II - GI Small Animal Flashcards by Jessica Hanaumi

In what clinical situations would administering appetite stimulants be most effective?

feeding tube cannot be placed
underlying cause of anorexia/Hyporexia has been removed but patient is still not eating
short term during diagnostic phase
secondary to behavioral or environmental factors
overcome food aversion
chronically ill or palliative cases when a feeding tube cannot be placed

How well did you know this?

Not at all

Perfectly

List five appetite stimulants.

Cyproheptadine
Mirtazapine
Capromorelin (Entyce - dog, Elura - cat)
Benzodiazepines: Diazepam
Glucocorticoids

How well did you know this?

Not at all

Perfectly

MOA: 5-HT3 (serotonin) antagonist

Hypothalamus secretes opiates which stimulate appetite, and serotonin inhibits opiate release

Cyproheptadine

How well did you know this?

Not at all

Perfectly

This appetite stimulant shows some efficacy in cats as they are more sensitive to serotonin changes.

Cyproheptadine

How well did you know this?

Not at all

Perfectly

Adverse effects of Cyproheptadine (4)

Sedation
Paradoxical CNS stimulation/aggression
Anticholinergic effects
Dry mucous membranes

How well did you know this?

Not at all

Perfectly

MOA:
5HT3 (serotonin) antagonist - anti nausea, increased app.

Alpha adrenergic receptor antagonist - increased norepinephrine leads to increased app.

Histamine receptor antagonist - sedation

Mirtazapine

How well did you know this?

Not at all

Perfectly

Adverse effects of Mirtazapine (5)

Sedation
Focalization
Behavior changes
GI upset
Irritation of pinna

How well did you know this?

Not at all

Perfectly

Mirtazapine is an effective appetite stimulant for _______.

Dogs and cats

How well did you know this?

Not at all

Perfectly

MOA: Ghrelin receptor agonist - directly signals hypothalamus and increases growth hormone excretion from the pituitary

Capromorelin - Entyce (dogs), Elura (cats)
Appetite stimulant

How well did you know this?

Not at all

Perfectly

Adverse effects of this appetite stimulant identified so far are increased salivation after dosing and GI upset.

Capromorelin - Entyce (dogs), Elura (cats)

How well did you know this?

Not at all

Perfectly

Capromorelin is FDA approved for which species?

Dogs (Entyce) and cats (Elura)

How well did you know this?

Not at all

Perfectly

MOA: GABAminergic inhibition of satiety center

Benzodiazepines: Diazepam

How well did you know this?

Not at all

Perfectly

As an appetite stimulant, diazepam is most effective in _______.

Cats

How well did you know this?

Not at all

Perfectly

This appetite stimulant is administered IV and has a short half-life.

Diazepam

How well did you know this?

Not at all

Perfectly

_________ cause polyphagia in dogs but are not recommended as an appetite stimulant due to side effects such as catabolic muscle loss.

Glucocorticoids

Also poor effects on appetite in cats

How well did you know this?

Not at all

Perfectly

Name three receptors found in the Emetic/Vomiting Center

Neurokinergic - NK1
Serotonergic - 5HT3
Adrenergic - a2

How well did you know this?

Not at all

Perfectly

Name six receptors found in the Chemoreceptor Trigger Zone (CRTZ)

Neurokinergic - NK1
Serotonergic - 5HT3
Adrenergic - a2
Dopaminergic - D2
Cholinergic - M1
Histaminergic - H1

How well did you know this?

Not at all

Perfectly

CRTZ in cats:

Poorly developed ______ receptors.
Absence of ______ receptors.
Higher number of _______ receptors.

Dopaminergic - D2
Histaminergic - H1
Adrenergic - a2

How well did you know this?

Not at all

Perfectly

CRTZ in dogs:

Well developed ________ and ________ receptors
Lower number of ________ receptors

Dopaminergic - D1 and Histaminergic - H1
Adrenergic - a2

How well did you know this?

Not at all

Perfectly

Inducing emesis is most productive when performed within what time period?

Within 2-3 hours of ingestion

How well did you know this?

Not at all

Perfectly

List five emetics used in small animal medicine.

Apomorphine
Ropinerole (Clevor)
Xylazine
Dexmedetomidine
Hydrogen peroxide 3%

How well did you know this?

Not at all

Perfectly

MOA: Stimulates dopamine D2 receptors in CRTZ to cause vomiting in dogs

Two drugs

Apomorphine
Ropinerole (Clevor)

How well did you know this?

Not at all

Perfectly

Three adverse effects of apomorphine

Ocular irritation
Lethargy
Protracted nausea/vomiting

How well did you know this?

Not at all

Perfectly

This drug is the emetic of choice in dogs.

Apomorphine

How well did you know this?

Not at all

Perfectly

Apomorphine can be given ________.

IV (preferred) or conjunctival (tablet)

MOA: Alpha-2 agonist Two drugs for inducing emesis.

Xylazine Dexmedetomidine

In addition to ocular irritation and protracted vomiting, this drug inhibits prolactin and should not be used during pregnancy or lactation (staff should also be cautious when handling).

Ropinerole (Clevor)

How would you treat protracted nausea/vomiting brought about by Ropinerole and apomorphine?

Dopamine antagonists such as metoclopramide

Two drugs used to induce emesis in cats

Xylazine Dexmedetomidine IM or IV

How do you reverse Xylazine and Dexmedetomidine?

Xylazine - yohimbine Dexmedetomidine - atipamezole

Depending on the dose used, sedation is a possible side effect for ______________ and _______________.

Xylazine and Dexmedetomidine

MOA: generates water and gas, foam expands the stomach, irritation stimulates GI nerve endings to induce emesis

Hydrogen peroxide

Why isn’t hydrogen peroxide recommended for inducing emesis in cats?

Low efficacy and increased risk of adverse effects

Adverse effects of hydrogen peroxide for inducing emesis

Gastritis Esophagitis GI ulceration Air embolus *particularly if overdosed or wrong concentration used

Name four antiemetics.

1. Metoclopramide (Reglan) 2. Maropitant (Cerenia) 3. Ondansetron (Zofran) 4. Dolasetron (Anzemet)

MOA: Serotonin antagonist and antidopaminergic; also a pro-motility agent

Metoclopramide (Reglan)

Which antiemetic works better in dogs than in cats?

Metoclopramide (Reglan)

Which antiemetic has a very short half-life and must be a CRI if given IV?

Metoclopramide (Reglan)

Adverse effects of metoclopramide (Reglan) - 3

Change in mentation/behavior Disorientation Constipation

MOA: Neurokinin-1 receptor antagonist; inhibits substance P - a key neurotransmitter involved in vomiting; works directly at the emetic center

Maropitant (Cerenia)

This antiemetic is used in dogs and cats

Maropitant (Cerenia)

Adverse effect of maropitant (Cerenia) - 1

Pain at site of injection (esp. SQ) *refrigeration may reduce pain

MOA: serotonin antagonists

Ondansetron (Zofran) Dolasetron (Anzemet)

Which antiemetics are often used for chemotherapy induced nausea?

Ondansetron (Zofran) Dolasetron (Anzemet) Maropitant (Cerenia)

Ondansetron can be given _______.

IV or PO

Dolasetron can be given ________.

PO, IV, SQ

Possible side effect for Ondansetron and Dolasetron - 1

P-glycoprotein substrates may cause neurological toxicity in herding breed dogs with the MDR1 mutation

Risk factors for GI ulceration

- Drugs: NSAIDS, corticosteroids - Stress - Compromised mucosal blood supply: anesthesia, dehydration, hypoadrenocorticism - Inflammatory bowel disease - Gastronomy, adenocarcinoma - Helicobacter?

Risk factors for esophagitis and reflux

Gastroesophageal reflux Esophageal dysmotility Foreign body Toxins Caustic substances

Causes of gastroesophageal reflux

Primary idiopathic Anesthesia associated Secondary (inflammatory, neoplastic) Hiatal hernia, brachycephalic syndrome Many more

Causes of esophageal dysmotility

Megaesophagus Myopathies/neuropathies Neoplasia Etc.

List three antacids found OTC and give their MOA.

Aluminum hydroxide (Mylanta) Magnesium hydroxide (Milk of magnesia) Calcium carbonate (Tums) MOA: neutralize acid (don’t decrease production) * Insufficient evidence to recommend as treatment for ulceration or reflux in SA med; longer acting and more effective treatments are available

List four H2 antagonists used to reduce gastric secretions.

Famotidine (Pepcid) Ranitidine Cimetidine (Tagamet) Nizatidine

MOA: reversible, competitive antagonist at histamine H2 receptor in parietal cells; reduce gastric acid secretion; some have prokinetic effects

Histamine H2 Antagonists - Famotidine (Pepcid) - Ranitidine - Cimetidine (Tagamet) - Nizatidine

H2 antagonists are classically used for:

Uremic patients and mast cell tumors

Which H2 antagonist has the most drug interactions?

Cimetidine (Tagamet) - inhibits CYP 450

Name the two proton pump inhibitors used in small animal medicine.

Omeprazole (Prilosec) - PO Pantoprazole (Protonix) - IV

MOA: inhibit the gastric hydrogen-potassium-ATpase proton pump; reduces gastric secretion

Omeprazole (Prilosec) Pantoprazole (Protonix)

How often should PPIs be given?

Twice daily

What is considered to be the most effective treatment for increasing gastric pH and treatment of ulceration?

Proton pump inhibitors - omprazole (Prilosec) - Pantoprazole (Protonix)

When should PPIs be tapered in dogs and cats?

After prolonged use > 3-4 weeks

Which PPI inhibits CYP 450?

Omeprazole (Prilosec)

Which PPI takes effect more rapidly?

Pantoprazole (Protonix)

Name two mucosal protectants used in small animal medicine.

Misoprostal Sucralfate

MOA: Prostaglandin E1 analog; inhibits gastric acid secretion; increases bicarbonate secretion; increase mucus secretion; increase gastric blood flow

Mucosal protectant - Misoprostal

Clinical indications for misoprostal

Treatment and prevention of aspirin (and maybe other NSAID) induced ulcers No indication of efficacy for treating glucocorticoid induced ulcers

Adverse effects of misoprostal

GI distress Uterine contractions, vaginal bleeding, induction of parturition - risk to women, handle with care

MOA: When combined with acid forms sucrose octasulfate and aluminum hydroxide; binds to exposed epithelial cell membranes and not normal mucosa; protects mucosa against HCl, bile, pepsin; possibly stimulates local prostaglandin production

Sucralfate

Drug interactions with Sucralfate

Affects oral absorption of drugs

Is Sucralfate helpful in preventing/treating esophageal injury?

Which drugs are superior for treatment of ulceration?

Proton Pump Inhibitors - Omeprazole - Pantoprazole

A dog’s esophagus is essentially all ________.

Skeletal muscle

The lower esophageal sphincter is made of ______.

Smooth muscle

The cat’s esophagus is ________ the cranial 2/3 and ________ the distal 1/3.

Skeletal muscle Smooth muscle

Which receptors are sympathetic?

Adrenergic - inhibit motility - fight or flight

Which receptors are parasympathetic?

Cholinergic - enhance motility - rest and digest

List six prokinetic drugs used in small animal medicine.

Metoclopramide Cisapride Ranitidine (no longer on the market) Nizatidine Erythromycin Bethanechol

The clinical uses of this drug include ileus, GDV - post op, delayed gastric emptying, gastroesophageal reflux (increases LES tone).

Metoclopramide

This drug’s site of action is mainly the proximal GI tract as the distal GI tract is less responsive.

Metoclopramide

MOA: serotonin antagonist and antidopaminergic Promotility MOA: sensitizes GI smooth muscle to effects of acetylcholine

Metoclopramide

MOA: enhances acetylcholine from intrinsic cholinergic neurons; not antidopaminergic

Cisapride

The site of action of this drug is smooth muscle from esophagus through to the colon.

Cisapride

This prokinetic is metabolized by CYP 450, so it is affected by drugs that inhibit this enzyme.

Cisapride

This prokinetic has minimal side effects that can include vomiting, diarrhea, and abdominal discomfort.

Cisapride

Clinical uses for this drug include megaesophagus in cats, mega colon in cats, gastroesophageal reflux, delayed gastric emptying, and ileus.

Cisapride *does not work in megaesophagus in dogs as their esophagus is all skeletal muscle

Two prokinetics with MOA: H2 receptor blocker, inhibition of acetylcholinesterase activity

Ranitidine (no longer on the market) Nizatidine

Clinical uses for this drug include delayed gastric emptying, constipation, pseudo-obstruction of the intestines, and gastroesophageal reflux

Nizatidine

What is the site of action of Nizatidine?

What is the site of action of Ranitidine?

GI, especially stomach

MOA: macrolide antibiotic with motilin-like activity

Erythromycin

Why is ertythromycin less effective in the distal GI tract and diseased GI tract?

Lack of motilin receptors

This drug is used for decreased colonic motility in dogs only.

Erythromycin

This prokinetic inhibits CYP 450 (and interacts with Cisapride)

Erythromycin

Possible adverse reaction of erythromycin.

Possible reactions with MDR1 mutations Drug interaction - inhibition of CYP 450

Cholinergic / prokinetic mainly used to improve bladder contractility but has potential use in megaesophagus

Bethanechol

Adverse effects of this drug include SLUD, bradycardia, increased gastric acid secretion, and increased pancreatic secretions

Bethanechol

What is the primary indication for drugs that suppress motility?

Diarrhea *may be contraindicated for infectious causes of diarrhea

List the motility modifiers / anti-diarrheals - 6

Diphenoxylate (Lomotil) Loperamide (Imodium) Kaolin/Pectin Bismuth salts, charcoal Metronidazole (Flagyl) Tyrosine (Tylan)

These two motility modifiers are not recommended for use in cats due to excitatory behavior.

Diphenoxylate and loperamide

These motility modifiers cause constipation, bloat and sedation in dogs.

Diphenoxylate, loperamide

Which motility modifers do not require a prescription?

Loperamide (Imodium) * Bismuth salts, charcoal (Pepto-Bismol) - efficacy unknown; can make stool black - don’t confuse with Melina; give with food due to GI upset

Which motility modifier causes reactions in dogs with the MDR1 mutation?

Loperamide (Imodium)

Motility modifier that binds enteric opioid receptors; direct inhibition of GI motility (2)

Diphenoxylate Loperamide (Imodium)

MOA: demulcent / protectant; relieves irritation by lining mucosal surface; absorbs some potential toxicants

Kaolin/Pectin Efficacy as tx for diarrhea unknown GI upset - give with food

MOA: Synthetic nitroimidazole compound; disrupts bacterial DNA synthesis; effective against certain protozoal species and anaerobic bacteria

Metronidazole (Flagyl)

This motility modifier has a wide range of doses, with increased risk of adverse effects at higher doses and extensive hepatic metabolism.

Metronidazole (Flagyl)

Clinical uses for this drug include altering GI microbes, chronic enteropathy, EPI, and hepatic encephalopathy; Giardia, clostridium, anaerobic infections.

Metronidazole (Flagyl)

Adverse effects of this drug include GI upset, hepatotoxicity, neurotoxicosis, and reduced olfactory function (hyposmia) in dogs.

Metronidazole (Flagyl)

This drug does not improve outcome in dog with acute hemorrhagic diarrhea.

Metronidazole (Flagyl)

MOA: Macrolide antibiotic; inhibits 50s subunit of bacterial ribosomes to inhibit protein synthesis, mainly bacteriostatic

Tylosin (Tylan)

Adverse effects for this drug are considered minimal and uncommon but include potential hypersensitivity.

Tylosin (Tylan)

Clinical uses for this drug include alteration of GI microbes, treatment of antibiotic responsive diarrhea or GI dysbiosis, chronic enteropathy, and EPI.

Tylosin (Tylan)

This motility modifier can be given chronically but has a bitter taste so may need to be flavored or put in a capsule.

Tylosin (Tylan)

Three treatments for constipation

Laxatives - Psyllium, wheat dextrin, pumpkin; preferred tx due to safety, tolerance, and efficacy Osmotic - lactulose effective and commonly used Lubricants - not generally advised due to risk of aspiration

Megacolon is most commonly seen in _____.

Cats

Treatment for megacolon includes diet modification, fiber, enemas, and surgery plus what two drugs?

Lactulose (laxative) Cisapride

Secondary esophagitis in megaesophagus is treated with ____ and ____.

Omeprazole Sucralfate

Are metoclopramide, Cisapride, and Bethanacol (promotility drugs) effective in treating megaesophagus in dogs?

No - dogs have no smooth muscle in the esophagus These drugs only work on smooth muscle

This drug is used in megaesophagus in dogs and cats as it is thought to allow for better esophageal clearance of ingest into the stomach, which can reduce regurgitation and improve weight gain.

Sildenafil (Viagra, Revatio)

MOA: Phosphodiesterase-5 inhibitor that relaxes smooth muscle causing vasodilation; relaxes smooth muscle of lower esophageal sphincter for a short time

Sildenafil (Viagra, Revatio)

This drug is effective in treating both dogs and cats with megaesophagus.

Sildenafil (Viagra, Revatio)

Treatment options for EPI

Replacement pancreatic enzymes - viokase, pancreazyme Dried extracts of bovine or porcine pancreas Powdered form preferred Cobalamin supplementation - vitamin B12

EPI, chronic enteropathy, and pancreatitis (esp. cats) may need supplementation with ____.

Cobalamin - vitamin B12

Chronic enteropathy is classified as responsive to these four things:

Diet Fiber Antibiotics - metronidazole or tylosin Immunosuppressants - steroids, cyclosporine, Mycophenolate, Chlorambucil, leflunomide, azathioprine (dogs only!)

Denamarin, Denosyl, SAMe, and silymarin (milk thistle) are ______.

Hepatoprotectants

MOA: decreases hepatic synthesis/secretion of cholesterol and intestinal absorption of cholesterol; allows solubilization of cholesterol-containing gallstones; increases bile flow; reduces hepatotoxic effects of bile salts; may reduce hepatocellular inflammatory changes and fibrosis

Ursodiol

Clinical uses for this drug include cholestasis, gallbladder sludge, and mucoceles.

Ursodiol Ursodeoxycholic acid

Two drugs used to treat hepatic encephalopathy

Lactulose Neomycin (or amoxicillin, metronidazole)

Hepatic encephalopathy is seen with severe liver failure (>70% loss) and _____.

Portosystemic shunts

MOA: once reaching the colon, increases osmotic pressure drawing water into the bowel - laxative effect; metabolized by bacteria into acid metabolites; acidifies colonic contents; causes NH3 ammonia to migrate from blood into colon where it is trapped as NH4 ammonium and expelled with feces

Lactulose - nonabsorbable disaccharide

MOA: given orally has minimal systemic absorption; local effects in the GI tract to reduce the number of ammonia producing bacteria

Aminoglycoside antibiotic - Neomycin