GI: Diarrhea, Abdominal Pain, and Constipation Flashcards
What 5 drug classes can be sed for diarrhea?
- Prostaglandin Inhibitors
- Bismuth - Opioid Agonists
- loperamide, diphenoxylate, eluxadoline - 5HT3 antagonists
- alosetron - Cl Channel Inhibitors
- Crofelemer
Does loperamide cross the BBB?
No, so no need to worry about addiction as much
-watch for cardiac toxicities though!
MOA for loperamide and diphenoxylate?
Interferes with peristalsis, so it slows transit time
-increases segmental peristalsis, so increases bulk
Side effects for Mu Opioids (loperamide and diphenoxylate)?
Anticholinergic (Dry as a cracker, hot as a hare, mad as a hatter, red as a beet.. you get it)
What is given with diphenoxylate to prevent addiction?
Can cross BBB, so give with small dose of atropine to avoid overdose
MOA for Eluxadoline?
Mu and Kappa agonist
-slows peristalsis
Antagonist at Delta opioid receptors
-stomach, pancreas, biliary secretions decreased
When would you prescribe eluxadoline?
IBS, diarrhea predominant
Side effects for Eluxadoline?
Hepato/pancreatotoxicity
-pancreatitis is especially high risk in those without gallbladder
CNS related
-sedation, euphoria, impaired cognition
If a patient doesnt have a gallbladder, what do you need to watch out for in a patient taking eluxadoline?
Pancreatitis
-deaths have occurred due to this
What are some contraindications to taking eluxadoline?
- Biliary obstruction
- alcoholism
- pancreatitis
- Severe hepatic impairment (liver disease, cirrhosis)
If a patient is taking eluxadoline and has constipation for more than 4 days, what should you do?
Stop the therapy!
What is the indication for alosetron?
Chronic, severe IBS-D that is unresponsive to other therapies (especially in women)
Say a patient has IBS-D, and has tried all other conventions to stop it and all have failed.. what would you presribe?
Alosetron
Side effects for Alosetron?
- Ischemic Colitis
- pts must have follow up to get again, patients at significant risk! - GI related
- constipation, dyspepsia
Contraindications for alosetron?
History or current:
- GI obstruction, perf, toxic megacolon
- diverticulitis, Chrons, UC
- Severe constipation
- -STOP IMMEDIATELY
What drug is derived from the dark red sap of the Croton lechleri tree?
Crofelemer
-Cl- channel blocker
MOA of Crofelemer?
Inhibits Cl- secretion by blocking cAMP stimulated CFTR
-less Cl- means less water.. so bulks up the stool
If an HIV/AIDs patient comes in with diarrhea that is caused by their antiretroviral therapy what should you prescribe?
Crofelemer
Side effects for crofelemer?
GI issues
-abdominal distention, elevated AST/ALT
Infections
-respiratory/urinary
Agents used for Abdominal pain, mainly IBS related?
Antimuscarinic agents
- Hyoscamine
- Dicyclomine
MOA of hyoscamine and Dicyclomine?
they are antimuscarinic agents, so competitively inhibit post ganglionic cholinergic receptors
Side effects of hyoscamine and Dicyclomine?
They are antimuscarinic agents, so Dry as a cracker, hot as a hare, mad as a hatter, red as a beet.. you get it
Drugs used for constipation
- Laxatives
- Peripheral Opioids
- methylnaltrexone, naloxegol, alvimopan - Guanylate Cyclase Agonists
- Linaclotide - Selective Cl (C2) channel activators
- lubiprostone
MOA of Methylnaltrexone, naloxegol, and alvimopan?
They are peripheral mu-opioid receptor antagonists
-so block the effects to relieve constipation
If a patient is taking and opioid and are constipated.. what should you prescribe?
A mu opioid antangonist
-Methylnaltrexone, naloxegol, or alvimopan
or
Lubiprostone
If you are wanting to accelerate GI recovery for a patient following bowel resection surgery with an anastomosis.. what would you prescribe?
Alvimopan
What is a warning when taking alvimopan?
can cause MI
-Max of 15 doses according to REMS program
MOA for LIncaclotide?
Activates guanylate cyclase-c for constipation
-stimulates CFTR ion channel, more Cl- in lumen, water will follow to relieve constipation
When would you prescribe lincaclotide?
- IBS-C
2. Chronic Idiopathic Constipation
MOA of lubiprostone?
A prostaglindin E derivative for constipation
-activates ClC-2 channels, Cl- out and water will follow to relieve constipation
First three letters are Lub(e), so it helps things slide out
Indications for Lubiprostone?
- IBS-C (women)
- Chronic Idiopathic Constipation
- Opoid induced constipation
What are the bulk forming agents used in diarrhea?
Fiber/Bran
Psyllium
Cellulose agents
Calcium Polcarbophil
Adverse effects of bulk forming agents?
Bloating and obstruction
-must drink lots of water
Also interactions with drugs!
What agents are used as stool softeners? how do they work?
- Docusate salts
- Mineral Oil
Work to lubricate feces and decrease fluid resorption from GI tract
Which agents are used as stimulants (irritants) for laxatives?
Senna Bisacodyl Castor Oil Glycerin Sodium Picosulfate
Which stimulate is used for pre-colonoscopy bowel prep?
Sodium picosulfate
MOA of stimulants?
- Irritate the enterocytes, leads to inflammation
- causes Na/K inhibition and can increase prostaglindin synthesis - Promote water/electorlyte accumulation in GI
What is castor oil hydrolyzed to?
ricinoleic acid
Which of the stimulates acts as a tri-hydroxyl alcohol and functions as an irritant, osmotic agent, and lubricant?
Glycerin
When is the effect of stimulants noticed?
12-36 hours
Which stimulant can cause red/brown urine?
Senna
What are the two saline agents used as laxatives?
- Magnesium salts (mag. sulfate, mag. hydroxide)
2. Sodium Phosphate
How do the saline agents work?
Magnesium/phosphate is poorly absorbed, so created a hyperosmolar solution to retain water in GI tract
What drugs do saline agents interact with?
diuretics
What are the contraindications in someone taking a saline agent as a laxative?
Renal Disease (electrolytes) CHF/HTN
What are the osmotic agents used as a laxative?
lactulose
Magnesium Citrate
Sorbitol
Polyethylene Glycol
Effects seen in 1-3 hours in large doses
What can lactulose be used for besides as a laxative?
Severe liver disease (Hepatic Encephalopathy) causing hyperammonemia, as it changes pH to trap ammonia in GI
What are the adverse effects of osmotic agents?
Can cause severe dehydration fro electrolyte disturbances
-so watch at risk populations!
Which osmotic agents is used in large doses for bowel prep?
Polyethylene glycol
-smaller doses for constipation
