Calomel

КАЛОМЕЛЬ (Hydrargyrum chloratum, mercurous chloride, Hg₂Cl₂), Calomel. There are three grades of calomel on the market: 1. Hydrarg. chlorat. mite, s. levigatum - a product of sublimation of corrosive sublimate with mercury, a finest crystalline white or slightly yellowish powder, very slowly decomposing in light. 2. Hydrarg. chlorat. vapofe paratum, obtained by cooling the vapors of K. in a stream of steam or cold air, a finest amorphous, completely white powder, yellowing upon strong rubbing. 3. Hydrarg. chlorat. praecipitatum, s. via humida paratum, prepared by precipitation from a solution of mercury salt, a finest amorphous white powder. The first two preparations are official in the USSR (FS VII).-K. is insoluble in water, alcohol, and ether. Upon introduction per os, K. passes through the stomach unchanged, and in the intestine only a very small part of it turns into soluble compounds, apparently mercury albuminates (Meyer-Gottlieb), and, acting on the mucous membrane of the intestine, excites its peristalsis, and also significantly increases the secretion of fluid from the intestinal glands, without inhibiting enzymatic processes (Savich). At the same time, under the influence of K., there is a delay in the absorption of fluid by the intestine, which leads to a strong thinning of the intestinal contents and, together with the strengthening of peristalsis, causes a significantly more rapid movement of intestinal masses through the small and large intestines, the result of which is a laxative action. A significantly larger part of the introduced K. remains in the intestines unchanged and is excreted in this form with the feces, which is why, upon taking «3 even large doses, mercury poisoning does not occur. However, if K., for some reason, does not cause laxation and is retained in the intestine, it can be absorbed in an amount capable of causing symptoms of mercury poisoning (colitis, nephritis, etc.). Besides its laxative action, K. exerts an antiseptic action on the contents of the intestine, which is confirmed by the absence in the feces after K. of indole, one of the products of putrefaction, and the fecal odor caused by it, as well as a decrease in ether-sulfuric acids. However, some authors, due to the insignificant amount of K. turning into a soluble state in the intestine, see the main cause of its disinfecting action in the rapid and complete emptying of the intestine (Cushny). Feces after K. are colored greenish, which was previously explained by the presence in them of undestroyed bile pigments due to the suppression by K. of fermentation processes, but since even in the absence of bile in the intestines the feces have the same characteristic color, most authors attribute the latter to the formation of mercury sulfide compounds. There is an opinion that upon introduction of K. per os it can also exert a choleretic action, probably not direct, but indirect, connected with its laxative effect, assisting the excretion of bile into the intestine. Finally, upon oral intake, K. can increase urination, especially in the presence of edemas (see Diuretics). Absorbed K. is excreted with the urine, and although the amount excreted is insignificant, it can exert a harmful irritating action on diseased kidneys, which is why in such cases the administration of K. is contraindicated.-Local application of calomel is mainly in ophthalmic practice, based also on the fact that a certain part of it gradually turns into a soluble state, exerting an antiseptic and weak local irritating action.-Being one of the mercury compounds, K. finds application also as a specific agent in syphilis both for local action, e.g. in syphilitic papules and condylomas, and for general action in the form of per os intake or intramuscular injections. Such application of K. has the disadvantage that upon intake it is absorbed only partially and can easily cause digestive disorders. Upon intramuscular injection, absorption occurs very unevenly, and the possibility of retention of K. in tissues with subsequent symptoms of subacute mercury poisoning is not excluded if intensified absorption of the formed reserve begins. In all cases of application of K., even external, e.g. on the mucous membrane of the eye, it is impossible to simultaneously administer iodine preparations, since at this very point very acrid mercuric iodide can be formed; it is also necessary to avoid simultaneous administration of acids and sodium chloride or the use of salty and sour dishes, since they can enhance the absorption of calomel. Preparations. 1. Hydrarg. chloratum mite (FS VII) - per os as a laxative and intestinal disinfectant, especially at the beginning of acute infectious diseases, intestinal and general, 0.3-0.5-0.6 (1) pro dosi, 1.8 (!) pro die, for children from 1 year to 5 years 0.02-0.15 pro dosi; for children up to 1 year it is now rarely prescribed; as a diuretic in dropsies on the basis of heart and liver diseases 0.2 three or four times a day; as a choleretic in gallstones, biliary colic, beginning cirrhosis of the liver 0.06 every 1-2 hours until the appearance of characteristic green feces; in the treatment of syphilis 0.025-0.05 for adults; 0.0005-0.01 for children 2-3 times a day or in the form of intramuscular injections (for adults) in an oily solution (1:10) 0.1 once a week, a total of 4-6 injections. 2. Hydrarg. chlorat. vapore paratum (FS VII) - per os, as the previous preparation, but usually in somewhat smaller doses, because as a finer powder it acts more strongly; externally - in gonorrheal conjunctivitis, opacity of the cornea, herpes corneae, etc.; as a powder in moist syphilitic papules and condylomas. 3. Calomelol, Hydr. chloratum colloidale (Hygrolum), colloidal mercurous chloride, a grayish powder giving a colloid milky solution with water (1:50), alcohol, and ether; also dissolves in weak salt solutions and in blood serum; contains 75% mercurous chloride and 25% protein; acts faster than K., but is less toxic. Per os as a laxative instead of K. and in syphilis between courses of specific treatment 0.01-0.03 three times a day; as a powder or in a 2% solution (wet dressing) in syphilitic ulcers; as a 30% mercurial ointment 4.0-6.0.