Formula

Hc7h5o3.

Derivation

Salicylic Acid is obtained by combining carbolic acid with caustic soda, and subjecting this compound to dry carbonic acid under the influence of heat, the portion of salicylate of sodium remaining behind after the carbolic acid distills over being saturated, in the form of a hot, aqueous solution, with muriatic acid, which liberates the salicylic acid in small crystals. The crystals are washed, dissolved in hot water, and by re-crystallization, obtained in the form of a powder of a light brown color, which is then bleached until it is quite white; but most of that sold is of a light cream-color with a reddish tinge. The coloring matter, however, which is present, does not interfere with its efficacy. It is sometimes obtained from the product of plants, such as wintergreen. It has no smell, a slight taste, and is soluble in alcohol and ether and in hot water and glycerine. It can also be obtained from salicin, the vegetable principle existing in willow, poplar, etc., and from oil of gaultheria (wintergreen) and from spiraea ulmariae (meadow sweet).

Medical Properties And Physiological Action

Salicvlic acid is a powerful antiseptic, and is said to be as effective in small quantities as any other antiseptic, in arresting putrefactive and fermentative processes. When properly reduced in strength it causes no pain or irritation in the parts to which it is applied. It will destroy minute organisms, and a small quantity will arrest vinous fermentation and prevent the decomposition of animal fluids. Although free from any poisonous action when administered in a reasonable quantity, yet in large doses it will cause nausea and vomiting. It is thought to combine with the soda of the blood, where it is present as a salicylate. It has little or no affinity for cold water; but the addition of certain alkaline salts, such as sodium phosphate, increases its solubility. Combined with sulphite of sodium, which is also antiseptic, and water, a solution is formed which is free from irritating properties and especially applicable to the treatment of zymotic diseases. Glycerine warmed will dissolve 1/50 its weight of salicylic acid, and the solution may then be diluted with water to any desirable extent.

Therapeutic Uses

It is employed in fevers as an antipyretic or febrifuge; also for the same purpose in acute rheumatism, pneumonia, phthisis, diphtheria, etc. Externally it is employed as a disinfectant and deodorizer, many preferring it, on account of its freedom from odor, to carbolic acid. It is also employed as a local application in eczema of the head and face, syphilitic ulcers, and to cancer, gangrenous and sloughing wounds, in the form of powder, and as an ointment for burns.

Salipyrine

Prof. Dr. von Hosengeil (Bonn, Germany) claims that the action of antipyrine in such cases of influenza which show no rise of temperature is that of a cardiac poison. Salicyl and quinine have also such action. By combining salicylic acid and antipyrine he claims to have found a preparation which he names salipyrine, which has proven itself to be a most excellent specific anti-influenzic remedy in just such cases. The dose he employs is from 15 to 30 grains.

Dose

Of salicylic acid, gr. x to gr. xx or xxx.

Dental Uses

Salicylic acid is employed in the treatment of suppurating and gangrenous pulps of teeth, in the form of the dry powder introduced into the pulp canals and permitted to remain for several days. An ethereal solution of salicylic acid, introduced on a small piece of punk, has also been employed for the same purpose, where it is difficult to introduce the dry powder; the ether volatilizes in a few minutes. Salicylic acid is also employed with advantage in inflamed conditions of the mucous membrane of the mouth and gums, and in the treatment of aphthae, thrush and other ulcers, in the form of a solution. For such purposes its combination with powdered cassia or cinnamon, equal parts, is recommended, to be applied with a soft brush. Salicylic acid has also been found efficacious in all inflammatory conditions resulting from decayed and dead teeth and roots. It has also been recommended as a dentifrice, in the form of an alcoholic solution of the acid perfumed with oil of gaultheria; but its use for such a purpose is questioned, on account of its softening effect upon the tooth structure. As tannic acid interferes with the action of salicylic acid, these agents should not be used in combination.

Dental Formulae

A Disinfectant Month Wash.

Acidi salicylici . . 1 part Sodii phosphas . . 3 parts Aquae destillatae . 30 parts. M. Signa. - Use as a gargle.

A Disinfectant and Stimulant Mouth Wash.

Acidi salicylici .... Spiriti vini rectificati . Signa. - Use as a gargle.

For Perspiration of Hands and Feet. Acidi salicylici . 3 parts Magnesii silicat . 87 parts. M.

Signa

Use in the form of a powder.

An Emollient and Antiseptic Gargle.

Acidi salicylici . . . Sodii boratis ....

Glycerini.....

Aquae destillatae . .

Signa

Add 1 or 2 drachms to half a pint of warm water.

For Warts.

Unna.

Acidi salicylici ....

Creasoti.......

Cerae, or Adipis . . . . aa q.s. to make a firm ointment that will adhere to the skin.

For Burns.

Acidi salicylici . . . Olei Olivae .... Signa. - Apply as a lotion.

For Alveolar Pyorrhaea.

Acidi salicylici . . .

Eucalyptol.....

Signa

Apply to pockets by means of cotton or a broach.

Antiseptic solution.

Thiersch.

Acidi salicylici............... 4 parts

Acidi borici................ 12 parts

Water..................1000 parts. M.

Useful as an antiseptic wash and especially during treatment of fractures of maxillae.