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..
Purified native Saltpetre.
Colorless, transparent, six-sided rhombic prisms or a crystalline powder, odorless, and having a cooling, saline and pungent taste. Solubility. - In 3.8 parts of water; very sparingly soluble in Alcohol.
Sulphates, chlorides and lime, and the metals.
Potassium Nitrate is used to prepare Argenti Nitras Dilutus.
Dose, 5 to 20 gr.; .30 to 1.20 gm.
Potassium Nitrate Paper. Potassium Nitrate, 200; distilled water, 800. Dissolve the Potassium Nitrate in the Distilled Water. Immerse strips of white, unsized paper in the solution, and dry them.
Stomach and Intestines. - It is liable to cause nausea, vomiting, diarrhoea, symptomatic of the gastritis and enteritis produced by it.
Owing to its high diffusion power it quickly passes into the blood unchanged. External to the body, nitrates prevent the coagulation of the blood, or dissolve the clot if it be already formed; but it is not known that they have any effect on the blood in the body.
Potassium nitrate is a powerful cardiac depressant, causing the beats to become feeble and few. Large doses lead to great weakness, fainting, and death.
Small doses are diuretic from their direct action on the renal cells, but large ones are liable to inflame the urinary passages, causing haematuria. The drug is excreted unchanged in the urine.
Potassium nitrate is a mild diaphoretic.
Large doses retard respiration and tend to paralyze unstriped muscular fibre.
Blood. - On account of its supposed action in preventing the coagulation of the living blood, it has been used in rheumatic fever and many inflammatory conditions, but it is now discarded. Probably, as it is a cardiac depressant, it only does harm.
It is sometimes employed as a diuretic and diaphoretic in febrile conditions, but the acetate and the citrate are much preferable.
Potassium nitrate is an anti-spasmodic for the reason given above. For the treatment of this symptom potassium nitrate paper, in pieces about 1 1/2 inches 4. cm. square, is lighted, one at a time, and the patient inhales the fumes. Ringer considers it better to dip the paper also into a solution of potassium chlorate, and to burn a piece large enough to fill a whole room with the fumes. This treatment often relieves, and nitre is a common ingredient of so-called asthma powders.