A treatise on pharmacy for students and pharmacists / by Charles Caspari, Jr.

  • Charles Caspari
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on pharmacy for students and pharmacists / by Charles Caspari, Jr. Source: Wellcome Collection.

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    British Pharmacopoeia admits pepsin from the stomachs of hogs, sheep, and calves, and gives the following directions for its prepara- tion: The stomach of one of these animals recently killed, having been cut open and laid on a board with the inner surface upward, any adhering portions of food, dirt, or other impurity are to be re- moved and the exposed surface slightly washed with cold water; the cleansed mucous membrane is then to be scraped with a blunt knife or other suitable instrument, and the viscid pulp thus obtained is to be immediately spread over the surface of glass or glazed earthen- ware and quickly dried at a temperature not exceeding 100° F. The dried residue is to be reduced to powder and preserved in a stoppered bottle. The official British pepsin is thus seen to consist in part of the dried secretion of the mucous membrane, which naturally contains substances liable to putrefy, and this, no doubt, accounts for the offensive odor noticed in some samples dispensed in this country. Such a pepsin also has a weak digestive power, and the British Phar- macopoeia does not demand that official pepsin shall dissolve more than lifty times its weight of hard-boiled egg albumen in thirty minutes, at a temperature of 54.4° C. (130° P.). French pepsin is chiefly obtained from sheep stomachs, and Bou- dault's preparation contains starch and sometimes lactic acid. The German Pharmacopoeia does not prescribe the source of official pep- sin nor the manner of its preparation; the stomachs of hogs and calves are, however, usually employed. Official German pepsin is required to dissolve 100 times its weight of hard-boiled egg albumen in one hour, at a temperature of 45° C. (113° F.). Pepsin exposed on a watch-glass to the air, even in damp weather, should not become sticky in the course of a few hours, showing the absence of an undue amount of peptone. It should form, with dis- tilled water, an almost clear solution, which is not rendered turbid by the addition of acetic acid, showing the absence of mucus. (Pep- sin made by Scheffer's process never yields a perfectly clear solution with water owing to the presence of syntonin or acid albumin.) It should be free from any disagreeable or ammoniacal odor due to the presence of putrescible matter. A drop of tincture of iodine added to a solution of pepsin should not develop a blue or purplish-red color, showing the absence of starch and dextrin. The greater the proportion of peptone present in pepsin the more rapidly does it absorb moisture from the air, and the greater the absence of mucus the less unpleasant will be the odor and the more perfectly clear will be the solution of pepsin in water, especially if the water be acidulated with acetic acid. Except in minute quanti- ties, sodium chloride impairs the activity of pepsin ; the same is true of alcohol. An aqueous solution of pepsin will decompose in a short time; after addition of hydrochloric acid it remains clear but gradu- ally loses its effects on albumen. Glycerin, on the other hand, pre- serves its virtues. Tannin and the alkali carbonates and bicarbon-
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