laxatives and purgatives

laxatives and purgatives

prepared by Dr.Heba Saleh

objectives

at the end of this lesson, the student should be able to: 1. define laxatives and purgatives 2. determine the types of laxatives, and their mechanism of action 3. mention examples for each type

Laxative and purgative

 Laxatives are compounds and/or drugs taken to loosen the stool  The terms may used interchangeably, but work different,  Cathartic or Purgative is a substance that accelerates defecation, produce intense action  This is in contrast to a laxative, which is a substance which eases defecation, usually by softening feces produce mild gentle stimulation. It is possible for a substance to be both a laxative and a cathartic

uses :

 most often taken to treat constipation. Certain stimulant, lubricant and saline laxatives are used to evacuate the colon for rectal and/or bowel examinations, and may be supplemented by enemas under certain circumstances.  Laxatives may be oral and/or in suppository form

Types of laxative:

1 st Bulk-forming agents  A bulk-forming agent is a substance, such as fiber in food, that adds bulk and soak up water and expand to distend the rectum ,  Also known as bulking agents or roughage, these include insoluble dietary fiber. Bulk-producing agents cause the stool to be bulkier and to retain more water, as well as forming an emollient gel, making it easier for peristaltic action to move it along. They should be taken with plenty of water. Bulk-producing agents have the gentlest of effects among laxatives and can be taken just for maintaining regular bowel movements  May not be effective in elderly patient  Depend on ability of colon to respond to destination Examples:  Bran (insoluble fiber),  psyllium (Metamucil)®  methylcellulose  dietary fibre,  Agar.

Types of laxative:

2nd hyperosmotics laxative  works by the osmotic effect, which retains water in the colon,  administered orally or rectally to draw water into the feces  lactulose( dupulac)® lowering the pH through bacterial fermentation to lactic, and acetic acid, and increasing colonic peristalsis. Lactulose is also indicated in Portal systemic encephalopathy. May used in elderly people, and for long term treatment of constipation  Glycerin suppositories work mostly by hyperosmotic action,  Solutions of electrolytes (sodium chloride, sodium sulfate) are used for whole bowel irrigation, a process designed to prepare the bowel for surgery or colonoscopy and to treat certain types of poisoning.. (intense effect)  Saline Examples: sodium phosphate, magnesium citrate, magnesium hydroxide ,magnesium sulfate (Epsom salt)®. Saline laxatives attract and retain water in the intestinal lumen, increasing intraluminal pressure and thus softening the stool. Saline laxatives may alter a patient's fluid and electrolyte balance.

Types of laxative:

3 rd Stimulant or irritant - Stimulant laxatives (also called "irritant laxatives") act on the intestinal mucosa or nerve plexus, altering water and electrolyte secretion. - They also stimulate peristaltic action and can be dangerous under certain circumstances - They are the most powerful among laxatives and should be used with care , very habit forming

Types of laxative:

4 th Stool softeners (lubricant laxative) These simply make the stool slippery, so that it slides through the intestine more easily. An example is mineral oil, which also retards colonic absorption of water, softening the stool. Mineral oil may decrease the absorption of fat-soluble vitamins and some minerals. mild laxative Good for pregnancy , lactation , children

Types of laxative:

Thanks!