Single doses of mercury or its compounds have no action upon the mouth, the characteristic salivation being produced only after many doses. Their typical action on the bowel is purgative, the effect varying with the state of the mercury. So relatively inert is metallic mercury that a pound of it has been given without ill effects in cases of intestinal obstruction, which it was hoped to relieve by the mere weight of the metal. Half a grain of the perchloride, on the other hand, is a highly toxic dose. The action of mercurials on the bowel is mostly exerted on the duodenum and jejunum, though the lower part of the bowel is slightly affected. Hence a dose of mercury usually needs a saline aperient to complete its action, as in the "blue pill and black draught" of former days. Mercurials do not cause, in therapeutic doses, much increase in the intestinal secretion, the action being mainly exerted on the muscular wall of the bowel. The bile is rapidly removed from the duodenum, before any re-absorption can occur, and the bacterial action which decomposes the bile-pigment is arrested by the antiseptic power of the drug, so that the excreta are of a very dark colour. The classical experiments of William Ruther ford (1839-1899), of Edinburgh, showed that calomel does not increase the amount of bile formed by the liver. Corrosive sub limate does, however, stimulate the liver to a slight degree. In large doses mercurials somewhat diminish the secretion of bile. The greater part of the mercury administered by the mouth, in whatever form, is excreted as mercuric sulphide. Prior to this decomposition the mercury exists as a complex soluble compound with sodium, chlorine and albumen. When perchloride of mer cury is injected subcutaneously the sodium chloride in the blood similarly prevents the precipitation of the albuminate of mer cury, and it is therefore desirable to add a little sodium chloride to the solution for injection of mercuric chloride.
Mercury is largely used in affections of the alimentary canal, and has an obscure but unquestionable value in many cases of heart-disease and arterial degeneration. But its value in syphilis (see VENEREAL DISEASES) far outweighs all its other uses.
Toxicology.—Acute poisoning by mercurials usually occurs in the case of corrosive sublimate. There is intense gastrointestinal inflammation, with vomiting, frequent "rice-water" stools and extreme collapse. The treatment, except when the case is seen at once, is very difficult, but white-of-egg or other form of albumin is the antidote, forming an insoluble compound with the per chloride.
Chronic poisoning (hydrargyrism or mercurialism) is of great importance, since any indication of its symptoms must be closely watched for in patients who are under mercurial treatment.
Usually the first symptom is slight tenderness of the teeth whilst eating, and some foetor of the breath. These symptoms become more marked and the gums become the seat of severe inflamma tion, being spongy, vascular and prone to bleed. The salivary glands are swollen and tender, and the saliva pours from the mouth, and may amount to pints in the course of a day. The teeth become quite loose and may fall out. The symptoms are aggravated until the tongue and mouth ulcerate, the jaw-bone necroses, haemorrhages occur in various parts of the body, and the patient dies of anaemia, septic inflammation or exhaustion. The treatment consists, besides stopping the intake of poison and relieving the symptoms, in the administration of potassium iodide in small, often repeated doses.
Mercuro Zinc Cyanide, (Lister's antiseptic), was suggested in the early days of antiseptics (1886) by W. Martin dale. In the form of "cyanide gauze" and "cyanide wool," this dressing has been largely used, both in general surgery and for the requirements of war.
Mercurochrome "220" (di-sodium hydro-oxy-mercury dibromo fluorescein) has been advocated through the work of various authorities in the United States for a variety of affections. This compound has an English equivalent mercurome, which is identical chemically. The drug is deemed of very great service as an antiseptic for vesical injections in cystitis, pyelitis, etc., and as a skin antiseptic it is highly recommended. Considerable strides have been made with the intravenous injection of this compound, e.g., in puerperal fever, typhoid and grave bacterial infections in general, and it has been suggested for use intravenously in plague. As the limits of dosage are not as yet completely determined, mercurochrome is to be used with caution. At the same time, the remarkable fact remains that this compound, containing approxi mately 23% of mercury in a non-ionised form has been injected in the massive dose of 3 grains (0.2 gram) in contrast with an ordinary intravenous dose of mercuric chloride of about to grain (o•ooi to 0.002 gram).