Transcript Antiulcer Drugs - Dr. Brahmbhatt`s Class Handouts

Chapter 11
Gastrointestinal Drugs
Dr. Dipa Brahmbhatt VMD MpH
[email protected]
Emetics
• Emetics (don’t use in unconcious/seizuring/compromised animal)
– Drugs that induce vomiting
– Used in the treatment of poisoning and drug overdose
– Vomiting should not be induced if caustic substances
have been ingested (Ammonia, lye, bleach)
• Always check with poison control prior to inducing vomiting
– Can be centrally acting (working on the CRTZ) or
peripherally acting (working on receptors locally)
Emetics
Centrally acting
• Apomorphine (Apokyn)
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Choice for Dogs
Stimulates dopamine receptors in CRTZ
Morphine derived emetic
Peripherally: SQ/IM: vomit in 5-10 minutes
Subconjunctivally: Conjunctiva sac: vomit in 10 – 20 minutes
SE: Protracted vomiting, CNS depression and restlessness
• Xylazine
– Choice for cats
– SE: bradycardia, decreased respiratory rate
Inducing Emesis
Apomorphine
Xylazine
Emetics
Peripherally acting
• Ipecac syrup
– 2 alkaloids: emetine & cephaeline
Irritate gastric mucosa and stimulate
CRTZ
– Stomach and SI evacuated: 10-30 mins
– SE: Higher doses cause CV problems
• Home remedies
– Hydrogen peroxide
– Salt and water/ mustard and water/ salt followed by water
– Less reliable than other emetics
Emetics
• Activated charcoal is given if emesis is contraindicated
• It absorbs many chemicals and drugs in the upper GI tract
• Liquid/ Powder form (reconstituted with water)
• SE: Constipation, diarrhea and blackening of feces
• Superchan, Vet Powder, Vet Liquid, Toxiban (activated
charcoal and kaolin)
Ulcers
• Ulcer: erosions of mucosa
– Causes: metabolic disease, drug therapy & stress
– C.S.: Anorexia, melena, abdominal pain, and
hematemesis
– Protected by
• Mucus which protects mucosa from gastric secretions
• Sphincter muscles: cardiac and pyloric prevent reflux of
acid to esophagus and duodenum
↑ release of HCL
from
parietal cells - stomach
Activated by
Histamine
Gastrin
Acetylcholine
Cimetidine (Tagament®)
Ranitidine (Zantac®)
Famotidine (Pepcid®)
Antacid
Systemic: sodium bicarbonate,
calcium carbonate
Nonsystemic: magnesium
hydroxide,
aluminum/magnesium
hydroxide,
aluminum hydroxide
Omeprazole
Lansoprazole
Misoprostol
Sucralfate
Antiulcer Drugs
• Antiulcer drugs
– Help prevent the formation of ulcers
– Categories include
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Antacids
Histamine-2 receptor antagonists
Mucosal protective drugs
Prostaglandin analogs
Proton pump inhibitors
Antiulcer Drugs
• Antacids
• Promote ulcer healing by neutralizing
HCl and reducing pepsin activity
• Rapid onset and short duration of action
• Interact with other drugs
– By adsorption or binding the other drugs
– By increasing stomach pH (decrease of absorption
of certain drugs)
– By increasing urinary pH (inhibit elimination of
weak bases)
Antiulcer Drugs
• Antacids
• May be systemic or nonsystemic
• Examples:
– Systemic (in blood): sodium bicarbonate, calcium
carbonate
– Nonsystemic (in GI):
» Magnesium hydroxide: milk of magnesia, given to
cows to treat rumen acidosis (increases rumen pH)
» Aluminum/magnesium hydroxide, aluminum
hydroxide: Mylanta used in foals and dogs in adjunct
treatment for ulcer
» Aluminium hydroxide: Amphojel lowers phospahte
levels
Antiulcer Drugs
• Histamine-2 receptor antagonists
• Prevent acid reflux by competitively blocking the H2 receptors of
the parietal cells in the stomach, thus reducing gastric acid secretion
• SE: rare, diarrhea and inhibition of liver enzymes
• Examples:
– Cimetidine (Tagament®)
– Ranitidine (Zantac®)
– Famotidine (Pepcid®)
More potent than tagamet
Longer duration of action
Than tagamet
Most potent
Fewer SE than zantac
Less bioavailable
Antiulcer Drugs
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Mucosal protective drugs
 Combine with protein to form an adherent
substance that covers the ulcer and protects it
from stomach acid and pepsin
 An example is sucralfate
 SE: Constipation
 Don’t give with H2 receptor antagonist
Antiulcer Drugs
• Prostaglandin analogs
• Suppress gastric secretions and increase mucus production in the
GI tract
• An example is misoprostol, which is usually given to animals
taking NSAIDs
• Pregnant women need to be careful while handling
• SE: GI: diarrhea, vomiting, abdominal pain
• Proton pump inhibitors
• Bind irreversibly to the H+-K+-ATPase enzyme on the surface of
parietal cells of the stomach; this inhibits hydrogen ion transport
into the stomach so that it cannot secrete HCl
• Examples:
– Omeprazole (gastroguard)
– Lansoprazole
Antiulcer Drugs
• Omeprazole
– Horses and foals > 4 wks of age
– Heal gastric ulcer and prevent
re-occurrence
• Causes: feeding problems (less hay)
• Intensive training
• Development/growth
• Lansoprazole (Prevacid)
– Used to tx. Gastroesophageal reflux and ulcers
– Extra lable
BLOAT
•Foamy/pasture/legume
•Rumen is distended
•Asphyxiate the animals
Antifoaming Agents
– Reduce or prevent the formation of foam
– Used in ruminants, whose rumens are subject to acute
frothy bloat
– Make this foam less stable, breaking it up to promote gas
release through belching
– Administered as solutions by stomach tube directly into the
forestomach
– Examples include poloxalene and polymerized methyl
silicone
Motility Enhancing
• Prokinetic agents
– Increase the motility of parts of the GI tract to enhance
movement of material through it
– Types of prokinetic agents are:
• parasympathomimetics
• dopaminergic antagonists
• serotonergic agents
Prokinetic Agents
• Parasympathomimetic agents include
– Acetylcholinesterase inhibitors, which compete with ACh
for acetylcholinesterase, resulting in increased intestinal
tone and salivation
• An example is neostigmine
• Tx of rumen atony and to diagnose
myasthenia gravis in dogs
• SE: Vomiting diarrhea and increased
salivation
– Cholinergics, which make a precursor to acetylcholine
• An example is dexpanthenol
Prokinetic Agents
• Dopaminergic agents stimulate gastroesophageal
sphincter, stomach, and intestinal motility by
sensitizing tissues to the action of the
neurotransmitter ACh
• Examples include metoclopramide and domeridone
• Don’t use reglan with antichlinergic drugs
• Serotonergic agents stimulate motility of the
gastroesophageal sphincter, stomach, small
intestine, and colon
• An example is cisapride
Enzyme Supplements
– Pancreatic enzymes must be supplemented in the diet
when the pancreas is not functioning properly (as in
pancreatic exocrine insufficiency)
– Pancrealipase contains primarily lipase, but also
contains amylase and protease
– Can be irritating to the skin on contact and to nasal
passages upon inhalation
Appetite-Stimulating Drugs
• Serotonin antagonist antihistamines
– Promote appetite by inhibition at the serotoninergic receptors
which control satiety
– Side effects include sedation and dry mouth
• Benzodiazepines
– Effective appetite stimulants in cats but not dogs
– Side effects include sedation and ataxia
• Tetracyclic antidepressants
– Stimulate appetite by antagonizing alpha2-receptors
– Side effects include sedation, vocalization
Appetite Stimulating Drugs
• Glucocorticoids
– Stimulate steroid-induced euphoria which stimulates
appetite
– Side effects include polydipsia, polyuria, dull haircoat,
weight gain, and behavioral changes
• Anabolic steroids
– Stimulate hematopoiesis, appetite, and weight gain
– Side effects include hepatotoxicity, masculinization, and
early closure of growth plate in young animals
Appetite Stimulating Drugs
• Progestins
– Used to stimulate appetite and promote weight gain in
anorectic cats and dogs
– Side effects include behavioral changes, endometritis, and
mammary enlargement
Appetite Suppression
• Dirlotapide (Slentrol®)
– Drug for management of obesity in dogs
– Side effects include vomiting, diarrhea, lethargy, and
anorexia
Dental prophylaxis