Respiratory Pharmacology Flashcards
What two major drug categories do we use to treat asthma?
– Bronchodilators: treat the primary symptom of asthma, i.e bronchoconstriction
– Antiinflammatory agents: reduce the level of airway smooth muscle hyperresponsiveness resulting from airway inflammation.
What is cromolyn sodium?
Inhaled anti-inflammatory agent used in asthma to stabilize Mast Cell: Exact mechanism not known
When is cromolyn sodium used?
chronic control of asthma
Prophylaxis of bronchospasm
NOT FOR RESCUE
not used in USA
What are the three main classes of bronchodilators?
– β2 Adrenergic agonists (sympathomimetics)
– Theophylline (a methylxanthine)
– Anticholinergic agents (muscarinic receptor antagonists)
What are 2 Inhaled β2
agonists?
Albuterol &Salmeterol
Why are Albuterol & Salmeterol used in asthma?
- bronchodilator treatment of choice in asthma
- most effective bronchodilators
- have minimal side effects when used correctly
What is the short acting beta-2 agonist?
Inhaled short-acting β2-selective agonists (SABA) (albuterol) have a duration of action (3-6 hours)
What is the long acting beta-2 agonist?
Inhaled long-acting inhaled β2
agonists (LABA) (salmeterol and formoterol) have longer duration of effect, providing bronchodilation and bronchoprotection for >12 hours
What is the MOA of beta-2 agonists?
directly stimulate β2
receptors in airway smooth muscle -> activation of the Gs
-adenylyl cyclase-cAMP-PKA pathway. PKA phosphorylates a variety of target substrates and Decrease calcium
What are some Other Effects of beta2 Agonists in Airways?
– Prevent mediator release from mast cells
– Prevent bronchial mucosal edema
– Enhance mucociliary clearance
– Reduce reflex cholinergic bronchoconstriction
What are some adverse effects of beta2 agonists?
muscle tremor, tachycardia, hypokalemia, restlessness, hypoxemia.
all are dose related and decreased risk with drug inhaltion
Which beta 2 agonist is a rescue medication?
albuterol: Onset of action w/i minutes after inhalation and lasts for `3-6 hrs
Which beta 2 agonist can improve asthma control?
Salmeterol: protect against bronchoconstriction > 12 hrs
Are beta2-agonists Safe?
Two randomized controlled safety trials found that LABAs were associated with three- to fourfold risks for asthma-related death
should not be the first medicine used to treat asthma should be added to the asthma treatment plan only if other medications do not control asthma, including the use of low- or medium-dose corticosteroids
Why do some patients have adverse events or effects when using inhaled beta-agonists?
49 different polymorphisms having been identified – importance of these polymorphisms remains controversial
What is the Methylxanthine used for asthma?
Theophylline (related to caffeine) - Oral - used in the treatment of asthma since 1930 still widely used in developing countries because it is inexpensive.
What is the MOA of Methylxanthine (Theophylline)?
nonselective phosphodiesterase (PDE) inhibitor (increased levels of cAMP and cGMP) & Adenosine receptor antagonism (adenosine helps release histamine and leukotrienes)
What are the side effects of Theophylline toxicity?
- headache
- palpitation
- dizziness
- nausea
- hypotension
- tachycardia
- severe restlessness
- agitation
- seizures
How do Anticholinergics help with asthma?
– Relaxes airway smooth muscle
– Decreases mucus secretion
What is the MOA of Anticholinergics?
competitive antagonists of acetylcholine (ACH) binding to muscarinic cholinergic
receptors
ACH acts on bronchial smooth muscle muscarinic receptors to cause constriction and increased mucous secretion
What is the antiocholinergic drug we should know to treat asthma?
Ipratropium bromide
What are some things we should know about Ipratropium bromide administration?
- Inhaled
- maximal responses develop over 30-90 min
- Effects last for 4-6 hours
What are some adverse effects of Ipratropium bromide?
Predictable consequences of muscarinic receptor blockade – Dry mouth – Constipation – blurred vision – dyspepsia – cognitive impairment
less when inhaled
When is Ipratropium bromide indicated for asthma treatment?
- effective in acute severe asthma but less effective than β2agonists.
- In the acute and chronic treatment of asthma, have additive effect with β2 agonists and considered when control of asthma is not adequate with inhaled β2 agonists