Lower GI Pharm - Gauthier Flashcards

1
Q

What is the go-to treatment for diarrhea?

A

Oral rehydration–medication is reserved for significant or persistent diarrhea! Anti-diarrheals treat only symptoms, and may worsen outcomes in infectious etiologies.

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2
Q

What is the mechanism of action of Loperamide?

How is Diphenoxylate different from Loperamide?

A

µ receptor agonist, reduces GI motility.

Diphenoxylate firstly is a prodrug (de-esterified to difenoxin). It also has CNS effects (and so is coadministered with atropine)

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3
Q

What role do bulk increasers and absorbents play in treating diarrhea?

A

(eg Kaopectate, fiber)

Increasing bulk may slow motility and absorb water. Infectious toxins may also be sequestered and removed.

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4
Q

Describe the mechanism of action and side effect profile of the drug indicated for traveler’s diarrhea.

A

Bismuth Subsalicylate; the metal is thought to be anti-secretory, anti-inflammatory, and antimicrobial. Side effects: Black tongue and black stool (product of bismuth + bacterial sulfides)

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5
Q

How would you treat someone with carcinoid-induced diarrhea?

What are some other uses for this drug?

A

Octreotide (somatostatin analog; reduces hormone secretion).

Also for “post-operative dumping syndrome” and stopping active variceal bleeds.

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6
Q

By what 3 mechanisms is constipation treated?

A
  1. Increase retention of intralumenal fluid
  2. Decrease absorption of intralumenal fluid
  3. Increase motility (propulsive, not segmenting)
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7
Q

By what mechanisms does fiber treat constipation?

Side effects?

A

Fermentable (water-soluble) fibers are fermented by colonic bacteria, producing SCFAs which facilitate motility. SE: Gas, bloating.

Nonfermented fiber retains water and increases bulk. SE: (Contraindicated in obstructive constipations)

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8
Q

Milk of magnesia belongs to what class of laxatives?

Describe how this class treats constipation.

A

“Saline cathartics”, a subset of osmotic laxatives.

Mostly consists of inorganic ions that are not absorbed (eg Magnesium, not phosphate)

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9
Q

What is lactulose’s mechanism of action? Side effects?

A

Lactulose is a carbohydrate that reaches the colon undigested. Metabolism by bacteria there generates SCFAs (pro-motility) as well as acidifying and trapping ammonia.

Side effects: Gas, cramping.

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10
Q

How is PEG administered?

Contrast its mechanism of action with that of ducosate salts.

A

As a powder, generally mixed with isotonic Na and K salts.

PEG relies on osmotic effect to reduce constipation. Ducosate salts are anionic surfactants which lower stool surface tension.

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11
Q

Compare and contrast the mechanisms and kinetics of bisacodyl and senna

A

Both are stimulant laxatives which promote diarrhea by irritating the mucosal lining of the colon.

Bisacodyl is a diphenylmethane prodrug, activated by bowel esterases.

Senna is a plant-derived anthraquinone prodrug, activated by colonic bacteria.

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12
Q

Lubiprostone is a ___ analog that activates ____. It is used to treat ____, and has the side effects of nausea, headache, and diarrhea.

A

PGE1 analog, activates chloride channels, to treat chronic constipation and constipation-dominant IBS (not IBD!).

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13
Q

Describe the structure of linaclotide.

What is its mechanism of action?

Side effects?

A

14-amino acid peptide.

Activates GC to increase cGMP both intracellularly (increases chloride/bicarbonate secretion) and extracellularly (decreases visceral pain).

Diarrhea, abdominal pain.

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14
Q

Name two µ opioid receptor ANTagonists.

A

Methylnaltrexone and alvimopan.

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15
Q

What role might a 5-HT3 receptor antagonist play in irritable bowel disease? Can you name such a drug and its side effects?

A

5-HT may underlie the bowel wall sensitivity and motility. Inhibition with a drug like alosetron may improve symptoms at the risk of ischemic colitis (not bolded…)

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16
Q

When are steroids indicated in the treatment of IBD?

How do patients generally respond to them?

A

For moderate to severe attacks.

Response stratified into responsive & non-dependent (40%), responsive & dependent (40%), and unresponsive (20%).

17
Q

Distinguish between budesonide and prednisone.

A

Both are corticosteroids for the treatment of IBD. Budesonide is enteric-coated and is directed more towards Crohn’s.

18
Q

What is the mechanism of action of 5-ASAs?

Can you name 3 such drugs? Which are azo drugs?

A

5_ASAs have an unclear mechanism; they may inihibit IL-1/TNF/LPO, and may scavenge free radicals.

Mesalamine, Olsalazine (*azo prodrug), Sulfasalazine (*azo prodrug)

19
Q

Compare and contrast the kinetics and side effect profile of Mesalamine, Olsalazine, and Sulfasalazine.

A

Mesalamine: Available delayed or pH-dependent release. SEs: Headache, dyspepsia, skin rash.

Olsalazine: Prodrug converted to mesalamine. SEs: Diarrhea

Sulfasalazine: Prodrug converted to mesalamine. SEs: Fever, malaise, vomiting, headache.

20
Q

What role do immunosuppressors (not steroids) play in treating IBD?

Name three. What is each one used for?

A

Reduce the inflammatory response.

Azathioprine (+6MP; both), Methotrexate (Crohn’s), Cyclosporine (UC).

21
Q

Name 3 immunoglobulins against TNFa.

What is the mechanism of the fourth remaining immunotherapy?

A

Infliximab, Adalimumab, Certolizumab (actually a Fab fragment)

Natalizumab, binds 4-integrin to reduce leukocyte extravasation.

22
Q

What side effects are seen in biological TNFa inhibitors such as Infliximab?

A

Lupus-lke symptoms, delayed hypersensitivity, increased infections (URIs), non-hodgkin lymphomas.

23
Q

What extremely bizarre method is being researched as a potential therapy for IBD?

A

Helminths and helminth-associated molecules, which may reduce disease activity.

They’re not only for victorian women anymore!