Origin

Subnitrate of bismuth is prepared by dissolving the metal in nitric acid, and pouring the resulting solution into water. Two salts are formed; one a supernitrate, with great excess of acid, which remains dissolved, the other a subnitrate, which is thrown down. The latter is the preparation in question.

Properties

It is a heavy, white powder, without smell or taste, very slightly soluble in water, but readily dissolved by nitric acid. It becomes grayish on exposure to the air, and blackens under the influence of sulphuretted hydrogen. It has been ascertained by Prof. R. E. Rogers, of Philadelphia, that subnitrate of bismuth, as found in the shops, often contains arsenic; and, though this is in small proportion, the fact is sufficient to put the physician upon his guard against prescribing large doses of the medicine, unless assured of its perfect freedom from that poisonous ingredient.*

Lactate of Zinc has been recommended by M. Herpin in epilepsy, as a substitute for the oxide, to which it is preferable on account of its solubility, more ready entrance into the circulation, and greater uniformity of action. The dose is two grains thrice daily, to be increased as the stomach is found to bear it.

* Besides the preparations above mentioned, several others have been employed.

Iodide of Zinc has been recommended as peculiarly useful in cases of chorea, connected with a scrofulous taint. From two to five grains may be given three times a day; but, as the salt is deliquescent, it is best kept and administered in the form of syrup.

Phosphateof Zinc has been used in epilepsy, by Dr. Barnes, of London, under the impression that in this disease, which especially affects the brain, there might be a demand for phosphorus to supply the cerebral waste. He has employed it, with the like object, in other affections attended with exhaustion of the brain. He directs four grains, three times a day, to be given with dilute phosphoric acid, which is its proper solvent

Effects on the System

Ordinarily, when given internally, the oxide produces little observable effect; and very large quantities have been exhibited with perfect impunity. These facts might lead to the suspicion that former observers were mistaken in ascribing active irritant properties to the medicine. But the apparent discrepancy is explained by reference to the very feeble solubility of the salt in water, and to its ready solubility in some of the acids. Whether, therefore, it shall prove nearly inert, or powerfully irritant, may depend on the absence or presence of an acid in the primae viae, capable of dissolving it. An instance of death is recorded, which resulted from swallowing two drachms of the subnitrate with a little cream of tartar. It produced the ordinary symptoms of inflammation of the mucous membrane of the stomach and bowels, as pain, vomiting, purging, swollen abdomen, hiccough, etc.; and, besides these, cramps and coldness in the limbs, intermittent pulse, laborious breathing, swelling of the hands and face, suppression of urine, salivation, and delirium. Some of these symptoms were clearly the result of the absorption of the medicine. The patient, who was a man, died on the ninth day. Dissection showed marks of inflammation and gangrene throughout the alimentary canal. (Christison on Poisons.) It is quite possible that the accompaniment of bitartrate of potassa may have had some influence in the result, by rendering the salt of bismuth more soluble. Bismuth has not been detected in the urine of persons using it. The effects of the medicine on the system are quite equivocal; but it may probably be ranked with the metallic tonics of the present section more safely than elsewhere.

Therapeutic Application

Subnitrate of bismuth was introduced into medicine by Dr. Odier, of Geneva. It has been supposed to have a peculiar influence over painful affections of the stomach, either directly blunting the sensibility of the nervous tissue of the organ, or operating through the nervous centres. It has been more especially recommended in gastralgia, gastric spasm, cardialgia. and pyrosis; and has been found also to allay nausea and vomiting. At a comparatively recent period, it has been very much employed in different forms of diarrhoea, with great assorted advantage. It is not impossible that the small portion dissolved may operate as an astringent; but it is not in this way that the extraordinary effects claimed for it can be explained. Perhaps, as suggested by M. Monneret, it may act by deposition upon the inner surface of the membrane, and the protection thus given against the irritant action of the contents of the primae viae. Hence, it is recommended by that practitioner in very large quantities, not less than two or three drachms in a day. It has been specially recommended as extraordinarily efficient in the diarrhoea of phthisis, that of enteric or typhoid fever, and the chronic diarrhoea of children. I can say little of the remedy from my own experience. Having almost constantly failed with it in the gastric affections in which it was originally recommended, I have long ceased to employ it. The dose, as formerly given was too small. From five to twenty grains may probably be administered with safety, under any ordinary circumstances, to the adult. Cream is said to be an excellent excipient. The caution should be strictly observed, not to accompany its use with that of nitric acid, or indeed any other acid. Dr. Rodolfo Rodolfi, of Brescia, in Italy, has met with much success in arresting the night-sweats, and diminishing the exhausting expectoration in phthisis, from the administration, every two hours, of about two grains of the subnitrate, with the same quantity of sulphur, and about seven grains of bicarbonate of soda. In four or five days, the colliquative sweats are arrested or materially diminished; and in fifteen or twenty days, the expectoration is less copious and easier, and the patient altogether improved. (Journ. de Pharm. et de Chim., Juin, 1866, p. 468.) Topically, the subnitrate has been used, with great asserted benefit, as an injection in gonorrhoea and leucorrhoea, and as an application to scrofulous ulcers. For these purposes, it is either sprinkled on the diseased surface, or applied mixed with water, in the proportion of one part of the powder to six or seven of the vehicle. The subnitrate has also been used advantageously by Dr. W. R. Hamilton, of Illinois, in protecting the skin against pitting from the small-pox eruption. He first lubricated the face and hands well with olive oil, and then sprinkled the powder over the surface; and repeated the application twice daily. (Am. Journ. of Med. Sci., Oct. 1865, p. 563.) The subnitrate. sprinkled in fine powder on the surface of suppurating wounds and putrescent ulcers, not only promotes suppuration, but is asserted by Riemslach to act also powerfully as a disinfectant, completely destroying the offensive odour. (Journ. de Pharm. et de Chim., 3e ser., xliii. 224)..

For further particulars in reference to the iodide and lactate of zinc, see the U. S. Dispensatory, and, in reference to the phosphate, the London Lancet, Am. ed., i. 343. (Note to the second edition).

* The presence of arsenic may be detected by treating, by means of Marsh's apparatus, a solution made by boiling the subnitrate with an equal weight of potassa in five times its weight of water, filtering, and saturating with sulphuric acid. (Note to the second edition).