Cinchona Alkaloids.

Related entry: Cinchona,—Peruvian Bark

Quinine, Quinidine, Cinchonine and Cinchonidine; and of these the chief, the king of antizymotic, antipyretic, antiperiodic agents, is Quinine, which has already been described on page 64. The composition of Quinine is represented by the formula C₂₀H₂₄N₂O2; it is soluble in about 1670 parts of water and in 6 of alcohol at 59° F.; but it is rarely employed in its uncombined form, its various salts being much more soluble. The salt generally employed is the Sulphate, but the Bisulphate, Hydrobromate and others, are frequently used. The Carbamide Hydrochlorate is the most soluble and the least irritating of its salts, and therefore the best one for hypodermic administration.

Substitutes for Quinine.

The synthetical production of Quinine has been the "philosopher's stone" of the modern chemists, who have prosecuted with untiring energy the search for an artificial product possessing all its properties. In this search they have discovered several organic bodies, which closely resemble each other and also quinine, both in chemical constitution and physiological action. These substances belong to the aromatic series of carbon compounds, all of which are derivatives of Benzene or Benzol, C₆H6, the Hydride of the organic radical Phenyl, C₆H5. The distinctive action of the lower members of this series is their antiseptic and antipyretic powers,—as that of the fatty series of carbon compounds is stimulant and anaesthetic (Brunton). Many of these agents are obtained from coal-tar oil (petroleum) by fractional distillation, etc.,—and they are all derivatives of Benzene (Benzol), either directly or from some of the products formed therefrom by substitution; various radicals replacing the different constitutent atoms of H and C.

Thus, by the ring-arrangement of atoms peculiar to this series, there are formed from Benzene, (C₆H6), the following substances, viz.:—

Phenol, or Carbolic Acid, C₆H₅OH-by replacing H by OH, (hydroxyl).

Pyrocatechin, or Ortho-di-hydroxy-benzene, C₆H4(OH)2—by replacing 2H by 2OH.

Resorcin, or Meta-di-hydroxy-benzene, C₆H4(OH)2—by replacing 2H by 2OH.

Hydroquinone, or Para-di-hydroxy-benzene C₆H4(OH)2—by replacing 2H by 2OH.

Pyrogallol, Pyrogallic Acid, Tri-hydroxybenzene C₆H₃(OH)₃,—3H by 3OH.

Amido-benzene, or Anilin, C₆H5.NH2—by replacing H by NH2 (amidogen).

Nitro-benzene, C₆H5.NO2—by replacing H by NO₂ (nitroxyl).

Benzoic Acid, C₆H5CO.OH—by replacing H by CO.OH (carboxyl).

Salicylic Acid, HC₇H₅O3—by replacing 2H by OH and CO.OH.

Naphtaline, C₁₀H8—by uniting two Benzenes in an overlapping ring.

Pyridin, C₅H5N—by replacing tetrad C by triad N.

Chinolin, C9H7N—uniting Benzene (C₆H6) and Pyridin (C₅H5N).

Derived from Chinolin is the hypothetical base

Chinicin or Quinicin, C9H9N2,—represented in Antipyrin.

Also Kairin, Thallin, and other compounds.

The members of the Chinolin series of compounds destroy life either by exhaustive convulsions or gradual paralysis of the respiratory centre,—the lower ones acting chiefly on the sensory centres of the brain and reflex centres of the cord, destroying voluntary and reflex movement; while the higher ones act principally on the motor centres, first as irritants, causing violent convulsions, and afterwards producing paralysis (Brunton).

A Compend of Materia Medica, Therapeutics, and Prescription Writing, 1902, by Sam'l O. L. Potter, M.D., M.R.C.P.L.