drugs for nausea and vomiting Flashcards
vomiting
this is the forceful expulsion of stomach contenets and the contents of the proximal small intestine
potassium deficiency, sodium depletion, alkalosis, malnutrition, differential diagnosis, esophageal and gastric injury, dnetal injury are all consequences of what
vomiting
what does the act of vomiting not include
regugriation and rumintation
what is regurgitation
this is the return of previously swallowed food or secretions into the mouth
what is the return of previously swallowed food or secretions into the mouth
regurgitation
what is rumination
this is the repetitive, effortless regurgitation of recently ingested food into the mouth followed by rechewing and re swallowing
what is the effortless regurgitation of recently ingested food into the mouth followed by rechewing and re swallowing
rumintation
what is nausea associated with (3)
decreased gastric motility, increased small intestine, reverse proximal small intestin peristalisis
what are the three distinct units that control vomiting
vomiting centres, nucleus tractus solitarius, chemoreceptor trigger zones
vomiting canters, nucleus tractus solitarius, chemoreceptor trigger zones - are what?
3 units in the braisntem that control vomiting
where are the bilateral vomiting centres found
found in the reticular formation of the medulla
bilateral vomiting centres - role, what do they integrate signals from, what does this activation trigger
they integrate signals from a large number of outlying sources - the activation tirggers vomiting
where do the vomiting centres receive afferent signals from
CTZ and NTS
visceral afferants from the GI tract and outside the gi tract
visceral afferents from the Gi tract
vagus or sympathetic nerves, mucosal irritation
visceral afferents from outside the GI tract
bile ducts, peritoneum, heart, and a variety of other organs
afferents from the extramedullary centers in the brain
odors, fear, vestibular disturbance, cerebral trauma
where do afferent signals come from that attricbute to fear
the extramedullary center
where do vistubular disturbances come from - motion sickness
the extra medullary center
chemoreceptor trigger zones (heart)
these are bilateral centres in the brainstem that are located under the floor of the fourth ventricle
does electrical stimulation cause vomiting
no, however, an emetic drug would
what does noxious stimuli cause
vomiting
what does the CTz act as
acts as an emetic chemoreceptors for the VC
what do CTZ detect
detect chemical abnormailities
What signals does the CTZ send
they send excitatory signals
what would be described as a chemical abnormaility
diabetic ketoacidosis, antiemetic drugs, hypoxia
vomiting pathways - absorbed toxic chemicals and drugs in the blood go where
ctz –> vomiting centre
vomiting pathways - where do mechanical stimuli within the GI tract go
vagal afferents –> VC
where do inputs from the vestibular system go
vestibular nuclei –> ctz –> vomiting centre
stimuli within the CNS how do they get to the vomiting center
cerebral cortex –> limbic system –> vomiting centre
why does chemotherapy make people vomit/nausea
because the drugs directly stimulate the CTZ
what does chemotherapy stimulate what cells to release what
chemotherapy stimulates cells in the Gi tract to release serotonin
what does the release of serotonin stimulates what
the release stimulates the 5ht3 receptors in 3 areas
what areas do the serotonin activate 5-HT3 receptors
NTs
CTZ and vagal afferents in the GI
NTS, CTZ, and vagal afferents are stimulated by what in chemotherapy
serotonin
anticipatory nausea and vomtiing
triggered by specific odours, tastes, objects that pt associates with treatment
what vomiting occurs within 24 hours after cancer treatment
acute
delayed onset nausea and vomiting
occurs more than 24 hours after cancer treament and may continue for several days
anticholinergics
they are a muscainic receptor antagonist in the NTS and CTZ
side effects of anticholinergics
sedation, dry mouth, constipation, urinary retention
antihistamines
targetr the H1 receptors in the NTs and CTZ
cannabinoids
CB1 receptor in he cortex and VC
what are cannabinoids used for
to increase appetite
what are dopamine antagonists good for
good for drug induced nausea and vomiting
what do the dopamine antagonists target
the D2 receptors in the CTZ and MTS
serotonin antagonists
are more important for drug induced and chemotherapy induced
what do the serotonin antagonists do
they trigger the 5ht3 receptors in the CTZ and the NTS
glucocorticoids
they inhibit serotonergic tone
what are glucocorticoids helpful for
chemotherapy
what does the inhibition of serotinergic tone do
stops the 5ht3 release and the receptor density, thus stopping the signal from going to the ctz, nts
what drugs have direct central action within the CNS
glucocorticoids
what are glucocorticoids commonly combined with
5HT antagonists and NK1 antagonists
neurokinin receptor antagonists (NK1)
blokc the binding of substance p at the NK1 receptor
what block the binding of substance p at the NK1 receptor
NK1 receptor antagonists
what are some adverse effects of NK1 receptor antagonists
it inhibits the CYP3A4 enzymes
when should benzos be prescribed
for ptsd, chemo panic
motion sickness (CTZ) - prescribe
histamine or muscarinic antagonists
chemo meds and opiods
NK1, histamine, cannabinoid
Chemo
serotinergic
