This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
Argenti Iodidum. Silver Iodide. AgI=234.19.
From Silver Nitrate and Potassium Iodide, washing and drying the precipitate. AgNo3+ K1=AgI+Kno3.
Dose, 1/4 to 1 gr.; .015 to .06 gm.
The action of silver salts is very like that of lead salts, but they are more powerful. Therefore silver nitrate is much used as a caustic, but it does not act deeply; it is consequently an admirable agent when we wish a limited caustic action on any particular part. Lotions of it may be used as astringents, but they are not so useful as lead lotions, for they are more irritating and cause pain. Silver salts, like lead salts, are haemostatic, acting in precisely the same way. Weak solutions of the nitrate stimulate to healthier action indolent ulcers and other inflamed surfaces.
Silver salts, when locally applied to the mucous membrane of the mouth, act as upon the abraded skin. In the stomach the nitrate is decomposed; we do not know what compound is formed, but it is said to have no astringent action. Silver is absorbed from the alimentary tract, for its long-continued use leads to a bluish-slate color of the skin (argyria). This color is due to the deposition of minute granules of metallic silver. Very little is known about its further action. In acute poisoning severe vomiting and nervous symptoms, as convulsions, are met with; in the chronic form, seen more often when silver was frequently prescribed internally, is shown by paralysis like that due to lead, albuminuria, and the discoloration above mentioned. Some is passed in the faeces as the sulphide; some is deposited in the internal organs, especially the kidney.
Silver nitrate is much used because it is, from its limited action, one of the best caustics, and may be employed to destroy warts and exuberant granulations, or to apply to bites; but it must be remembered that it is of no use when an extensive or deep action is required. Silver nitrate is a dangerous caustic to employ in deep bites, for the pellicle of silver albuminate retains the poison in the wound. Because of its combination of an irritant stimulating effect with an astringent influence, lotions of it, of generally about 5 gr.; .30 gm. to the fluid ounce; 30. c.c. of water are of much benefit when applied as a paint to weak ulcers, to bedsores, to the affected parts in chronic pharyngitis or laryngitis, or as an injection in gleet or inflammation of the cervix uteri. An useful injection in gonorrhoea is silver caseinate (Argonin, not official) in 1.5 per cent. solution which causes the speedy disappearance of gonococci, but since this is not astringent, other remedies must be employed to relieve the inflammation. Silver lactate (Actol, not official) is used as an antiseptic in sore throat, gonorrhoea, etc., in a 2 per cent. solution. Silver citrate (Itrol, not official) in 1 to 4000 solution is employed for the same purpose. Weaker solutions (1 to 240) are employed for granular lids and various forms of ophthalmia. Ophthalmia neonatorum is best treated by early applications of a 1 per cent. aqueous solution of silver nitrate. This is commonly known as Crede's method, but the original formula as prescribed by him was double this strength. Solutions of the nitrate will sometimes relieve pruritus, and may be applied to the red skin of a threatening bedsore; very strong solutions have been recommended as a local application in erysipelas. Tinea tarsi is often treated by the application of solid silver nitrate, and ulcers of the mouth and other parts may be touched with it. It is an excellent haemostatic for leech-bites. It is also applied to smallpox vesicles to prevent pitting, to boils, and to the uterus in chronic cervical catarrh. Protargol not official, a proteid compound containing 8 per cent. of silver easily soluble in water, is used as an injection for gonorrhoea. The usual strength is 1 per cent. Argentamine (not official) a 10 per cent. solution of silver nitrate in a 10 per cent. solution of ethylen-diamine has been used in gonorrhoea and conjunctivitis in a 1 to 4000 solution; also as a disinfectant. This sterilizes a pure culture of gonococci in from five to seven minutes. It can be used in as strong a solution as 1 to 1000 in the urethra, it penetrates deeply into the tissues without altering them, and by the seventh day the discharge is usually quite thin and gonococci can hardly be found. It then disappears rapidly. The iodide possesses the general properties of the nitrate.
Silver, soluble in water, an allotropic form discovered by Lea about 1890, now termed colloidal silver (not official), has recently been well received and has obtained a permanent place in therapeutics. It is employed as a 15 per cent. ointment (Crede) by inunction. It has been used successfully for chronic furunculosis, phlebitis and other septic processes.
Silver salts are not much used internally, and their continuous employment is objectionable on account of the discoloration of the skin produced. They were formerly often given in nervous diseases; but there is no evidence that they did any good. Although it is said that the compound of silver formed in the stomach is non-astringent, silver nitrate will certainly check severe diarrhoea, especially that of children. Colloidal silver is entirely soluble in water, and in albuminous fluids is unirritating, so that it can be administered hypodermatically and intravenously as well as by inunction, as is mentioned above. For internal use, to prevent its conversion into a chloride in the stomach, it is first dissolved in equal parts of albumin and glycerin. The dose is 1/6 gr., . o 1 gm., two or three times daily. Crede claims that it has a very beneficial influence and often affords a rapid cure in recent and also in chronic sepsis, when secondary changes in the vital organs have not occurred. It seems to inhibit the action of staphylococci and streptococci or destroy them altogether. It has been used in various conditions: osteomyelitis, so-called gonorrhoeal rheumatism, puerperal fever, cerebro-spinal meningitis, and diverse septic processes. Thus far no instance of argyria from its use has been reported. Sixty grains 4. gm. of silver nitrate dissolved in three pints 1500. c.c. of tepid water, and injected high up the rectum, have been used with great benefit in dysentery.
Toxicology. The nitrate sometimes causes acute poisoning. Symptoms. - These are intense pain in the abdomen and muscular spasm, followed by vomiting and purging. The face is livid and covered with perspiration. The vomited matter is black and contains coagulated mucus. Chronic poisoning or argyria shows itself by a permanent slaty discoloration of the skin, conjunctivae and labial mucous membrane and ulcerations in the digestive tract.
This consists of administering a solution of sodium chloride (common salt), soothing the mucous membranes by injection of milk and relieving pain with opium. The chronic form is avoided by interrupting the treatment, using eliminating remedies, and preventing staining of the skin by baths of sodium hyposulphite.