A mixture of alkaloids, mostly amorphous, obtained as a by-product in the manufacture of the crystallisable alkaloids from cinchona.

Characters. - A brownish-black or almost black solid, breaking when cold with a resinous shining fracture, becoming plastic when warmed, odourless, having a bitter taste and an alkaline reaction.

Solubility. - Almost insoluble in water, freely soluble in alcohol, chloroform, and diluted acids.

Use. - It is of uncertain composition, and liable to adulteration, and is employed instead of quinine on account of its cheapness.

Doses Of Cinchona Alkaloids And Their Salts

Quinina .....................................

1/2 - 2 gr. as tonic; 2-5 gr. repeated every 2-4 hours as antipyretic. 15-20 gr. a large dose.

Quininae Sulphas ....................

..The same.

" Bisulphas ..............

..A little larger.

" Hydrobromas ............

..The same as for quinina.

" Hydrochloras..

,,

" Valerianas ..................

..1-2gr.

Quinidinae Sulphas ....................

..Same as quinina.

Chinoidinum .................................

..Somewhat larger than of the crystalline alkaloids.

Chinonidinae Sulphas ..................

..1-15 gr.

Cinchonina ..............................

..About one half more than of quinina.

Cinchoniae Sulphas ...................

" " " "

The preparations in thick type belong both to the B.P. and U.S.P.; the others to the U.S.P. alone.

Physiological Action.

General Action. - A solution of quinine when added to albumen loses its fluorescence and seems to enter into combination with it, for the albumen is rendered less soluble and more coagulable (p. 58).

It lessens protoplasmic and amoeboid movements (pp. 61, 62, 65), and destroys low animal and vegetable organisms, but salt-water amoebae seem to withstand the action of quinine to a great extent.

Quinine diminishes oxidation (p. 72) and diminishes and prevents the development of a blue colour on the addition of a few drops of blood to a solution of tincture of guaiac and ozonic ether (p. 69). A similar but less marked effect is seen if blood be taken from an animal into which quinine has been previously injected, instead of mixing the quinine directly with the blood.

Quinine diminishes and in large doses arrests fermentation, especially when it depends on organised ferments (as alcoholic, lactic, or butyric fermentations), but does not prevent the change of starch into sugar by ptyalin or diastase. It has, however, an action on some enzymes, and diminishes the action of pepsin on albumin, and the change of amygdalin into oil of bitter almonds by emulsin. It is a powerful antiseptic (p. 94), and a dilute solution will preserve meat, milk, butter, or urine for a length of time. It is absorbed from all mucous membranes, and is better given in solution, as some of the powder passes out in the faeces. It forms with the bile a salt which is sparingly soluble, except in excess of bile; hence before giving quinine in malaria, clear out the liver by administering an emetic and a cholagogue purgative.

Special Action. - On the Alimentary Canal. - When taken into the mouth, quinine causes a persistent bitter taste if the solution be neutral or only slightly acid, for then the alkalinity of the saliva precipitates the alkaloid; but if given with an excess of acid, and a little water, the bitter taste soon disappears, leaving a sweetish one behind. The bitter taste produces increased flow of saliva by reflexly influencing the centre in the medulla. When quinine is injected into the duct of the submaxillary gland it prevents the secretion of watery saliva by paralysing the ends of the chorda tympani, or by acting directly on the secretory cells themselves (p. 354). The secretion of the thick ropy saliva is not prevented, for the sympathetic is not paralysed except by large doses (p. 355). The vaso-dilator nerve fibres are not paralysed, for if they be stimulated the blood-vessels dilate, the lymph-spaces become full and the gland cedematous, but no secretion takes place.

When taken into the stomach small doses increase the appetite, especially in atonic dyspepsia, but if the stomach is irritable quinine in large doses causes loss of appetite and may produce nausea and vomiting (p. 362 et seq.). When it causes vomiting, the addition of hydrobromic acid will often enable it to be borne. If the stomach be congested the flow of mucous secretion will be increased by quinine.

The action of quinine on the secretions and peristalsis of the intestines is unknown, as also is its action on the secretion of bile, though it is certain that it does not increase it.

When absorbed into the blood, quinine causes contraction of the spleen, and in large doses lessens the contractile power and amoeboid movements of the white blood-corpuscles. It thus checks the diapedesis of the white blood-corpuscles (p. 62).

The size of the red corpuscles is increased (p. 63), but their power of giving up oxygen seems to be diminished, as is shown by the guaiacum test (p. 69).

On the Circulation. - Small and moderate doses increase the strength of the circulation, but how they act has not been ascertained.

Large doses diminish the blood-pressure, chiefly by weakening the heart, but partly by paralysing the vaso-motor centre, thus causing dilatation of the vessels. This paralysis occurs from very large doses. It is evidenced by the fact that irritation of a sensory nerve or asphyxia no longer produces contraction of the vessels and rise of blood-pressure.

The heart's action is weakened by quinine, from its action on the motor ganglia, and probably also on the muscular fibres of the heart itself.

The vagus nerve is little affected by moderate doses, but is finally paralysed by very large doses. In poisoning by quinine death generally occurs from failure of the respiration, and only occurs through cardiac paralysis if the drug be injected directly into the circulation in large doses; the animal then dies in convulsions consequent on stimulation of the nerve-centres by the venous condition of blood thus produced.

On the Respiration. - Small doses have no effect on it. Moderate doses quicken the respiratory movements, but large doses first slow, and then stop them, by paralysing the respiratory centre. The amount of oxygen taken in and of carbon dioxide exhaled is diminished. This is due to the action of the drug on tissue-change and on the red blood-corpuscles (p. 72).

On Tissue-change. - Moderate doses diminish tissue-change (p. 415) and lessen the relative amount of nitrogen and sulphates in the urine, but increase the total quantity. In fever, especially when due to septic poisoning, the temperature of a patient is lowered by quinine. It is also lowered in an animal even after section of the cord and wrapping up in cotton-wool, showing that the fall is due to the lessened tissue-change and oxidation in the body. When given in fever quinine increases the amount of nitrogen in the urine.