Jalapa

JALAPA, Tubera Jalapae, Radix Jalapae, tubers of J.; plants producing it are Exogonium purga Bentn. (Wenderoth), Convolvulus purga Wenderoth, family Convolvulaceae. Native to the eastern Mexican Cordilleras. Grows at an altitude of 1,200-2,400 m. Cultivated in East India, on the island of Ceylon, Jamaica, and in South America. The dried tubers contain from 10 to 17% of jalapa resin, which consists of 95% ether-insoluble convolvulin, 3-5% ether-soluble jalapin, 20-25% sugar, 10-15% brown extractive substance, 6-6% starch, 7-10% moisture, and 8-12% fiber. The German and Austrian pharmacopoeias require a minimum of 10% resin content in the tubers. This resin, Resina Jalapae (Ph. VII), is obtained from the powder of J. tubers by extraction with warm strong alcohol. A characteristic feature of true J. tubers are the concentric resinous rings on the surface of the cut or break of the tubers. As a strongly acting agent, J. is kept with caution. Used in medicine as a drastic remedy in doses of 1-2 g per dose, and as a laxative from 0.1 to 0.3 g. J. resin, Resina Jalapae, is given in doses of 0.03 to 0.1 three times a day, usually in the form of pills. Preparations: extract of J., tincture of tubers and tincture of resin (Tinct. Jalapae Tuberis and Tinct. Resinae Jalapae). Jalap soap, Sapo jalapinus, prepared from equal parts of jalapa resin and medical soap, is less commonly used, usually in pill mass.