22-Drugs for Nausea and Vomitting Flashcards
Vomiting is….
Forceful expulsion of stomach contents and the contents of the proximal small intestine
True or False:
Vomiting is a symptom NOT a disease
True
What are some consequences of vomiting?
- Potassium deficiency
- Sodium depletion
- Alkalosis
- Malnutrition
- Esophageal and gastric injury
- purpura
- aspiration pneumonia
the three steps in the act of vomiting
- Nausea
- Retching (‘Dry Heaves’
- Vomiting
What is projectile vomiting and who can do it?
normally for children as they have little food in their stomach and can push it out with greater force
What are the two things that are NOT vomiting?
Regurgitation = Return of previously swallowed food or secretions into the mouth (involuntary)
Rumination = Repetitive, effortless regurgitation of recently ingested food into the mouth followed by re-chewing and re-swallowing (voluntary, purposeful)
Why is nausea called a “psychic” experience?
it is very personal, hard to explain + describe
Physiologically, nausea is associated with… (3)
Decreased gastric motility
Increased small intestinal tone
Reverse proximal small intestinal peristalsis
what are the 5 highly coordinated series of events in vomiting?
- A deep breath,
- The glottis closes and the larynx is raised to open the upper esophageal sphincter
- The soft palate is elevated to close off the posterior nares
4, The diaphragm is contracted sharply downward
- Downward movement of the diaphragm, contraction of the muscles of the abdominal walls
what are the three area in the brainstem that control vomiting
Vomiting Centres (VC)
Nucleus tractus solitarius (NTS)
Chemoreceptor Trigger Zones (CTZ)
why do we think that vomiting has a neurological control?
it is a complex, stereotypical set of activities
why is the location of the CTZ important? where is it?
it is located very close to the fourth ventricle where the blood brain barrier is at it’s thinnest
there is the greatest opportunity here for the CTZ to pick up bad stimuli
where are the bilateral vomiting centers found and what do they do?
found in the reticular formation of the medulla
their activation by electric stimulation induces vomiting
where does the vomiting centers (VC) receive signals from
the chemoreceptor trigger zone & Nucleus Tractus Solitarius
Visceral afferents from the GI tract
Visceral afferents from outside the GI tract
Afferents from extramedullary centers in the brain
What are… Visceral afferents from GI Tract
Vagus or sympathetic nerves
GI distention (very potent),
mucosal irritation
What are… Visceral afferents from outside GI Tract
Bile ducts, peritoneum, heart and a variety of other organs
What are… Afferents from extramedullary centers in the brain
Psychic stimuli (odors, fear)
Vestibular disturbances (motion sickness)
Cerebral trauma
What are the chemoreceoptor Trigger Zones? (CTZ) where are they located?
they are bilateral centers in the brainstem
they detect chemical abdominal for the VC and sends them excitatory signals
True or false:
Like the VC, the CTZ can cause vomiting rom electrical stimulation
False
Only emetic drugs can cause vomiting in the CTZ
how does chemotherapy induce nausea and vomiting?
- Chemotherapeutic drugs directly stimulate the CTZ
- they stimulate GI cells to release serotonin which activates 5-HT receptors in the CTZ, vagal afferents in the git and the nucleus tractus solitarius
why can the cerebral cortex be our friend or enemy?
We can teach ourselves not to vomit until we get to a washroom
But it can create a Pavlov like response to the chemotherapy
what is Anticipatory nausea and vomiting
Occurs before or during therapy in individuals who have had severe symptoms with previous therapy
Triggered by specific odors, tastes, or objects that a patient associates with treatment
what is Acute nausea and vomiting
- occurs within 24 hours after cancer treatment
what is Delayed (late onset) nausea and vomiting
Occurs more than 24 hours after cancer treatment and may continue for several days
Anticholinergics drugs effects and what they are good for treating.
Muscarinic receptor antagonist in the NTS and CTZ
Reduces feelings of nausea and vomiting
Good for motion sickness, not chemo
Antihistamines drugs action and what they treat.
H1 receptors in the NTS and CTZ
Soothes feelings of upset stomach and nausea
Cannabinoids drugs action and what they treat
CB1 receptor in the cortex and VC
Not as good as preventing these feeling but they maintain hunger
Better able to tolerate feelings of nausea and vomiting
Serotonin antagonists actions
5HT3 receptors in the CTZ and NTS
What population is the Serotonin antagonists drug Palonosetron used on vs the drug Ondansetron?
Palonosetron= safe for people with heart issues
Ondansetron = for people with NO heart issues
action of Dopamine antagonists drugs
D2 receptors in the CTZ and NTS
what Dopamine antagonist “keeps the gut moving in the right direction?”
metoclopramide
Mechanism of action of Glucocorticoids (4)
Anti-inflammatory & analgesic effects
Inhibition of serotonergic tone (5HT release & receptor density)
Reversal of chemotherapy induced HPA hypofunction
Direct central action within the NTS
what drug are Glucocorticoids commonly combined with?
5HT antagonists and NK1antagonists
Neurokinin receptor antagonists drug action
Block the binding of Substance P at the NK1 receptor
Aprepitant & Rolapitant; highly selective for NK1 receptor
Commonly co-prescribed with 5HT receptor antagonists and glucocorticoids, generally well tolerated
True or false: Glucocorticoid dose should be reduced if co-administered as an antiemetic drug
True
when is antiemetic therapy called for?
Not for chronic use
Normally for people who are, for example, prone to intense vomiting before giving speeches
can also be helpful for PTSD
What are the 5 steps in the treatment approach for nausea + vomiting?
- Assess likely cause
- Assess consequences
- Treat consequences
- Confirm the cause
- Treat the cause
t/f: antiemetic drugs are safe to use during pregnancy
true
