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Pharmacology > CH 21: GI Meds > Flashcards

CH 21: GI Meds Flashcards

1
Q

Nausea and vomiting comes from what?

A 
Drugs, including prescriptions
alcohol
illness
motion sickness
head injury
ETC
  • involves sites in Medulla Oblongata (emetic center or chemoreceptor trigger zone (CTZ)),, including various neurotransmitter systems
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2
Q

Goal of therapy for GI meds

A

reduce feelings of nausea

reduce incidence of vomiting

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3
Q

Phenothiazines

A

Prochlorperazine (Compazine);
Promethazine (Phenergan)
- Often used for mental illness; block dopamine receptors in the CTZ, and possibly cholinergic or histaminergic sites

Side effects:
caution in patients taking other meds that cause CNS depression

  • tend to cause drowsiness/ sedation
  • can lead to extrapyramidal side effects (DA receptors) (drooling, pill-rolling, etc). –> may treat w/ anti-histamines
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4
Q

Anti-histamines

A

Used for mild nausea/ motion sickness
- Block afferents that stimulate nausea / vomiting

  • include:
    Hydroxyzine, Meclisine (Bonine), Dimenhydrinate (Dramamine) and Scopolamine

Side effects:
drowsiness; anti-cholinergic side effects (dry mouth, constipation)

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5
Q

Benzodiazepines

A

(Lorazapam)

  • anxiolytics; beneficial for the anticipation of nausea as well as by activating inhibitory receptors in vomiting center
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6
Q

Serotonin-3 receptor blockers

A

Dolasetron, Granisetron, Ondasetron

Serotonin receptors in CTZ get blocked. Used initially for cancer chemotherapy nausea

  • can lead to headache and gastric pain (in some)
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7
Q

Corticosteroids

A

Used for chemotherapy-induced nausea

- may work through inhibitory for PG’s

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8
Q

Cannabinoids

A

ONLY for nausea & vomiting associated w/ chemo

- believed to work through THC receptors

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9
Q

Neurokinin 1 antagonists

A

Aprepitant (interferes w/ vomiting reflexes)

Can be used with:
5HT-3 blockers
Corticosteroids

(Used to treat nausea and vomiting associated with chemotherapy)

  • NEWEST class of antiemetics
  • Antagonists at the neurokinin type-1 receptors
  • Substance P is a neurokinin neurotransmitter that acts through neurokinin type-1 receptors found in the central and peripheral NS to induce nausea & vomiting
  • FDA approved when used w/ standard antiemetics to prevent PONV in patients undergoing high ematogenic chemotherapy
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10
Q

What causes GERD

A
  • obesity
  • fatty foods, peppermint, chocolate, citrus, tomato, caffeine
  • medications
  • recumbent position
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11
Q

Medications for GERD

A
  • Antacids:
    neutralize stomach acid (thus less reflex to esophagus)
Aluminum hydroxide (Rolaids) (constipation)
Calcium carbonate (TUMS)
Magnesium hydroxide (diarrhea)
  • can get acid rebound&raquo_space; neutral pH stimulates acid secretion
  • take 1 (lasts 2 hrs), take another (last 4 hrs)
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12
Q

H-2 Antagonists

A
  • Histamine causes peripheral cells to release HCl in stomach
  • Histamine acts at an H-2 receptor to induce this response

Cimetidine (Tagamet), Rantidine (Zantac), Famotidine (Pepcid)
- 90% decrease in acid release

Side effects:
confusion in elderly (rare)
headache
dizziness

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13
Q

Zantac (ranitidine)

A
  • relieves/prevents heartburn & acid digestion
  • fast acting
  • all day/all night relief
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14
Q

Anti-cholinergics for acid

A

ACh stimulates proton pump in stomach

Pirenzipine:
Specific for muscarinic receptors in stomach mucosa; blocks secretions w/out dry mouth, constipation, etc of anti- cholinergics

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15
Q

Proton Pump Inhibitors

A

Prevent proton pump (H+/K+ ATPase) from producing acid
(may also be anti-bacterial to H pylori)

Omeprazole (Prilosec)
Lansoprazole (Prevacoid)
Pantoprazole (Protonix)

  • Most effective at treating acid & healing ulcers
    can get acid rebound w/ discontinuing usage
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16
Q

Misoprostol

A

(prost. E1 analog)

- ONLY used to treat ulcers assoc. w/ aspirin (acid inhibitory and mucosa protective)

17
Q

Sucralfate

A

disaccharide (sucrose salt)

- polymerizes over ulcers to heal ulceration

18
Q

Metoclopramide

A

block DA (D2) receptors centrally (anti-emetic), but also cholinergic that increase GI motility and secretions

(restless, drowsiness)

  • can cause extrapyramidal side effects (EPS)
19
Q

Antibiotics

A

Used for peptic ulcer disease, the culprit is usually H pylori

Amoxicillin, Clarithromycin, Metronidazole, tetracycline

20
Q

Algorithm

A

FOR GERD

  1. H2 blockers or proton pump inhibitors
  2. Proton pump inhibitors
21
Q

Anti- diarrheal’s

A

A. Opioids:
lead to reduced GI motility

  • Diphyenoxylate, Loperamide (Imodium: non-prescription) and Eluxadoline
    (no sedation or addiction; don’t cross BBB)
  • Nausea, gut pain, constipation

B. Adsorbents:
Kaolin and pectin (stick to agents that cause diarrhea)
- constipation over long usage

C. Bismuth salicylate:
absorb water, antibiotic action, decrease PG’s… less motility

22
Q

Laxatives

A

“speed up motility”

  • some are “bulk-forming” (Metamucil, citrucel)
  • bind fecal material and pull H20 into GI tract
  • some are stimulants (dulcolax, Senna (Senacot))
  • increase smooth muscle motility in GI tract
  • some are “hyperosmotics” (glycerin, lactulose, MgOH)
  • pull H20 into GI tract
  • some are lubricants (mineral oil)
  • some are chloride channel activators (lubiprostone)

Cathartics: cause rapid evacuation
Metoclopramide: increase motility

23
Q

What is Irritable Bowel Syndrome?

A
  • abdominal discomfort that can be relieved w/ defecation

- occurs often after meals: can alternate b/w constipation and diarrhea; bloating, gassiness, distention

24
Q

Treating Irritable Bowel Syndrome

A

1st: avoid food that trigger, exercise, and reduce stress

use laxatives/ anti-diarrheal’s as necessary

may also use antispasmodics (anticholinergics), including cicyclomine or hyoscyamine (muscarinic blockers), or the chloride channel activator, Lubiprostone

25
Q

7 Common causes of constipation

A 
lack of fiber
dehydration
autoimmune disease
hypothyroid & hashimoto's
food sensitivities
bowel obstruction 
disruption of gut flora
26
Q

Bulk-forming agents

A
  1. absorbs water in GI tract
  2. Viscous, bulky stool distends colon
  3. increase peristalsis, decrease transit time
  4. stool passage
27
Q

What does Irritable Bowel Syndrome reduce?

A
  • smooth muscle/ gut activity

esp for severe diarrhea-predominant IBS (esp women)

Alosetron: 5-HT3 antagonist

28
Q

Anti-emetics

A

decrease nausea and vomiting associated with motion sickness, surgery recovery, or chemotherapy

  • Anti-histamines: meclazine and dimenhydrinate
  • Anti-cholinergics: scopolamine
  • Aprepitant: NK-1 blocker
  • Ondansetron: block 5-HT3 in gut and CNS
29
Q

Emetics

A

Stimulate medullary emetic center

  • Ipecac
  • Apomorphine
30
Q

Other diseases that causes Inflammatory Bowel Disease

A

Crohn’s disease (CD): chronic inflammation along any part of GI tract

Ulcerative Colitis (UC): inflammation in rectum or colon

(symptoms are quite similar and may need endoscopy to differentiate)

31
Q

Ulcerative colitis

A

typically begins in the rectum & may extend continuously to involve the entire colon

  • usually affects ONLY the inner layer of the bowel wall
32
Q

Crohn’s disease

A

most commonly involves the end of the small intestine and beginning of the colon and may affect any part of the GI tract in a patchy pattern

  • may affect ALL layers of the bowel wall
33
Q

Treatments for Inflammatory Bowel Disease

usually anti-inflammatory

A

1) Aminosalicylates (for mild to moderate)
- Sulfasalazine, mesalamine, olsalazine, balsalazine
- reduce PG’s, which reduces production of inflammatory agents

2) Corticosteroids
- Prednisone, hydrocortisone

3) Immunosuppressives
- Azathioprine, methotrexate, cyclosporine

4) Antibiotics:
some evidence that in CD metronidazole or ciprofloxacin work

5) Biological agents:
- Those that block TNF-alpha seem to work, ad TNF-alpha is very pro-inflammatory

  • Infliximab, adalimumab, certolizumab
  • each are monoclonal antibodies that bind to and/or block TNF-alpha activity

6) Other Mab’s:
vandolizumab, ustekinumab

Pharmacology (17 decks)

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