Antiemetics - H1 antagonists Flashcards
1
Q
What are examples of H1 antagonist medications?
A
- Cyclizine
- Cinnarizine
- Promethazine
2
Q
What is the mechanism of action of histamine antagonists?
A
Histamine (H1) and acetylcholine (muscarinic) receptors predominate in the vomiting centre and in its communication with the vestibular system. Histamine antagonists block these receptors, making them useful for nausea and vomiting particularly associated with motion or vertigo
4
Q
What causes of vomiting do H1 antagonists act against?
A
- Drug-induced
- Post-operative
- Radiotherapy
- Motion sickness
- Vertigo
5
Q
What are adverse effects of H1 receptor antagonists?
A
- Drowsiness
- Anticholinergic effects - Dry mouth, dilated pupils, blurred vision, reduced bowel sounds, and urinary retention
- Transient tachycardia - palpitations
6
Q
What interactions should you be aware of when using H1 antagonists?
A
- Benzo’s
- Opioids
- Ipratropium/tiotropium - anticholinergic effects
7
Q
How can cyclizine be given?
A
- Orally
- IV
- IM
8
Q
Does there need to be a dose conversion between methods of administration for cyclizine?
A
No
