PHARM: Constipation and Diarrhea Flashcards
What type of laxatives are:
Psyllium hiusk
Semisynthetic celluloses
Plycarbophils
Dietary fiber (bulk forming laxatives)
What type of laxatives are:
Docusates (dioctyl sodium sulfosucinate)
Poloxamers
Castor Oil
Surfactant Laxatives
What type of laxatives are:
Diphenylmethanes
Anthraquinones
Stimulant laxatives
What type of laxatives are:
Magnesium Containing Laxatives
Phosphate Containing Laxatives
Nondigestable Sugars/Alcohols (Lactulose, Glycerin, and polyethylene glycol solution)
Osmotic Laxatives
What type of laxatives are:
Mineral Oil
Caster Oil
MIscellaneous laxatives
What is the most potent class of laxatives?
stimulant laxatives
Which stimulant laxative is a synthetic prodrug?
diphenylmethanes (converted by enteric bacteria into desacetyl active form)
Which stimulant laxative is a natural laxative?
anthraquinones
In a patient with diarrhea, what MUST be done before treating for diarrhea?
Stool culture needs to be taken before you treat! RULE OUT infection!
Which diarrhea treatments act by absorbing water?
Cellulose Derivatives
Semisynthetic Polysaccharides
Which diarrhea treatments are adsorbers of etiological factors in the lumen?
Bismuth Subsalicylate
Charcoal
Which diarrhea treatments alter intestinal motility?
Opiods
Anticholinergics (antispasmodics)
MOA: unabsorbed material that sucks water into the colon so that there is more water in the stool, increases bulk of stool, and reduces pressure in the sigmoid colon.
Psyllium Husk
Semisynthetic celluloses
Polycarbophils
MOA: Salt that decreases the surface tension between the stools and rectal epithelium to result in easier passage of the stool. NO effect on peristalsis
Dioctyl Sodium Sulfosucinate
What are surfactant laxatives used for?
stool softeners
MOA: NON-ionic substance that decreases the surface tension between the stools and rectal epithelium to result in easier passage of the stool. NO effect on peristalsis
Poloxamers
MOA: NON-ionic substance that decreases the surface tension between the stools and rectal epithelium to result in easier passage of the stool. STIMULATES peristalsis.
castor oil
Which surfactant laxative is used for complete evacuation of the bowels (catharsis)?
Castor oil
MOA: increase permeability of intestinal (colon) mucosa
Diphenylmethane and Anthraquinones (more gentle)
What is the effect of increasing colonic mucosa?
leakage of the water back into the lumen after it is absorbed, increase the propulsive contractility of the colon (nerve plexus activation) and stimulate PG synthesis and increase intestinal secretions
MOA: stay in intestine and draws water in (so it stays isoosmotic) to make stool more watery.
Magnesium sulfate
Magnesium Hydroxide
Magnesium Citrate
Sodium Phosphate
What is the other MAJOR action of osmotic (Mg-containing) laxatives?
These also stimulate the release of CCK (increase motility and secretion).
Which Mg-containing laxative is used for colonoscopy prep?
Magnesium citrate
What other osmotic laxatives are used for colonoscopy prep (but can be ORAL or enema)?
sodium phosphate
MOA: Semisynthetic disaccharide which is NOT absorbed and produces an osmotic laxative effect (metabolized by enteric bacteria into organic acids→ fecal acidification that traps ammonia in the non-toxic ammonium form.
Lactulose
MOA: Sugar alcohol that is used as suppository—stay in intestine and draws water in (so it stays isoosmotic) to make stool more watery
glycerin
MOA: Electrolytes stay in intestine and draws water in (so it stays isoosmotic) to make stool more watery and provide COMPLETE EVACUATION.
Polyehtylene glycol electrolyte solution
GOLYTELY
How and why is GOLYTELY taken?
Solution that is dissolved into 4L and ingested 8 oz every 10 minutes for colonoscopy
MOA: Mixture of hydrocarbons that penetrates and softens the stool.
Mineral oil
MOA: Emulsion that irritates the mucosa and produces a cathartic effect.
castor oil
MOA: Activates intestinal Cl- channels in a PKA-independent fashion. Activation of these channels increases intestinal fluid secretion and motility and alleviates the symptoms associated with chronic idiopathic constipation.
lubiprostone
MOA: Peptide agonist of guanylate cyclase 2C that acts on intestinal cells to indirectly activate the Cl- channel (cGMP made from GTP to activate PKG II which activates channel)
Linaclotide
MOA: Adsorbs harmful bacteria, viruses or toxins that cause diarrhea.
Bismuth Subsalicylate
MOA: OVERALL increase contact time between ingested material and reabsorptive intestinal epithelium!
Paregoric
Diphenoxylate with Atropine
Loperamide
What diarrhea treatment is esentially grinded up opiates?
paregoric
What diarrhea treatment is a mixture of opiate and anti-cholinergic to reduce dose and abuse?
Diphenoxylate with Atropine
What diarrhea treatment is an opiate that inhibits calmodulin (Ca2+ binding protein)?
Loperamide
How do opiates prevent diarrhea?
- Decrease secretions (salivary, gastric, and intestinal)
- Decrease motility (stomach, intestines),
- Increase muscle tone
- Increase tone of intestinal sphincters (including external anal sphincter→ reduce urgency)
- Act as antispasmodics (decrease cramps)
MOA: Block cholinergic receptors and reduce vagal stimulation—antispasmodic!
Propantheline
Dicyclomine
What type of drugs are propantheline and dicyclomine?
Quaternary ammonium derivatives of atropine (do NOT cross BBB).
What is the indication for propantheline and dicyclomine?
reduce cramps
What drug is an Anticholinergic + benzodiazepine?
Librax
What is the indication for Librax?
Cramps and Anxiety
Describe the cause of cyclical laxative use.
Over time, the overuse of laxatives leads to thorough constipation that requires several days to accumulate bulk (this lag is interpreted by patient as continued constipation so this encourages them to take more).