Antiemetics Flashcards Preview

Summer pharm 4 > Antiemetics > Flashcards

Flashcards in Antiemetics Deck (37):
1

What causes nausea

Physiologic, Metabolic, Treatment related, and Emotional.spiritual/psych all transmit signals to the Vomiting center of the brain AKA the lower medulla

2

What receptors are associated with nausea and vomiting

Cytotoxics, opiates: D2, 5HT3, NK1
Pain, anxiety, depression: H1, GABA in cortex and thalamus
Vertigo, motion: AChM, H1 in vestibular system
Cytotoxics, gastric irritants, ipecac: 5HT3 in GI
ALL those report to Emesis center receptors: AChM, H1, 5HT3, mu, and NK1

3

What is the "vomiting center"

Neuronal region in lateral medullary reticular formation
Coordinates vomiting thru CN VIII and X (control respiratory, salivatory, and vasomotor centers)
High concentrations in M1, H1, NK1, D2, GABA, and 5-HT receptors in the vomiting center

4

What are 4 important sources of afferent input to vomiting center

1. Chemoreceptor trigger zone: emetogenic stimuli
2. Vestibular system: motion sickness
3. Vagal and spinal afferent nerves (from GI): chemo, radiation, distention, gastroenteritis
4. CNS: psych d/p, stress, anticipatory vomiting before chemo

5

How does N/V present

Simple: self limiting, resolves spontaneously, requires Sx therapy. complain of "queasy" or discomfort
Complex: no relief after anti-emetic. Noxious agents or psych events. can cause weight loss, fever, abdominal pain

6

What lab tests can you get for n/v

simple: none
complex: Electrolytes, upper and lower GI eval
Both: fluid input/output, Med history, recent behavior or visual change, HA, pain, stress, or FHx of psychogenic vomiting

7

Treatment of choice for n/v involves

ID of neurotransmitters involved with emesis!
Can use combo meds that have different MOA, esp if vomiting 2/2 chemo

8

MC drugs used are

Antacids
Antihistamine/anticholinergic
Benzodiasepines
Corticosteroids
5-HT receptor antagonists
Phenothiazine
Substance P/NK1 receptor antagonist

9

When should Antacids be used

Simple N/VUse sodium bicarbonate, calcium carbonate, magnesium hydroxide, or aluminum hydroxide
OTC liquid or oral

10

Slide 14 says ADE

Listen to recording

11

What are the serotonin antagonists (5HT3)

Ondansetron
Granisetron
Dolasetron
Palonosteron

12

What is the PK of 5-HT3 antagonists

Centrally block the 5HT3 receptors, which are in the vomiting center on extrinsic intestinal vagal and spinal afferent nerves

13

Antiemetic action of 5-HT3 antagonists is restricted to emesis attributable to

Vagal stimulation (post-op)
Chemotherapy
-NOT good for motion sickness

14

What is palonosetron

New IV agent with greater affinity for 5HT3 receptors
Has longer half life (40 hours)
-All others have a half life 4-9 hrs and PO or IV

15

What happens to 5HT3 antagonists in the body

Extensive hepatic metabolism
Renal and hepatic excretion
Do not inhibit dopamine or muscarinic receptors
No effect on esophageal or gastric motility
May slow colonic transit**

16

Do you need to adjust 5HT3 antagonists

NO dose reduction in elderly with renal excretion
Only reduce Zofran dose if w/ hepatic insufficiency

17

When should you take 5HT3 antagonists for chemo

IV, 30 minutes prior to getting chemo
PO 1 hr before chemo (but higher doses)
They are preventive, but have little efficacy in curing delayed n/v
Efficacy enhanced if combined w/ corticosteroid (DXM) or NK antagonist

18

5HT3 antagonists are also used for

post-op and post-radiation n/v, esp whole body radiation

19

What are ADE of 5HT3 antagonists

Headache*
Constipation*
Dizziness
QT prolongation (esp. dolasetron)

20

5HT3 antagonists interact with

Nothing significant!
Some CYP450 hepatic metabolism
But do not affect metabolism of other drugs
Slide 22, listen (red question marks)

21

What are NK1 antagonists

Aprepitant (emend), Fosaprepitant, Rolapitant (varubi); Netupitant + Palonosetron (Akynzeo) for acute and delayed prevention
They provide relief from delayed emesis associated with emetogenic meds

22

What are the ADE of NK1 antagonists

Constipation
diarrhea
HA
hiccups

23

What do you monitor when on NK1 antagonists

assess for efficacy as prophylaxis
episodes of n/v and hydration status

24

What antihistamines are used for nausea

Dimenhydrinate (Dramamine) OTC
Diphenhydramine (Benadryl) Rx/OTC
Hydroxizine (vistaril, atarax) Rx
Meclizine (bonine, antivert) RX/OTC
Scopolamine (transderm scop) Rx
Trimethobenzamide (tigan) Rx

25

What is Dramamine used for/ADE

Can cause drowsiness, confusion, blurred vision, dry mouth, and urinary retention
Used for: Episodic relief of motion sickness or n/v

26

What is Meclizine especially good for

Vertigo

27

What phenothiazines are used for nausea

Prochlorperazine (compazine): simple n/v and breakthrough chemo
Promethazine (phenergan)
Chlorpromazine (thorazine): simple n/v

28

What are ADE of phenothiazines

Compazine: *prolonged QT interval, sedation, tardive dyskinesia
Phenergan: drowsy, sedation
Thorazine: constipation, dizziness, tachycardia, tardive dyskinesia

29

What are the Butyphenones good for nausea

Haloperidol (haldol): great for palliative care
Droperidol (inapsine): limited use outside of clinical trial

30

What are the ADE of butyphenones

Haldol: sedation, constipation, hypotension- obs for sedation if used w/ narcotics
Inapsine: QT prolongation, Torsades- ECG prior to admin and 2-3 hours after

31

What benzos are used for nausea

Alprazolam (xanax) Rx: anticipatory n/v, take prior to chemo
Lorazepam (ativan) Rx: give the night before chemo

32

What are ADE of benzos

xanax: dizziness, sedation, appetite changes, memory impairment

33

What corticosteroids can be used for nausea

Dexamethasone, Rx: antiemetic by enhancing efficacy of 5HT3 antagonists
Monitor for nausea, vomiting, and hydration status
Useful as single agent or combo for prophylaxis of CINV and PONV

34

ADE of dexamethasone are

Insomnia
GI Sx
Agitation
appetite stimulation

35

What can cannabinoids be used for nausea

Dronabinol (marinol): Sx relief and refractory CINV. May cause euphoria, somnolence, xerostomia
Nabilone (cesamet): may cause somnolence, vertigo, xerostomia

36

What miscellaneous agents can be used for nausea and vomiting

Metoclopramide (reglan): prokinetics are useful in diabetics with gastroparesis! Watch for asthenia, HA, or somnolence
Olanzapine (zyprexa): breakthrough CINV. watch for sedation

37

What antiemetics can be used in pregnancy

Before meds: dietary changes or lifestyle mod
1. Pyridoxine w/ or w/o doxylamine
Persistence: IV fluids w/ Thiamine
Ondansetron: NVP
Methylprednisolone: refractory NVP or hyperemesis gravidarum