Respiratory Flashcards
- Define asthma.
Reversible airway obstruction as a result of bronchial hyper-reactivity, airway inflammation, mucous plugging, and SM hypertrophy. [The airway obstruction is due to inflammation of the bronchial wall, constriction of the bronchiolar SM and increased mucous secretion.]
- What endogenous products play an important role in asthma?
- Prostaglandins
- ACh
- B2-adrenergics
- Histamine
- Adenosine
- What are the major triggers of an asthma attack?
- Allergens – induce mast cells
- Infections – viral upper respiratory tract infection
- Pharmacological factors – B-blockers, cholinergics, adenosine, aspirin
- Exercise and Stress – vagal and adrenergic influence
- What are the different categories of drugs used to treat Asthma?
- bronchodilators → B2 receptor agonists, antimuscarinic drugs, methylxanthines [control bronchoconstriction and symptoms]
- Anti-inflammatory agents → corticosteroids, leukotriene inhibitors, mast cell stabilizers, anti-IgE antibodies [control bronchial hyperreactivity]
- What are the different short and long acting B2 adrenergic agonists? How do B2 adrenergic agonists tx asthma?
Short acting B2 agonists (SABAs) → Albuterol, Pirbuterol, Terbutaline [used for acute relief of bronchospasm]
Long acting B2 agonists (LABAs) → Salmeterol, Formoterol
*B2 agonists increase intracellular cAMP resulting in relaxation of the bronchial smooth muscle and subsequent bronchodilation. When administering these drugs they are inhaled minimizing their systemic effects b/c B2 agonists are poorly absorbed into the circulation via the lungs. [available via MDI (metered-dose inhalers), spaces of VHC (valved holding chambers)]
- What is a concern in regards to using long acting beta agonists?
A small percentage of the population may have a genetic predisposition (polymorphism at the b2 receptor) that causes worsened asthma → exacerbations → death. ??
- When should LABAs be used clinically?
- do not take as rescue medication
- use in conjunction with inhaled steroid
- if asthma worsens after starting LABAs – seek medical help
- if you take LABAs and suffer asthmatic exacerbations that does not respond normally to quick-relief – seek medical help
- How do you treat exercise induced bronchoconstriction (EIB)?
- SABAs prior to exercise will prevent up to 2-4 hrs
- LABAs prior to exercise will prevent up to 12 hrs
- Montelukast will decreased EIB in 50% of pts up to 24 hrs
- What are adverse effects of inhaled B2 adrenergic agonist bronchodilators?
Tremors, tachycardia arrhythmias, hyperglycemia, tolerance, paradoxical bronchospasm
- Which anticholinergics are used as bronchodilators?
- Ipratropium – short acting inhaled anticholinergic that can be used in asthma to prevent vagal mediated bronchoconstriction and drug induced bronchospasm (ex. B-blocker)
- Tiotropium – long acting anticholinergic used once a day for COPD
- What is the mechanism of how anticholinergics are used as bronchodilators?
Parasympathetic stimulation causes bronchial constriction and mucous secretion. Anticholinergics are used to block the muscarinic receptors in the smooth muscles and maintain bronchial dilation of the airway.
- What are adverse effects of Ipratropium?
- Dry mouth
2. Use with caution in pts with Glaucoma, BPH, bladder neck obstruction
- What Methylxanthine drugs are used to treat asthma? What is the mechanism of action of these drugs?
- Theophylline – limited role in asthma due to small therapeutic window
- Aminophylline
* These methylxanthine derivates inhibit phosphodiesterase (enzyme responsible for metabolism of cAMP → AMP) allowing for increased levels of cAMP resulting in bronchodilation. These drugs also block adenosine receptors. An increase in caffeine or tea may have similar effects to theophylline with increased CNS and cardiac effects.
- What drugs interact to increase and decrease theophylline levels?
Increase levels → Cimetidine, erythromycin, ciprofloxacin
Decrease levels → phenytoin, phenobarbitone, carbamazepine
- What are complications of theophylline overdoses?
Tremor, insomnia, GI distress, nausea, hypokalemia, hyperglycemia, seizures, arrhythmias