Nausea and Vomiting Flashcards
What is vomiting?
vomiting (emesis) is a protective reflect allowing removal of harmful toxins from body by involuntary, forceful explosions of stomach contents through mouth and sometimes nose.
What are some causes of nausea and vomiting?
- food poisoning
- vertigo or labryinthitis
- migraine
- disease
- pregnancy
- head trauma
- anxiety and stress
- travel sickenss
- side effects of some medications
What is the physiology of vomiting?
co-ordinated by area of brian called vomiting centre. Receives signals from other pars of the body which trigger process of emesis.
What are the different types of anti-emetic drugs?
- antimuscarinic drugs
- dopamine antagonists
- antihistmines
- ondansetron
- neurokinin receptor antagonists
How do antimuscarinic drugs work?
Block muscarinic receptors in vomiting centre of brain. Can be taken orally or given transdermaly. Cause side effects such as drowsiness, constipation, dry mouth, blurred vision, urinary retention.
Hyoscine butlybromide used for motion sickness
What are the different drugs in the drug class dopamine antagonists?
prochlorperazine, metoclopramide, domperidone
What are the key points about prochlorperazine
Given as buccal tablet. Also given orally and by IM injection. Can be used to treat labryrinthine disorders. Can cause movement disorders, also acute dystonia, akathisia, and tardive dyskinesia.
What are the key points about metoclopramide?
Acts within the brain. Also acts as a prokinetic; works peripherally to stimulate gastric emptying, can reduce vomiting. Also causes extra-pyramidal side effects
What are the key points about domperidone?
Blocks peripheral dopamine receptors. Doesn’t enter the brain so does not cause movement disorders. Has been associated with cardiac arrythmias.
What are some key points about antihistamines?
cyclizine, promethazine, cinnarizine - used for motion sickness, vertigo and labryinthine disorders. Antagonise histamine h1 receptors and muscairnic M1 receptors in vomiting centre. Side effects include drowsiness, constipation, dry mouth, blurred vision and urinary retention
What are some key points about ondansteron.
5-HT1 antagonist - acts on peripheral nervous system, blocks 5-HT3 receptors in GIT, and central nervous system - blocks 5-HTS receptors in CTZ. Licensed for chemotherapy induced and post-operative nausea and vomiting. Also used in pregnancy. Better tolerated due to fewer side effects. Can cause significant constipation and cardiac arrhythmia.
What are some key points about neurokinin receptor antagonists?
New group of drugs that antagonise neuokinin NK1 receptors in CTZ. Aperpitant (given orally) and fosaprepitant (given IV). Used for prevention of nausea and vomiting associated with highly emetogenic chemotherapy
