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GI 2 Exam 1 > Pharm - Tx of Nausea and Vomiting > Flashcards

Pharm - Tx of Nausea and Vomiting Flashcards

1
Q

what are the 6 important receptor antagonists in nausea/vomiting reflex

A
  • Serotonin (5-HT3)
  • Neurokinin (NK1)
  • Histamine (H1)
  • Dopamine (D2)
  • Muscarinic (M1)
  • Cannabinoid
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2
Q
  • dolasetron
  • granisetron
  • ondansetron
  • palonosetron
A

serotonin (5-HT3) receptor antagonists

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3
Q

what is the -setron drug that is only indicated for IBS (not N/V)?

A

alosetron

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4
Q

what is the MOA of 5-HT3 antagonists?

A

block serotonin type-3 receptors at vagal nerve terminals and block signal transmission to CTZ

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5
Q

what is the main therapeutic use of 5-HT3 antagonists?

A

CINV, RINV, post-op, NVP (N/V in pregnancy)

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6
Q

what is the most worrisome adverse effect of 5-HT3 antagonists?

A
  • *dose-dependent QT prolongation** (Torsade’s)

- extreme caution when using with other QT-prolonging agents (antiarrhythmics, CCB’s like diltiazem, verapamil)

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7
Q

what is another adverse effect of 5-HT3 antagonists?

A

serotonin syndrome - worry when pt on multiple drugs that are serotonin affectors

  • metabolic instability
  • feel terrible
  • can be life threatening
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8
Q

all 5-HT3 antagonists have short half-lives except which?

A

Palonosetron and sustained-release formulation of granisetron (subQ)
- 24+ hr half-life makes them effective for delayed CINV as a single dose

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9
Q
  • aprepitant
  • fosaprepitant
  • netupitant (combo only w/palonosetron)
  • fosnetupitant (conbo only w/palonosetron)
  • polapitant
A

neurokinin (NK1) antagonists

- moderate antiemetic agents

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10
Q

what are the therapeutic uses for NK1 antagonists?

A
  • most effective when used in combination with 5-HT3 and glucocorticosteroid for CINV
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11
Q

aprepitant is used as prophylaxis for what?

A

post-operative N/V

- given 3 hrs prior to anesthesia

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12
Q

what are the pharmacokinetics of NK1 antagonists?

A
  • netupitant/rolapitant have moderate-major active metabolites, longer half-lives so give once a day
  • mild-moderate inhibition of a few key CYP450 enxymes, but less worried about than H2 and PPI’s
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13
Q
  • diphenhydramine
  • dimenhydrinate
  • hydropxyzine
  • promethazine
  • meclizine
  • cyclizine
A

Histamine (H1) receptor antagonists

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14
Q

what is the unique initial therapy for N/V during pregnancy?

A

Doxylamine (H1 antag) + pyridoxine (Vit B6) = Diclegis (PO)

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15
Q

what is the MOA of anti-histamines?

A

block Histamine type 1 receptors in VC and vestibular system

- agents exhibit varying levels of central anticholinergic properties

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16
Q

what is the treatment for motion sickness/vertigo?

A
  • *meclizine and cyclizine**

- only indication!

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17
Q

what are the adverse effects of anti-histamines?

A

classic anticholinergic effects!

  • drowsiness (CNS depression)
  • dry mouth
  • constipation
  • urinary retention
  • blurred vision
  • hypotension
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18
Q
  • phenothiazines (chlorpromazine, perphenazine, prochlorperazine)
  • metoclopramide
A

Dopamine (D2) antagonists

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19
Q

what D2 antagonist stimulates ACh actions in GI tract, enhancing GI motility and lowering LES tone?

A

metoclopramide

- anti-emetic used to treat gastroparesis/dysmotility (but has no impact on GI secretions)

20
Q

what antagonists exhibit anticholinergic effects?

A

anti-histamines, dopamine antagonists, muscarinic blocker

- effects can be cumulative if taken together (similar to serotonin syndrome)

21
Q

what is scopolamine?

A

muscarinic (M1) antagonists, patch worn for 72 hours

- weak antiemetic agent, used for motion sickness (also used for end-of-life care for excessive secretions)

22
Q
  • dronabinol

- nabilone

A

cannabinoid antagonists

23
Q

what does it mean cannabinoids are FDA-scheduled/controlled?

A

limits on quantity/refill number, etc

24
Q

which cannabinoid antagonist is C-III?

A

dronabinol

25
Q

which cannabinoid antagonist is C-II

A

nabilone (higher abuse potential)

26
Q

what treatment are cannabinoids reserved for?

A

treatment-resistant CINV (last resort d/t FDA-scheduling, but very strong entiemetics)
- appetite stimulation in select patients due to severe disease

27
Q

what is the MOA os cannabinoids?

A

stimulate predominantly-central (CB1) and predominantly-peripheral (CB2) cannabinoid receptors in VC/CTZ

  • GPCR signal transduction results in decreased excitability of neurons
  • minimizes 5-HT3 release from vagal afferent terminals
28
Q

what are the adverse effects of cannabinoids?

A
  • euphoria/irritability
  • vertigo (dizziness)
  • sedation
  • impaired cognition
  • xerostoma
  • appetite stimulation
29
Q

which cannabinoid has a large first-pass effect and is metabolized into ONE active metabolite?

A

dronabinol

NOTE: both have short-time to onset and long duration of action(24-36 hrs)

30
Q

which cannabinoid is metabolized into SEVERAL active metabolites?

A

nabilone, allows fewer doses/day

NOTE: both have short-time to onset and long duration of action(24-36 hrs)

31
Q

when should cannabinoids be used with caution?

A

when in use with other CNS depressants, other cardiovascular agents, and sympathomimetics

32
Q

what is the timeline for acute N/V?

A

occurs <24 hrs after chemo

33
Q

what is the timeline for chronic N/V?

A

occurs >24 hrs after chemo

34
Q

what is the timeline for anticipatory N/V?

A

occurs BEFORE chemo given, customarily in non-treatment-naive patients

35
Q

what is the HIGH-emetogenic drug regimen for chemo patients?

A

3 drugs, 3 days after chemo!

  1. NK1 antag
  2. 5HT3 antag
  3. dexamethasone

*give tx prior to chemo (for acute N/V) and for 3 days after (for delayed N/V)

36
Q

what can be added if 3-drug regimen doesn’t resolve N/V?

A
  • may add olanzapine (D2)

- may add cannabinoid

37
Q

what is the MODERATE-emetogenic regimen for chemo patients?

A

2 drugs, 2 days after chemo!

  1. 5HT3 antag (polanos/granis subQ)
  2. dexamethasone

*give tx prior to chemo (for acute N/V) and for 2 days after (for delayed N/V)

38
Q

what can be added if 2-drug regimen doesn’t resolve N/V?

A
  • may add NK1 antag or olanzapine

- may add cannabinoid if treatment-resistance

39
Q

what is the LOW-emetogenic regimen for chemo patients?

A

1 drug, 1 day after chemo

  • dexamethasone, OR
  • 5HT3 antag, OR
  • metoclopramide or prochlorperazine (less likely)

*give tx day of chemo (for acute N/V)

40
Q

what is the MINIMAL-emetogenic regimen for chemo patients?

A

0 drug regimen!

  • no routine prophylaxis recommended
  • if you need to prescribe, back up to LOW-emetogenic **Segars would probably prescribe 5HT3 antag
41
Q

what is the general principle of breakthrough treatment for chemo-induced N/V?

A 
add one agent from a different drug class to the current regimen
- if not on a D2 antag, give a D2 antag
42
Q

what is the go-to anticipatory emesis prevention/treatment?

A

benzodiazepine

- also important to consider non-pharmacologic measures (relaxation exercises, yoga, acupuncture, hypnosis)

43
Q

what is the standard tx for motion sickness?

A

scopolamine (patch), dimenhydrinate, OR meclizine

44
Q

what is the standard tx for vertigo?

A

meclizine OR cyclizine

45
Q

what is the standard tx for diabetic gastroparesis?

A

metoclopramide

46
Q

second time: what is the step-wise tx for pregnancy induced N/V?

A
  • *Vit B6 with anti-histamine OR 5HT3 antag**
  • dopamine antag
  • steroid OR different dopamine antag

GI 2 Exam 1 (22 decks)

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