Lecture 15 and 16 Flashcards
What is meant by the term emetic?
drugs that induce vomiting
What is meant by the term anti-emetic?
drugs that prevent vomiting
What is meant by the term anti-diarroeals?
drugs that stop diarrhea
What is meant by the term laxative?
drugs that promote voluminous stools
What is meant by the term pro-kinetics?
drugs that promote gut motility
What is meant by the term anti-ulcers?
drugs that make GI ulcers better
What is the main function of the CTZ?
The chemo-receptor trigger zone (CTZ) is driven by histamine and some other neurotransmitters. It deliberately remains outside of the brain itself which is very good if you happen to have digested a toxin that could kill you and doesn’t cross the blood brain barrier.
What is the difference between vomiting and regurgitation?
Vomiting = an active process Regurgitation = a passive process
Provide examples of species where vomiting is well developed and species that are not able to vomit:
Well developed = people, dogs, cats
Poorly developed = horses, ruminants, rodents, guinea pigs and rabbits
Provide an example of where vomiting may be a useful reflex:
Ingestion of a toxin e.g. snail pellets
Provide an example of a home remedy oral emetics?
Note these are all unreliable:
- 3% hydrogen peroxide
- hypertonic saline
- syrup of Ipecac
- SODA CRYSTALS - MPEC
Provide an example of a 100% efficacious emetic for dogs?
Apomorphine
What form does apomorphine come in and how can it be given?
- comes as very crumbly small tablets. Add to syringe dissolve in water for injection IV or SC or instill underneath the eyelid (conjunctival sac)
Can apomorphine be used for cats?
No
What is the scheduling of apomorphine?
Not an S8 (so S4)
Provide an example of an emetic that could be used in cats and briefly explain the mechanism of action of it:
Xylazine induces emesis in most cats. alpha-2 agonist at the CTZ
Why would an anti-emetic be beneficial?
to prevent loss of water (dehydration), pain, loss of electrolytes, loss of nutrients etc.
What is an important consideration to rule out before using anti-emetics?
GIT obstruction
What is the most commonly used anti-emetic?
Metoclopramide
Briefly describe the effects of metaclopramide and how they occur:
- anti-emetic effect (central action) - the central action is dopamine (low dose) and 5HT3 (high dose) antagonist at the CTZ
- weak upper GI prokinetic effect (peripheral action)
- 5HT4 agonist and DA antagonist sensitizing the stomach to muscarinic stimulation - the neurotransmitter dopamine is capable of inhibiting ACh
- increased tone of lower esophageal sphincter
- increased force and frequency of antral contractions
- relaxes pyloric sphincter
- promotes duodenal and jejunal peristalsis
How can metaclopramide be given and what is the duration of action of the drug?
can be given pretty much anyway and has a short duration of action - approximately 6 hours (as a result it needs to be given regularly)