This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
In ordinary doses, quinia is not apt to produce deleterious effects, unless through want of appropriateness to the pathological condition in which it may be prescribed; but, when very largely administered, it sometimes causes unpleasant symptoms from congestion or over-excitement of the brain, among which a greater or less degree of deafness is the most common. Generally this deafness subsides, with the other phenomena, in a period of time varying from a few hours to two or three days; but sometimes it persists much longer, at length gradually yielding; and, in very rare instances, has proved permanent and incurable. Cases are on record in which death has occurred from inflammation of the brain, under the excessive use of quinia; though there is reason to believe that there may have been, in these cases, either a strong predisposition requiring only a special cause to call it into action, or a certain amount of pre-existing inflammation, which was easily aggravated into fatal violence. Still, experiments upon animals have shown that, even in healthy conditions of the brain, encephalitis may possibly result from the abuse of this medicine. In all cases of over-excitement of the brain, the obvious remedies are leeching or cupping behind the ears, cold water to the head, a saline purgative not only to deplete and act revulsively. but to carry off any unabsorbed portion of the alkaloid, and, lastly, bleeding from the arm, if the symptoms should be urgent, and the pulse permit.
The irritation occasionally produced by quinia in the urinary passages, during its elimination, is said, in some instances where large doses have been taken, to have been aggravated into cystitis; and even retention of urine is asserted to have been produced by it.
Another danger from quinia is the great secondary prostration from enormous doses, which, in persons already feeble, may possibly in some instances prove fatal.* Experience has shown that, under such circumstances, stimulants are not only safe, but useful. Carbonate of ammonia I should prefer to the alcoholic stimulants, as it excites the heart, with less effect on the brain; but, if this fail, recourse maybe had to wine or other fermented liquor, and even to brandy, should the prostration be alarming. If much nervous disturbance, as tremulousness, convulsions, or delirium, attend the prostration, one of the salts of morphia may be employed. Giacommini found coffee useful in cases of cinchonic syncope which came under his notice. In all cases in which the salts of the cinchona alkaloids have been given too largely, tannic acid or an astringent infusion should be administered internally; for, though the tannate is not without effect on the system, it is certainly less rapidly absorbed than the soluble salts.
* It is strange, however, considering the powerful effects often produced by comparatively moderate doses, how far the quantity may be increased without fatal results. The case of Giacommini has already been referred to (see page 235). Another is mentioned by Briquet, in which 41 grammes (about ten drachms and a half) were taken in the course of a few days. The patient lost for a time sight, hearing, and speech, and became as cold as a corpse, but nevertheless recovered. (Trait. Therap. du Quinquina, p. 490).