Antiemetic Agents Flashcards
Describe the brainstem “vomiting center”
Coordinates the act of vomiting through CN VIII, X, & networks in the nucleus tractus solitarius
High concentrations of M1, H1, NK1, D2, GABA, & sertonin (5-HT3) receptors
What are the 4 sources of afferent input to the vomiting center?
- “Chemoreceptor trigger zone” (D2, opioid, NK1, & 5-HT receptors)
- Vestibular system (M1 & H1 receptors)
- Vagal & spinal afferent nerves (5-HT receptors)
- CNS
What drug classes are used to relieve vomiting? (6)
Antihistamine-anticholinergics
Benzos
Corticosteroids
5 HT receptor antagonists
Phenothiazines
Substance P/Neurokinin 1 receptor antagonist
What do all 4 of the serotonin 5-HT3 antagonists end in?
“setron”
Do you need to reduce the dose of serotonin 5-HT3 antagonists in geriatric patients or patients w/ renal insufficiency?
Nope!
Which serotonin 5-HT3 antagonist may require dose reduction in patients w/ hepatic insufficiency?
Ondansetron
What is an action of serotonin 5-HT3 antagonists?
May slow colonic transit
Describe the efficacy of serotonin 5-HT3 antagonists for the prevention of delayed N/V (> 24hr after chemo) when used alone
Little to none
How is the efficacy of serotonin 5-HT3 antagonists enhanced?
By combining w/ a corticosteroid & NK-receptor antagonist
What are ADEs of serotonin 5-HT3 antagonists?
HA, dizziness, constipation
QT prolongation (most pronounced w/ dolasetron)
What can other drugs do to the 5-HT3 receptor antagonists?
Reduce hepatic clearance –> increased 1/2 life
What are the actions of substance P/neurokinin 1 receptor antagonists?
Provide relief from delayed emesis a/w emetogenic meds
Possess antidepressant, anxiolytic, & antiemetic properties
What are ADEs of dimenhydrinate (Dramamine - an antihistaminic/anticholinergic)?
Drowsiness, confusion, blurred vision, dry mouth, urinary retention
What are examples of phenothiazines?
Prochlorperazine
Promethazine
Chlorpromazine
What are ADEs of prochlorperazine?
QT prolongation
Sedation
Tardive dyskinesia
