Constipation, Diarrhea, & IBS Flashcards
Rx meds that cause constipation
opioids anticholinergics TCAs CCBs *Verapamil!! anti-Parkinson's meds antipsychotics
OTC meds that cause constipation
antacids
Ca & Fe supplements
anti-diarrheals (including bismuth)
“Red Flags” that indicate further WU
recent onset of constipation in pts >50yrs obstructive sx rectal bleeding weight loss FH of colon CA Fe deficiency anemia Heme (+) stool
before starting meds, pts should make sure they are optimizing _____ & _____
fluid & fiber intake
Acute/Subacute constipation options
- bulk laxatives (OTC)
- stool softeners (OTC)
- saline laxatives (OTC)
- stimulant laxatives (OTC)
- hyperosmolar laxatives
- lubricant laxatives
- suppositories
- enemas
- perineal massage
all bulk laxatives are what type of fiber?
soluble fiber
are bulk laxatives helpful with OIC? (opioid-induced constipation)
nope
contraindications for bulk laxatives
obstructive sx, dysphagia, frail/bed-bound pts
stool softeners MOA
facilitates emulsification of water & fat content of stool to increase the luminal mass –> increased peristalsis
are stool softeners effective?
not really (poo just gets really mushy)
saline laxatives MOA
act as a hyperosmolar agent (draws fluid into gut) –> increases peristaltic action
are saline laxatives tolerated well?
no
stimulant laxatives MOA
alter electrolyte transport & stimulate myenteric plexus to increase peristalsis
what are the 2 main types of hyperosmolar laxatives?
lactulose & polyethylene glycol (PEG 3350)
when do we mainly use lactulose?
- hepatic encephalopathy
- constipation (produces osmotic effect in colon)
when do we use PEG 3350?
- bowel preps (colonoscopy)
- chronic constipation (Miralax!)
what is the biggest ADR associated with lubricant laxatives?
malabsorption of fat-soluble vitamins w prolonged use
MOA of suppositories?
induce evacuation by local rectal stimulation
who should NEVER get a suppository or enema?
pts with neutropenia or thrombocytopenia (distending the colon filled w bacteria is not a good idea for immunocompromised pts)
who is CIC most common in?
women & elderly pts
main sx of CIC?
infrequent BMs (<3/wk)
straining during defecation
lumpy/hard stools
sensation of blockage or incomplete evacuation
need for manual maneuvers to aid with defecation
what types of channels does Lubiprostone act on in the luminal surface of the GI tract?
chloride channels (this stimulates intestinal fluid secretion & decreases transit time of feces)
clinical indications for Lubiprostone
- CIC (ALL adults at any age)
- IBS-C (women >18yrs)
- OIC (chronic non-CA pain)
contraindications of Lubiprostone
pts w known or suspected mechanical obstruction OR mod-severe gatroparesis
Linaclotide & Plecanatide MOA
activate CFTR ion channel which increases the secretion of Cl & HCO3 into the lumen of intestines to accelerate transit time
Linaclotide & Plecanatide clinical use
- CIC
- IBS-C
- only mildly effective though
Prucalopride MOA
selective agonist of 5HT4 receptors which stimulates secretions & increases intestinal transit time
Prucalopride clinical use
CIC ONLY!!
modestly effective
Options to treat CIC?
- Lubiprostone
- Linaclotide
- Plecanatide
- Prucalopride
constipation recommendations for “regular outpatients”
1 dietary/supplemental fiber PLUS H2O & exercise
2 add stimulants* or PEG if step 1 doesn’t work
*Bisacodyl has the most data & can be taken long term
constipation recommendations for “hospitalized / opiate patients”
PEG
*MUST start when opiate is started (especially in the elderly)
what is the best way to treat OIC?
PREVENT IT!!
clinical indications of Methylnaltrexone
- OIC in pts w advanced illness who are receiving palliative care
- OIC in pts taking opioids for chronic NON-CA pain
Naloxegol Clinical indications
-OIC in NON-CA pts
Naloxegol & Naldemedine are substrates of which CYP?
3A4
Naldemedine clinical indications
-OIC in NON-CA pts
1st line for constipation in pregnancy?
bulking laxatives (after increases fluids, fiber, & exercise)
2nd line for constipation in pregnancy?
PEG (still used frequently even though C recommendation)
lactulose is a B recommendation but can cause problems for pts who are lactose intolerant
Other options for constipation in pregnancy?
-stimulant laxatives (bisacodyl»_space;Senna)
long-term use is not recommended (C recommendation)
-stool softeners (docusate; C recommendation)
^be careful, already contained in some prenatal vitamins!
constipation agents that are contraindicated in pregnancy?
Lubricants
- mineral oil (C)
- castor oil (X)
most common type of pediatric constipation
functional or withholding constipation
functional constipation:
constipation w/o an organic cause
what is the main cause of functional constipation?
a painful BM that leads the child to voluntary withholding (bad cycle continues)
what are the 2 categories of pharmacologic tx for functional constipation?
- disimpactions
- maintenance (dietary & medications)
Disimpaction can be performed ___ or ____
manually or pharmacologically
how do you begin disimpactions for pediatrics?
start with oral PEG, NOT enemas or digital disimpaction
–being PEG with a big loading dose (1-1.5g/kg/day) x3 days then decrease to maintenance levels
maintenance dose of PEG for peds?
0.4-1 g/kg/day
titrate as needed for 1-2 soft stools/day
how long should PEG maintenance continue?
at least 6 months (need to break the cycle of holding stools out of fear of pain)
most acute diarrhea is infectious or non-infectious?
infectious
what are the two types of infectious diarrhea?
inflammatory and non-inflammatory
what is the OTC version of bismuth subsalicylate
Pepto Bismol
MOA of bismuth subsalicylate
anti-secretory, anti-inflammatory, & antimicrobial action (against GI bacterial & viral pathogens)
clinical indications of bismuth subsalicylate
- sx tx of mild, nonspecific diarrhea
- prevention & control of traveler’s diarrhea (MUST be non-inflammatory!)
how old should kids be before they can have bismuth subsalicylate?
at least 12yrs…worry about Reye’s syndrome (ASA derivative!)
ADRs of bismuth subsalicylate:
- darkening of tongue & stool
- constipation»_space; impaction (dose-dependent)
- effects of ASA
Loperamides MOA
acts on intestinal muscles via opioid receptors to decrease peristalsis & increase transit time of fevels.
(additionally it increases viscosity an decreases fecal volume and flui/electrolytes)
*it is a poorly absorbed opioid!!
loperamide clinical indications:
acute nonspecific NON-INFLAMMATORY diarrhea
also uncommonly used for IBS-D
what happens when OTC loperamide is abused?
serious arrhythmias & death
can cross BBB at very high doses so patient can get high on opioid-like effects
contraindications to loperamide?
acute IBD or inflammatory infectious diarrhea
2nd line tx for diarrhea (not OTC)
diphenoxylate & atropine
diphenoxylate is an “opioid”. what is its MOA?
inhibits excessive GI motility & propulsion
what discourages abuse of diphenoxylate c/t loperamide?
subtherapeutic amounts of atropine (unpleasant ADRs if too much is taken)
diarrhea management in pregnancy:
generally try to avoid medications d/t safety concerns
is IBS m/c in males or females?
females (2-2.5x more common)
IBS definition:
chronic, intermittent abd pain accompanied by altered bowel habits (dx of exclusion!)
what are the 4 types of IBS?
IBS w constipation (IBS-C)
IBS w diarrhea (IBS-D)
IBD w mixed sx (IBS-M)
IBS unclassified (IBS-U)
physiologic considerations of IBS:
- change in the gut microbiome
- stress response
- sensory & motor fnx of gut
- host genetic factors
since the exact cause of IBS is unknown, the goal of tx is…
symptom control!
bc most IBS tx are only “modestly effective” we should use…
a combined treatment approach
IBS management strategies:
1 stress reduction (v important!)
2 exercise (also v important)
3 diet education/modification (Low FODMAPs?)
4 dietary/supplementary fiber
5 laxatives? (IBS-C; PEG, stool softeners, colonic stimulants)
6 antidiarrheals? (IBS-D)
7 antispasmotics? (help tx abd pain)
recommended (SOLUBLE) fiber intake for adults:
20-40 g/day
when is the best time to take antispasmotic drugs?
PRN for acute attacks of pain or before meals if pts have postprandial sx
Other IBS meds for refractory pts (just know at an awareness level, GI will be managing this!):
- Lubiprostone
- Linaclotide & plecanatide
- Tegaserod
- Tenapanor
- Eluxadoline
- Alonsetron
- Rifaximin
- Antidepressants (TCAs»_space;>SSRIs)
- probiotics
- peppermint oil
- CBT
which drug alters the gut microbiota & reduce mucosal inflammation?
Rifaximin
-VERY costly w just a small benefit
peppermint oil MOA?
antispasmotic properties d/t Ca channel blockade
