Pharmacology Flashcards
Is prednisolone commonly ulcerogenic?
Not at normal doses. Unless concurrent gastric hypoxia, hypoperfusion, severe spinal disease, or concurrent use of NSAIDs
When are gastrointestinal protectants indicated?
In case of gastrointestinal ulceration or erosion
After initiating GI protectant therapy - when is improvement expected to be noted?
After 2-5 days if inciting cause is removed
Drug class - cimetidine, ranitidine, and famotidine
Histamine-2 Receptor antagonists (H2 receptor antagonists)
How do H-2 receptor antagonists function?
Block histamine receptor on gastric parietal cell - decrease gastric acid secretion
When is peak effect noted with H-2 receptor antagonists?
Almost immediately after beginning medication (does not need to build up efficacy)
Which is the most potent H2 receptor antagonist?
Famotidine
When should you give cimetidine in relation to food?
On an empty stomach - before feeding
Which H-2 receptor antagonists utilize P-450 enzymes?
Cimetidine, ranitidine
Which H-2 receptor antagonist utilizes P-450 enzymes and may cause toxic buildup of theophylline, lidocaine, and metronidazole (among others) when administered concurrently?
Cimetidine
Which H-2 receptor antagonist causes reduced hepatic blood flow?
Cimetidine
How are famotidine and nizatidine excreted from body?
Almost unchanged in urine
Which H-2 receptor antagonist may cause vomiting and lethargy if administered IV?
Ranitidine
Which H-2 receptor antagonist may cause interference with serum gastrin concentration?
Famotidine - causes transient increase in serum gastrin
Drug class - Omeprazole, pantoprazole, esomeprazole
Proton pump inhibitors (PPIs)
How do proton pump inhibitors function?
Inhibit hydrogen-potassium ATP on parietal cell - stop secretion of hydrogen into gastric lumen
Which PPI has longest duration of effect?
Dexlansoprazole
How long does it take for PPIs to reach maximum effect?
2-5 days
Where is omeprazole absorbed?
In duodenum
When should omeprazole be given in relation to food?
On empty stomach - one hour before meal
How are PPIs metabolized?
First pass hepatic metabolism
Which PPIs affect P-450 enzymes?
Omeprazole and esomeprazole
What are potential risks of alteration of gastric pH?
Altered metabolism of some drugs which rely on pH for absorption, potential for admission of some bacteria which would otherwise be destroyed by gastric pH
How does sucralfate function?
Locally acting - binds to epithelial cells, especially at erosions and ulcers and protects from pepsin and bile acids
What is sucralfate composed of?
Sucrose and aluminum hydroxide
When should sucralfate be administered in relation to antacids?
Prior to antacids
Drug class - misoprostol
Prostaglandin E1 analog
How does misoprostol function?
Antisecretory effect on parietal cells - inhibition of acid secretion, also stimulates secretion of mucus and bicarbonate to increase gastric mucosal blood flow
Where is misoprostol metabolized?
First pass metabolism in liver -to active form
Which gastroprotectants are prodrugs?
Misoprostol, omeprazole
What are adverse effects of misoprostol
Diarrhea (self limiting) and uterine contraction resulting in abortion
When are antiemetics indicated?
If vomiting makes it difficult to maintain energy, fluid, or electrolyte hemostasis, or when quality of life adversely impacted by nausea. Also indicated if patient at risk of aspiration pneumonia
Drug class - maropitant
Neurokinin-1 receptor antagonist (NK-1 receptor antagonist)
How does maropitant function?
Blocks action of substance P in CNS and at peripheral NK-1 receptors in GI
How is maropitant metabolized?
First pass metabolism in liver
Drug class - ondansetron, granisetron, dolasetron
5-HT3 receptor antagonists
How do 5-HT3 receptor antagonists function?
Competitive blocking of 5-HT3 receptors peripherally and centrally
How is ondansetron metaboized?
Liver
How is dolasetron metabolized and then eliminated?
Prodrug - metabolized by ubiquitous carbonyl reductase then eliminated by P-450 enzymes
What is true of simultaneous administration of ondansetron and tramadol?
Ondansetron may reduce efficacy of tramadol
How does metoclopramide function?
Both antidopaminergic activity and blockade of 5-HT3 receptors - blocks CRTZ
Why is metoclopramide less effective in cats?
Less dopamine receptors
How is metoclopramide eliminated?
Kidneys - use caution in patients with reduced glomerular filtration
What can happen with administration of metoclopramide to patients with renal dysfunction?
Extrapyramidal signs may occur
Drug class - Chlorpromazine, prochlorperazine, acepromazine
Promazine derivatives
How are the promazine derivatives metabolized?
By the liver
What is a side effect of the promazine derivitives?
Vasodilation, may increase CVP and change HR as well
How do the promazine derivatives prevent nausea?
Antidopaminergic and antihistaminic effects - block CRTZ and higher doses also block MVC
Which anticholinergic is used as an antiemetic in dogs?
Aminopentamide
Drug class - cisapride
5HT4 serotonergic antagonist
How is cisapride eliminated?
Via first pass metabolism in liver
What is the effect of cisapride administration?
Enhanced gastric emptying with increased gastroesophageal sphincter pressure
How does erythromycin function as a prokinetic?
Stimulates motilin receptors
Increases lower esophageal sphincter pressure and peristalsis
How do ranitidine, and nizatidine function ans prokinetics?
Inhibition of acetylcholinesterase encourages gastric emptying
How does bethanechol function as a prokinetic?
A true cholinomimetic drug binding to muscarinic receptors - affects motility through GI tract
How does misoprostol function as a prokinetic?
Enhances colonic motility - used for non-responsive constipation
How does capromorelin work?
Mimics action of endogenous ghrelin - results in growth hormone secretion and appetite stimulation
Where does capromorelin function?
Stimulates appetite via hypothalamus and increases IGF-1 in liver and pituitary gland
What do beta blockers do?
Bind to beta receptors in sympathetic nervous system
Located in heart, vascular system, and bronchioles
What does stimulation of the Beta 1 receptors do?
Increases heart rate, increase AV nodal conduction velocity, and increases myocardial contraction
What does stimulation of the Beta 2 receptors do?
Vasodilation of skeletal muscles, bronchodilation
Propranolol
Beta 1 & 2 blocker
Monitor for bradycardia, lethargy, depression, AV conduction arrhythmias, hypotension, worsening of heart failure, hypoglycemia, bronchospasm
Atenolol and metoprolol
Beta 1 blocker (high doses block beta 2)
INCREASE hypoglycemic effects of insulin
Esmolol
Ultra-short acting beta blocker similar to atenolol - used either as CRI or to test efficacy of beta blocker therapy
Drugs for supraventricular bradyarrhythmia
Atropine or glycopyrrolate
-helps to assess if arrhythmia is vagally induced
Occasionally terbutaline - beta 2 agonist effects
Drugs for ventricular bradyarrhythmia
Isoproterenol
-Often ventricular bradyarrhytmias are related to 3rd degree AV block and need pacemaker
Drugs for supraventricular tachyarrhytmias
Calcium channel blockers (amlodipine, diltiazem)
Can also use beta blockers and digitalis glycosides to slow conduction through AV node
Drugs for ventricular tachyarrhytmias
Class I antiarrythmics - lidocaine, procainamide, quinidine, tocainidine, mexiletine
Class III antiarrythmics - sotalol, amiodarone
What is the aerodynamic equivalent diameter size of particles that will be aerosolized into the peripheral airways of the respiratory tree?
0.5-5 micrometers
What compressor settings are recommended for jet nebulization of inhaled medications?
20 - 30 psi, 8-10 LPM
Recommended length of time for nebulization via jet nebulizer or ultrasonic nebulizer?
5 - 10 minutes
How long should an animal be allowed to breathe a dose of metered dose inhaler from the spacer device?
1-2 minutes with an average of 7-10 breaths
Inhaled bronchodilators
Beta-2 adrenergic receptor agonists
Albuterol, salmeterol
Manage bronchoconstriction from inflammatory lower airway disease
Decrease intracellular calcium and thereby cause smooth muscle relaxation of bronchial wall
Which type of albuterol is preferred in small animals?
R-albuterol (levalbuterol - xopenex) preferred
the S-albuterol (albuterol - ProAir or Ventolin) may cause increased lower airway inflammation
Inhaled glucocorticoids
Fluticasone, flunisolide
Take two weeks for steady state concentrations of fluticasone so patient needs systemic glucocorticoids
Control airway inflammation with minimal systemic side effects
Ipratopium bromide
Acetylcholine antagonist that helps relax smooth muscle
Minimal systemic absorption
Used in humans for treatment of bronchitis
