GI Drugs (final exam) Flashcards
Centrally-acting emetics control vomiting through what three structures?
Vomiting (emetic) center
Chemoreceptor Trigger Zone (CRTZ)
Vestibular apparatus
What is unique about feline emetic receptors?
Cats have more a2 and 5-HT receptors
Also fewer D2 and H1 than dogs
Apomorphine mechanism of action
D2 agonist in Chemoreceptor Trigger Zone
What is the emetic drug of choice in dogs?
Apomorphine
Apomorphine adverse effects
Respiratory depression on overdose
Reverse with naloxone (will not reverse emetic effect)
Xylazine mechanism of action
A2 agonist in vomiting center and Chemoreceptor Trigger Zone
What is the emetic drug of choice in cats?
Xylazine
Why is Xylazine more effective in cats?
Cats have more a2 receptors than D2 receptors.
3% hydrogen peroxide mechanism of action
Direct irritation of oropharynx and GI lining
Hydrogen peroxide uses
Emesis in dogs (NOT cats)
Owner can administer at home
Hydrogen peroxide contraindications
Cats, risk of hemorrhagic gastroenteritis
Pre-existing GI ulcers/bleeding
What are the physiological inhibitors of appetite?
Serotonin
Cortisol releasing hormone
What are the physiological stimulants of appetite?
Norepinephrine Dopamine GABA agonists Ghrelin Serotonin antagonists
Mirtazapine mechanism of action
Serotonin antagonist
Inhibits satiety
Mirtazapine uses
Dogs > cats (both unreliably)
Variable onset
Cyproheptadine mechanism of action
Serotonin antagonist
Inhibits satiety
Cyproheptadine uses
Cats, more effective than dogs
Onset 2-3 days
Sedation is most common side effect
Capromorelin mechanism of action
Ghrelin receptor agonist (selective)
Capromorelin use
Increase ghrelin -> stimulate hypothalamus, increase appetite
Antiemetics
Maropitant citrate
Ondansetron
Dolasetron
Metoclopramide
Maropitant citrate mechanism of action
Blocks substance P
Neurokinin receptor antagonist (NK1)
Vomiting center and Chemoreceptor Trigger Zone
Maropitant citrate uses
Antiemetic in cats and dogs
Motion sickness in dogs
Maropitant citrate contraindications
GI obstruction
Exception if patient with obstruction is going into surgery
Ondansetron and Dolasetron mechanism of action
Serotonin receptor antagonist
Central and peripheral 5-HT receptors
Ondansetron and Dolasetron uses
Chemotherapy related nausea Severe vomiting (no prokinetic activity)
Ondansetron and Dolasetron contraindications
May mask ileus
Potential GI obstruction
Metoclopramide mechanism of action
Dopamine receptor antagonist (D2) in chemoreceptor trigger zone
5-HT3 antagonism at high dose
Prokinetic
Increase lower esophageal sphincter tone
Metoclopramide uses
Antagonize apomorphine-induced emesis
Anti-emetic
Prokinetic
Metoclopramide contraindications
Suspected GI obstruction
Immediately post-operative GI resection
GI effects of autonomic and enteric nervous system
Increase activity via acetylcholine, serotonin, peptides.
Decrease activity via norepinephrine, dopamine, endorphins.
Drugs used to increase GI motility
Metoclopramide Cisapride Ranitidine Erythromycin Lidocaine Neostigmine
Antacids and GI protectants
Antihistamine H2 blockers
Proton pump inhibitors
Prostaglandin E analog
Sucralfate
Antihistamine H2 blockers mechanism of action
H2 receptor inhibition
Inhibit HCl and pepsin secretion
Antihistamine H2 blockers
Famotidine (most common)
Cimetidine
Ranitidine (prokinetic)
Proton pump inhibitors mechanism of action
H+/K+/ATPase proton pump inhibition in GI
Decrease HCl production
Most effective antacid for pH increase
Proton pump inhibitors
Omeprazole (oral)
Pantoprazole (injectable)
Prostaglandin E analog mechanism of action
Increase mucous secretion in GI (ulcer healing)
Prostaglandin E analog
Misoprostol
Misoprostol contraindications
GI cramping
Diarrhea
Abortifacient
Sucralfate mechanism of action
Binds directly to and protects ulcer site
Requires low pH to bind
Sucralfate uses
Treat gastric ulcers
Poorly absorbed
Pancrelipases
Viokase
Pancrezyme
Pancrelipase mechanism of action
Supplemental exocrine pancreas enzymes
Viokase has high efficacy
Pancrelipase uses
Exocrine pancreatic insufficiency
Lifelong treatment
Hepatobiliary drugs
Lactulose
N-acetylcysteine
S-adenosyl-methionine
Urosdiol - synthetic ursodeoxycholic acid
Lactulose mechanism of action
Enhances NH3 fecal excretion
Lowers systemic NH3
Lower colonic pH
Lactulose uses
Manage hepatic encephalopathy
Stool softener (megacolon in cats)
Retention enema
N-acetylcysteine mechanism of action
Replenishes tissue glutathione
N-acetylcycteine uses
Hepatotoxic conditions with oxidative stress
Acetaminophen toxicity antidote
S-adenosyl-methionine mechanism of action
Nutraceutical hepatoprotectant
Antioxidant
S-adenosyl-methionine uses
Adjunct for hepatic disease and acute hepatotoxicity
Osteoarthritis
Cognitive dysfunction
Urosdiol mechanism of action
Choleretic (increase bile flow)
Immune-modulating
Urosdiol uses
Chronic inflammatory liver disease (small animals)
Urosdiol contraindications
Biliary obstruction
Can interfere with bile acid tests
Misoprostol treats _____
NSAID-induced gastric ulcers
