Constipation & Diarrhea

Question 1

Definition of constipation

Answer 1

no bowel movement after 3 days or difficulty passing stools (straining, incomplete evacuation, etc)

Question 2

Definition of chronic constipation

Answer 2

constipation that persist for several weeks of longer

Question 3

Lifestyle modifications for constipations

Answer 3

incr fluid intake (64 oz/day)
Incr physical activity
eat more whole grains and fiber
avoid delays in going to the bathroom

Question 4

Key drugs that cause constipation

Answer 4

aluminum antacids
anticholingeric drugs 
Non-DHP CCB (dilt, verapamil)
Bismuth
Clonidine
Colesevelam (welchol)
Iron 
opioids
Sucralafate

Question 5

Usual 1st line constipation treatment for most pts

Answer 5

fiber laxative
fiber requires adequate fluid intake
also preferred in pregnant pts

Question 6

If fiber doesn’t work for a pt, what is the next options?

Answer 6

Add osmotic laxative (Miralax, Milk of Magnesia)
or
Stool softener

Question 7

Recommended agent for pts with constipation cause by iron supplements

Answer 7

docusate

Question 8

Preferred agent for pts taking opioids

Answer 8

stimulant +/- docusate

Question 9

Onset of action for stimulant laxatives

Answer 9

~10 hours

recommended to take at bedtime so pt will have bowel movement in the AM

Question 10

Agents used for Bowel Prep

Answer 10

PEGs
sometimes Sodium phosphates (Fleet enema, Osmoprep)

avoid sodium phosphates in pts with renal or cardiac disease –> electrolyte abnormalities

Question 11

MOA of fiber laxatives

Answer 11

create matrix in the stool, which soaks up fluid into the stool and adds bulk to the stool

Question 12

Fiber laxative notes

Answer 12

do not use if GI obstruction
SEs: incr gas, bloating 
Onset: 12 - 72 hrs
Take 2 hours before or after other meds 
requires adequate fluid intake to work properly

Question 13

Available Osmotic laxatives

Answer 13

Milk of Magnesia (Mg hydroxide)
Miralax (PEG 3350)
Glycerin (suppositories)

Question 14

Osmotic laxative notes

Answer 14

SEs: electrolyte abnormalities, gas, dehydration
Onset of action: 30 min - 96 hrs
Suppository onset: 15-30 mins
avoid Milk of Mg in pts with renal impairment

Question 15

Available stimulant laxatives

Answer 15

Senna (Ex-Lax, Senokot) 17.2 - 50 mg QD-BID

Bisacodyl (Dulcolax) 5-15 mg QD (available in supp)

Question 16

Stimulant laxative notes

Answer 16

Avoid use if stomach pain, n/v
SEs: cramping
onset: 6-12 hours
Give 30 mins after a meal, ideally

Question 17

Docusate notes

Answer 17

50-360 mg daily or divided doses
CIs: Abd pain, n/v, use with mineral oil
onset: 12-72 hrs
Use when stool is hard/dry
available as enema as well

Question 18

Mineral oil notes

Answer 18

do not use with docusate (too much mineral oil absorption)
do not use < 6 y/o, pregnancy
risk of aspiration

Question 19

Bowel prep notes

Answer 19

Osmoprep (sodium phospahtes) can cause neuropathy (BBW)
onset of action within 1-6 hours
Clear liquid diet day before colonoscopy
avoid liquids with red or blue/purple food coloring
Prepopik: 150 mL x 2 doses (contains stimulant and osmotic laxatives)

Question 20

MOA of lubiprostone

Answer 20

Amitiza

activates chloride channels in the gut; incr fluid and peristalsis

Question 21

Lubiprostone notes

Answer 21

24 mcg BID for opioid-induced constipation and chronic idiopathic constipation
8 mcg BID for IBS-C
CI: mechanical bowel obstruction
SEs: n/d, HA
take with food and water

Question 22

Linaclotide notes

Answer 22

Linzess
MOA: agonist of guanylate cyclase C --> decr GI transit time
145 mcg daily for chronic costipation
290 mcg daily for IBS-C
Do not use if < 6 y/o, GI obtruction
SEs: diarrhea, abd distension
Keep in original container

Question 23

Plecanatide

Answer 23

Trulance
3 mg daily for chronic constipation
same MOA as Linzess

Question 24

Peripherally acting mu-opioid receptor antagonist used pre-op to reduce risk of ileus

Answer 24

Alvimopan (Entereg)

Do not use in pts who have taken opioids for more than 7 straight days prior to surgery

Question 25

Other peripheral opioid antagonists used for OIC:

Answer 25

methylnaltresone (Relistor)
naloxegol (Movantik)
Naldemdine (Symproic)

Question 26

most common cause of diarrhea

Answer 26

viral infections

most common cause of bacterial diarrhea is E. coli

Question 27

Key drugs that cause diarrhea

Answer 27

Mg containing antacids
Antibiotics (esp broad spectrum)
Antineoplatics
colchicine
laxatives
metoclopramide
misoprostol
quinidine

Question 28

common treatment for non-infectious diarrhea

Answer 28

hydration and electrolyte replacement

loperamide or bismuth subsalicylate

Question 29

Bismuth subsalicylate notes

Answer 29

Pepto-Bismol
1-2 doses every 30-60 mins prn
CI: salicylate allergy, coagulopathy
Caution in pts on ASA, anticoagulants, renal insufficiency
Avoid in children recovering from viral infections (Reye’s syndrome)
Black tounge/black stools

Question 30

Loperamide notes

Answer 30

Immodium
2 tabs after 1st losse stool, then 1 tab (2 mg) for each loose stool
max 16 mg/day
Do not self-treat for more than 48 hrs
Qt prolongation (torsades with higher than 16 mg/ day)
Do not use if bloody diarrhea, C. Diff diarrhea, etc

Question 31

diphenoxylate/atropine notes

Answer 31

Lomotil
Max: 20 mg/ day (given QID)
Rx only (CV drug)
atropine in formulation to discourage abuse

Question 32

Dicyclomine notes

Answer 32

Bentyl
Antispasmodic
max 80 mg/day (given QID) 
take before meals
anticholinergic
caution in mild-mod UC (toxic megacolon)
SEs: dizziness, dry mouth, nausea, blurred vision

Question 33

Eluxadoline

Answer 33

Viberzi
peripheral mu opioid agonist
used for difficult cases of IBS-D
can only be used in pts with a gallbladder
can cause sphincter of Oddi spasm

Question 34

Infants less than 6 mons with diarrhea can be treated with self-care (t/f)

Answer 34

FALSE

must see MD