This section is from the book "Materia Medica And Therapeutics - Vegetable Kingdom", by Charles D. F. Phillips. Also available from Amazon: Materia Medica And Therapeutics: Vegetable Kingdom.
Active Ingredients. - The active element of the V. odoratais the alkaloid violine, discovered in the root by Boullay (1828). It is a pale-yellow, bitter-tasting powder, which, on the application of heat, first melts and then burns like a resin. It is still uncertain whether violine is or is not identical with emetine, the active principle of ipecacuanha, but it appears to be more soluble in water, and less soluble in alcohol and ether than the latter substance. Pereira affirmed the operation of the two substances to be similar, and states that the violet-root may be employed as a substitute for ipecacuanha; but the experiments of Orfila and Chomel thr6w much doubt upon this, and show at least that violine is very inconstant in its action. Possibly violine may be an impure form of emetine, as suggested by Husemann.
Physiological Action. - Violine is distinctly irritant to the alimentary canal; though the degree in which it will produce vomiting or purging in any individual man or animal is always uncertain. Its extreme effects are seen in such experiments as those of Orfila, when he placed 5 1/2 grains in the stomach of a dog, and ligatured the oesophagus: in 12 hours the animal became exceedingly depressed, with rapid pulse, and in 48 hours died in convulsions; gangrenous inflammation of the stomach was found on dissection. The same quantity of violine subcutaneously injected, proved fatal to a dog in 10 hours; a corresponding dose killed a dog when injected into the jugular vein; but the half of this quantity, when thrown into the circulation, produced no effect. Chomel's experiments upon men proved that the power of violine to produce vomiting or diarrhoea varies very much. Garrod says that the root of the Viola odo-rata is purgative and emetic in doses of 30 to 60 grains.
Therapeutic Action. - In the present state of uncertainty as to whether violine is a really independent substance, or merely an impure emetine, it seems impossible to accept as satisfactory any statement respecting the medicinal uses of the plant before us. Those species of Violaceae which contain emetine, require, on the other hand, no special mention here, since their possible actions will be tacitly included in the remarks to be made under the head of the therapeutic action of ipecacuanha. It may be mentioned, however, that syrup of violets has been found a very useful remedy in coughs of a nervous spasmodic character, attended by much dyspnoea and little or no expectoration. In some cases of whooping-cough the employment of this medicine lessens the spasms considerably.
In Hysteria, attended by depression of spirits and constant weeping, it is also good. A mixture of equal parts of oil of almonds and syrup of violets, administered in a dose of one to two teaspoonfuls, often serves as a nice laxative for new-born infants.
The Viola canina is said not only to have emetic roots, but to be useful as a depurative, and to have been recommended for the cure of cutaneous disorders; while, in Italy, the herbage of the common pansy, Viola tricolor, is said to be employed in cases of tinea capitis.
Preparations And Dose. - None officinal. The shops keep a syrup of violets, dose 3 i. - ij. (5. - 10.)