On the Nervous System. - In man small doses give tone to the system generally.

Large doses cause symptoms to which the term cinchonism (or quinism) has been applied; these consist in a feeling of tightness across the forehead, ringing in the ears, deafness, diminution of the power of sight and of accuracy of feeling (p. 229). These symptoms may generally be relieved by giving 30 minims of solution of hydrobromic acid with each dose. Ergot also tends to prevent or remove them.

By still larger doses the powers of hearing and sight are more affected, complete deafness being sometimes produced. Giddiness, headache, staggering gait, and muscular weakness succeed, and the circulation becomes feeble.

With very large doses delirium occurs and occasionally death, sometimes in convulsions.

Small doses stimulate, large doses depress, the functions of the brain, lessening the powers of thought, but may stimulate the motor centres so as to cause epileptic fits (p. 190), and I have seen one case in which an epileptic fit appeared to be brought on by large doses of quinine.

Spinal Cord. - Reflex action is diminished, especially in the frog. Immediately after the injection of quinine into the lymph-sac of a frog a great depression of reflex action occurs. This was attributed by Chaperon to stimulation of Setschenow's centres by the quinine. It is probably, however, only reflex depression, due to the local irritation of the injection. At a later stage of poisoning considerable depression of the reflex action is also observed, which has been attributed to gradual paralysis of the cord from feebleness of the heart and consequent failure of the circulation. Sensory and motor nerves are only affected by the drug when locally applied. The muscles retain their irritability till near death, but their capacity for work as well as their irritability is diminished. The muscular curve is somewhat prolonged (p. 128). During its excretion quinine stimulates the genito-urinary tract, and occasionally produces irritability of the bladder and urethra. It is said to produce contraction of the gravid uterus, and is therefore to be given with care in pregnancy.

Uses. - From its power of destroying germs and preventing putrefaction, quinine is used as a local antiseptic. As a lotion it is useful in conjunctivitis, and in the diphtheritic form of this disease quinine destroys the power of the secretion to cause inflammation when inoculated into another eye.

Hay fever, which probably is caused by the presence of the pollen of grasses, is often relieved by washing the nose with a saturated aqueous solution of sulphate of quinine (about 1/2 grain to 1 fl. oz.), (p. 478). Sometimes it is quite useless.

Sore-throat is often relieved by a gargle of quinine (cf. p. 816).

Whooping-cough is often relieved by quinine, which may be inhaled in the form of spray of the strength of 2 grains to the ounce in Richardson's ball spray or 4 grains to the ounce in Siegel's apparatus.

After the evacuation of an empyema or pleural effusion, a solution of quinine may be injected as an antiseptic into the pleural cavity. It is a useful injection (2 gr. to the ounce) in chronic cystitis and otorrhoea.

As a tonic it is useful in general debility; it increases the appetite and muscular strength; it may be advantageously combined with iron.

As an antiperiodic it is used in ague, malarial fever, and all malarial remittent affections, with great efficiency, being almost a specific. It should be given in doses of 3 or 4 grains, three times a day, or in a single dose of 10 grains just before a fit comes on; it will often cut short a fit of moderate intensity. An emetic or cholagogue purgative should be given before it (p. 405). In malarial cachexia without distinct fits, it is much less serviceable.

In neuralgia of the intestine, when due to malaria, 5 grains should be administered in one dose, followed by 5 more in a quarter of an hour if no relief is obtained. It will also cure other forms of neuralgia not apparently due to malaria, and even when not of a periodic character. It is especially useful in supra-orbital neuralgia.

Intermittent headache is often greatly relieved by 5 grains of quinine, especially if calomel, grey powder, or podophyllin be also given along with it to act on the liver (cf. pp. 375, 406).

As an antipyretic large doses (5-20 gr.) lessen the temperature in typhus, enteric, and other fevers. It is better to give a single large dose once a day, or two doses of 5 grains given within an hour, between five and six in the evening.

In symptomatic fevers quinine has been used to reduce the temperature, as in pneumonia.

In rheumatism and exanthemata it is not much used.

In the treatment of worms quinine is useful to prevent the accumulation of mucus which forms a nidus for the worm.

As a prophylactic agent against ague and all intermittent affections quinine is invaluable.

Warburg's tincture, containing quinine and a number of aromatics, is very useful in cases of ague in doses of one to four drachms, and of collapse from various causes in doses of half an ounce.

The other alkaloids of cinchona seem to have very much the same action as quinine.

Sometimes people who work with cinchona barks are attacked with great irritation of the skin; this is probably due to the mechanical action of minute spicules of the bark.