GI Pharmacology 2 - Slides 16-30 Flashcards
MOA of laxatives?
Increase motility
Increase water content of stool
Decrease colonic water and NaCl absorption (keeps more water in the stool)
Indications for laxatives?
Prepare bowel for surgery Hasten bowel excretion of toxins Post-operative stimulation Minimize straining in CV disease pts Relief of TEMPORARY constipation
Contraindications for laxatives?
Underlying bowel disease
Side effects of laxatives?
Acute: Nausea, abdominal cramps, diarrhea
Chronic (Cathartic Colon Syndrome): Mucosal inflammation Atrophy of outer muscle layers Damage to nerve plexus Malabsorption, dehydration, protein loss Disruption of intestinal flora
What types of laxatives are there?
Stimulants or irritants
Bulk forming - dietary fiber
Stool softeners
Osmotic agents
What is castor oil?
A laxative (stimulant/irritant), increases motility and electrolyte secretion
What is Senna?
A laxative (stimulant/irritant), increases colonic motility
What is Bisacodyl?
A laxative (stimulant, irritant), increases colonic motility
What is Phenothalin?
A laxative (stimulant/irritant) - was removed
Side effects of laxatives?
Abdominal cramps
Diarrhea
Muscle weakness
What type of laxative is the strongest?
Stimulants or irritants
Name the bulk forming, non-digestable dietary fibers
Psyllium
Methylcellulose
How should Psyllium, Methylcellulose be taken
Mixed with water before taking
How do Psyllium, Methylcellulose work?
They increase bulk and water content of stool to increase motility
Also increased volume augments peristalsis
Adverse effects of Psyllium, Methylcellulose?
Binds drug
Flatulence
Cramps
Name the stool softeners
Mineral oil
Glycerin
Docusate sodium (Colase)
How do stool softeners work?
They emulsify with stool to increase water content and lubricate
Name the osmotic agents
Magnesium sulfate
Magnesium hydroxide
Lactulose
Mannitol
How do osmotic agents work?
Increase water content
Increase motility
What is Diphenoxylate?
Atropine
Ant-diarrheal agent, increases water absorption and decreases GI motility locally
What is Difenoxin?
Active metabolite of diphenoxylate
Atropine
Ant-diarrheal agent, increases water absorption and decreases GI motility locally
What is Loperimide?
Ant-diarrheal agent, increases water absorption and decreases GI motility locally
Adverse effects of anti-diarrheal agents?
Constipation
Exaggerated GI effects
Megacolon
What is Bismuth subsalicylate?
Inhibits intestinal secretions
Effective in INFECTIOUS diarrhea
Taken frequently
Worry about bismuth and salicyalate toxicity
What is Kaopectate?
Anti-diarrheal agent
Now contains bismuth subsalicylate
What is Ulcerative collitis?
Confluent inflammation of mucosal layer of the colon
What is Chron’s disease?
Transmural nonconfluent inflammation of submucosal layer near ileocecal valve leads to strictures and fistulas
What is Mesalamine?
5-ASA
Metabolized to 5-ASA in colon
Exact mechanism unknown
Inhibits TNF, IL-2, NF-KB
Toxicities of Mesalamine?
Headache
Dyspepsia
Sulfa
Headache, fatigue, allergic reactions
What is Sulfasalazine?
Prodrugs for 5ASA in ulcerative collitis
What is Olsalazine?
Prodrug for 5ASA in ulcerative collitis
What is Balsalazide?
Prodrug for 5ASA in ulcerative collitis
Where do Sulfasalazine and Osalazine release 5ASA?
In the colon
How do dif Mesalamine preparations differ?
Vary in where along the GI tract 5 ASA is released
Sulfasalazine and Osalazine release 5 ASA in the colon
Other tx for IBS (Chrohn’s disease)?
Glucocorticoids
Azathioprine, 6-Mercaptopurine (severe chrohn’s disease after surgery)
Methotrexate
Cyclosporine
Infliximab (anti TNF antibody)
Antibiotics (Metronidazole, ciprofloxacin, clarithromycin)
