Abstract
When gastric contents are acid, the rat stomach rapidly absorbs most acidic drugs. In contrast, all but the very weakest basic drugs are poorly absorbed. When gastric contents are alkaline, absorption of acidic drugs is impeded and that of basic drugs facilitated. These observations have been presented in terms of the hypothesis that the gastric mucosa is predominantly a lipoid barrier. Gastric absorption of drugs can be explained by the diffusion of the unionized form of a weak electrolyte across such a barrier.
The unionized forms of drugs traverse the mucosa at rates approaching deutenium oxide movement and usually more rapidly than ethanol.
Rapid absorption by the stomach is not limited by gastric mucosal blood flow. When absorption is rapid, diffusion and mixing within the gastric lumen may become the limiting factors.
Footnotes
- Received April 4, 1957.
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