Diarrhea, Abdominal Pain, and Constipation Pharm Flashcards
What are the main drug classes used for diarrhea?
- prostaglandin inhibitors (bismuth)
- opioid agonists
- serotonin (5HT3) antagonists (alosetron)
- chloride channel inhibitors (crofelemer)
What is loperamide?
(MOA and side effects)
Loperamide - opioid agonist
acts directly at intestinal smooth muscle to slow motility
Side effects:
-anticholinergic effects
-no analgesic/opiate effects like other -> no dependence risk
What is diphenoxylate?
(MOA and side effects)
Diphenoxylate - opiate agonist
acts at directly at intestinal smooth muscle to slow motility
Side effects:
- atropine added to prevent abuse -> anticholinergic effects
- opioid effects (only at high doses)
What is eluxadoline?
(MOA and side effects)
Eluxodoline - mu/kappa opioid agonist but delta antagonist
Directly in GI:
- slows peristalsis (mu/kappa)
- decreases GI secretions (delta)
Side effects:
- hepatic/pancreatic toxicity (especially post-cholecystectomy)
- opioid/analgesic effects
What opioid agonist is indicated for IBS-D only, instead of diarrhea in general?
-eluxadoline
What is alosetron?
Alosetron - serotonin (5HT3) antagonist
-selectively targets GI 5HT3 receptors inhibiting GI motility and secretions
Side effects:
- GI symptoms
- ischemic colitis
What is the indication for alosetron use?
- only severe, chronic IBS-D that has not responded to other treatments
- only in women
What contrainidcation/black box warning is associated with alosetron?
Contrainidications:
- risk factors for bowel ischemia
- GI obstruction (discontinue if constipation develops)
Black box warning:
-ischemic colitis
What is crofelemer?
(MOA and side effects)
Crofelemer - Cl- channel inhibitor
inhibits CFTR and CaCC (chloride channels) preventing secretory diarrhea associated with their functions
Side effects:
- GI (distension)
- elevated LFTs
- resp./uri. infections
What is the indication for crofelemer use?
non-infectious diarrhea in HIV/AIDS
What drug class is used for abdominal pain/spasms?
(specific drugs and side effects)
antimuscarinics:
- hyoscyamine
- dicyclomine (bentyl)
Side effects:
-anticholinergic effects
What drug classes are used for constipation?
- peripheral opioid antagonists
- guanylate cyclase-C agonists (linaclotide)
- selective chloride (C2) channel activators (lubiprostone)
- laxatives/cathartics
What are peripheral opoid antagonists?
(specific drugs and indication)
- methylnaltrexone
- naloxegol
- alvimopan
Indicated only for opioid-induced constipation
-alvimopan specificaly used only after surgery for post-operative ileus
What is the black box warning associated with alvimopan?
- increased risk of MI
- restricted to 15 does
- REMS program to use/prescribe
alvIMopan <-> MI
What is linaclotide?
(MOA and indication)
Linaclotide - guanylate cyclase-C (GC-C) agonist
-increases cGMP -> activate CFTR -> water secretion
Indications:
- IBS related constipation (IBS-C)
- chronic idiopathic constipation (CIC)
What is lubiprostone?
(MOA and indication)
Lubiprostone - selective chloride (ClC-2) channel activator
PGE-1 derivative that activates GI-specific Cl channels (ClC-2) -> water secretion
Indications:
- IBS-C
- chronic idopathic (CIC)
- opioid-induced (OIC)
What is the difference between laxative and cathartics?
Laxative:
-loosens stool, allowing easier defecation
Cathartic:
- accelerates defecation
- used to clear bowel (commonly for surgery)
What are the main types of laxatives/cathartics?
- bulk forming agents
- stool sofeners
- stimulants
- salines
- osmotics
What are bulk-forming agents?
What types of agents are these?
increase stool volume and water content
substances:
- dietary fiber
- psyllium
- cellulose derivatives
- calcium polycarbophil
What are important notes in bulk-forming agents?
they require increased water intake to increase fluid content of stool, without this they will just cause constipation
2-4+ days to see effect
caution use with renal failure, can take water away from the kidneys
What drug interactions occur with bulk-forming agents?
many, trap other medications in GI track
What are stool softeners?
What types of agents are these?
anionic surfactants that increase fluid in stool
- docusate “salts” (increases secretion)
- mineral oil (add oil to stool/lubricate)
What are stimulants?
What types of agents are these?
Irritates enterocytes/enteric nervous system causing water/electrolyte secretion
- senna
- bisacodyl
- castor oil
- glycerin
- sodium picosulfate
What are side effects of simtulants?
- cramping
- fluid/electrolyte imbalances
What stimulant has an unusual adverse effect?
Senna
-yellow-brown/red-pink urine
-brown discoloration of the colon (melanosis coli)
What stimulant is used in pre-colonoscopy bowel prep?
sodium picosulfate
What are saline agents?
What types of agents are these?
contain poorly absorbed ions that increase water retention in the stool -> increasing volume -> shortens transit time
magnesium/phosphate salts
What drug interaction and cautions are there in saline agent use?
Drug interactions:
-diuretics (electrolye disturbances)
Cautions with use in:
- renal disease
- CHF/HTN
What are osmotic agents?
What types of agents are these?
attract and retain water -> increasing moisture, softness, and volume
- small quantities act as laxatives (1-2 days)
- large quantities act as cathartics (hours)
Agents:
- lactulose
- magnesium citrate
- sorbitol
- polyethylene glycol
What osmotic agent is used in bowel prep for surgery?
polyethylene glycol in large doses
What osmotic agent is used for liver disease with hyperammonemia?
lactulose
