This section is from the "A Handbook of Useful Drugs" book, by State Medical Examining and Licensing Boards.
A 20 Per Cent. Solution Of Tannic Acid In Glycerin.
Dosage: 1 c.c. or 15 minims corresponding to 0.2 gm. or 3 grains of tannic acid. This preparation is chiefly used externally and affords a convenient agent for making dilute solutions for local use. For local applications solutions containing from 0.5 to 2 per cent. of tannic acid are appropriate.
To prevent the astringent action of tannic acid on the gastric mucosa, various organic combinations of tannic acid have been prepared which resist the action of the gastric juice to a greater or less extent and escaping solution in the stomach, do not become active until they reach the intestine.