Flashcards in GI Drugs - Kumar TS Deck (132):
What neurotransmitter stimulates appetite? Which one inhibits appetite?
Stimulated by GABA
inhibited by serotonin
Which appetite stimulant is used in cats and acts through GABA?
Which appetite stimulant for cats is an antihistaminic and antiserotonin agent?
What is the anti obesity drug used for dogs?
What animals are NOT able to vomit effectively?
horses, ruminants, rodents
What are the the 4 afferent sources that can stimulate vomiting?
peripheral sensory receptors
What are the 5 neurotransmitters involved in vomiting?
dopamine, histamine, serotonin, Ach, substance P
What is the most important neurotransmitter for the CTZ to initiate vomiting?
What is the neurotransmitters used to cause vomiting in the vestibular system?
Histamine and muscarinic
What is the primary neurotransmitter for peripheral sensory receptors?
What are the transmtters used for higher CNS centres for vomiting?
cholinergic and histamine
What pathway initiates emesis from increased intracranial pressure?
What is the primary neurotransmitter used in psychogenic vomiting?
Where are NK-1 receptors found?
emetic center and CTZ
Which peripheral acting emetic should not be dosed twice in cats?
What are the 3 peripheral acting/reflex emetics?
salt water, hydrogen peroxide, ipecac
What are the 2 centrally acting emetics?
Which centrally acting emetic is used in cats?
What is the MOA for apomorphine?
opiod - dopaminergic receptors in CTZ`
How is apomorphine adminisstered?
subq or conjuctival
What is the contraindication of apomorphine?
animals with existing central depression because it depresses respiratory centers
What is the MOA of xylazine?
stimulates alpha 2 receptors in CTZ
What are the side effects of xylazine?
What can be used to prevent emesis at the vestibular apparatus?
What antimuscarinic can cross the BBB in dogs to prevent emesis?
What are the SE of antimuscarinics?
xerostomia, drowsiness, constipation, urine retention
What are the 5 anti emetic drugs acting on the CTZ?
2. butyrophenone derivatives
4. peripheral serotonin antagonists
5. Nk1 receptor blockers - cerenia
What antiemetic drugs are "broad" spectrum?
What should be done before giving animals phenothiazines (ace)?
What are the contraindications of phenothiazines?
animals with seizures
What anti emetic effectively antagonizes apomorphine induced emesis?
What is the MOA for metoclopramide?
dopamine antagonist, serotonin agonist and serotonin receptor antagoonist to CTZ
What CTZ anti emetic blocks transmission to CTZ an interferes with action of serotonin on peripheral receptors in GI tract?
peripheral serotonin antagonists (cyproheptadine)
What drug acts by blocking NK-1 receptor?
maropitant citrate (cerenia)
Why can't cerenia be used in puppies less than 11 weeks of age?
can induce bone marrow hypocellularity
What are the 3 ways anticholinergic drugs exert its antiemetic activity?
relax GI smooth muscle
inhibit GI secretions
What receptors do butyrophenone derivatives act on?
What are the 2 SE of butyrophenone derivatives?
sedation and hypotension
What drug effectively antagonizes apomorphine induced emesis?
Why is the bioavailability of metclopramide only 50%?
extensive hepatic first pass metabolism
What are the SE of metclopramide in horses and cats?
hyperactivity, restlessness, tremors
What group of drugs are indicated for emesis induced by chemotherapeutic agents?
peripheral serotonin antagonists
What peripheral serotonin antagonist is used in small animals?
What are some other examples of peripheral serotonin antagonists?
granisetron, palonosetron, ondansetron
What anti emetic is a NK-1 receptor blocker?
maropitant citrate (cerenia)
What is the contraindication of maropitant citrate (cerenia)?
puppies less than 11 weeks - bone marrow hypocellularity
What are the 3 ways anticholinergics exert antimetic activity?
relax GI spasm
inhibit GI secretions
What is the one drawback of anticholinergic drugs?
delays gastric emptying - dont use for more than 3 days
What are the 3 MOA for drugs to modulate gastric acid secretion?
block endogenous secretagogues
block proton pump
enhance cytoprotective effect
Which antisecretory drug is anticholinergic and selective for gastric M1 receptors?
Which H2 receptor antagonist (of the antisecretory drugs) has the longest duration of action?
What is the order of potency for H2 receptor antagonists of the antisecretory drugs?
What drug is clinically useful in preventing acetaminophen toxicity in case of accidental overdose?
What are the SE of H2 receptor antagonists?
thrombocytopenia, rebound acid hypersecretion, relapse ulcers, cutaneous drug eruption in cats
What is the MOA of omeprazole (prilosec)?
inhibits proton pump
What are the clinical indications of omeprazole (prilosec)?
short term treatment of gastric ulcers associated with gastrinomas
What are the 4 adverse reactions to omeprazole (prilosec)?
1. suppression of acid barrier - bacteria
2. aspiration pneuomonia (megaesophagus)
4. inhibits CYp450
What drug does not alter serum gastrin levels, hence prevents rebound acid hypersecretion?
What are the 3 non-systemic antacids?
salts of aluminum, magnesium, calcium
What is the antacid of choice for mild ruminal acidosis?
What drug is used as a systemic antacid?
What are the 4 SE of antacids and which drug is most associated with each SE?
constipation - Al and Ca
Diarrhea - Mg
Hypercalcemia - Ca
hypophosphatemia - Al
What drug is considered a potent agent in gastroduodenal ulcer healing caused by NSAIDs?
What drug binds to the gastric ulcer, protects it, and promotes healing?
What cytoprotective drug should be used cautiously in cats?
bismuth subsalicylate (glucoronidation)
What is the MOA of bethanechol?
cholinergic agonist, enhances amplitude of GI contractions
What are the indications of bethanechol?
postoperative ileus, urinary retention
What are the SE of bethanechol?
obstruction, peritonitis, intestinal wall is compromised
What is the MOA of metoclopramide?
enhances release of Ach in GI. peripherally antagonizes D2 receptors (blocks inhibitory)
What are the 4 actions of metoclopramide?
increase tone of esophageal sphincter
increase GI contractions
relax pyloric sphicter, rapid emptying
penetrates BBB - antagonizes D receptors
What are the 2 clinical indications of metoclopramide?
gastric motility disorders
What drug has the broadest spectrum of all the prokinetic agents?
What are the indications for cisapride?
same as metoclopramide, constipation (mega colon in cats), and post operative ileus
What is a prokinetic agent that peripherally antagonizes dopamine receptors only?
What are the main indications for using anticholinergic drugs for GI?
control diarrhea in calves and mild colin
What is the net effect of using opiods on the GI?
decreased GI motility and secretions
increase tone of sphincters
Opiods are superior to antimuscarinics in treating what?
non specific diarrhea
What are the contraindications for using opiods during diarrhea?
when diarrhea is from invasive bacterial infection
What is diphenoxylate used for clinically?
What is the active metabolite of diphenoxylate?
What does loperamide do?
reduce excessive intestinal secretion, prolongs transit time
What drug is a tincture of opium and used as an antidiarrheal in foals?
What Gi protectant and adorbent should be used cautiously in cats?
What 2 drugs absorb E-coli enterotoxins?
Bismuth salts and activated charcoal
What is the best choice for emergency treatment of poisoning?
What should be done after administering activated charcoal?
saline laxative 30-45 minutes afterwards
What does cholestyramine bind to?
acidic side chains of bile acids
What is the clinical indication for cholestyramine
pruritis associated with increased bile acids
What are the adverse effects of cholestyramine?
nausea, constipation, steatorrhea, decreased B vitamins
What kind of stool do cathartics/purgatives produce?
more fluid than laxatives
What are the 3 emollient laxatives?
mineral oil, docusate sodium, paraffin
What are aspects of emollient laxatives?
unchanged, not absorbed, soften and lubricate fecal mass
What are aspects of bulk forming laxatives?
hydrophilic in nature, reflex peristaltic contractionn
What are the 2 bulk forming laxatives?
bran, psyllium granules
What is the most useful mild laxative for horses with sand colic?
What animals are saline/osmotic purgatives contraindicated in?
Which osmotic purgative is fermented to organic acids and lowers the pH of colon contents?
What can lactulose be used to treat?
dogs and cats - constipation, hepatic encephalopathy
horses - hepatic encephalopathy
can be admin by rectum
What are examples of irritant/stimulant cathartics?
castor oil, ricinoleate, anthraquinones
What is the MOA of irritant cathartics?
stimulate local myenteric reflexes, provoke fluid accumulation in intestinal lumen by active secretory mechanisms
What irritant stimulant can cause superpurgation in horses when administered repeatedly?
What is the MOA of neuromusular purgatives?
muscarinic actions - increase motility
What is the contraindication of neuromuscular purgatives?
mechanical obstruction of intestine
What is the contraindication of ALL cathartics??
animal showing signs of abdominal pain
what are the adverse effects of overdosing cathartics?
diarrhea, abdominal colic, dehydration, shock
What type of enema preparations should not be used in cats?
ones that contain phosphate
What can be given to foals to help pass the meconium?
What do cholagogues do?
contraction of gall bladder
What do choleretics do?
increase secretion of bile
What can be used to dissolve gallstones non surgicially?
Ursodeoxycholic acid (UDCA)
What drug can reduce the surface tension of gas bubbles causing them to coalesce?
What drug is used in the prevention and treatment of frothy bloat?
What is contra indicated in ruminal bloat and stabalizes foam?
What do phenothiazines NOT control for emesis?
labyrinthine stimulation (vestibular?)
What are the 3 centrally acting emetics that are antidopaminergics?
What are examples of phenothiazine drugs?
What are examples of peripherally acting antiemetics?
demulscents, antacids, protectants such as kaolin, pectin
anticholinergic drugs, prokinetics
What can chronic administration of antisecretory drugs to GI result in?
What are the 2 SE associated with using misoprostol for decreasing gastric secretion?
increases uterine contraction (pregnancy contraindicated)
How does omeprazole inhibit the proton pump?
goes to acidic environment of parietal cells, protonated and irreversibly binds pump
What 2 non systemic antacids can be combine to balance bowel movements?
aluminum and magnesium
What does sucralfate require in order to break up and bind to ulcers?
What part of Bismuth subsaliicylate is absorbed?
What is postoperative illeus?
atony or paralysis of stomach or bowel
What is the most potent and broad spectrum prokinetic agent?
What prokinetic acts PERIPHERALLY as a dopamine antagonist?
Mineral oil should not be used with what because emulsification of the oil would facilitate its absorption?
What species should diphenoxylate be used cautiously because it causes excitabilty?
What happens to castor oil after it is ingested?
hydrolyzed by pancreatic lipase into glycerol and ricinoleic acid
What does ricinoleate do?
reduces absorption of fluid and stimulates peristalsis
What are 2 substances that are cholagogues?
dietary fat and concentrated magnesium sulfate