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Block 4 Pharm > GI drugs > Flashcards

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
Q

What is an example of a natural anti-emetic?

A

Ginger

26
Q

What treatment is the cornerstone to significant diarrhea?

A

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
Q

What other drugs can be used for diarrhea?

A

Metamucil
Kaopectate
Pepto-Bismol
Loperamide (opioid) => use octreotidewhen loperamide fails
Clonidine => alpha 2 adernergic antagonist

28
Q

What are antacids and what are they used for?

A

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
Q

What are the changes in bowel habits that can be seen in antacids?

A

Aluminum hydroxide can cause constipation

Magnesium hydroxide has laxative properties

30
Q

What is cimetidine?

A

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
Q

What is the cause behind cimetidine’s side effects?

A

Cimetidine inhibits metabolism by cytochrome P450

32
Q

What is omeprazole and how does it work?

A

Omeprazole is a PPI (which are all prodrugs) that covalently and irreversibly blocks proton pumps

33
Q

What are the indications of use for omeprazole?

A

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
Q

What are the effects of PPIs (omeprazole) if they are used long term?

A
  • Increased C. difficile infections; risk of fractures; acute interstitia nephritis
    • Also: hypomagnesemia, thrombocytopenia, iron deficiency, vitamin B12 deficiency, rhabdomyolysis
35
Q

What is Alosetron (Lotronex)?

A

Alosetron is a 5-HT3 receptor antagonist used for IBS

- It works by reducing motility and intestinal sensitivity to distension

36
Q

What is Tegasarod?

A

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
Q

How do we treat mild/moderate IBD?

A

Mild to moderate disease is treated with sulfasalazine/mesalamine and steroids.

38
Q

What is used for IBD patients who cannot take steroids?

A

Steroid refractory or intolerant patients are treated with methotrexate or cyclosporine for short-term efficacy and azathiopurine/6-mercaptopurine for long-term therapy.

39
Q

What is sulfalazine?

A

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
Q

What is the preferred agent for moderate/severe IBD?

A

Prednisone (watch for toxicity/side effects)

41
Q

What steroid is approved for mild/moderate Crohn’s in the ileum/colon?

A

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
Q

What may cause serum concentrations of Budesonide to increase?

A

P450 inhibitors (ie erythromycin, ketoconazole, or grapefruit juice)

43
Q

What is Azathioprine/6-mercaptopurine?

A

Prodrug (and metabolite) that are immunosuppressive agents used to treat moderate to severe IBD and to maintain remission.
- takes weeks to see results

44
Q

What major side effects are associated with azathioprine/6-mercaptopurine?

A

Major side effects are bone marrow depression, leukopenia, teratogenesis.

45
Q

What is methotrexate?

A

Methotrexate is an alternative immunosuppressant used for IBD
- More effective for Crohn’s disease than in UC

46
Q

What types of IBD patients can use metotrexate?

A

Methotrexate is reserved for patients with IBD that is steroid-resistant or steroid-dependent, although treatment has largely been replaced by biological therapies

47
Q

In what patients should biologicals for IBD not be used in?

A

Potentially dangerous in individuals with chronic infections, cancers, or immune deficiencies

48
Q

What is the drawback to biologicals in IBD treatment?

A

Possible induction of neutralizing antibodies (“antidrug antibody” or ADA), with loss of response to drug

49
Q

How does infliximab work in IBD patients?

A

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
Q

How does natalizumab work in Crohn’s patients?

A

Natalizumab, a humanized mAb specific for integrin α4

  • integrins are essential for regulation in cell growth and function
51
Q

How does vedolizumab work in Crohn’s patients

A

Vedolizumab, humanized mAb specific for integrin α4β7

Block 4 Pharm (5 decks)

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