylic acid on gastric ionic fluxes or pepsin output.