PICRIC ACID.—Picric acid (trinitro phenol; picronitric, picrinic, carbazotic, nitrozanthic, or nitrophenisic acid) is ob tained from phenol (carbolic acid) by nitration. It occurs in yellowish, lus trous, flat crystals, without odor, but of an intensely-bitter taste. It is soluble in alcohol, ether, chloroform, benzene, and slightly soluble in water. It is an antiseptic and an oxidizing substance.
Physiological Action.—The main ac tion of picric acid seems to be exercised upon the blood, that of rabbits slowly poisoned by it having been found by Erb to assume a dirty-brownish hue. Distinct nuclei were found floating in the serum in their free state, and in the red corpuscles, while the white corpus cles were markedly increased in number. It causes distinct jaundice in man, in suitable doses, the skin, conjunctive, and urine being colored reddish yellow. Poisonous doses cause hypothermia, diarrhoea, collapse, and death.
Therapeutics. — Picric acid was for merly used internally in malarial dis eases, in trichiniasis, and as an anthel mintic and tonic. Experience has shown that it possesses little or no action in these conditions. In doses larger than 5 grains it is poisonous (antidote: albu min).
It is chiefly used after the method of the French surgeons, Thierry and Fil leul, for the treatment of burns and scalds. In solution (1 to 200) it is anal gesic, antiseptic, and keratogenous, and its use is free from the accidents some times provoked by antiseptics, as it is not irritant, caustic, or toxic. Filleul (Ftinion Pharm., Dec., '95) advises the use of a solution obtained by adding the crystals to boiling water, the excess be ing removed by decanting. The golden yellow solution thus obtained is left to cool in a vessel stoppered with cotton to insure asepsis. After cleansing the burn and pricking all blisters, compresses of tarlatan previously boiled to remove the stiffness, or plain aseptic cheese-cloth or gauze, are dipped into boiling water, then into the solution, wrung out, and applied in several thicknesses over the burning areas. Over this may be placed a layer of dry absorbent cotton, fastened in place by a roller bandage lightly ap plied. The dressing dries rapidly and
may be left in place several days. For removal it is moistened with the solu tion so as to soften it. A fresh dressing is applied and left for a week. This application relieves all pain, inhibits suppuration, and leaves a smooth cica trix (Thierry, Provincial Med. Jour., Dec. 2, '95).
Flare the following solution: Picric acid, 75 grains; alcohol, 2 ounces; distilled water. 2 pints. Mix. (See BURNS, TREATMENT.) Case of poisoning with picric-acid so lution applied locally, in adult patient. There occurred much prostration and all the symptoms of carboluria, with very dark urine. Henry Waldo (Brit. Med. Jour., Feb. 6, '07).
Picric acid is only useful in burns of the first and second degrees, its particu lar action being to stimulate the growth of epidermis. It allays pain. In burns of the third degree it checks suppura tion, but does not hasten granulation. C. Willems (Ann. de la Soc. Beige de Chir., May 15, '98).
By use of picric acid healing in burns of the first and second degrees takes place rapidly without suppuration. The punctured vesicles must be accurately flattened out. No impermeable material must be placed over the simple gauze, which should be dipped in a saturated aqueous solution of the acid and applied after being squeezed fairly dry. Ab sorbent wool and a light gauze bandage further encourage evaporation, and thus retard the growth of any bacteria which may have gained access to the wounded surface. A pair of thin rubber gloves may be used to avoid the staining of the dresser's hands by the acid. Re newal of the dressing need not take place for four or five days, unless there are clear signs of suppuration. Beckett (Brit. Med. Jour., May 13, '99).
Picric acid recommended in the treat ment of superficial burns: (1) because of its simplicity of application, (2) its painlessness, (3) the rapidity of its heal ing power, (4) absence of local irritation or of general toxic effect, and (5) the production of a smoother, more natural cicatrix than that obtained with other methods. McDonald (Brit. Med. Jour., May 13, '99).