GI: Emesis Flashcards
(35 cards)
the two areas vomiting is triggered and WHERE
*which is sensory and motor ?
BRAINSTEM:
1. chemoreceptor Trigger zone–SENSORY mechanism of vomiting
- Vomiting Center–now called central pattern generator–MOTOR mechanism of vomiting
which zone is outside the BBB
chemoreceptor trigger zone
% of patients who experience N/V who undergo chemo
70-80%
why is it good that the Chemoreceptor trigger zone is outside the brainstem
it can respond DIRECTLY to chemical stimuli in the blood or CSF
the Vomiting Center responds to?
afferent input from:
- vestibular system
- periphery (pharynx/GI tract_
- higher brainstem and cortical structures
vestibular system mainly plays a role in?
motion sickness
emetic actions of chemotherapeutic agents
- directly activate?
- which NTs are involved
- peripherally?
- reflex response?
- directly activate the medullary Chemoreceptor trigger zone or vomiting center
- dopamine receptor type 2 and serotonin type 3 (5-HT)
- color of the drugs or smells can even trigger vomit reflex
- act peripherally: damage cells in GI tract–they release serotonin from enterochromaffin cells of SI–serotonin then activates 5-HT3 receptors on vagal and splanchnic afferent fibers–carry signal to medulla–emetic response
list common clinic uses for anti-emetics
*post-op
*opiates
*radiotherapy
*chemotherapy induced Nausea and vomiting (CINV)
*
which tx regimen works best for CINV
COBMO regimen
list the 7 categories of anti-emetics
- Phenothiazines
- 5-HT3 rec blockerrs
- Substituted Benzamides
- Butyrophenones
- Benzos
- Coticosteroids
- Substance P/Neurokinin-1 receptor antagonists
list the drugs under Phenothiazines
*ending?
Prochlorperazine
Chlorpromazine
-AZINE
Prochlorperazine
- drug class
- MOA
- routes of admin
- onset of action
- indications
- SE
- BBW?
class: Phenothiazines
MOA: block dopamine receptors in CTZ. Increasing the dose will improve anti-emetic effect
Indications: low or moderately emetogenic (causing vomiting) chemotherapeutic agents (such as fluorouracil and doxorubicin)
Routes: PO, IM, IV, Rectal
OOA: 10-20 mins for IV, IM
SE: dose dep
- extrapyramidal signs
- ECG abnormalities
- hypotension
BBW: in US for eldery–incr rate of mortality
which drug classes work good for motion sickness
anticholinergics–esp Scopolamine
and
H1 receptor antagonists–Dimenhydrinate, Meclizine, Cyclizine
List the 5-HT3 receptor blockers
*end in?
-setron
dolasetron
granisetron
ondansetron
palonosetron
5-HT3 receptor as a class:
- MOA
- inidcations (very effective for? Less effective for?)
- OOA
- DOA/ T1/2
- Routes of admin and timing of admin
- metabolism
- SEs
*MOA: selectively block serotonin or 5-HT3 receptors in periperhy (visceral vagal afferent fibers) AND in brain (CTZ)
- Inds:
1. very effective in CINV and Post-op N/V both ADULTS AND KIDS can be given as a single dose before chemo*
2. less effective at suppressing acute nausea (motion sickness) - OOA: rapid
- DOA and T1/2: Long
- Routes: IV and PO–same effectiveness. can be given as a single dose before chemo session
- metabolism: HEAVILY hepatic… adjust dose for hepatic dz PTs
SE:
- QT Prolongation (high doses of ondansetron + dolasetron)
- HA
- serotonin syndrome
- GI
Which 5-HT3 receptor drugs are effective in preventing emesis in PTs treated with Cisplatin (chemo)
*also with post-op N/V
Ondansetron
Granisetron
which is the only 5-HT3 rec blocker that needs adjustment dosing for hepatic insuff PTs
ondansetron
where is 5-HT3 rec found and what kind of receptor
GI tract
*ligand gated ion channel
Metoclopramide (reglan)
- drug class
- MOA (3)
- indications
- routes
- metabolized where
- OOA for all routes
- SEs
*class: Substituted Benzamide
- MOA:
- acts as dopamine antagonist centrally and peripherally aka inhibits dopamine in the CTZ
- it is a weak 5HT3 antagonist at high doses
- stimulates cholinergic receptors on gastric smooth muscle cells (increases gastric motility) and AcH release at NMJ
*Routes: PO, IV
*OOA
IV: 1-3 mins
PO: 30-60 mins
*metabolized in kidneys–renal function impairment need to adjust dose
- indications:
- good/mainly used for gastroparesis
- modest anti-emesis effect for CINV
SE:
-tardive dyskinesia– involuntary movements of the face and jaw.
-dystonia–a state of abnormal muscle tone resulting in muscular spasm and abnormal posture
(movement s/e bc MOA acting on NMJ)****
relationship b/w dopamine and serotonin
dopamine is a weak serotonin antagonist
list the drugs that are Butyrophenones
Droperiodol
Haloperidol
first gen antipsychotics
Butyrophenones as a class:
- MOA
- BBW
- indications
- DOA and T1/2
- SE
MOA:
- dopamine antagonists–1st gen antipsychotics
- they act as tranquillizers that potentiate the effect of opioids
BBW: increased mortality in elderly
INDS:
- pre-anesthetic sedation
- moderately effective anti-emetics (post-op**) BUT not the 1st drug we reach for
DOA:
- droperidol short acting
- Haldol is longer acting bc longer half life (18 hrs)
SE:
- QTc»_space;»
- Torsades
name the benzos used as anti-emetics
Alprazolam–xanax
Lorazepam–ativan
Benzos as a class:
Indications
Anticipatory vomiting (esp for chemo patients)
- sedative
- anxiolytic
- amnestic
antiemetic potency is LOW*
