Respiratory Pharmacology - Pfister Flashcards
What are the two goals sought in treatment of asthma?
Which phase of mast cell activation do they correspond to?
Bronchodilators to reverse the initial bronchoconstriction (mast cell degranulation)
Anti-inflammatories to counter the late-phase obstruction (delayed mast cell mediator release)
What is the mechanism of action and indication for Cromolyn sodium?
What are its side effects, and how popular is it?
Cromolyn sodium stabilizes mast cells through an unknown mechanism, and is used for chronic control of asthma.
It is inhaled, has few side effects, yet isn’t available in the US.
Omalizumab
What is its mechanism of action?
What are its indications?
Omalizumab
Inhibits IgE receptors (FceRI/II) to inhibit mast cells and other inflammatory processes.
For very severe asthma, with concomitant allergic rhinitis.
Omalizumab
How is it administered?
What are its adverse effects?
Omalizumab
Subcutaneously, once every 2-4 weeks.
Same as any mAb: Injection site reaction, anaphylaxis.
What are three classes of bronchodilators?
What do they accomplish?
Which is the treatment of choice for asthma?
Beta-2 agonists, methylxanthines, and anticholinergics.
Relax airway smooth muscle to cause bronchodilation (or prevent bronchoconstriction).
Beta-agonists are the drug of choice.
Distinguish between albuterol, salmeterol, and formoterol.
Albuterol is a short-acting beta-agonists (SABA), used as a rescue inhaler.
Salmeterol & formoterol are long-acting beta-agonists (LABAs), used for management of chronic asthma.
Compare and contrast the pharmacokinetics of SABAs and LABAs.
Why might salmeterol, for example, have a comparably long half-life?
SABAs act quickly and last 3-6 hours.
LABAs take longer to cause effect (inappropriate for rescue), and last for at least 12 hours.
Salmeterol’s aliphatic side-chain binds a beta-2 receptor exosite for binding stability.
What is the pathway activated by beta-2 agonists in airway smooth muscle?
How is this helpful in fighting Asthma & COPD?
Beta-2 receptor is a Gs, activates AC/cAMP/PKA to reduce intracellular calcium.
This causes relaxation of the smooth muscle cell, reducing bronchial tone.
Asides from bronchodilation, what beneficial effects to beta-2 agonists have?
Prevent mediator release from mast cells
Prevent bronchial mucosal edema
Enhance mucociliary clearance
Reduce reflex bronchoconstriction (?)
What side effects can be associated with beta-2 agonists?
Why is this, and how can they be reduced?
Muscle tremor, tachycardia, hypokalemia, restlessness, hypoxemia. Also, tolerance with chronic use.
Mostly due to extrapulmonary beta receptor activation. Give drug as an inhalant.
Why is it meaningful to ask a patient how often they use their rescue inhaler?
How frequently should a LABA be used?
Increased SABA usage indicates the need for anti-inflammatory therapy.
LABAs are generally used twice daily (~12hr duration)
Why aren’t LABAs considered first-line treatments for asthma?
They are too slow to be used for immediate relief, and may be associated with higher mortality (especially in children)
What role may pharmacogenetics play in the context of asthma treatment?
There are multiple polymorphisms of the beta-2 receptor. Some may correspond to more adverse effect with SABA/LABA use.
Theophylline
What class of drug does it belong to?
What are its mechanisms of action?
Theophylline
It is a methylxanthine (like caffeine)
Weak, nonspecific PDE inhibition and adenosine receptor antagonism, which both promote bronchodilation.
Theophylline
How is it administered?
What are its side effects?
Theophylline
Administered orally.
Broad side effects (headache, palpitations, dizziness, nausea, hypotension), some related to the adenosine receptor antagonism (seizures, arrhythmias). Less popular than beta-agonists.