Palliation of Constipation & Nausea/Vomiting Flashcards
Fecal Impaction
Fecal impaction is a mass of dry, hard stool that will not pass out of the colon or rectum. Fecal impaction is dry stool that cannot pass out of the body.
What are some bulk laxatives?
- Dietary fiber
* Psyllium
Bulk Laxatives MOA
○ Bulk-forming laxatives cause retention of fluid and an increase in fecal mass, resulting in stimulation of peristalsis.
○ They usually have an effect within 12 to 24 hours and reach a maximum after several days
Bulk Laxatives SE
Flatulence
Bulk Laxatives Contraindications
In debilitated patients who cannot drink adequate fluid (1.5 – 2 liters/day) could result in fecal impaction, intestinal obstruction
What are some osmotic laxatives?
- Nonabsorbable sugars
- Saline and Mg
- Polyethylene Glycol
Lactulose and Sorbitol MOA
Bacteria in the colon degrade the sugar and the increase in osmotic pressure and acidification of intestinal contents which in turn, softens the stool by promoting stool water content.
Lactulose and Sorbitol SE
○ Bloating, cramps, flatulence
○ Very sweet – may be difficult for patients to tolerate
○ Dehydration
MOA of:
○ Magnesium citrate
○ Magnesium hydroxide (Milk of Magnesia)
○ Sodium Phosphate (Fleets Phospho-Soda)
○ Saline laxatives have an osmotic effect causing increased intraluminal volume that acts as a stimulus for intestinal motility.
○ Laxatives that contain magnesium have been shown to release cholecystokinin that causes intraluminal accumulation of fluid and electrolytes and promotes
Mg Salt Laxative SE
○ Can produce dehydration without adequate fluid replacement
Mg Salt Laxative Contraindications
- Bowel obstruction
- Renal failure
- CHF
- Liver failure
Mg Salt Laxative Indications
○ Magnesium citrate and sodium phosphate indicated for bowel cleansing in preparing patients for surgery or the colon for x-ray or endoscopy
○ Magnesium hydroxide is indicated for relief of constipation
Polyethylene Glycol MOA
Polyethylene glycol is an osmotic agent that causes retention of water in the stool resulting in a softer stool and more frequent bowel movements.
Polyethylene Glycol SE
Minimal to none
Polyethylene Glycol Indications
o Large volume (ie 4 liters) ingested rapidly causes rapid evacuation for bowel cleansing before endoscopy
o Smaller daily doses can be used for constipation.
What are some stimulant laxatives?
- Senna
* Bisacodyl
Bisacodyl MOA
Bisacodyl is a contact laxative that acts on the large intestine to produce strong but brief peristaltic movements. This agent stimulates sensory nerve endings to produce parasympathetic reflexes that results in peristalsis of the colon. Local axon reflexes and segmental reflexes are stimulated, which produces widespread peristalsis of the colon.
Senna MOA
Senna undergoes conversion to active metabolites in the colon that stimulate the myenteric plexus and induce net fluid secretion.