Pharm - Diarrhea, Abd Pain, and Constipation Flashcards
what are the 4 families of drugs used to treat diarrhea
- prostaglandin inhibitors
- opioid agonists
- serotonin (5HT3) antagonists
- chloride channel inhibitors
list the prostaglandin inhibitors used to treat diarrhea
bismuth
list the opioid agonists used to treat diarrhea
- loperamide
- diphenoxylate
- eluxadoline
list the serotonin antagonists used to treat diarrhea
alosetron
list the chloride channel inhibitors used to treat diarrhea
crofelemer
MOA loperamide
direct action on circular and longitudinal muscles of intestinal wall to interfere with peristalsis
side effects loperamide
dizziness, fatigue, drowsiness, urinary retention (anticholinergic)
why is atropine added to diphenoxylate
to discourage deliberate abuse/over-dosage
MOA diphenoxylate
exerts effects locally and centrally on GI smooth muscle cells to inhibit GI motility and slows excess GI propulsion
side effects diphenoxylate
dizziness, drowsiness, urinary retention (anticholinergic, atropine)
MOA eluxadoline
agonist at opioid mu and kappa receptors to slow peristalsis and delay digestion
antagonist at delta opioid receptors to decrease secretions
indications for eluxadoline
IBS with diarrhea (DIARRHEA ONLY)
side effects eluxadoline
- GI related (n/v/d/abd pain)
- hepatic/pancreatic toxicity (PANCREATITIS)
- CNS related (dizziness, sedation, euphoria, impaired cognition)
contraindications eluxadoline
- biliary duct obstruction
- alcoholism
- history of pancreatitis
- hepatic impariment
when should you stop eluxadoline therapy
if severe constipation develops and lasts 4+ days
MOA alosetron
selectively blocks GI-based 5HT3 receptors (serotonin antagonist)
indications for alosetron
chronic, severe IBS with diarrhea (women)
female patient with severe IBS-D comes in and is not responsive to other conventional therapies, what should you give her
alosetron
side effects alosetron
- GI: CONSTIPATION, dyspepsia, GERD, N/V
- ISCHEMIC COLITIS
which drug has ischemic colitis as a possible side effect
alosetron
what must occur in order to prescribe and refill alosetron
- no refills w/o follow up exam
- physicians must enroll in prescribing program
- pts & physicians must sign risk-benefit statement
- additional self-training and testing
contraindications to alosetron
history or active:
- GI obstruction, perforation, stricture, adhesions, toxic megacolon
- diverticulitis, crohn’s, UC
- impaired intestinal circulation
- severe constipation
MOA crofelemer
inhibits chloride ion secretion by blocking cAMP-stimulated CFTR and Ca2+ activated chloride channels
indications for crofelemer
NON-INFECTIOUS diarrhea in HIV/AIDS patients on RETROVIRAL THERAPY
what is the drug indicated for non-infectious diarrhea in HIV/AIDS patients on retroviral therapy
crofelemer
side effects crofelemer
GI: abd distention, elevated AST/ALT/bilirubin
Infections (pts are immunocompromised)
list the antimuscarinic agents used for abd pain in IBS
- hyoscyamine
- dicyclomine
- clidinium/chloridazepoxide
MOA antimuscarinic agents for abd pain in IBS
competitively inhibit autonomic, post-ganglionic cholinergic receptors to decrease GI motility and spasms
indications for antimuscarinic agents in IBS
abdominal pain/spasms
side effects of antimuscarinics for abd pain/spasms in IBS
classic anticholinergic effects
- dry mouth
- urinary retention
- constipation
- drowsiness
- mental confusion
- blurred vision
list the peripheral opioid antagonists used for constipation
- methylnaltrexone
- naloxegol
- alvimopan
list the guanylate cylase-C agonists used for constipation
linaclotide
list the selective chloride (C2) channel activators used for constipation
lubiprostone
MOA linaclotide
binds to guanylate cyclase-C of intestinal epithelium and increases concentration of cGMP –> activation of CFTR –> stimulates secretion of Cl-/HCO3- into lumen
indications for linaclotide
- IBS-C
(IBS constipation predominant subtype) - chronic idiopathic constipation (CIC)
side effects linaclotide
- diarrhea
- GERD/dyspepsia/N/V
MOA lubiprostone
a prostaglandin E1 analog that increases intestinal fluid secretion by activating GI specific Cl- channels
indications for lubiprostone
- IBS-C (IBS constipation predominant subtype) - women
- chronic idiopathic constipation (CIC)
- OPIOID INDUCED CONSTIPATION
side effects lubiprostone
nausea, dyspepsia, dizziness
MOA methylnaltrexone
antagonizes peripheral mu-opioid receptors
indications for methylnaltrexone
- opioid induced constipation
what drug is used as prevention against postoperative ileus
alvimopan
indications for alvimopan
prevention of postoperative ileus
side effects methylnaltrexone
abd pain, diarrhea, nausea, vomiting
warnings for alvimopan and what are the REMS limitations
carries a risk of MI
REMS: requires use only in approved institutions for maximum of 15 doses
list the stimulants of the laxative and cathartic agents
- bisacodyl
- castor oil
- glycerin
- senna
- Na+ picosulfate
list the osmotics of the laxative and cathartic agents
- lactulose
- mag citrate
- polyethylene glycol
- sorbitol
list the salines of the laxative and cathartic agents
Magnesium hydroxide
Na+ phosphate
list the bulk forming substances of the laxative and cathartic agents
- dietary (fiber/bran)
- fruits/grains/cereal
- psyllium
- methylcellulose/carboxymethylcellulose
- calcium polycarbophil
list the stool softeners of the laxative and cathartic agents
- docusate
- mineral oil
MOA of bulk forming agents used for constipation
work to increase bulk-volume and water content to increase GI motility
adverse effects bulk forming agents
bloating/obstruction
drug interactions with bulk forming agents
LOTS mainly with psyllium and the celluloses
MOA stool softeners
anionic surfactants that soften/lubricate the feces
- increase fluid secretion into GI tract
- inhibit water reabsorption
- mineral oil penetrates stool to soften
how long does it take for stool softeners to take effect
1-3 days
adverse effects of stool softeners
GI related
when is sodium picosulfate used
pre-colonoscopy bowel prep
MOA stimulants
Na+/K+ ATPase inhibition and/or increase in prostaglandins –> irritation and inflammation to enterocytes –> stimulates peristalsis
how does castor oil promote water/electrolyte accumulation in the GI tract
it is hydrolyzed to ricinoleic acid
how does glycerin act as a stimulant
it functions as an irritant, an osmotic agent, and a lubricating agent
when do stimulants take effect
12-36 hours (sooner w/ glycerin)
adverse effects stimulants
- abd cramping
- urine discoloration (with senna)
- fluid/electrolyte disturbances
what drug taking for constipation will discolor the urine
senna
contraindications of stimulants
GI obstruction/ileus/impaction
cautions for prescribing stimulants in pregnant women
several of the stimulants pass into the breast milk
MOA saline agents
magnesium and phosphate ions are poorly absorbed in the GI tract so they osmotically retain water in the GI tract
drug interactions w/ saline agents
diuretics
cautions when prescribing saline agents
pts w/ renal disease and CHF/HTN
MOA osmotic agents
work to osmotically attract and retain increased water in the colon
other than constipation, what is lactulose used for
severe liver disease pts with hyperammonemia
adverse effects osmotic agents
electrolyte disturbances, GI related issues
other than constipation, what is polyethylene glycol used for
LARGE doses used for bowel prep prior to GI scopes, radiological procedures, or surgery
(small doses are for constipation)
