Constipation Flashcards
List the Bulk Laxatives
Dietary Fiber
Psyllium (metamucil)
Bulk Laxatives
MOA
Increase stool weight, bringing in more water and activating peristalsis
Effective within 12-24 hours (max several days)
Bulk Laxatives
Adverse Effects
Flatulence
Requires increased fluid intake or else they will become even more constipated
Osmotic Laxatives
What are the big 3 categories?
Nonabsorbable sugars
Saline and magnesium salts
Polyethylene glycol
List the Nonabsorbable Sugars used as osmotic laxatives
Sorbitol
Lactulose
Nonabsorbable Sugars
MOA
Help liquid enter stool via osmosis, increasing osmotic pressure and acidifying the stool
Nonabsorbable Sugars
Adverse Effects
Bloating
Cramps
Flatulence
“Sickly” sweet tase
Nonabsorbable Sugars
Indication
Constipation
Works after a day or two to reach full effectiveness
List the Saline and Magnesum Salts
Magnesium citrate
Magnesium hydroxide (MOM)
Sodium phosphate
Saline and Magnesium Salts
MOA
Osmotically active particles enter gut and pull fluid into stool. Stimulates intestinal activaity
Magnesium may also stimulate CCK to push gut forward and cause peristalsis
Saline and Magnesium Salts
Adverse Effects and Contraindications
Bowel Obstruction
Dehydration
Electrolyte abnormalities
- do NOT use in renal failure; be careful with CHF and liver failure
What is a specific adverse effect that comes with Sodium Phosphate agents?
Acute phosphate nephropathy
- Intratubular deposition of Calcium and Phosphorous
- Happens in sick people with lots of comorbidities
Magnesium Citrate and Sodium Phosphate
Indications
Bowel preps (for colonoscopies, surgeries)
Magnesium hydroxide (MOM)
Indications
Constipation
Polyethylene Glycol
Indications
Depends on dose taken. Small doses are good for constipation, while large doses (4L) are used for bowel prep.
Polyethylene Glycol
MOA
Osmotically active, nonabsorbable sugars that retain water in the stool. Cause softer stools and more frequent bowel movements
List the Stimulant Laxatives
Senna
Bisacodyl (Dulcolax)
Stimulant Laxatives
MOA
Senna stimulates the myenteric plexus in the colon
Bisacodyl stimulates sensory nerve endings, which increases parasympathetic stimulation to activate peristalsis
Stimulant Laxatives
Adverse Effects
Cramping
Melanosis Coli (when used chronically, lamina propria macrophages increase product of drug which appears as brown pigment)
Stimulant Laxatives
Indications
Constipation
Detergent Laxatives
What is the main drug used clinically in this category?
Docusate
Docusate
MOA
Stool softener
Surfactant that sits in gut, allowing stool to break up more and mix with water
Docusate
Indication
PREVENTS formation of hard stool
What are the lubricants used in clinical practice?
Glycerin suppository/enema
Mineral oil enema
What is a suppository?
Small tablet inserted into rectum, which breaks up and makes stool in rectum more slippery. Other drugs may be given via suppository (acetaminophen).
What is an enema?
Large bag filled with a liquid (often tap water), squeezed into rectum
Lubricants
MOA
Soften stool to make it easier to pass
May see a response in as fast as 30 min
Why should mineral oil NEVER be given orally?
If the patient aspirates it, is can cause a lipoid pneumonitis (fat pneumonia)
Lubricants (Glycerin or mineral oil)
Indication
Fecal impaction
What is fecal impaction?
Mass of stool that has caused a bowel obstruction. Can become rock hard
What are some complications of fecal impaction?
Rectum filled with rock hard stool
May distend bladder and cause inability to empty (urinary retention and increased risk for infection)
