Chapter 8 - GI drugs

Forceful ejection of stomach contents

vomiting

emetics (drugs that induce vomiting) usually remove apx. __% of stomach contents

80

emetics must be administered w/in ____ hrs. of ingestion

2-4

two types of emetics

centrally acting

locally acting

Centrally acting emetics act on

CRTZ or emetic center

Apomorphine and Xylazine/Domitor are _______ acting emetics

centrally

Emetic of choice in dogs

Apomorphine

Apomorphine side effects

Protracted vomiting, restlessness, depression

Emetic of choice in cats

xylazine

xylazine is also a

Sedative analgesic

Locally acting emetics act on

peripheral receptors (GI tract)

Hydrogen Peroxide 3% is a _____ acting emetic

locally

which drug works by irritating oropharynx and stomach lining

Hydrogen Peroxide 3%

Which species can you not use Hydrogen Peroxide 3% in?

cats

Aspiration pneumonia and Gastric ulceration are side effects for …

Hydrogen Peroxide 3%

Types of antimetics

Phenothiazine derivatives, Procainamide derivatives, Antihistamines, Serotonin receptor antagonists, NK-1 receptor antagonists

Act centrally by blocking dopamine receptors in CRTZ & by inhibiting vomiting center

Phenothiazine Derivatives

Acepromazine and Chlorpromazine are

Phenothiazine Derivatives

Phenothiazine Derivatives are very useful in preventing

motion sickness in dogs/cats

acepromazine adverse effects

Sedation, hypotension, paraphimosis (stallions), may lower seizure threshold

Procainamide Derivatives act

both centrally and peripherally

used in cases of parvo, uremic vomiting, or chemotherapy

Metoclopramide

which drug is contraindicated if obstruction is suspected

Metoclopramide

Most effective when vomiting is due to motion sickness or inner ear abnormalities

Antihistamines

Meclizine (Antivert), Dimenhydrinate (Dramamine), and Promethazine (Phenergan) are all

Antihistamines

Promethazine (trade name)

Phenergan

Dimenhydrinate (trade name)

Dramamine

Meclizine (trade name)

Antivert

Antihistamines Work by blocking ________ and inhibiting ________

H1 receptors

vomiting reflex at level of CRTZ

Block serotonin receptors on vagal nerve terminals and in CRTZ → antiemetic activity

Serotonin Receptor Antagonists

Ondansetron (Zofran) is an

Serotonin Receptor Antagonists

Ondansetron (trade name)

Zofran

Serotonin Receptor Antagonists uses

severe vomiting in dogs and cats, Especially chemotherapy associated

Maropitant trade name

Cerenia

Block binding of substance P to NK-1 receptors in CRTZ

NK-1 Receptor Antagonists

Melena indicated issues in the

upper GI tract

H2 =

Gastric production

H2 Receptor Antagonists…

Block acid production

Cimetidine (trade name)

Tagamet

Ranitidine (trade name)

Zantac

Famotidine (trade name)

Pepcid

most common H2 Receptor Antagonist

Famotidine (Pepcid)

Proton Pump Inhibitors treat and prevent

recurrent gastric ulcers in horses & foals

Omeprazole (Prilosec) is an

Proton Pump Inhibitor

Omeprazole (trade name)

Prilosec

Antacids function

Neautralizes acid that is already produced

Renal patients should NOT be given _______ & _________ long- term due to absorption & excretion by kidneys

aluminum & magnesium

Aluminum/magnesium hydroxide (Maalox), Magnesium hydroxide (Milk of magnesia), Magnesium hydroxide (Magnalax) are all

antacids

Sucralfate (Carafate) is a

Gastric Mucosal Protectants

Sucralfate (Carafate) uses

Forms paste-like barrier in stomach that binds to surfaces of gastric ulcers

Protects ulcer from further damage & promotes healing

Sucralfate trade name

Carafate

Misoprostol is a

Prostaglandin E1 Analogue

Misoprostol…

Directly inhibits parietal cell from secreting hydrogen ions into stomach - decreases acid produced

used for treatment & prevention of gastric ulcers associated w/ NSAIDs

Misoprostol

Parasitism is a common cause and should always be ruled out in cases of ________

diarrhea

Acute diarrhea often responds to

dietary management and conservative treatment

Untreated diarrhea can result in substantial fluid/electrolyte loss →

dehydration, acidosis, weakness, anorexia, hypovolemic shock

Narcotic analgesics, Anticholinergics/antispasmodics, and Protectants/absorbents are all used to treat

diarrhea

Considered by many clinicians to be Narcotic analgesic of choice for diarrhea

Loperamide (Imodium)

Loperamide trade name

Imodium

________ appears opaque on x-ray and may cause stools to look black

Bismuth

protect/absorbent action

Coating action protects inflamed mucosa from further irritation

Bismuth subsalicylate (Pepto bismol), Kaolin/pectin (Kao-Pec), Activated charcoal (Toxiban) are all

Protectants/absorbents

Bismuth subsalicylate trade name

Pepto bismol

why must you take caution w/ salicylates in cats

they convert to aspirin

May destroy normal inhabitants of GI tract allowing pathogenic bacteria to grow

antibodies

Indications for use of antibodies -

bloody diarrhea or signs of sepsis

Metronidazole trade name

Flagyl

Flagyl toxicity signs

CNS signs (disorientation, head tilt, seizures)

Metronidazole, Amoxicillin/Clavamox, and Tylosin are all

antibiotics

_____ promote a balance between beneficial & harmful bacteria in GI tract essential to maintaining healthy animals

Probiotics

increase peristalsis

irritants

Saline/hyperosmotic agents, Bulk-producing agents, Lubricants, Surfactants/stool softeners, Irritants are all

laxatives

megacolon is a _______ issue

motility

Contain magnesium or phosphate anions that pull water into the GI tract osmotically to soften stool

Saline/Hyperosmotic Agents

Magnesium sulfate (Epsom salts) are Saline/Hyperosmotic Agents used in

birds and horses

indigestible plant material (psyllium!) that act by absorbing water (softens stool) & swelling to increase bulk of intestinal contents (stimulates peristalsis)

Bulk-producing Agents

Bulk-producing Agents uses

Constipation

Sand impaction (horses)

Metamucil, Equine Enteric Colloid, SandClear, Bran mash, Vetasyl (dog,cat) are all

Bulk-producing Agents

Dopaminergic Antagonists

▪ Stimulate motility of the proximal GI tract:

Metoclopramide (Reglan) work in

esophagus, stomach, and Small intestine (cranial portion of GI tract)

Cisapride is a _________ drug

Serotonergic

Cisapride

Stimulates GI tract

Cisapride works on the ______ aspect of the GI tract

caudal

Stimulate proximal GI motility by mimicking effect of hormone motilin

• Esophageal sphincter, stomach & SI

Erythromycin

Dexpanthenol uses

Postoperative tx of ileus & equine colic

drugs that Treats symptoms only

appetite stimulant

Diazepam, Cyproheptadine, Mirtazapine (Remeron), Capromorelin (Entyce)

Appetite stimulants

what dose can you give to cats intravenously to temporarily stimulate their appetite

Diazepam

obstipation definition

severe constipation

used in cases of colitis

Sulfasalazine and Olsalazine

Converted to aspirin by intestinal bacteria producing anti-inflammatory effect, useful in tx of colitis (dogs, cats)

Sulfasalazine

when using Sulfasalazine or Olsalazine, Use w/ caution in ____ due to conversion to aspirin

cats

Bloat Guard, Bloat-Pac, Therabloat are all

Antifoaming Agents

Pancrelipase, Viokase-V, Pancrezyme Powder are all

digestive enzymes

Contains pancreatic enzymes that aid in the digestion of fats, proteins, and carbohydrates

Digestive Enzymes

Digestive Enzymes are used in cases of

Exocrine pancreatic insufficiency (EPI)

Lactulose uses

reduces blood ammonia levels in some hepatic disease

Typically oils or other hydrocarbon derivatives that soften fecal material

Lubricants

Lubricants uses

Constipation

Fecal impaction