PURGATIVES (Lat, porgatiros, cathartic, from porgare, to cleanse, from pains, pure agere, to drive, to do). Medicines which. within a comparatively short time after administration, produce a more or less fluid evacuation of the bowels. These drugs act partly by stimulating the peristaltic motion (q.v.) of the intestine, whereby the contents of the bowel are hurried in their passage to the rectum, and partly by determining the passage of a large amount of finid into the intestine from the blood vessels. Purgatives may be classified as follows: (1) Laxatives (q.v.). (2) Simple purgatives, includ ing aloes. rhubarb. cascara sagrada. senna, and ox-gall. (3) Drastic purgatives, such as jalap, scammony, gamboge, Croton oil, colocynth. elate rium, and calomel. Small doses of the drastie pur gatives act as mild cathartics; when taken in large doses. they act as irritant poisons. and arc employed when milder purgatives have proved -inefficient, or when it is necessary to remove a large quantity of fluid from the system, as in dropsical affections. Certain of these drugs, as jalap, elaterimn. and scammony. are called by
dragogue cathartics, because of the large amount of secretion they excite. (4) saline pargatires. These also increase the secretion of intestinal fluid and hinder its reabsorption, so that a large amount of it accumulates in the bowel and excites gentle peristalsis and a free evacuation. The salines are largely used as habitual purgatives. They form the essential ingredient of most pur gative mineral waters (q.v.). In this class are sulphate of magnesia, sulphate of soda, phos phate of soda, and the potassio-tartrate of soda either in simple solution or in the form of Seid litz powder (q.v.). (5) Cholagogue purgahrcs are those which have a stimulating effect either on the secretion or flow of the bile, and produce green-colored or 'bilious' stools. Srveral of the drugs already mentioned possess tins property. Among the cholagogues most frequently em ployed are podophyllin, calomel, mercury, and the phosphate and sulphate of soda. Consult Pot ter. ilateria Pharmacy, and tics (New York, 1903 ) .