Salicin and Salicylic Acid
Salicinum, Salicin, C13H18O7,—is a neutral principle obtained from several species of Salix (willow) and Populus (poplar), also found in Gaultheria procumbens (wintergreen) and in Betula lenta (sweet birch), the volatile oils of which consist almost entirely of methyl salicylate. It occurs in white, silky, crystalline needles; soluble in 28 of water and in 30 of alcohol. Dose, gr. x-ʒj.
Acidum Salicylicum, Salicylic Acid, HC7H5O3,—is an organic acid, existing in various plants, but most largely prepared synthetically from carbolic acid. Occurs in fine, prismatic needles or a crystalline powder; soluble in about 450 of water and in 2 ½ of alcohol, but readily soluble in water containing 8 per cent. of borax or 10 of sodium phosphate. Dose, gr. v-ʒj.
Salicylic Acid is a derivative of Salicin, probably by double oxidation; but may also be considered as a substitution-derivative of Benzene, formed by replacing 2 atoms of its hydrogen, the one by hydroxyl, and the other by carboxyl. (See page 180, ante.) It is obtained, therefore, either synthetically by combining the elements of Carbolic Acid with those of Carbonic Acid, and subsequent purification,—or from natural Salicylates as the oils of wintergreen and sweet birch,—or from Salicin, by heating with caustic potash and treating the mass with hydrochloric acid. The acid prepared from natural sources is purer and more efficient than that prepared artificially, and will often be tolerated by a patient who cannot bear the latter.
- Sodii Salicylas, Sodium Salicylate,—soluble in ¾ of water and in 6 of alcohol, also in glycerin. Dose, gr. v-ʒj.
- Lithii Salicylas, Lithium Salicylate,—very soluble in water and in alcohol. Dose, gr. v-ʒj.
- Salol, Phenyl Salicylate,—is the salicylic ether of phenol, obtained by heating salicylic acid, the air being excluded. Warmed with an alkali Salol splits up into Salicylic Acid 60, Carbolic Acid 40. It is soluble in 10 of alcohol, nearly insoluble in water. Dose, gr. v-xv.
- Oleum Gaultheriae, Oil of Wintergreen,—consists almost entirely of methyl salicylate. Dose, ♏v-xv.
- *Salipyrin, Antipyrin Salicylate,—See under Antipyrin.
- *Salophen, Para-amidophenol Salicylate,—contains nearly 51 per cent. of Salicylic Acid. Dose, gr. v-xv, up to ʒj or jss in 24 hours.
Physiological Action. Salicin is a bitter tonic, an antipyretic, antiferment, and antiseptic, being destructive to low organisms. It prevents the reaction between amygdalin and emulsin, and that of ptyalin on starch. It seems to be devoid of toxic power on man, and is probably excreted as Salicylic and Salicyluric acids. It has some slight power as an antiperiodic.
Salicylic Acid has properties similar to the above, but acts with greater energy. In small doses it stimulates the stomach, heart and respiration, but large doses derange the stomach, causing nausea and vomiting, depress the heart and respiration, lower the arterial tension, and reduce the temperature in fever. It causes vertigo, dilated pupils, tinnitus aurium, a sensation of tension in the frontal cerebrum, delirium, and occasionally collapse, from sudden depression of the circulation. A lethal dose produces death by paralysis of the respiration. During its administration bed-sores are frequently observed, being due to the depressed state of the circulation which it induces. During its excretion it often irritates the kidneys and causes albuminuria. It colors the urine green by transmitted and brown by reflected light, and under its use the urine contains a substance which reduces copper solution—(Brunton). It is destructive to the torula, prevents alcoholic fermentation and that caused by the organic ferments (pepsin, ptyalin, etc.). In solutions containing bacteria it will prevent their development, if in the proportion of one per cent., and in that of 1 in 60 it will destroy them though in full activity.
Sodium Salicylate is remarkably antipyretic in doses of gr. xv, given 4 or 5 times in 24 hours. It is a powerful diaphoretic, and an efficient cholagogue, and it is supposed to possess the curious property of increasing the fluidity of the bile, at the same time that it promotes its secretion,—other cholagogues increasing the proportion of solids therein (Brunton). It has no antiseptic power unless with a strong mineral acid to liberate the salicylic acid.
Salol is antiseptic, antipyretic and germicide, in a higher degree than either of its constituents. As an antipyretic in fever it stands next after Antipyrin, and it acts with such force as to frequently depress the temperature a degree or two below normal. It is sedative to the cerebro-spinal system, and somewhat analgesic. It causes profuse sweating, and in a few cases considerable depression has accompanied its antipyretic employment; but it is not toxic, and may be used freely, in its proper dosage, which ranges from 5 to 60 grains, up to 2 or 3 drachms in the 24 hours.
Therapeutics. Salicin and its derivatives are chiefly used in Acute Rheumatism, to lower temperature, relieve pain, and reduce articular swelling. They are most suitable to strong, vigorous patients, and if not promptly efficient they should be abandoned. Salicylic Acid is much used as an antipyretic in fevers, especially those of the septicaemic kind. It is a useful local application to Corns and Warts, also in—
- Eczema of hands and feet.
- Fetid Pespirations,—in which it is used in solution with Borax.
- Gangrenous Wounds.
Sodium Salicylate is employed in 3 to 5-grain doses internally after meals, to arrest gastric fermentation, and to prevent acidity and flatulence. It is used instead of the acid in acute and chronic rheumatism, to relieve headaches, and for phlegmasia alba, in which it is considered very efficient,—also in cases where there is a tendency to the formation of gall-stones.
Salol is a most efficient remedy for duodenal catarrh, catarrh of the bileducts and catarrhal jaundice; also in the bilious form of sick-headache, and in some forms of neuralgia Its greatest power is manifested over acute rheumatism, in which disease many clinicians maintain that it has no superior, if given in 15 to 30-grain doses, Up to 2 drachms in the 24 hours, and continued for some time after the acute symptoms have subsided. It should prove an efficient disinfectant in catarrh of the bladder, as its constituents are excreted with the urine, and come in contact with the vesical mucous membrane for a considerable period of time.
A Compend of Materia Medica, Therapeutics, and Prescription Writing, 1902, by Sam'l O. L. Potter, M.D., M.R.C.P.L.