Pulmonary Pharmacology 1 Flashcards
effects of B2 stimulation on the bronchial smooth muscles
relaxation of bronchial smooth muscles (bronchiole dilation)
general classes of meds used for COPD & asthma
*bronchodilators (ex. albuterol, salmeterol, formoterol)
*corticosteroids (ex. budesonide, fluticasone, beclomethasone, prednisone)
*leukotriene antagonists (ex. montelukast, zileuton)
*phosphodiesterase inhibitors (ex. roflumilast)
*Cromolyn
*biologic immunomodulators
bronchodilators - overview
*relax constricted airway smooth muscle and cause immediate reversal of airway obstruction
*3 main classes available:
1. beta2 adrenergic agonists
2. methlyxanthines
3. muscarinic cholinergic antagonists
bronchodilator: beta 2 adrenergic agonists - MOA
*stimulate adenylyl cyclase and increase cyclic adenosine monophosphate (cAMP) in smooth muscle cells
*increase in cAMP results in a powerful bronchodilator response
*results in rapid decrease in airway resistance
bronchodilator: beta 2 adrenergic agonists - 2 types
- short-acting (“reliever” - treat attack)
-inhaled beta-agonists are most widely used and effective bronchodilators in the treatment of asthma
-duration of action: ~3-4 hours
-ex: ALBUTEROL - long-acting (“controller” - prevent attack)
-duration of action: > 12 hours
-do not act quickly enough to be used to treat an attack
-ex: SALMETEROL, FORMOTEROL
-combination inhalers exist with corticosteroid
albuterol - drug class, MOA, & uses
*drug class: beta 2 adrenergic agonist
*MOA: stimulate adenylyl cyclase → increased cAMP → relaxation of bronchial smooth muscle (bronchodilation)
*uses: SHORT-ACTING; used to TREAT asthma attacks
salmeterol - drug class, MOA, & uses
*drug class: beta 2 adrenergic agonist
*MOA: stimulate adenylyl cyclase → increased cAMP → relaxation of bronchial smooth muscle (bronchodilation)
*uses: LONG-ACTING; used to PREVENT asthma attacks
formoterol - drug class, MOA, & uses
*drug class: beta 2 adrenergic agonist
*MOA: stimulate adenylyl cyclase → increased cAMP → relaxation of bronchial smooth muscle (bronchodilation)
*uses: LONG-ACTING; used to PREVENT asthma attacks
bronchodilator: beta 2 adrenergic agonists - ADEs
*unwanted effects are dose-related and due to stimulation of extrapulmonary beta receptors
*not common with inhaled therapy, but quite common with oral or IV administration
*example ADEs: skeletal muscle tremor, palpitations, tachyarrhythmias, restlessness, and hypokalemia
bronchodilator: methylxanthines (ex. Theophylline) - MOA, use, metabolism
*likely causes bronchodilation by inhibiting phosphodiesterase → increased cAMP levels; blocks actions of adenosine
*limited use clinically
*rapidly and completely absorbed
*eliminated by liver CP450 drug-metabolizing enzymes (esp. CYP1A2)
*factors affecting clearance: age, smoking, drug inducers or inhibitors
bronchodilator: methylxanthines (ex. Theophylline) - ADEs
*undesirable effects generally occur at higher serum levels (theophylline has a very narrow therapeutic window)
*overall, ADEs are cardiotoxicity and neurotoxicity
*ADEs include:
-headache
-nausea/vomiting
-diuresis
-CARDIAC ARRHYTHMIA
bronchodilator: muscarinic cholinergic antagonists - MOA
*blocks the effects of endogenous ACh at muscarinic receptors
*activity from inhibition of M3 subtype receptor
*PREVENTS CONSTRICTION of airway smooth muscle and prevents the increase in secretion of mucus that occurs in response to vagal activity
*useful in COPD > asthma
bronchodilator: muscarinic cholinergic antagonists - 2 types
- short-acting
-relatively slow onset of bronchodilation
-duration of action: 6-8 hours
-often combined with short-acting beta2 agonist (albuterol)
-ex: IPRATROPIUM - long-acting
-once-daily dosing
-duration of action: 24+ hours
-useful for COPD
-ex: TIOTROPIUM, glycopyrrolate, umeclidium, aclidinium
bronchodilator: muscarinic cholinergic antagonists - ADEs
*generally well-tolerated
*dry mouth
*unpleasant bitter taste
*urinary retention in elderly patients (rare)
ipratropium - drug class, MOA, uses
*drug class: muscarinic cholinergic antagonist
*MOA: competitively blocks muscarinic receptors → prevents bronchoconstriction
*uses: SHORT-ACTING; often combined with albuterol
tiotropium - drug class, MOA, uses
*drug class: muscarinic cholinergic antagonist
*MOA: competitively blocks muscarinic receptors → prevents bronchoconstriction
*uses: LONG-ACTING; useful for COPD
why do we use ipratropium/tiotropium instead of atropine as our go-to anticholinergics for asthma/COPD?
*these drugs have much fewer ADEs compared to inhaled atropine because they are quaternary ammonium compounds with poor absorption and CNS penetration (i.e. less systemic effects)
methacholine
*analogue of acetyl choline, used for diagnosis
*produces smooth muscle CONTRACTION of the airways and increased tracheobronchial secretions
*Methacholine Challenge Test: to diagnose bronchial airway hyper-reactivity in patients who do not have clinically apparent asthma
corticosteroids in asthma - MOA
*alter gene expression → changes mRNA → changes in protein synthesis
*effects in asthma because they DOWNREGULATE INFLAMMATORY GENES (inhibit the synthesis of virtually all cytokines)
*biggest impact in asthma due to decreased infiltration of airways by lymphocytes, eosinophils, and mast cells
*this process takes time, so most effects of steroids are not seen instantly
inhaled corticosteroids for asthma
*quicker onset of action
*fewer side effects
*examples: BECLOMETHASONE, BUDESONIDE, ciclesonide, flunisolide, mometasone, and FLUTICASONE
*low dose steroid-beta-2 agonist combo now recommended as a “reliever”
systemic corticosteroids
*IV and oral forms
*slower onset of action
*more side effects
*examples: hydrocortisone, methylprednisolone, prednisone
inhaled corticosteroids - efficacy and toxicity
*efficacy of inhaled drug is dependent on:
-delivery to the lung
-residency time in the lung
-potency of the steroid
*systemic toxicity of inhaled drug is dependent on:
-delivery to non-lung areas with absorption
-metabolism of the drug
inhaled corticosteroids - ADEs
*dysphonia
*oropharyngeal candidiasis (use a spacer and rinse mouth after each use to avoid)
*slight increased risk of osteoporosis and cataracts with chronic use