Lower GI Drugs Flashcards
What is the best treatment for an active episode of Crohns or Ulcerative Colitis?
corticoteroid/prednisone
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?
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)
Your patient needs a colonoscopy. What medication can you give for preparation and how does it work?
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
For which medical condition is Mg(OH)2 contraindicated
and why?
Renal insufficiency because it can cause hypermagnesemia
Loperamide is a mu opioid receptor agonist. Why does it have a low level of drug abuse?
It has poor GI absorption so there is no effect on pain.
When is loperamide contraindicated and why?
Ulcerative colitis and acute dysentary because it can cause toxic megacolon
What is the first line treatment for ulcerative colitis?
What is the MOA?
Mesalamines (sulfasaline)
MOA: interferes with intermediate metabolites re inflammation
True or False?
Sulfasalazine should be given topically as an enema or suppository.
True
It is not given systemically.
Your patient has moderate chronic ulcerative colitis. You tried a 5-ASA and it did not work. What do you try next?
A thiopurine anti-metabolite such as azathioprine.
What are the side effects of mesalamines (5-ASAs such as sulfasaline)?
What percentage of patients cannot tolerate them?
Why is that?
Side effects: nausea, diarrhea, HA, hypersensitivity, bone marrow suppression
Up to 40% cannot tolerate
Determined by genetics concerning enzyme coding
What is the concerning side effect of azathioprine?
Bone marrow suppression
What is the MOA of infliximab (Remicade)?
It is an antibody to TNF alpha: it binds and blocks the inflammatory effects
What are the side effects for infliximab?
Increased risk of infections
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?
It decreases colonic motility via CNS blockade of 5HT3 and can cause fatal ischemic colitis. (rare)
Antibiotics are helpful for which form of Inflammatory Bowel Disease?
Which ABX to you prescribe?
Crohns
Prescribe: metronidazole or Ciprofloxacin
When are laxatives/cathartics contraindicated?
Cramps, colic, nausea, vomiting, appendicitis or other undiagnosed abdominal pain
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?
Loperamide is less likely to cross the blood brain barrier
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?
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)
