Cudbear. N.F. IV. Persia. Orseille de terre, Fr.—"A purplish-red powder prepared from species of Roccella De Candolle, Lecanora Acharius, or other lichens." N. F. IV. Cudbear is described in N. F. IV as follows: "An aqueous or alcoholic preparation of Cudbear is of a deep red color which is rendered lighter in tint by the addition of acids and changed to purplish-red on the addition of alkalies. Agitate 2 Gm. of Cudbear occasionally with 200 mils of water during thirty minutes and then filter; the deep red-colored filtrate conforms to the following tests: Add to 5 mils of the filtrate 5 drops of glacial acetic acid and boil for one minute; then add 5 drops of stannous chloride T.S., and boil again for one minute; the liquid is only faintly pink (brazilwood or logwood which produce solutions of a deep red color); add 25 Gm. of kaolin to 100 mils of the filtrate in an Erlenmeyer flask, shake frequently during one hour and then filter; the filtrate is almost entirely decolorized in comparison with some of the original filtrate (a number of coal tar colors). Cudbear yields not more than 35 per cent. of ash, consisting mainly of sodium chloride." N. F. IV.
Cudbear was introduced into the National Formulary solely for coloring liquids. Two preparations were made official, Tinctura Persionis, N. F. IV (Tincture of Cudbear) and Tinctura Persionis Composita (Compound Tincture of Cudbear). Both tinctures are used to give a deep red color to syrups, tinctures, solutions, and elixirs of the National Formulary. George M. Beringer has given much attention to cudbear with a view of securing a uniform product. (See Proc. New Jersey Pharm. Assoc., 1912, 56.) He declares that all of the ordinary methods, as color charts, colored yarns, threads, glass, etc., are unsatisfactory and inapplicable to pharmacy. He advocates the preliminary purification of cudbear by washing it with water to remove the sodium chloride so largely used as a diluent and the ammonium salts with their empyreumatic odor. He states that if the washing is properly done the cudbear loses scarcely any of its tinctorial power. He gives a table showing comparative values of eight tinctures prepared with various menstrua. He believes that the best results, however, would follow the preparation and use of a standard extract. Alexander Gardner gives the name persionin to an acetone extract of cudbear made as follows: The process consists in percolating commercial cudbear with purified benzin until free from wax, then drying the drug, repacking it in a percolator and percolating it with acetone to exhaustion—about 2500 mils being required for 1000 Gm. of cudbear. The acetone is recovered by distillation, the residual extract heated for thirty minutes to 98.8° C. (210° F.) in a porcelain capsule, then pulverized and placed in a sulphuric acid desiccator for three days, during which it loses about 25 per cent. of its weight. So obtained, "persionin" is a black, lustrous powder with an aromatic odor, soluble in alcohol, glycerin, chloroform, ether, and hydro-alcoholic liquids, but is only sparingly soluble in water. Five different lots of cudbear yielded, respectively, 6.5, 7, 6, 5, and 5.5 per cent. of persionin. Each sample of "persionin" was tested by dissolving 1 part in 100 parts of alcohol and 3 parts of glycerin. One mil -of this was added to 99 mils of distilled water, and in each particular the color was the same. (J. A. Ph. A., 1913, 51-52.) H. V. Arny (J. A. Ph. A., 1913, 47) proposes to remove a brown pigment present in cudbear (which interferes with the tinctorial power) by macerating an alcoholic extract with chloroform and extracting the residue with acetone. The final product is then "scaled."
Because of the difficulty of completely extracting cudbear the liquid preparations are rarely uniform in color value. For this reason the N. F. uses powdered cudbear in several preparations, allowing it to macerate until all color is extracted. This plan results in more uniform coloring than if the tincture was directed.