Drugs for treating GI disease in small animals Flashcards
Antiemetics are for
control of nausea or prevention of vomiting
Neurokinin-1 (NK-1) receptor antagonists are…
give example
antiemetic drugs with unique anxiolytic, antidepressant, and antiemetic properties. The discovery of NK-1 receptor blockers was crucial in preventing emesis associated with cancer chemotherapy.
maropitant
What is a serotonin 5HT3 antagonist?
give examples
Selective serotonin receptor (5-HT3) antagonists block serotonin both peripherally on vagal nerve terminals in the gastrointestinal (GI) system and centrally in the chemoreceptor trigger zone in the area postrema of the fourth ventricle, resulting in powerful antiemetic effects.
(ondansetron, dolasetron, granisetron, and tropisetron)
what is D2 dopaminergic antagonist?
give example
Dopamine antagonists are medications that keep dopamine from activating certain types of cells in your brain and body.
A dopamine D2 receptor antagonist is used in the prevention and treatment of postoperative nausea and vomiting.
metoclopramide
alfa 2 adrenergic antagonist antiemetics?
give example
Alpha-2 adrenergic antagonists are a class of drugs that work by blocking the alpha-2 adrenergic receptors, thereby inhibiting the action of norepinephrine and other neurotransmitters.
While they are primarily used for conditions such as hypertension, anxiety, and some psychiatric disorders, they have also been investigated for their potential as antiemetics, drugs used to prevent or relieve nausea and vomiting.
such as yohimbine, mirtazipine
humoral pathway to vomiting
involves the stimulation of specific receptors in the gastrointestinal tract and other organs, which triggers a series of neural and hormonal responses ultimately leading to the sensation of nausea and the act of vomiting.
neural pathway to vomiting
The neural pathways involved in vomiting can be broadly categorized into central pathways originating in the brainstem and peripheral pathways arising from receptors in the gastrointestinal tract and other organs (humoral path).
The Chemoreceptor Trigger Zone or CTZ, located near the area postrema, is sensitive to various chemical stimuli such as toxins, drugs, and metabolic disturbances.
Activation of receptors in the CTZ can trigger the vomiting reflex directly or indirectly by stimulating the vomiting center.
most important mediators in vomiting (5)
dopamine-2 receptors (in the CTZ)
5-HT3 receptors (serotonin)
neurokinin 1 & substance P (P acts on the neurokinin1 receptors to induce nausea and vomiting)
H1 receptors (in the GI tract can stimulate vomiting)
maropitant is what type of drug
an NK1 neurokinin antagonist antiemetic
inhibits binding of substance P (key neurotransmitter in vomiting).
also acts as an antitussive and visceral analgesic.
contraindicated in toxicoses and GI obstructions.
tradenames: prevomax & cerenia
ondansetron is what type of drug
5HT3 serotonergic antagonist
both a central and peripheral antiemetic
used for nausea and vomiting but in combo with other antiemetics.
especially indicated for chemotherapy induced nausea.
metoclopramide is what type of drug
D2 dopaminergic antagonist, central antiemetic and prokinetic.
poor antiemetic in cats.
prokinetic in stomach and proximal GI tract so is okay for diarrhea cases (ie. parvo), will not worsen it.
maropitant and ondis are more effective and better tolerated though, but metoclopramide still has its place for use.
side effects: behavioral changes, vocalization etc.
indications for induction of emesis (2)
suspected or confirmed ingestion of a toxin
gastric foreign body
contraindications for induction of emesis (3)
symptomatic toxin/FB ingestion case
dangerous ingested object (corrosive, sharp etc.)
anesthetized animals
induction of emesis drug
in dogs
in cats
dogs: apomorphine
cats: dexmedetomidine
admin. antiemetic after vomiting complete. + atipamezole for the cats of course.
indications for gastroprotective therapy (5)
NSAID injury
other ulcers and gastritis (e.g. peptic ulcer disease)
stress-related mucosal damage
Chronic use of corticosteroids
Gastroesophageal reflux disease
what type of gastroprotectants are there (3)
proton pump inhibitors (acid suppressants)
antacids (neutralize)
mucosal protective agents (form a barrier over damaged mucosa)
antacids
such as aluminum hydroxide or magnesium hydroxide or calcium carbonate
less effective than acid suppressants
not monotherapy
neutralize gastric acid by directly reacting with it. They provide rapid but short-term relief from symptoms of heartburn and indigestion.
describe sucralfate
tradename antepsin
a gastric protectant, affinity for injured mucosa high
should be admin. in combo with acid suppressants but with 2 hours in between
particularly beneficial where there is pain
side effect: constipation
histamine type 2 antagonists are
acid suppressants such as, ranitidine and famotidine (Zantac, Pepcid)
should not be combined with proton pump inhibitors as there is no benefit.
ranitidine is more commonly used to promote GI motility because is weak acid suppressant.
indications: when weak acid suppressant activity is required. short term need such as anesthesia.
describe proton pump inhibitors
omeprazole, esomeprazole (nexium)
work by irreversibly blocking the hydrogen/potassium adenosine triphosphatase enzyme system (H+/K+ ATPase) in the gastric parietal cells. This inhibition significantly reduces gastric acid secretion, providing effective acid suppression.
more effective than H2-receptor antagonists.
esomeprazole is the drug of choice for for NSAID induced GI injury. not prophylactically though.
admin. on empty stomach, twice daily.
side effects: diarrhea, dysbiosis, rebound gastric acid secretion etc.
prostaglandin analogs
such as misoprostol are not really used because we have PPIs.
side effect: abortion etc.
indications for prokinetics
give drug examples (4)
gastric emptying and motility disorders
admin. only when GI obstruction ruled out.
e.g. metoclopramide, ranitidine, cisapride, eryhtromycin etc.
metoclopramide
tradename primperan
both prokinetic and antiemetic
initial choice in animals with metabolic diseases with vomiting and/or delayed gastric emptying
cisapride
no antiemetic effect, is prokinetic
more potent in gastric emptying of solids than metoclopramide is but also has more drug interactions
promotes esophageal motility in cats too (megaesophagus)
ranitidine
zantac
acid suppressant and prokinetic
erythromycin
prokinetic used in some countries
Erythromycin is a macrolide antibiotic that is well-known for its antibacterial properties. However, it also has an interesting side effect related to gastrointestinal motility.
Erythromycin has been found to stimulate gastrointestinal motility by mimicking the action of motilin, a gastrointestinal peptide hormone.
types of laxatives: (5)
bulk forming
emollient
lubricant
hyperosmotic
stimulant
multiple can be used at the same time.
bulk forming laxative
fiber
emollient laxative
also known as stool softeners, are a type of laxative medication that works by softening the stool to make it easier to pass.
The main mechanism of action of emollient laxatives involves the incorporation of water and fat into the stool, which helps to lubricate and soften it.
docusate, potassium sulfosuccinate etc.
lubricant laxatives
Lubricant laxatives are a type of laxative medication that works by coating the surface of the stool and the lining of the intestine with a slippery substance, making it easier for the stool to pass through the digestive tract.
mineral oil etc.
hyperosmotic laxatives
Hyperosmotic laxatives are a type of laxative medication that works by drawing water into the bowel, softening the stool and increasing its volume, which stimulates bowel movements.
These laxatives contain substances that are not absorbed by the body and remain in the intestine, creating an osmotic gradient that pulls water into the colon.
lactulose (first choice), polyethylene glycol
stimulant laxatives
Stimulant laxatives are a type of laxative medication that work by directly stimulating the nerves in the intestines, leading to increased motility and bowel movements.
bisacodyl does this
simethicone is a
nonabsorbable antifoaming agent
indications: gaseous colic, flatulence
efficacy hasn’t actually been proven but is still used.
mirtazepine
serotonin receptor antagonist/antidepressant for appetite stimulation
side effects include agitation, vomiting etc.
appetite stimulants (5)
mirtazapine
benzodiazepines (dia + mida)
cyproheptadine (not available or used much anymore)
propofol (has been noted to improve appetite)
maropitant also seems to improve appetite whilst preventing nausea
adsorbents/protectants for the GI tract (3)
activated charcoal (adsorbent)
kaolin/pectin (combo adsorb+protec.)
bismuth subsalicylate (protectant)
synbiotics =
pre + probiotics
best to admin. 2h after antibiotic admin. because the AB will kill the probiotic.
cobalamin,
indications
vit. B12
deficiency secondary to GI tract disease or EPI
GI disease pain management (2)
favor maropitant and opioids
immunosuppressive therapy indicated in GI cases when..?
when evidence of mucosal inflammation is present and no underlying cause is found
examples of immunosuppressants (6)
prednisolone
azathioprine
chlorambucil
methotrexate
cyclosporine
mycophenolate
sulfasalazine is an
anti-inflammatory
It belongs to a class of drugs called 5-aminosalicylates, which work by reducing inflammation in the gastrointestinal tract.
indicated for inflammatory large bowel disease
The exact mechanism of action of 5-ASA is not completely understood, but it is believed to work by inhibiting the production of inflammatory chemicals in the intestine and by scavenging free radicals, which can contribute to inflammation and tissue damage.
young dog: frequent vomiting for few hours, slightly bloody. foreign body + obstruction ruled out. dog BAR and everything within normal limits.
choose treatment.
maropitant
esomeprazole
sucralfate/antepsin
6m BAR puppy: diarrhea 2-3 days, 1x vomiting + giardiosis
treatment?
fenbendazole/pyrantel/praziquantel
1x maropitant
kaolin+pectin
probiotic
adult cat: constipation, no dysuria. BAR otherwise.
treatment?
enema if severe enough but lactulose laxative initially.
once feces is softer we can switch to prevention so, sufficiently high fiber diet.
3month old puppy: ADR, parvo confirmed.
treatment?
IVFT + added K+ and GLU
maropitant & ondansetron (synergistic)
esomeprazole
metoclopramide too for the prokinetic & antiemetic properties. in severe viral GI disease you may see gut stasis so you also need the prokinetic.
if secondary infection then AB.
buprenorfine
if pain worse, methadone/fentanyl (ket+lido CRI)
paracetamol for the fever
adult dog: acute vomiting, hematochezia, ADR. dx acute hem. diarrhea syndrome
treatment?
IVFT
maropitant
(ondansetron if need)
esomeprazole if need
metoclopramide CRI
bupe/methadone/fentanyl
adult female dog: acute vomiting, no diarrhea. dx pancreatitis.
IVFT + supplemental K+
maropitant
ondansetron if needed
methadone
iv parasetamol
ultra low fat diet
