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cantharides, and chrysarobin ointment. Tinea versicolor never requires severe irritants.

(2) As parasiticides for itch, sulphur ointment, balsam of Peru, and storax are all effectual.

(3) Pediculi vestimentorum will be killed by any mild parasiticide. Staphisagria: 1 part of the fluidextract, 2 parts each, olive oil and lard, is often used.

(4) Pediculi capitis and pediculi pubis are also easily killed by mild parasiticides; mercurials or staphisagria are employed.

D. Antiperiodics are drugs which in diseases, which recur periodically, lessen the severity of the paroxysms or arrest their return. Some, and probably all, act as direct poisons to the micro-organism causing the disease.

They are cinchona bark, quinine and its salts (by far the most powerful), quinidine, cinchonine, cinchonidine, arsenic trioxide, eucalyptus, hydrastis, salicin and salicylic acid. They are used for all forms of malarial fever and neuralgia.

All doses of official drugs and preparations are to be understood as the "average approximate (but neither a minimum nor a maximum) dose for adults," and are given with each substance and its preparations which are employed for internal administration'

THE ANTISEPTICS

MERCURY

For the Preparations of Mercury and its Salts see p. 76.

ACTION OF MERCURY AND ITS SALTS

External. Locally the metal itself and many of its salts are inert. The action of others varies from that of a mild stimulant to the effect of a powerful irritant and escharotic. Thus, the acid solution of mercuric nitrate is strongly caustic. Mercury and its salts are readily absorbed by the skin, so that all the physiological effects of the drug can be produced by inunction. When metallic mercury, rubbed into fine globules, is applied to the integument in ointment, it passes into the gland ducts and along the roots of the hairs, and, after being oxidized, is dissolved and taken up into the tissues. It is also possible for the vapor to be absorbed by the mucous membrane of the lungs, and this pulmonary absorption of the drug is not at all uncommon when volatilized mercurial preparations are applied to

the skin. Some of these preparations, when locally applied, have considerable efficiency in allaying itching, however produced, and a large number of them (among which may be mentioned the oleate, oxide, ammoniate and corrosive chloride) are anti-parasitic, destroying the animal and vegetable parasites which infest the skin. Mercury is possessed of great germicidal power.

Lower Forms of Life.—Its germicidal potency is due to the fact that it is poisonous not only to higher, but also to lower, organisms. Whenever it comes into intimate contact with albumins, it forms an albuminate and destroys life, and therefore corrosive mercuric chloride and the other soluble salts of mercury are among the most important antiseptics at present known. It has been demonstrated that the bichloride in the strength of 1 to 50,000 destroys infusoria in about twenty minutes, and that even a solution of 1 part in 1,000,000 destroys algæ in the course of a few days. While the bacteria are somewhat more resistant than these, it is claimed that a solution of 1 to 1,000,000 will delay the development of some of them, and the anthrax bacillus, it has been found, fails to grow in blood which contains 1 part in 8000. At the same time, it is true that the germicidal power of the bichloride has been considerably over-estimated; for, while it has been commonly accepted that a strength of I to 1000 is sufficient to completely disinfect fluids within a few hours, it has been proved that anthrax spores, after having been exposed to the action of a 1 per cent. solution for many hours, are still capable of developing as soon as the antiseptic is removed. Calomel, it has been demonstrated, has some effect as an intestinal antiseptic; but, owing to the difficulty of bringing the insoluble salts into intimate contact with the microbes, they are naturally much less efficient as germicides than the soluble ones.

Internal. Mercury, unlike other metals, has, as is shown by its powerful germicidal influence, a strong specific action on protoplasm, due to its marked affinity for nitrogenous molecules. While its different salts have different external actions, yet after absorption their effects on the system are as a rule much the same. Both the local and general effects of a soluble salt, such as the bichloride, are more pronounced than those of one like calomel (which is entirely insoluble in water) since it comes into more intimate contact with the tissues, and acts more energetically locally, and is absorbed more rapidly and in larger amount. When, however, mercury in the form of calomel

has been absorbed, the general effects are the same as if an equal amount had been taken up by the tissues as the bichloride. When mercury is absorbed, it circulates in the blood in the form of an albuminate, which is insoluble in water, but is rendered soluble by excess of proteid, and, also by such quantities of sodium chloride as are met with in the tissues. It has a marked corrosive action, which is the more powerful because the precipitate formed with proteids is less insoluble in the surrounding fluids of the body, and therefore affords less protection to the surface, than those formed by the other heavy metals; so that this destructive influence extends into the deeper cells.

Absorption and Elimination.-When mercury is administered regularly for a considerable time, elimination fails to keep pace with absorption. It disappears from the blood and is then deposited, in less soluble form, in the tissues and organs, and this accumulation is especially liable to occur in certain parts of the body, like the kidneys, the intestinal walls, the liver, the spinal cord, and the medullary cavities of long bones. Absorption of the drug may take place from all surfaces, and especially from serous ones. It is excreted principally by the bowels, but also to some extent in the urine, saliva, perspiration and milk. The excretion by the kidneys, which begins in about two hours, has been noted as long as six months after its use has been discontinued. Mercury has been found in serum and in pus from ulcers.

Alimentary Tract. with in the mouth.

The first evidences of mercurialism are met The initiatory symptoms are usually a slight fetor of the breath, which is later accompanied by a disagreeable metallic taste, and tenderness of the teeth when they are forcibly brought together. These are followed by stomatitis, sponginess of the gums, swelling of the tongue, and profuse salivation. That this condition is not due to any local action of the mercury is shown by the fact that it also may occur when the drug is administered by inunction or by subcutaneous injection. The salivation is apparently due to the direct effect of the agent on the secretory apparatus, and sometimes it is the first symptom to make its appearance. If the administration be cóntinued, the quantity of saliva poured out becomes enormous; it is altered in character, contains mercury, and irritates the skin over which it flows. The fetor is excessive and the gums are intensely inflamed, being marked by a dark red line at their

junction with the teeth, and bleeding at the slightest touch. Both the parotid and submaxillary glands are enlarged and tender. The teeth become loosened in their sockets and may fall out, and excoriations caused by the irritation of the drug lead to the formation of ulcers, particularly where there are accumulations of microbes, as around carious teeth. Finally, the maxillary bones may undergo necrosis, as a result of the penetration of these ulcers, which sets up periostitis. Children under the age of three years are seldom salivated, but they are not exempt from the other untoward effects. In the stomach the action of the drug is less marked, but it may produce more or less hyperæmia, and in instances of poisoning this is accompanied by small hæmorrhages. In the small intestine also it has comparatively little effect, but in the cæcum and colon it gives rise to congestion and tumefaction of the mucous membrane, which later result in necrotic patches of considerable extent and ulcers about the folds; the appearances presented being practically identical with those met with in chronic dysentery. Perforation of the bowel may eventually occur. The intestinal inflammation is naturally accompanied by excessive purging and intense abdominal pain, with tenesmus. The stools, which are fluid in character and sometimes present a ricewater appearance, contain blood, mucus and shreds of mucous membrane. Small doses of the insoluble salts, however, usually cause loose passages without any griping or straining. They pass through the stomach undissolved, it is believed, but in the intestine, where time is afforded for the exercise of their affinity for epithelium, they become partially dissolved and produce the characteristic irritant effect of the drug. While a small proportion of such preparations is absorbed from the bowel, by far the greater part passes off unchanged in the fæces. It is possible, therefore, for very large doses of calomel to be taken without giving rise to any serious disturbance of the system. That salt, it has been found, exerts no action on the digestive ferments, but it has the effect of limiting the decomposition of food by retarding putrefaction in the intestine; its antiseptic action being aided by the removal of the decomposing mass in consequence of the increased peristalsis which it induces. After the use of calomel a diminution of the double sulphates in the urine is noted, due as much to its cathartic as to its antiseptic qualities. When calomel is administered it is likely that a small portion will be changed into the corrosive chloride, thus enhancing its antiseptic effects.

Further, it should be noted that the same transformation may take place after prolonged trituration with sugar of milk.

Liver. At the present time there is no sufficient evidence, to show that, with the exception of the corrosive chloride, which increases the biliary secretion, the liver is directly affected by mercurials. It was formerly believed that calomel and some of the other mercurial purges increase the secretion of bile. This was suggested by the spinachgreen color of the stools after the administration of calomel, but the latter is due to the circumstance that the bile is prevented by this drug from decomposition in the intestine. Mercury acts in the bowel even when the bile is suppressed, and the greenish color of the stools is due to bile pigment. Commonly this is decomposed by the microbes in the intestine, with the formation of the fæcal pigment, but mercury prevents, by its antiseptic properties, the growth of the microbes, and the bile therefore appears in the stools undecomposed and having its ordinary color. It is true that so-called “biliousness" is very frequently relieved by mercurials, but this is readily explained by the fact that the condition thus designated is one not dependent upon the liver, but a disorder of the alimentary tract. Where the good effects of mercury were supposed to be due to its power to increase the flow of bile, equally satisfactory results may be obtained by the use of other remedies not regarded as cholagogues. At the same time, it is true, as mentioned, that the corrosive chloride does actually have some effect in increasing the amount of bile, and it may possibly be the fact that occasionally when calomel is administered, some of it, owing to the presence of special conditions, is converted into that salt.

Kidneys.-Mercury in the form of calomel has but a comparatively feeble influence on the kidneys. When dropsy due to cardiac disease is present, however, it has been found that a moderate dose of calomel induces marked diuresis. In the accumulations of fluid resulting from cirrhosis of the liver and from renal disease its action in this respect is less constant, but may be sometimes pronounced. While the question has not been definitely determined, it seems probable that, since calomel and other salts of mercury are known to have an irritant effect upon the kidneys, the diuresis produced by them is due to their direct action upon the renal epithelium. Calomel probably produces its beneficial effects more from the catharsis which it excites than from its action on the kidneys. Mercuric chloride, on

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