PURGATIVES

PURGATIVES

Aperient (Latin: aperire: to open); lenitive (Latin: lenire=to soften); laxative (Latin: laxare= to loosen); evacutive (Latin=e=from, vacuare=to empty); purgative (Latin: purgare=to purify or cleanse); cathartic (Greek=kathartikos=make utterly clean)

A no of synonymous represent drugs that have been used for frequent emptying of bowels; they are arranged in the order of increasing severity or potency. However, laxatives and purgatives are commonly used terms now a day.

Laxatives are used to prevent undue straining and stool because this may produce hernia, prolapse of rectum, fainting or even cerebrovascular accident.
Purgatives may be given:
1. To remove poisons from GIT.
2. To remove parasites or worms from GIT.
3. To empty bowels for surgery.
4. To prepare patient for sigmoidoscopy or radiologic examination of colon.
5. To treat constipation.

CLASSIFICATION OF PURGATIVES
1. Bulk Purgatives
2. Saline or Osmotic Purgatives
3. Lubricant Purgatives. (As fecal softeners or emollients)
4. Stimulant or Irritant Purgatives

BULK PURGATIVES
Dietary fiber is the most satisfactory prophylactic and therapeutic agent for constipation. It is plant cell wall, which consists of varying quantities of fibrillar polysaccharides (pectin, hemicelluloses), lignins, cutins and glycoproteins.
Dietary fiber has the following important properties:
1. It is resistant to digestion by digestive enzymes, secreted into the lumen of the gut.
2. It has a great capacity to retain water, for example 1 gram of carrot fiber can hold 23 grams of water. However, water-holding capacity is insufficient to control secretory diarrhea.
3. It can bind to ions, which also draw water into the lumen of the gut.
4. Dietary fiber can be digested by colonic bacteria into metabolites, which contribute towards laxative action.
Various bulk forming agents can be utilized as supplements to dietary fibers. These bulk forming agents act by increasing the bulk of the colonic contents. The distension of intestine stimulates local parasympathetic nerves thus these agents encourage normal reflex intestinal activity rendering it more effective. They act within 1-3 hours. They must be taken with 2 liters per day of fluid. In the absence of sufficient fluid intake, intestinal obstruction may occur. They are helpful in anal fissure, hemorrhoids, diverticular disease and irritable bowel syndrome. The bulk purgatives are as under.
1. Bran: 25-50% of fibers: The recommended dose is 24grams per day.
2. Methylcellulose and carboxymethyl cellulose (CMC): they are given in dry forms like biscuits and wafers. They absorb water and their bulk may increase up to 30 folds.
3. Agar: It is obtained from see wood. In some countries, it is an article of diet eaten as jelly. This is taken as dry powder for its laxative action.
4. Psyllium (plantago psyllium) and Ispaghula (plantago ovata): These are seeds from plantago species, which contain pectin like heteroglycan that yield non-utilizable mucilaginous mass.
5. Others are lactulose, polycarbophil, etc.