Lecture 28 - Respiratory Drugs Flashcards
What are the changes seen in an asthmatics airway?
Epithelial damage
Mucus secretion
Mucosal inflammation + edema
Smooth muscle contraction
What is happening at the cellular level with allergies and the airway wall?
Allergen stimulates = Mast cell + DC
Mast cell = Stim. Neu + EOS
EOS = DC’s
DCs –> Th2 –> EOS
What molecule causes bronchodilation?
increase in cAMP
What two things affect the levels of cAMP?
AC + PDE
What occurs at the level of AC in regards to bronchial activity?
Beta agonists stimulate = Increase in AC = Increase cAMP
What occurs at the level of the PDE in regards to bronchial activity?
Theophylline inhibits = Increase cAMP
Also inhibits adenosine from causing constriction
What are B2 agonists really good at?
Bronchodialators
What is the mechanism in which B2 agonists are able to cause bronchodilation?
Increase cAMP = relax smooth muscle
Inhibit histamine release from mast cells
What are the respiratory drug families?
Beta-2 agonists Muscarinic antagonists Phosphodieseterase Inhibitors Corticosteroids Leukotriene inhibitors Janus Kinase Inibitors Respiratory Stimulant Antihistamine
Drugs within family: Beta-2 agonists
Albuterol Levalbuterol Clenbuterol Terbutaline Salmeterol
Drugs within family: Muscarinic Antagonists
Ipratopium
Tiotropium
Drugs within family: Phosphodiesterase inhibitors
Theophylline
Aminophylline
Drugs within family: Corticosteroids
Fluticasone
Budenoside
Prednisilone
Drugs within family: Leukotrine inhibitors
Zafirlukast
Montelukast
Drugs within family: JAK inhibitors
Oclacitinib
Drugs within family: Respiratory stimulants
Doxapram
Drugs within family: 1st gen. antihistamines
Diphenhydramine
Chlorpheniramine
Clemastine
Promethazine
Drugs within family: 2nd gen, antihistamines
Loratadine
Desloratadine
Fesofenadine
Cetirizine
What are the general characteristics of B2-agonists?
~4 to 6 hours of effect
Immediate action
Stops attacks
Which B2 agonist is NOT inhaled but rather oral?
Terbutoline
What is Salmeterol used for generally ?
Longer duration
Good for chronic use
What is Salmeterol NOT used for?
To stop attacks, doesn’t work for this
What is an adverse affect of Salmeterol?
Down-regulation of beta receptors
What can be given with Salmeterol to stop the down regulation of beta-receptors?
Corticosteroids
What B2 agonists is thought to have the least amount of side effects?
Levoalbuterol
What type (adminstration wise) of B2 agonist gives the most side effects?
Oral
What are side effects of Beta-2 agonist use?
Tachycardia
Skeletal muscle tremors
Why are the side effects so few and far between with the muscarinic antagonists used in the respiratory system?
Inhaled - very large compounds so they don’t get into the body
What are the muscarinic antagonists used for most commonly?
RAO in horses
How would Beta-2 agonists and corticosteroids be used together clinically?
Betas would be for rescue therapy
Given before inhaled corticosteroids to help increase the distribution when taken
What syrup is used in horses with RAO?
Clenbuterol - DO NOT USE IN CATTLE
What is the specific use of Salmeterol?
Improves signs of airway obstruction in horses with RAO
Use in mild to moderate cases
What beta-2 agonist is NOT TO BE USED IN COWS?
CLENBUTEROL
Which Beta 2 agonist can be injected into horses?
Terbutaline
What do the phosphodiesterase inhibitors cause biochemically?
Increase cAMP – inhibit PDE
Block adenosine receptors
What effects do phosphoesterase inhibitors have physiologically?
Relax smooth muscle
Stimulates CNS + Heart
May be anti-inflammatory
Why is phosphodiesterase inhibitors the best to work against bronchocontriction?
beta and muscarinics are not responsible for the process
Which phosphodiesterase inhibitor is injected?
Aminophylline
What are phosphodiesterase inhibitors mostly used for?
Dogs + Cats for bronchitis
What are side effects of PDE inhibtors?
SNS effects basically
CNS + Cardiac + Muscle
What is important to note when using PDE inhibitors with other drugs?
Under go liver metabolism - can react with many other drugs
Low TI
What is seen cellularly in inflammation of the airways?
Inflammatory cell infiltrates Bronchocontriction Hypersecretion of mucous Epithelium permeability + destruction Edema
What are corticosteroids used for?
Decrease inflammation
Reduce bronchial reactivity
Improve B agonist response
What two steroids are inhaled?
Fluticasone
– and –
Budesonide
What are inhaled steroids commonly used for?
RAO
– and –
Feline asthma
What are the upsides of using Leukotriene inhibitors?
Decrease the need for steroids
Few side effects
What is the down side to using Leukotriene inhibitors?
Not bronchodilators
No effect on in-progress attack
Cant be used alone - not strong enough
When is a respiratory stimulant used? What is the drug called?
Doxapram
Emergency in anesthesia
Decrease respiratory depression with opioids
Hypoxic-iscehmia encephalopathy
How does Doxapram work?
Works on chemoreceptors on carotid artery + aorta
Stimulate respiratory center
What are the two major effects of Histamine? What receptors are involved?
Vasodilation = H1 + H2
– and –
Bronchospasm = H1
What does H1 do for vasodilation?
Stimulates release of NO
What are the effects of Anti-histamines?
Inhibit smooth muscle response
Inhibit vasodilation
Inhibit flare + itch
Which type of anti-histamines have a CNS effect?
First generations
What are the first generations used for due to their CNS effects?
Motion sickness
Nausea + Vomiting
Which first generation antihistamine is used for nausea and vomiting?
Promethazine
What type of action do first generation antihistamines have at the receptor site?
Competitive antagonists
What are the different characteristics of second generation antihistamines?
No entrance into the brain
– and –
No anticholinergic effects
What is a good second generation antihistamine to use in patients with liver disease or those on several drugs? Why?
Cetirizine
Excreted completely by the kidney
What is the mechanism of Oclacitinib?
Decrease inflammatory mediators + Cytokines
Great for puritis + dermatitis
