Digitalis. - Synonym. - Foxglove. The leaves of Digitalis Purpurea Linne (nat. ord. Scrophularineae), collected from plants of the second year's growth.

Habitat

Europe, in sandy soil and the edges of woods.

Characters

From 10 to 30 cm. long, ovate or ovate-oblong, narrowed into a petiole; crenate; dull green, densely and finely pubescent; wrinkled above; paler and recticulated beneath; midrib near the base broad; odor slight; somewhat tea-like; taste bitter, nauseous. Resembling Digitalis leaves.- Matico leaves, which are more deeply reticulated.

Composition

The chief constituents are - (1) Digitoxin, a glucoside, crystallizable, the most active principle, very poisonous, cumulative. Insoluble in water, sparingly in Ether, easily in Chloroform and Alcohol. Exists as minute white crystals. Dose 1/250 to 1/50 gr. .00025 to .00125 gm. (2) Digi-talin, a crystalline glucoside, possessing in a high degree the actions of Digitalis. It is also called Digitalinum Verum. Soluble in water, I in 1000. Dose, 1/200 to 1/100 gr. .0003 to .0006 gm. subcutaneously. (3) Digitalein, an amorphous glucoside, not yet proved to be a definite chemical substance, soluble in water, and therefore suitable for hypodermatic injections; dose hypo-dermatically 1/100 gr.; .0006 gm., said to be non-cumulative. These three glucocides are said to represent the cardiac stimulating action of the drug, (4) Digitonin, C27H44O13 a glucoside closely allied both chemically and physiologically to, and perhaps identical with, the Saponin of Senega {q. v.). Dose, 1/300 to 1/100 gr. ;•0002 to .0006 gm. This is a cardiac depressant, and is therefore antagonistic to the other active principles. (5) Digitin, a glucoside devoid of physiological action. All these five glucosides are non-nitrogenous. (6) Two acids, Digitalic and Antirrhinic. (7) Other usual constituents of plants, as tannic acid, volatile oil, coloring matter, starch, sugar, gum, salts. It will be noticed that Digitalis contains no Alkaloids.

The following five substances, all soluble in alcohol, are met with in commerce: (A) Homolle's Digitalin (same as Quevenne's), an amorphous yellowish-white powder or small scales, intensely bitter, inodorous, but irritating to the nostrils. Soluble in 2000 parts of water. Consists chiefly of Digitalin with a little Digitoxin. Possesses the action of the leaves. Granules of it are much used in France; each usually contains 1/65 gr., .001 gm., which is equal to 1/2 gr.; .10 gm. of the powdered leaves. (B) Nativelle's Digitalin, C25H40O15, light, white, crystalline tufts of needles, very bitter. Soluble in Chloroform and in Alcohol, not in Water or Ether. It consists very largely of Digitoxin and is cumulative. Dose, 1/60 to 1/30 gr.; .001 to .002 gm. in a pill. (C) German Digitalinum Purum. Dose, 1/60 to 1/30 gr. .001 to .002 gm., soluble in water. Consisting chiefly of Digitalein, with some digitalin and digitonin. (D) Digitoxin, already described {see p. 421). (E) Digitalin. already described {see p. 421). None of the above constituents are official.

Incompatibles. - Ferric salts, lead acetate, and cinchona.

Dose, 1/2 to 3 gr.; .03 to .20 gm.

Preparations

1. Extractum Digitalis. - Extract of Digitalis. By maceration and percolation with Alcohol and Water, distillation of the Alcohol, and evaporation.

Dose, 1/4 to 1 gr.; .015 to .06 gm.

2. Extractum Digitalis Fluidum. - Fluid Extract of Digitalis. By maceration and percolation with Alcohol and Water, and evaporation.

Dose, 1/2 to 3 m.; .03 to .20 c.c.

3. Infusum Digitalis. - Infusion of Digitalis. Digitalis, 15; Cinnamon Water, 150; boiling water, 260; Alcohol, 100; cold water to 1000.

Dose, 1 to 4 fl. dr.; (note that it is drachms, not ounces); 4. to 15. c.c

4. Tinctura Digitalis. - Tincture of Digitalis. Digitalis, 150; Diluted Alcohol to 1000. By maceration and percolation.

Dose, 5 to 30 m.; .03 to 2.00 c.c

As the proportion of the many constituents varies in the preparations, some prefer always to give the powdered leaves.