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GI drugs Flashcards

1
Q

What is neostigmine and how is it used in the GI?

A

Neostigmine is a cholinergic agent used as a pro kinetic that reversibly inhibits acetylcholinesterase

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2
Q

What is domperidone and how is it used in the GI?

A

Domperidone inhibits the effects of dopamine in the myenteric plexus, but does not penetrate the BBB/CNS (i.e. pro kinetic)

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3
Q

What is the effect of dopamine on the GI system?

A

Dopamine inhibits gastric motility and reduces lower esophageal and intragastric pressure by reducing acetylcholine release

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4
Q

What is the drawback of other dopamine antagonists, like phenothiazines?

A

The phenothiazines are effective, but produce extrapyramidal side effects

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5
Q

What is metoclopermide and how is it used in the GI?

A

Metoclopramide is a pro kinetic that increases motility through stimulation of 5-HT4R on interneurons that facilitate acetylcholine release

  • it also inhibits D2R
    • Serotonin receptor agonism + dopamine receptor antagonism
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6
Q

What are the effects of metoclopramide on the GI system?

A
  • Increased resting esophageal sphincter tone
  • Improved gastric tone and peristalsis
  • Relaxes pyloric sphincter
  • Augmented duodenal peristalsis
  • Combined effect of metoclopramide on the GI tract leads to increased gastric emptying and decreased transit time through the duodenum, jejunum & ileum
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7
Q

What are the adverse drug effects of metoclopramide?

A

Rare extrapyramidal effects

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8
Q

What peptide regulates the MMC (migratory motor complex)?

A

Motilin

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9
Q

How is erythromycin used in GI?

A

Erythromycin is a macrolide antibiotic, and a motilin agonist that enhances upper GI motility with little or no effect in the colon.
- Useful in gastroparesis.

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10
Q

What drug can be used instead of erythromycin to promote upper GI motility?

A

Azithromycin

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11
Q

Why is erythromycin and azithromycin use limited?

A

The utility of macrolide antibiotics is limited by tolerance and antibiotic effects

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12
Q

What drug may serve as a motilin agonist (pro kinetic)?

A

Camicinal is a new, non-macrolide small molecule with potential to serve as the next generation motilin agonist

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13
Q

What new drug has demonstrated promise as a ghrelin agonist (pro kinetic)?

A

Relamorelin

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14
Q

What regulates the central emesis center?

A

Central emesis centers are regulated by 5HT3R, D2R, and opioid receptors.

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15
Q

What is the chemoreceptor trigger zone?

A

The Chemoreceptor Trigger Zone (CTZ) lacks a blood brain barrier and can therefore monitor blood and cerebrospinal fluid for toxicants.
- Feedback from gut to CTZ comes from vagal afferents and neurons enriched with receptors for enkephalins, histamine, and acetylcholine

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16
Q

What drugs are used to block severe vomiting?

A

phenothiazine, metoclopramide, or domperidone, are commonly used for serious vomiting and act by blocking D2R in the CTZ.

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17
Q

What drug is useful in acute vomiting situations but not chronically?

A

Phenothiozines are useful in acute or emergency situations, but have too many extrapyramidal side effects to warrant chronic use.

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18
Q

What drug is used for chemo-therapy induced vomiting/nausea?

A

High dose metoclopramide is more effective for use in chemotherapy-induced nausea due to its prokinetic effects

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19
Q

What is odansetron?

A

Odansetron is a 5HT3R antagonist used in the treatment of nausea, especially that which originates in the gut
- blocks 5HT3R on afferent vagus nerves

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20
Q

What are the indications for odansetron use?

A

Effective against chemotherapy or irradiation-induced nausea; also in pregnancy

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21
Q

What is dronabinol?

A

Dronabinol: a cannabinoid useful prophylactically for cancer chemotherapy-related nausea
- Stimulates a patient’s appetite; approved for AIDS-related anorexia and HIV wasting syndrome

22
Q

What drug/class of drug is effective for motion sickness induced nausea?

A

Diphenhydramine => anti-histamine (H1 antagonist)

23
Q

What drug/class of drug is effective in vestibular disorders and motion sickness?

A

Scopolamine patches => muscarinic antagonists

24
Q

What drug is most commonly used in combination anti-emetic therapy?

A

Dexamethasone (a glucocorticoid steroid) is the most commonly used agent in combination anti-emetic therapy

25
What is an example of a natural anti-emetic?
Ginger
26
What treatment is the cornerstone to significant diarrhea?
Oral rehydration therapy is a cornerstone treatment of patients with significant diarrhea. - Sodium and chloride absorption is linked to glucose uptake by the enterocyte; this is followed by the movement of water in the same direction.
27
What other drugs can be used for diarrhea?
Metamucil Kaopectate Pepto-Bismol Loperamide (opioid) => use octreotidewhen loperamide fails Clonidine => alpha 2 adernergic antagonist
28
What are antacids and what are they used for?
Antacids neutralize gastric acid but do not alter acid secretion (raise pH to inactive pepsin) - Most clinically useful preparations are combinations of aluminum or magnesium hydroxide - Liquids are more effective than tablets.
29
What are the changes in bowel habits that can be seen in antacids?
Aluminum hydroxide can cause constipation | Magnesium hydroxide has laxative properties
30
What is cimetidine?
Cimetidine is an H2-receptor antagonist used to block basal acid release (most effective against nocturnal acid release) - Highly effective when given between evening meal and bedtime
31
What is the cause behind cimetidine's side effects?
Cimetidine inhibits metabolism by cytochrome P450
32
What is omeprazole and how does it work?
Omeprazole is a PPI (which are all prodrugs) that covalently and irreversibly blocks proton pumps
33
What are the indications of use for omeprazole?
Short term treatment/prevention of: - GERD (gastroesophageal reflux disease) - Peptide ulcer disease - Erosive esophagitis - H. pylori eradication (“triple therapy” in combination with 2 antibiotics)
34
What are the effects of PPIs (omeprazole) if they are used long term?
- Increased C. difficile infections; risk of fractures; acute interstitia nephritis - Also: hypomagnesemia, thrombocytopenia, iron deficiency, vitamin B12 deficiency, rhabdomyolysis
35
What is Alosetron (Lotronex)?
Alosetron is a 5-HT3 receptor antagonist used for IBS | - It works by reducing motility and intestinal sensitivity to distension
36
What is Tegasarod?
Tegasarod is a 5-HT4 agonist intended for short-term treatment of women with IBS-C, or chronic constipation. - Relieves pain, bloating and constipation. - Can induce mild to severe diarrhea, which is dose-dependent. - There may also be increased risk of ischemic colitis * ONLY USED EMERGENTLY
37
How do we treat mild/moderate IBD?
Mild to moderate disease is treated with sulfasalazine/mesalamine and steroids.
38
What is used for IBD patients who cannot take steroids?
Steroid refractory or intolerant patients are treated with methotrexate or cyclosporine for short-term efficacy and azathiopurine/6-mercaptopurine for long-term therapy.
39
What is sulfalazine?
Sulfalazine is a prodrug (active metabolite--> Mesalamine) used to treat mild to moderately active UC. - Major action is anti-inflammatory - Not given to patients with sulfa drug or salicylate allergies. - Azo linkage in sulfalazine prevents it from being absorbed in the stomach or small intestine (localized to the colon => for UC)
40
What is the preferred agent for moderate/severe IBD?
Prednisone (watch for toxicity/side effects)
41
What steroid is approved for mild/moderate Crohn's in the ileum/colon?
Budesonide is a locally active glucocorticoid that is approved for oral treatment of mild to moderately active Crohn’s Disease involving the ileum and/or the ascending colon.
42
What may cause serum concentrations of Budesonide to increase?
P450 inhibitors (ie erythromycin, ketoconazole, or grapefruit juice)
43
What is Azathioprine/6-mercaptopurine?
Prodrug (and metabolite) that are immunosuppressive agents used to treat moderate to severe IBD and to maintain remission. - takes weeks to see results
44
What major side effects are associated with azathioprine/6-mercaptopurine?
Major side effects are bone marrow depression, leukopenia, teratogenesis.
45
What is methotrexate?
Methotrexate is an alternative immunosuppressant used for IBD - More effective for Crohn’s disease than in UC
46
What types of IBD patients can use metotrexate?
Methotrexate is reserved for patients with IBD that is steroid-resistant or steroid-dependent, although treatment has largely been replaced by biological therapies
47
In what patients should biologicals for IBD not be used in?
Potentially dangerous in individuals with chronic infections, cancers, or immune deficiencies
48
What is the drawback to biologicals in IBD treatment?
Possible induction of neutralizing antibodies (“antidrug antibody” or ADA), with loss of response to drug
49
How does infliximab work in IBD patients?
TNF-alpha is over produced in IBD patients => leads to pro-inflammatory cytokine production - Infliximab is an mAbs targeting TNF-α (infliximab, adalimumab, and certolizumab) => induce the formation of regulatory macrophages with immunosuppressive properties - This population of macrophages inhibits proliferation of activated T cells and produces anti-inflammatory cytokines
50
How does natalizumab work in Crohn's patients?
Natalizumab, a humanized mAb specific for integrin α4 * integrins are essential for regulation in cell growth and function
51
How does vedolizumab work in Crohn's patients
Vedolizumab, humanized mAb specific for integrin α4β7

Block 4 Pharm (5 decks)

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