Turpethum, I.C.A. Turpeth.
Turpeth consists of the dried root and stem of Ipomoea Turpethum, R. Br. (N.O. Convolvulaceae), a native of India and Ceylon. The drug occurs in cylindrical pieces from 1.5 to 5 centimetres in diameter, the central woody portion being often removed by splitting the bark on one side. Externally the pieces are of a greyish-brown colour, and deeply furrowed longitudinally. The fracture is short; a transverse section, in which the central portion has not been removed, exhibits an outer cortical portion and a central woody column containing large wood vessels. The drug has but a faint odour and taste.
Constituents.—The chief constituent is about 10 per cent. of a grey resin, insoluble in ether, called turpethin, which resembles jalapin (convolvulin). The drug also contains a small quantity of an ether-soluble resin, and traces of volatile oil and fatty matter.
Action and Uses.—Turpeth has properties resembling those of jalap, but is slower in its action and rather less powerful. It is official in India and the Eastern Colonies for use in place of jalap.
Dose.—1 to 4 grammes (15 to 60 grains).