Alkalies, and their carbonates, and tannic acid are incompatible with quinine and the other alkaloids of cinchona. The alkalies precipitate them from solution, and tannin forms with them insoluble compounds. One grain of dilute sulphuric acid will dissolve one grain of quinine.
Quinine arrests some processes of fermentation and decomposition, and might, except for its cost, be used as a local antiseptic and disinfectant. It is readily absorbed, and is frequently given by rectum; it is also used hypodermically, though it is very irritating and liable to produce abscesses.
Quinine may be found in the blood a few minutes after being taken, and retards oxygenation. It enters the tissues quickly and is excreted slowly, several days being required. The maximum effect of a large dose is reached in about five hours. Small doses quicken the heart and raise the blood pressure. Large ones depress the heart, diminish the force and frequency of its contractions, and lower blood pressure. The respirations are also depressed by large doses.
Quinine acts strikingly on the nerve centres. Small doses stimulate the brain and increase the activity of the mind, while slight overdoses produce headache and ringing in the ears, with deafness, more or less pronounced. This deafness usually passes off quickly, but may be permanent. Full doses intensify these symptoms, and cause severe pain, constriction, and fulness in the head, confusion of the mental faculties, intense nervous irritability, giddiness, disorders of vision, and general prostration from depression of the spinal cord and circulation.
The pre-eminent power of quinine is shown in its control over malarial poisoning as a specific, anti-periodic, and prophylactic. (A medicine to be prophylactic must belong either to the class of restoratives, supplying a deficiency of some natural and essential condition of the body, or to the class of germicides, preventing disease by destroying the injurious agent.) Quinine has some power as an oxytocic, contracting the uterus. In times past it was taught that it was capable of producing abortion, but the weight of evidence is believed by most authorities to be against this theory.
Eruptions of the skin are sometimes observed after the use of quinine, even in small doses. A rash resembling that of scarlet-fever may appear, followed by severe itching and smarting, and desquamating finally.
More rarely the eruption resembles urticaria, popularly known as "hives" or "nettle-rash." Occasionally irritation of the urinary organs is caused, with pain, congestion of the kidneys, or even hemorrhage. This is more liable to occur with old people. Idiosyncrasy exists in a marked degree with some persons in regard to quinine, forbidding the use of even the smallest doses.
If much prostration follows the administration of quinine, strong black coffee with brandy is the best antidote. In giving quinine, ringing in the ears and deafness are the first symptoms to be looked for.
There are now eight official preparations of quinine - Quinine Bisulphate, Dihydrochloride, Hydrobromide, Hydrochloride, Salicylate, Sulphate, and Tannate, all of which except the last have an average dose of gr. 1 1/2-0.1 Gm. as tonics, and gr. xv.-I Gm. daily as antimalarial remedies. The dose of the tannate is gr. iii.-0.2 Gm.
Last is a preparation for hypodermic use, Quinine and Urea Hydrochloride. Average daily dose, gr. xv.-I Gm.
Quinine is usually given in pills or capsules on account of the bitter taste. Sometimes, when rapid action is desired, it is given in solution. The taste is 14 very persistent and is better removed by a piece of dry bread, or an olive, than anything else. The powdered sulphate may be given in sherry wine.
Quinine pills should not be more than ten days old, as then they become so dry and hard as to be useless, passing through the alimentary canal without dissolving. Quinine should be given on an empty stomach, or after the process of digestion is partly over. If a patient is on milk diet quinine should not be given in solution near the milk, as it is very liable to cause vomiting. Otherwise there is no incompatibility between quinine and milk.
A preparation with an exceedingly long formula, containing over a dozen drugs of vegetable origin, with a certain proportion of quinine, the most active ingredient (between 9 and 10 grains to the ounce). It is used as a diaphoretic, and is best given at night.
Dose, ℥ ss.-15 mils.