- Acidum Hydrocyanicum Dilutum, Diluted Hydrocyanic (Prussic) Acid, has 2 per cent. of absolute HCN and 98 of water. Dose, ♏j-v of a recent preparation. Forty minims have caused death. It is a constituent of the secret nostrum Chlorodyne, also of its various imitations, including the B. P. preparation Tinctura Chloroformi et Morphinae, recently introduced therein.
- *Scheele's Dilute Hydrocyanic Acid,—is a 4 or 5 per cent. solution, and is highly dangerous, even by inhalation.
- Oleum Amygdalae Amarae, Oil of Bitter Almond,—contains a varying quantity of Hydrocyanic Acid, due to the reaction between the principle Amygdalin and the ferment Emulsin. Dose, ♏¼ -j, in mixture.
- Potassii Cyanidum, Potassium Cyanide, KCN,—is soluble in 2 of water, sparingly soluble in alcohol. Dose, gr. 1/20-½. Locally, a solution of gr. j-v to the ℥ is as strong as should be used.
Physiological Action. Hydrocyanic Acid and Nicotine are the most powerful poisons known, gr. ss of the former having caused death. Its inhalation produces rapid insensibility and almost immediate exhaustion, death probably occurring from sudden paralysis of the heart in the more rapid cases and of the respiration in the slower ones. Some volitional movements may be made before death, unless the dose be very large. Its paralyzant action is expended on the brain centres, the peripheral afferent nerves, then on the spinal cord, the motor nerves and the muscular tissue, the muscles being fixed in tetanic rigidity after death. The blood is found, on post-mortem examination, to be dark and fluid, and the venous trunks and cerebral sinuses gorged therewith. The odor of Prussic Acid is fragrant, resembling that of bitter almonds or peaches. The effects of a medicinal dose pass off in an hour, at most. Potassium Cyanide, has similar action, and, in addition, possesses some peculiar to itself. Locally, it causes inflammation of the skin, with an eczematous eruption, and if applied in quantity to an abraded surface will produce fatal effects.
Toxicology. Atropine has antagonistic action to Hydrocyanic Acid, but is too slowly diffused to be of any value. Ammonia by inhalation, by the stomach, and by intravenous injection, with cold affusion to the spine and artificial respiration, are the measures most likely to avail in cases of poisoning, where there is time to do anything. In poisoning by Potassium Cyanide, the antidote is Ferrous Sulphate, producing Prussian Blue (Ferrocyanide of Iron). Then evacuation of the stomach, artificial respiration, and Ammonia by intravenous injection.
Therapeutics. Hydrocyanic Acid is a very useful and pleasant remedy. It is well employed in—
- Coughs of spasmodic character, whooping-cough, hiccough, laryngismus stridulus, and other neuroses of the respiratory organs, or affections involving the pneumogastric nerve.
- Gastralgia,—it is one of the most efficient remedies, also in Headache and Vertigo due to stomachal derangement; and in Nervous Vomiting.
- Acute Mania and Melancholia,—it has been successfully employed.
- Round Worms (Lumbricoides), are promptly killed by doses of 2 or 3 minims every 2 hours for 24 hours, followed by calomel. Both agents, being tasteless, are useful for children.
- Skin Diseases, Pruritus etc.—Hydrocyanic Acid is a very grateful application to allay itching. Or Potassium Cyanide in ointment, gr. v or vj to the ℥, carefully avoiding abraded surfaces.
- Headache, of reflex type,—Potassium Cyanide in solution, gr. iij-v to the ℥, applied locally on a compress, gives great relief.
- Stains from Silver Nitrate,—are removed by a similar solution.
A Compend of Materia Medica, Therapeutics, and Prescription Writing, 1902, by Sam'l O. L. Potter, M.D., M.R.C.P.L.