Formula

ZnCl2.

Derivation

Chloride of Zinc is obtained by the action of hydrochloric acid on granulated zinc, the solution thus made being purified by a solution of chlorine and carbonate of zinc when it is evaporated till it assumes a solid form. It is in the form of a white deliquescent salt, freely soluble in water, alcohol and ether, as soft as wax and capable of being melted and sublimed by heat. As it rapidly deliquesces when exposed to the air, it should be kept in glass-stoppered bottles. It has a styptic, metallic taste, which is very disagreeable.

Medical Properties And Action

Chloride of zinc is the most active of the zinc preparations, being a powerful and penetrating escharotic. Its local action as a caustic depends upon its affinity for albumen and gelatin, and when in contact with living parts it destroys their vitality, and uniting with the albuminous and gelatinous matters present, forms an eschar. It is also a useful antiseptic, deodorizer and disinfectant, and largely diluted has been employed as a nervine tonic ; but as the milder preparations of zinc answer the same purpose, it is rarely employed internally. On account of the great affinity for water and its power of combination with albumen, chloride of zinc penetrates and spreads deeply, and produces an eschar which is white, thick and hard. When applied to malignant and indolent ulcers, it promotes healthy granulations, and also when topically applied it not only destroys the diseased structure, but excites a new and healthy action in the surrounding parts. When employed as a caustic, it does not give rise to constitutional disorder from absorption, an effect which is sometimes caused by arsenical preparations. In over-doses it causes a burning pain in the throat and stomach, nausea, vomiting, cold sweats, decrease of pulse, cramps of the limbs, etc., being a powerful irritant poison. The antidotes in poisoning by zinc salts are albumen, carbonate of soda, magnesia and soap.

Therapeutic Uses

Chloride of zinc has been employed internally in chorea, epilepsy, neuralgia, scrofula, and combined with hydrocyanic acid, in facial neuralgia. Externally it is applied to malignant growths, gonorrhoea, indolent ulcers, etc. A solution of the chloride of zinc is used as an antiseptic and disinfectant.

Liquor Zinci Chloridi - Solution of Chloride of Zinc - known as " Burnett's Disinfecting Fluid," is composed of chloride of zinc, gr. cc, water, Therapeutic Uses 1488

Dose

Of chloride of zinc, gr. ss or gr. j, or gr. ij, largely diluted.

Dental Uses

Chloride of zinc is a valuable agent in dental practice, being employed as an external application to sensitive dentine. As an obtunding agent, a drop of the deliquescent chloride is placed in contact with the sensitive dentinal surface (which has previously been dried and is protected from all moisture), and allowed to remain from two to four minutes. Considerable pain follows the application of the chloride, which is of a steady continuous character, without the throbbing nature which characterizes the pain of an irritated dental pulp. Its painful action may be modified by bathing the sensitive surface, prior to the application of the chloride, with chloroform, tincture of aconite or atropine solution, or a combination made. When the pain has subsided, the excavation of the cavity can be pro-ceded with until the layer of dentine affected by the chloride has been removed, when another application may be necessary. As it is not absorbed by the dentine to any great degree, its action being superficial, it is not so dangerous an agent as is arsenious acid when employed for the same purpose.

In no case should the chloride of zinc be used as an obtunding agent, when there is danger of irritating the pulp of the tooth.

Chloride of zinc is also employed to arrest superficial hemorrhage from a wound of the gum during the filling of teeth; it will also temporarily arrest the secretion of mucus from the surface of the mucous membrane of the mouth. When applied to a cut surface, diluted, it induces union by first intention, by its effect upon the glutinous matter.

It has also been successfully employed as an injection for chronic alveolar abscesses, and in the treatment of ulceration of the gums attended with recession of gum and absorption of process from the necks of teeth; also as an injection in disease of the antrum. It has been claimed that its application in a diluted form will promote the formation of secondary dentine over a nearly exposed pulp, but its escharotic action must be considered in using the agent for such a purpose. When applied to the sulcus which often forms during ulceration and recession of the gum from the neck of a tooth, the application can be safely and conveniently made by means of a camel's-hair brush, or by a piece of orange wood so shaped as to permit of its being introduced to the bottom of such a sulcus.

Chloride of zinc is also employed as a stimulating astringent in alveolar pyorrhoea in the form of a solution of five to ten grains to the ounce of water. Chloride of zinc in a properly diluted form is an efficient disinfectant, and has been employed for such a purpose in gangrenous conditions of the mouth.

Chloride of zinc is one of the ingredients of the temporary filling material composed of the chloride of zinc in solution and the oxide of zinc, which has been employed to cap the exposed pulps of teeth. But owing to the escharotic action of the chloride this method has not been uniformly successful. The zinc preparations, however, answer good purposes as temporary filling materials, especially in sensitive cavities where the presence of metallic fillings would not be tolerated. (See Oxide of Zinc.)

Dental Formula

For Inflamed Gums and Mucous Membrane.

Dr. W. S. Elliott.

Zinci chloridum...............grs. x

Acidi carbolici................gtts. xx

Glycerini...................

Aquae....................

Dental Formula 1489Dental Formula 1490

Sulpho-carholate of zinc has to a great extent replaced the chloride of zinc as an antiseptic, as it is less toxic and irritating and much more potent.