Iodid of Mercury.—This salt occurs in two forms: Red Iodid or Biniodid (Hydrargyri Iodidum Rubrum) and Yellow or Green Iodid (Hydrargyri Iodidum Flavum). The first is an irritating preparation, somewhat resembling corrosive sublimate in its action; the latter is comparatively unirritating, and is much used internally as an alterative. The dose of the red iodid is from ¹/₆₀ to ¹/₁₂ grain (0.001-0.005 gm.); of the yellow or green iodid, ¹/₁₀ to ½ grain (0.006-0.03 gm.).
Nitrate of Mercury.—This preparation is used in the form of a solution (Liquor Hydrargyri Nitratis) as a powerful caustic.
Ointment of Mercury, or Blue Ointment (Unguentum Hydrargyri).—This is an ointment of metallic mercury. It is used as a stimulant and absorbent application in chronic inflammatory swellings, as a parasiticide in certain skin diseases, and by inunction in syphilis. When used for the latter purpose about a dram (4 gm.) should be rubbed in the axilla, groin, or inner surface of the arm or thigh daily, a different region being selected each time, so as to avoid irritation of the skin.
Mercurial Poisoning.—Patients taking mercury continuously, even in small doses, should be carefully watched, as symptoms of ptyalism or salivation sometimes arise very speedily. This condition is manifested by fetor of the breath, soreness of the teeth when the jaws are brought together, increased flow of saliva, redness and swelling of the gums, and finally by ulceration of the tissues, loss of the teeth, and necrosis of the jaw bones. On the slightest evidence of these symptoms the drug should be suspended, and the mouth washed out frequently with a solution of hydrogen peroxid (1 : 4) or of potassium chlorate (1 dram to 8 ounces of water).
The ingestion of a single large dose of an irritant salt of mercury, such as the bichlorid or biniodid, gives rise to severe burning pain in the abdomen, vomiting, bloody purging, and collapse.
Nitroglycerin.—This drug is a depressant to the central nervous system, a heart stimulant, and a dilator of the peripheral blood-vessels. It is useful in certain local spasms (asthma), in heart failure, and in neuralgia of the heart. Owing to its action in dilating the vessels, it sometimes causes, even in small doses, headache, dizziness, and flushing of the face.
The dose of nitroglycerin is from ¹/₂₀₀ to ¹/₅₀ of a grain (0.0003-0.0013 gm.). The dose of the 1 per cent. alcoholic solution (Spiritus Glonoini) is from 1 to 5 minims (0.06-0.3 c.c.). The latter should be kept in well-stoppered bottles, in a cool place, remote from lights or fire.
Nux Vomica.—This is the seed of an East Indian tree. Its activity depends upon an alkaloid strychnin. It is a general stimulant, acting especially upon the spinal cord, respiratory center, heart, stomach, and intestine. It is employed in a great variety of affections in which there is deficient functional activity.
The limit of tolerance is indicated by restlessness, stiffness of the neck muscles, and jerking of the limbs. Toxic doses cause violent spasms closely resembling those of lock-jaw or tetanus. The convulsions of strychnin-poisoning, however, come and go, the muscles being completely relaxed in the intervals, and, moreover, they rarely involve the muscles of the jaw.
The dose of the Tincture of Nux Vomica (Tinctura Nucis Vomicæ) is from 5 to 20 minims (0.3-1.2 c.c.); of the Extract of Nux Vomica (Extractum Nucis Vomicæ), ⅙ to ¼ grain (0.01-0.016 gm.); of Strychnin Sulphate (Strychninæ Sulphas), ¹/₆₀ to ¹/₂₀ of a grain (0.001-0.003 gm.).