Pharm110 Chp 26 Laxatives and Antidiarrheals Flashcards
Stimulant laxatives
e.g. Bisacodyl
Action
- Chemical irritation of mucosa (Increase motility of the GI tract)
- Increase secretion of water into larger and small intestine
Adverse effect
- Absorbed into the systemic circulation
- Can cause skin rash, discoloration of urine
- Most likely to cause laxative dependance
Saline laxatives
Prefix “Magnesium”
e.g. Magnesium citrate
Action
- Increase osmotic pressure in the intestinal tract
- Cause more water to enter intestines
- Result in bowel distention, increased peristalsis, and evacuation
- Contain high sodium content (not for use in clients with heart failure or kidney disease)
- Systemically absorbed
- Poor client compliance
- Risk for dehydration
- Risk for congestive heart failure
Used for rapid evacuation of bowel for endoscopic examination or removal of unabsorbed poisons.
Bulk-forming laxatives
e.g. Psyllium hydrophilic muciloid (Metamucil), Methylcellulose (Citrucel), Polycarbophil (Fibercon)
Safest form of laxative
Action
- Absorb water to increase bulk
- Distend bowel to initiate reflex bowel activity
- Not systemically absorbed
- High fiber
- Natural or semisynthetic
Must be followed with a large amount of fluid to prevent esophageal obstruction and/or fecal impaction.
Lubricant laxatives
e.g. Mineral oil (liquid petroleum)
Action
- Lubricate the fecal material and intestinal walls, promoting fecal passage
- No caloric increase as not absorbable
Adverse effect
-Prevent fat-soluble vitamins from being absorbed. (A, D, E, K)
Vegetable oil
- Absorbable causes caloric increase
- Does not prevent fat-soluble vitamins from being digested.
Stool softeners
e.g. Docusate salts (Colace and Surfak)
Action
- Detergent like drugs
- Permit mixing of fats and fluids with fecal mass
- Stool becomes softer and is passed much easier
- Takes several days to work
- Not systemically absorbed
- Do not cause dependence or toxicity
Useful in infants, children and elderly bedridden clients
Suppositories
e.g. Glycerin (absorb water from tissues, creating mass)
Bisacodyl (Induce peristaltic contraction by direct stimulation of sensory nerves)
- Wax based
- Administered rectally
- Absorbed systemically
- Overuse is rampant
Lactulose laxatives
- 2 monosaccharides galactose and fructose that are not digested or absorbed.
- Digested in the colon by bacteria to form acid substances (lactic acid, formic acid, acetic acid)
- Acid substance causes water to be drawn into the colon
Adverse effect
- Cause ammonia to pass from blood into colon.
- Useful in clients with portal systemic encephalopathy (toxic levels of ammonia)
- For treatment of constipation 10-20g admin daily
- For treatment and prevention of portal systemic encephalopathy 20-30g admin 3-4 times daily.
GoLytely
e.g. Polyethylene glycol (electrolyte solution and salt)
Bowel cleansing prior to GI exam
Action
- Must consume 4 L within 3 hours
- Causes large volume of water to be retained in colon
- Acts within 1 hour
- Produces diarrheal state.
Enemas
e.g. Fleet enema
- Hyperosmotics
- Solution containing salt
- Administered rectally and cause laxative effect by osmotically drawing fluid into the colon to initiate defecation.
Long term laxative use implications
- Long term use often results in decreased bowel tone and may lead to dependency.
- Encourage (A healthy, high fiber diet, and increased fluid intake)
Adsorbents
e. g. Kaolin-pectin, Attapulgite (Keopectate)
- Most commonly used antidiarrheal agents
Action
-Bind drugs, digestive enzymes, toxins, bacteria and other substances that cause diarrhea.
-Claylike materials admind in tablet or liquid suspension form after each loose bowl movement.
Antidiarrheals
e.g. Loperarmide HCI (Imodium) (made from chemicals related to meperidine a narcotic)
Diphenoxylate HCI and Atropine sulfate(Lomotil) (Narcotic and anticholinergic drug, reduce GI motility)
Action
- Reduce GI motility
- Opium derivitives
- Decrease bowel motility
- Depress the CNS; monitor closely
- Decreases transit time through the bowel; more time for water and electrolytes to be absorbed
- Paregoric is an opium tincture
- May cause physical dependence
Anticholinergics
e.g. Belladonna alkaloids (Donnatal)
Action
-Decrease intestinal muscle tone and peristalsis of GI tract
-Slows movement of fecal matter through GI tract
Laxative key information
- In general avoid use of stimulant laxatives in the elderly.
- Nondrug measures, such as dietary modification, fluid intake, and exercise should be encouraged to promote regularity.
- Follow bulk-forming laxatives with at lease 1 glass of fluid to prevent gastrointestinal obstruction.
- Never administer laxatives to clients experiencing abdominal pain, nausea or vomiting until you have consulted their health care provider.
- Inform clients taking laxative that thy must drink 6-8 glass of water to avoid dehydration.
