B / 24 : Antiemetic drugs. Prokinetic agents. Flashcards
What are the 3 anatomical structures with a key role in emesis?
- Chemosensitive trigger zone (D2, 5-HT3)
- Vestibular nuclei (M1,H1) : motion emesis
- Nucleus of tractus solitarius (5-HT3, D2, NK1) : pharyngeal stimuli and toxins
What are prokinetic drugs?
Drugs that stimulate gut motor function. Helpful for gastroparesis or post surgical emptying delays.
When are prokinetic drugs contraindicated?
If obstructive ileus is suspected : risk of toxic megacolon and intestinal perforation
What are the antiemetic drugs? (7)
- Dimenhydrinate
- Metoclopramide
- Droperidol
- Ondansetron
- Palonosetron
- Aprepitan
- Some cannabinoid
Dianne dropped meth on a policeman
Dimenhydrinate
- MOA
- Effect
- Indication
- SE
- Extra
- H1 receptor antagonist + muscarinic blocade
- Inhibition of histamine + muscarinic receptors in the vomiting center
- For emesis associated with vestibular disturbances (ie motion sickness)
- CNS effects, atropine like effects, abuse liability
- Combined with diphenhydramine to reduce sedative effect
Metoclopramide
- MOA
- Effect
- Indication
- SE
- Dopamine D2 receptor antagonist
- Antiemetic and prokinetic effect
- For emesis after anesthesia and chemotherapy + prokinetic for GERD, gastroparesis
- Drug induced parkinsonism, hyperprolactinemia
How can metoclopramide have a prokinetic effect in the GI?
Because in the GI, dopamine inhibits ACh release -> metoclopramide is a dopamine receptor antagonist, which results in a reduced inhibitory effect
Droperidol
- MOA
- Effect
- Indication
- SE
- Dopamine D2 receptor ANTagonist
- Central effect : inhibition of D2 in CTZ
- For post-operative vomiting + dizziness
- CNS depression
Ondanseron, palonosetron
- MOA
- Effect
- Indication
- SE
- 5-HT3 ANTagonists
- Block serotonin receptors in CTZ and in the enteric nervous system
- For post-operative emesis and chemotherapy
- Headache, QT prolongation, arrhythmias
Aprepitant
- MOA
- Effect
- Indication
- SE
- NK1 (neurokinin) ANTagonist
- Inhibition of receptor in area postrema that plays a role in pain transmission : reduce pain-induced vomiting
- For prevention of chemotherapy-induced vomiting
- Fatigue, dizziness, diarrhea
What are the cannabinoids used as antiemetics
- Dronabinol
- Nabilone
Dronabinol, Nabilone
- MOA
- Effect
- Indication
- SE
- CB1 cannabinoid agonist
- Inhibit presynaptic releases (ie dopamine)
- For chemotherapy induced vomiting + appetite enhancer
- Euphoria, hallucination, increase of appetite
Which drug can be used as antiemetic AND prokinetic?
Metoclopramide
