Castor Oil is decomposed in the small intestine, and the resulting ricinolates are so irritant as to induce increased secretion and peristalsis.
Castor oil is used as a broom to sweep putrefactive masses out of the intestines.
Dose. - Oleum Ricini, 4 to 30 mils.
Croton Oil is similarly decomposed in the small intestine into glycerin and cro-tonoleic acid and a resinous anhydride which latter is very irritant
Croton oil is used in emergencies, or as a drastic purge to relieve cerebral congestion.
Dose. - Oleum Tiglii, 0.02 to 0.05 mil.
Rhubarb probably irritates the mucosa of the jejunum and ileum. It is useful in fermentative diarrheas.
Dose. - Tinctura Rhei Aromatica, 2 mils.
Senna mildly stimulates the whole small intestine. It is useful as a simple cathartic for children.
Dose. - Tinctura Sennae Composita, 8 to 15 mils.
Aloes is said to stimulate the mucosa of the sigmoid and rectum. It is useful as a temporary measure in depressed peristalsis of the lower bowel.
Dose. - Aloes, 0.25 Gm.
Cascara is said to increase secretion into the rectum. It is the one safe drug to use in chronic constipation of the simple type characterized by hard infrequent stools.
Dose. - Fluidextractum Cascarae Sagradae Aromaticum, 1 mil, much diluted with water.
These act by irritating the mucosa, sometimes producing inflammatory exudates. The seat of action is chiefly the small intestine, and the presence of bile seems essential.
The resinous glucosides are used to clear out the bowel, especially in those encumbered conditions due to overeating.
The saline cathartics act by increasing the fluidity of the intestinal contents thereby stimulating peristalsis. This increased fluidity is due to a retardation of absorption produced by the salines and to an exosmosis caused by the hypertonicity of the salts.
Salines are useful whenever a quickly-acting, non-irritating flushing out of the bowels seems desirable.
Dosage. - Magnesii Sulphas, 2 to 30 Gm.; Sodii Phosphas, 2 to 30 Gm.; Pulvis Effervescens Compositus, 1 powder.