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 principle of gentian is not, as was formerly supposed, the gentianine or gentianic acid, C14H10O5, a substance which crystallizes in yellow and silky needles, and is tasteless, and neutral in reaction; but gentio-picrine, C20H30O12, a bitter glucoside, first obtained by Kromager, in 1862. Gentio-picrine forms colorless crystals, which on exposure to the atmosphere become dull white. This substance is readily dissolved in cold water and in cold proof spirit, while gentianine is scarcely soluble even in boiling water, and but little soluble in spirit. Potash and soda solutions and hot solutions of ammonia dissolve it yellow. Cold concentrated sulphuric acid dissolves it without color; but the solution, when gently heated, changes to a lively carmine red. On the addition of water, gray flocculi are deposited.
Physiological Action. - There can now be little doubt that gentio-picrine, the true active principle of gentian, is a bitter closely allied to quinine, alike in physiological and in therapeutic action. The conflict of evidence which occurred respecting its power as an anti-periodic, unquestionably arose from the confusion between the true bitter and the tasteless gentianine. The former has been proved to be undoubtedly efficacious in cases of intermittents, by Lange, who published a series of 34 cases in which the attacks were cut short or prevented by 1/2 drachm doses. The effects of an overdose of gentian itself are dul-ness, weight in the head, oppression of forehead, and slight giddiness; symptoms, in fact, much resembling those induced by cinchonine. The face becomes flushed, and the conjunctivae are injected. The sweat and the urine acquire a bitter taste. The bowels are relaxed, and the stools have a bilious character. It is probable that, besides the gentio-picrine, there is some volatile ingredient in gentian which has a slighly inebriant action, since Planche states that water distilled over pure gentian possesses the latter quality.
Therapeutic Action. - Gentian root has long been employed as a valuable tonic; and, before the discovery of the cinchonas, occupied the first place in medicine as a febrifuge. It is very properly regarded as a pure and simple bitter, that is to say, as a bitter without the accompaniment, or nearly so, of either astringency or aroma. It agrees best with patients of a torpid and phlegmatic habit, but should be avoided where the temperament is irritable. Given in small doses, gentian is found beneficial in dyspepsia (especially in gastric dyspepsia connected with a gouty diathesis), also in hysteria and jaundice, and generally in all those cases of debility for which tonics are exhibited, and which are unaccompanied by symptoms of inflammation. Gentian is likewise valued in scrofula, in intermittents, and as a vermifuge; and, in the form of infusion, becomes an excellent vehicle for the administration of chalybeates, mineral acid, and neutral salt, with which it is often necessary to combine it.
Preparations and Dose. - Extr. Gentianae, gr. ij. - x (.13 - .65); Extr. Gentian. Fl., m x. - xx. (.60 - 1.20); Tinct. Gentian Co., 3 j. - ij. (4. - 8.); Infus. Gent. Co.,
- ij. (30. - 60.).