The trees belonging to the genus Cinchona are found native in South America, on mountains at a height of 5000 to 10,000 feet, and they are being successfully cultivated in other countries. The bark is the part used in medicine.
There are many varieties of the tree, the most important being Cinchona succirubra, from which "red bark" is obtained, and Cinchona calisaya, from which comes the "yellow" or "calisaya bark." A bark called "pale bark" is obtained from two minor varieties, and, finally, under the general name "cinchona" or "Peruvian bark" are included all other varieties of the tree yielding two or three per cent. of the alkaloids which contain crystallizable salts.
Cinchona contains four principal alkaloids: quinine, the most important; quinidine, the strongest anti-periodic, but existing in very small quantities; cincho-nine, about half the strength of quinine; and cinchoni-dine, a little stronger than cinchonine.
The yellow bark contains most quinine, the pale bark most cinchonine, and the red bark about equal quantities of each. Besides these important alkaloids and a number of unimportant ones, cinchona bark contains tannic and other acids, a resinous substance, coloring matter, etc.
The preparations of cinchona bark as a whole are used as bitter stomachics and tonics.
They are too bulky to be used as antipyretics or antiperiodics if quinine can be obtained. They have some astringent action, due to the tannin they contain. They should be given half an hour before meals.
Strength, 20%. Average dose, ʒ i.-4 mils.
Average dose, xv.-I mil.
The sulphates of cinchonine and cinchonidine are also official. Average dose, gr. iiss.-0.15 Gm.