Nausea/Vomiting Flashcards
Pathophysiology of Chemoreceptor Trigger Zone (CTZ)
3
- Area postrema located at the end of the 4th ventricle
- Outside the BBB & influenced by triggers in the blood or CSF
- Receptors involved – DA2, M1, H1, NK1, and opioid
Pathophysiology - Vagal afferent System (2)
- Triggers: chemotherapy, radiation, acute infectious gastroenteritis
- Receptors involved – 5-HT3
Pathophysiology - Vestibular System (3)
- Cranial nerve VIII
- Motion sickness
- Receptors involved –M1 and H1
5-HT3 Receptor Antagonists MOA (2)
- Effects occur at CTZ (potentially at peripheral sites as well)
- Block binding of serotonin
5-HT3 Receptor Antagonists Use in Therapy (4)
- Chemotherapy
- Post-operative N/v
- Cyclic vomiting
- Gastroenteritis
5-HT3 Receptor Antagonists Side effects (4)
- Headache
- QT prolongation
- Dizziness
- Constipation
5-HT3 Receptor Antagonists Available Agents (4)
- Ondansetron (Zofran®)
- Granisetron (Kytril®) — Longer half-life, Same QT prolongation, Anecdotal improved efficacy
- Palonosetron
- Dolasetron
Antihistamine and Anticholinergic Agents MOA
Weak anti-emetic properties but work by competing with histamine on H1-receptors or M1 (scopolamine)
Antihistamine & Anticholinergic Agents Use in Therapy (2)
- Additive agent
2. Motion sickness
Antihistamine and Anticholinergic Agents Side Effects (4)
- Dry mouth
- Sedation, dizziness
- Blurred vision
- Urinary retention
Antihistamine and Anticholinergic Agents Available Agents (5)
- Diphenhydramine (Benadryl®) – Oral tablet and liquid
- Hydroxyzine (Vistiril®)
- Meclizine (Dramamine®)
- Dimenhydrinate (Gravasol®)
- Scopolamine – Only available as patch, Long acting but takes time to work, Best for motion sickness
ALL AVAILABLE OTC
Dopamine Receptor Antagonists MOA
Work primarily affecting DA receptors but also bind to M1 and H1
Dopamine Receptor Antagonists Side Effects (3)
- Drowsiness (H1 effects)
- EPS: restlessness, dystonias
- QT prolongation
Dopamine Receptor Antagonists Available Agents (3)
- Prochlorperazine
- Promethazine
- Metoclopramide
Dronabinol (Marinol®) Overview (3)
- Synthetic delta-9-tetrahydrocannabinol (delta-9-THC)
- Natural occurring component ofCannabis sativa L.(marijuana), activates cannabinoid receptors CB1to stimulate appetite
- CIII