Quinine - New World Encyclopedia
Drug interactions -summary Quinine sulphate + Aluminium contng antacids-
delay or decrease absorption of concurrent quinine.
Anticoagulants oral -
quinine depress the hepatic enzyme system that synthesis
Vitamin K dependent clotting factors and enhance the action of
warfarin and other oral anticoagulants Cimetidine
reduce quinine oral clearance and increase its elimination half-life. Digoxin
serum concentrations increased by concurrent quinine. Mefloquine
do not use concurrently with quinine.
if required to be used delay meloquine admin. by at least 12 hours
after last dose of quinine. Risk of convulsions increased by coadmin.
Neuromuscular blocking agents-
blockade of these agents is potentiated by quinine, and result
in respiratory difficulties Urinary alkalinizers , acetazolamide , Sod bicarb
administered concurrently with quinine increase quinine blood levels. Drug/Lab Test Interaction: Elevated values for 17 ketogenic steroids may occur with Zimmerman method.
Quinine has the chemical formula C 20 H 24 N 2 O 2
CINCHONA BARK, ALKALOIDS OF. About 3o dis tinct alkaloids have been isolated from cinchona bark, of which quinine is by far the most important, followed by quinidine, cinchonidine and cinchonine. Owing to the therapeutical im portance of cinchona bark and its four principal alkaloids most of the National Pharmacopeias prescribe methods of estimating these constituents in the bark and lay down standards both for the bark and for quinine. Thus the British Pharmacopeia re quires that red cinchona bark should yield from 5% to 6% of alkaloids, of which not less than half must consist of quinine and cinchonidine, and for quinine sulphate a test is prescribed which excludes all but a minimum quantity of cinchona alkaloids, other than quinine. (For further information see ALKALOIDS.) Quinine, C20H2402N2.This alkaloid is rarely seen or used, except in the form of its salts with acids. Though it contains two atoms of nitrogen it behaves as a monoacidic base yielding a sulphate of the formula (C2oH2402N2)2, popularly known as "quinine." It crystallizes in bulky masses of colourless, glistening needles, which become dull on exposure to air owing to the loss of five of their molecules of water of crystallization, so that the thoroughly, stable, air-dry salt has the composition (C20H2402N2)2, H2SO4, 2H20. It is sparingly soluble in water, more so in alcohol and still more in a mixture of alcohol and chloroform. The solutions are laevorotatory and those in water, especially when acidified, are strongly fluorescent. Two other sulphates, C20H2402N2i (so-called disulphate) and (so-called tetra-sulphate) are known and are used when more soluble salts are required. Quinine hydrochloride HC1, which closely resembles the ordinary sulphate in appearance but has the advantage of being a little more soluble in water, is also in use. In addition, a great variety of special salts have been made in attempts to com bine the therapeutic advantages of quinine with those of medic inally valuable acids, e.g., quinine salicylate, acetylsalicylate, valerianate, cacodylate, etc.
These four cinchona alkaloids have been the subject of inves tigations designed to determine their constitution and permit of their synthesis, almost continuously since they were discovered in 1820. The reactions of the four alkaloids indicate that they can all be represented by the following general formula due to Rabe (1909) and based on that of (1906), which repre sents them as containing a quinoline (left) and a quinuclidine (right) nucleus, joined by a secondary alcohol group. The chemi cal differences between the two pairs (1) quinine and quinidine and (2) cinchonidine and cinchonine, depend on the fact that in the first pair R is the group and in the second pair R is a hydrogen atom. In all four alkaloids R' is the group CH : CH2 which can either be oxidized to a carboxyl group .COOH, giving rise to a new alkaloid from each of the four, or can be reduced to giving rise also to four new alkaloids (hydro-quinine, hydro-cinchonine, etc.). These eight new alkaloids can in turn each produce series of new derivatives, some of which are of special interest since in them the therapeutic properties of the parent alkaloids seem to be enhanced at least in certain directions.