Acidum Camphoricum. Camphoric Acid.
Other tomes: Ellingwood
C10H16O4 = 200.128.
Camphoric acid, C8H14(COOH)2, may be prepared by oxidising camphor with nitric acid. It is official in the U.S.P. It occurs in colourless, odourless, flaky crystals, or as a crystalline powder with an acid, bitterish taste. Melting-point, when pure, 186° to 187°; commercial samples sometimes have a lower melting-point, but it should not be under 180°. It gives a yellowish-brown precipitate with ferric chloride and a light blue precipitate with copper sulphate. It should have no odour of camphor, and be free from chlorides, sulphates, and nitrates. Titrated with normal solution of potassium hydroxide, nearly 100 per cent. of pure camphoric acid should be indicated.
Soluble in water (1 in 160), alcohol (1 in 1.5), or ether; insoluble in chloroform.
Action and Uses.—Camphoric acid has a mild camphor action; it is not very toxic and can be used in very large doses, up to 4 grammes (60 grains), without serious effects; it is supposed to paralyse the nerve-endings in the sweat-glands, and is used in the night-sweats of phthisis. It does not affect other secretions as does atropine, nor irritate the stomach like agaric acid. Camphoric acid is also employed in solution, 0.2 to 5.0 per cent., with sufficient, alcohol, as a local antiseptic to the nose, throat, and bladder. It is usually administered as a powder, or in cachets, but may also be given in mixtures suspended with compound powder of tragacanth, or dissolved by the addition of diluted alcohol or a flavouring tincture. When used as an antihydrotic the dose should be given two or three hours before bedtime.
Dose.—½ to 2 grammes (8 to 30 grains).