Lower GI Drugs

Question 1

What is the best treatment for an active episode of Crohns or Ulcerative Colitis?

Answer 1

corticoteroid/prednisone

Question 2

Two laxatives on our list have a laxative effect

by moving chloride into the GI lumen,

which is followed by Na+ and H2O.

One does this directly, the other indirectly. Which is which?

Answer 2

Lubiprostone directly effects the ClC2 channel

Linaclotide indirectly effects the CFTR channel

(It binds to the GC-C channel which causes release of GTP and then cyclic GMP which causes release of chloride from the Cystic Fibrosis Transmembraneconductase Receptor (CFTR)

Question 3

Your patient needs a colonoscopy. What medication can you give for preparation and how does it work?

Answer 3

Mg(OH)2

Hypertonic solution increases osmotic pressure in the lumen drawing in fluids and increasing peristalsis

Cathartic dose causing complete evacuation in <3 hrs

Question 4

For which medical condition is Mg(OH)2 contraindicated

and why?

Answer 4

Renal insufficiency because it can cause hypermagnesemia

Question 5

Loperamide is a mu opioid receptor agonist. Why does it have a low level of drug abuse?

Answer 5

It has poor GI absorption so there is no effect on pain.

Question 6

When is loperamide contraindicated and why?

Answer 6

Ulcerative colitis and acute dysentary because it can cause toxic megacolon

Question 7

What is the first line treatment for ulcerative colitis?

What is the MOA?

Answer 7

Mesalamines (sulfasaline)

MOA: interferes with intermediate metabolites re inflammation

Question 8

True or False?

Sulfasalazine should be given topically as an enema or suppository.

Answer 8

True

It is not given systemically.

Question 9

Your patient has moderate chronic ulcerative colitis. You tried a 5-ASA and it did not work. What do you try next?

Answer 9

A thiopurine anti-metabolite such as azathioprine.

Question 10

What are the side effects of mesalamines (5-ASAs such as sulfasaline)?

What percentage of patients cannot tolerate them?

Why is that?

Answer 10

Side effects: nausea, diarrhea, HA, hypersensitivity, bone marrow suppression

Up to 40% cannot tolerate

Determined by genetics concerning enzyme coding

Question 11

What is the concerning side effect of azathioprine?

Answer 11

Bone marrow suppression

Question 12

What is the MOA of infliximab (Remicade)?

Answer 12

It is an antibody to TNF alpha: it binds and blocks the inflammatory effects

Question 13

What are the side effects for infliximab?

Answer 13

Increased risk of infections

Question 14

Your patient has Crohns. She tried loperamide but it was not effective. She is desperate for a solution to her diarrhea. You consider prescribing Alosetron but its use is restricted. Why?

Answer 14

It decreases colonic motility via CNS blockade of 5HT3 and can cause fatal ischemic colitis. (rare)

Question 15

Antibiotics are helpful for which form of Inflammatory Bowel Disease?

Which ABX to you prescribe?

Answer 15

Crohns

Prescribe: metronidazole or Ciprofloxacin

Question 16

When are laxatives/cathartics contraindicated?

Answer 16

Cramps, colic, nausea, vomiting, appendicitis or other undiagnosed abdominal pain

Question 17

Your patient has Ulcerative Colitis with diarrhea. You prescribed low dose diphenoxylate but cannot increase the dose due to risk of CNS toxicity.

What mu opiod receptor agonist can you prescribe instead?

Answer 17

Loperamide is less likely to cross the blood brain barrier

Question 18

Your patient has been constipated for two days. You are considering how fast you need the treatment to work.

What treatments will solve the problem in 1-3 hours?

In 6-24 hours?

In 1-3 days?

Answer 18

1-3 hours: osmotic laxatives like Mg(OH)2

6-24 hours: stimulant laxatives (bisacodyl/senna), Cl channel activators (lubiprostone, linaclotide), opioid receptor antagonists (alvimopan), 5HT4 receptor antagonist (tegaserod)

1-3 days: bulk forming (psylllim/methylcellulose), stood surfactants (mineral oil)