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Flashcards in IBS Deck (36):
1

What is IBS

a chronic GI disorder with abdominal pain and altered bowel habits

2

What causes IBS

Visceral hypersensitivity
altered bowel motility
neurotransmitter imbalance
infection
psychosocial factors

3

Symptoms of IBS are

abdominal pain
distention
bloating
indigestion
various Sx of defecation

4

What are the 3 subcategories of IBS

Pain with diarrhea
Pain with constipation
Pain with diarrhea and constipation

5

Patients with IBS can self administer meds to alleviate these Sx

headache
sleep disturbance
MSK chest pain
nausea
heartburn
back pain

6

Foundation for treating IBS is

diet and lifestyle modification
Low FODMAP diet (fermentable oligo-, di-, and monosaccharides and polyols)
Exclude foods that increase flatulence, alcohol, and caffeine
Exercise

7

What foods are in FODMAP

O: wheat, barley, rye, onion, cashew, pistacchio, legumes, chickpeas
D: lactose
M: apple, pear, mango, cherries, asparagus
P: apricots, nectarines, mushrooms
(there are a ton more i didn't write)

8

Pharm therapy principle for treating IBS is

Tx directed at relieving abdominal pain and improving bowel function

9

For diarrhea predominant IBS, initial Tx is

antidiarrheal agent- Loperamide

10

For constipation predominant IBS, initial Tx is

Fiber to soften stool and reduce straining (but be careful bc increased gas production can exacerbate bloating)
1. Psyllium/ispaghula
if this fails, try Polyethylene glycol
Alternate: Lubiprostone, Linaclotide

11

What serotonin receptors are in the gut

Type 3 (5-HT3)
Type 4 (5-HT4)
They are responsible for secretion, sensitization, and motility

12

What is polyethylene glycol

Osmotic laxative
Improves constipation but NOT abdominal pain
Start w/ 17g powder in 8oz water, titrate up or down. Max 34g

13

ADE of PEG are

Bloating
Abdominal discomfort

14

What is Lubiprostone

Prostanoic acid derivative
Stimulates T2 chloride channels in small intestine= increase chloride secretion into sm. int= stimulate intestinal motility and shorten transit time
Good for women 18+ w/ IBS-C, efficacy for men unproven

15

ADE for Lubiprostone are

Nausea 2/2 delayed gastric emptying
Pregnancy category C, increased fetal loss in guinea pigs
Dose must be reduced if w/ severe hepatic impairment

16

What is Guanlyate Cyclase-C Agonist Linaclotide (Linzess)

Stimulates intestinal fluid secretion and transit time
Good for those with persistent constipation where PEG didn't work- improves abdominal pain, bloating, straining, stool consistency, and spontaneous BM x week
290 mcg daily

17

MC side effect of Linzess is

Diarrhea

18

What is Tegaserod

5-HT4 agonist that stimulates the release of NT and increases colonic motility
Used only for emergent Tx of IBS with constipation in women <55 y/o

19

Do we like Tegaserod

No, it was voluntarily removed from the market (except for emergency) 2/2 increased # of CV death

20

What does Loperamide do

Inhibit peristalsis
Prolong transit time
Reduce fecal volume
Decrease stool frequency and consistency, but does NOT relieve bloating, abd pain, or global IBS Sx
Take 2mg 45 min before meal
Good for alternating IBS!

21

What is Eluxadoline (Viberzi)

Mixed mu&kappa-opioid receptor agonist, and delta antagonist
Reduces abdominal pain and diarrhea w/o constipating effects
BUT has abuse potential!

22

Contraindications to Eluxadoline are

biliary d/o
pancreatitis (esp. severe in those w/o a gallbladder)
severe liver impairment (adjust dose)
heavy alcohol use

23

MC ADE of Eluxadoline are

nausea, constipation, abdominal pain
pancreatitis in those w/ biliary d/o or alcoholics
CNS depression

24

What is second line for IBS-D

Bile acid sequestrants (Cholestyramine, colestipol, colesevelam)

25

GI ADE of Bile Acid Sequestrants are

bloating
flatulence
abdominal discomfort
constipation

26

What are 5-HT3 antagonists

Ondansetron, Granisteron, Dolasteron, Palonosteron
Inhibiting this receptor stops the activation of afferent pain sensation from gut to spinal cord/CNS
= Less visceral pain, nausea, and bloating

27

Ondansetron and the other %-HT3 antagonists can also be used to Tx

Nausea and vomiting (zofran!)

28

5-HT3 receptor block on terminals of enteric cholinergic neurons inhibits

colonic motility, esp. in left colon= increased total transit time

29

Alsoteron is good for

women with severe IBS-D who did not respond to conventional therapies, and have been educated on risks
efficacy in men not established- not used for them

30

What are the PK of Alosteron

Very potent 5-HT3 antagonist
rapidly absorbed from GI tract (duration longer than 1/2 life makes it seem)
Extensive hepatic CYP450 metabolism
Renal excretion
Dissociates slower than other 5-HT3 antag. b/c it binds with higher affinity receptors

31

What is the efficacy of Alosteron

Reduce IBS related lower abdominal pain, cramps, urgency, and diarrhea
Leads to reduction in mean # of BM per day, and stool consistency

32

ADE of Alosteron are

rare but serious GI toxicity
Constipation
Hospitalization or surgery
Episodes of ischemic colitis
-Requires FDA approved restricted program

33

Alosteron interacts with

Nothing significant! Even though it is a CYP450 enzyme

34

Chronic abdominal pain in IBS can be treated with

Low dose TCA (Amitryptaline, Desipramine)- they're anticholinergics!
They alter central processing of visceral afferent information; Reduce stool frequency and liquidity; Alter NT receptors (serotonin) affectung visceral sensation

35

What anti-spasmodics are used in IBS

Dicyclomine and Hyoscyamine
They inhibit muscarinic cholinergic receptors in enteric plexus and smooth muscle
Use low dose to avoid autonomic effects
not usually used 2/2 efficacy not convincingly proven

36

ADE of high dose anti-spasmodics are

dry mouth
visual disturbance
urinary retention
constipation
(anticholinergics)