Week 2: GI Tract - Laxatives Flashcards
What are the 4 types of laxatives?
- bulk-forming
- surfactant
- stimulant
- Osmotic
Which medication is an example of a bulk-forming laxative? (2)
Psyllium
AKA meta mucil
What is the MOA of bulk-forming laxatives?
- Similar action to fiber
- increase in bulk leads to soft formed stool
good for people to struggle to meet fiber requirements
What is psyllium made of?
- polysaccharides and cellulose derived from grains and plants (nondigestible)
How should psyllium be administered and why? (3)
- Not absorbed systemically (side effects rare)
- Should be administered with large glass of water to avoid obstruction/impaction (esophageal)
- Produces a soft but still formed stool in 1-3 days
What are the indications for psyllium? (3)
- chronic constipation
- Prevent straining of stool
- IBS
Which 3 medications are examples of osmotic laxatives?
- lactulose
- Laxative salts: Magnesium Hydroxide
- Polyethylene Glycol (restoraLAX)
What is lactulose made of? (2)
combination of galactose and fructose
What is the MOA of lactulose? (3)
- Turns into lactic acid in the colon, which has an osmotic action similar to other osmotics
- Hepatic encephalopathy: helps with excretion of ammonia
- Produces a soft stool in 1-3 days
What are the side effects of lactulose? (2)
- Poorly absorbed and not digested by enzymes in the GI tract, cause N+V
- tons of adverse effects and more expensive than other laxatives
How do laxative salts like magnesium hydroxide work?
- Poorly absorbed salts and osmotic action draw water into the intestinal lumen
What are indications for magnesium hydroxide? In other words, when would you use low doses vs high doses?
Low dose therapy - stool within 6-12 hrs
High dose - Bowel evacuation prior to surgery or to purge poisons (2-6 Hours)
What is a risk of using magnesium hydroxide?
dehydration
What are contraindications for magnesium hydroxide?
- kidney disease (cannot excrete waste as efficiently, causing build up of Mg in bloodstream
What does purgative mean?
- vigorous evacuation of GI because we want to completely clean out our bowels
ie. before procedures