Quinine retards or impairs all the oxidizing powers of the body, and materially lessens the oxygen-carrying capacity of the red corpuscles. This is shown in the diminished metabolism of the body.

Nervous System. - Small doses stimulate the cerebrum. Large doses occasion cerebral congestion, with a sensation of dizziness, fulness in the head, and other symptoms described at length under "Cinchonism."

In mammals there is a transient stimulation of the spinal cord, followed by a depression. In lower animals, notably the frog, there is a primary increase in the reflex irritability, which subsequently is followed by depression, perhaps an index of the action of the drug on the protoplasm of the ganglionic cells. Muscular action is profoundly altered, quinine acting as a poison. Its action on sensory and motor nerves is not marked, and depressing effects on muscular contraction, formerly attributed to its action on the terminal end-plates of the motor nerves, have, of late years, been attributed to its action upon the muscle protoplasm itself.

Respiratory System. - Quinine exerts but little influence upon the respiration, small doses slightly increasing and large doses depressing the respiratory movements; death being due to respiratory paralysis, at least in the lower animals. Such paralysis is usually accompanied by paralysis of the heart and vagus. When toxic doses of quinine are thrown directly into the circulation, paralysis of the heart may be primary.

Absorption and Elimination. - The drug is quite rapidly absorbed from the alimentary canal. While its presence may be detected in the urine within fifteen minutes after the ingestion of a full dose, many hours, or even days, may elapse before the drug is finally excreted.

Some of the drug undergoes a change in the system, especially in the liver, and it may be detected in the urine as quinine and various isomeric modifications of it. While chiefly eliminated by the kidneys, it may escape from the system by other channels, having been found in the milk, sweat, saliva, tears, bile, and in dropsical effusions. Fully 90 per cent. has been recovered in the urine.

The excretion of uric acid, urea, and other nitrogenous material is considerably diminished under the use of quinine. Products by oxidation other than those derived from the nitrogenous elements are not markedly affected, hence it is probable that quinine only hinders the breaking down of proteids.

Temperature. - In health the temperature is unaffected by quinine, but in febrile conditions, particularly in malarial fever, the drug acts as a powerful antipyretic. Its antipyretic action is due, in all probability, to its action on the tissues directly. It also causes diaphoresis. Its action in malaria is naturally as a parasiticide. Many clinicians believe that it is destructive to bacteria as well as protozoa.

Eye. - There have been recorded several cases of amblyopia and of quinine amaurosis, with transitory blindness, color-blindness, wide dilatation of pupil - irresponsive to light, but responding to accommodation effort - pallor of the optic disks, with extreme diminution of both retinal veins and arteries and contraction of the visual field.

Quinine amaurosis, however, is probably very rare, but a limited number of cases being recorded, although Rogers believes that "incomplete ocular cinchonism" is of quite frequent occurrence.

Uterus. - After the inception of labor quinine seems frequently to stimulate the uterine contractions. It also increases a scanty menstrual flow. There appears to be no authoritative evidence that quinine is an abortifacient.

Untoward Action. - Besides the symptoms of cinchonism from which some persons suffer after the ingestion of a small dose, there are often occasioned various eruptions of the skin, often accompanied by marked pruritus, the eruption produced by the drug at times strongly resembling scarlatina.

Peculiar disturbances of vision and impaired hearing not infrequently attend the administration of quinine. Many patients cannot take it because of the incessant buzzing it causes. There have been recorded cases of renal and vesical irritation, varying in intensity, following the use of the drug. The administration of the salts of quinine in pill form is often followed by gastro-intestinal catarrh. The drug has also been known to occasion epistaxis and hemoptysis.

Poisoning. - Excessive doses of quinine produce a series of symptoms collectively termed cinchonism. They are - a feeling of fulness in the head, ringing or buzzing in the ears, varying degrees of deafness, headache, with possibly delirium, disturbances of vision, vertigo, and muscular weakness. In severe poisoning there is nausea and vomiting, swelling of the mucous membrane, bleeding from the nose, may be from the lungs, eruptions, albumin, and blood in the urine, with somnolence, coma, small rapid pulse, respiratory failure, and death. The lethal dose is difficult to determine. 1 to 2 Gm. have been fatal in children; doses of 30 Gm. have been taken without serious inconvenience.

Treatment of Poisoning. - Potassium bromide and hydrobromic acid are the best agents to relieve the symptoms of cinchonism, full doses of the latter given with quinine being said to prevent untoward results.

Should the dose be sufficient to depress the heart and respiration in a marked degree, cardiac and respiratory stimulants would be indicated.

Therapeutics. - Externally and Locally. - Powdered cinchona bark is an ingredient of many tooth-powders. Quinine also enters into the composition of many "hair tonics," and is highly recommended by some physicians in the treatment of alopecia.

The drug has been employed with varying success in many diseases of the nose and throat, such as hay fever, whooping-cough, ozena, tonsillitis, etc.

Ledetsch has highly recommended quinine bisulphate, 1 part to 100 parts of water and glycerin, as an injection in gonorrhea. The drug has been used with tincture of ferric chloride as a paint to prevent the spread of erysipelas. A 2 per cent. solution has proved an efficient remedy in cystitis, effectually preventing the decomposition of the urine.