Asthma Flashcards
What are the relievers of asthma?
Bronchodilators:
Short acting betan2 adreno receptors (SABAs)
Long acting “ (LABAs)
CysLT1 receptor antagonists
Methylxanthines
What are the controllers/prevent or of asthma?
Anti inflammatory agents that reduce airway inflammation:
Glucocorticoids
Humanised monoclonal IgE antibodies
Cromoglicate
Methylxanthines
Aerosol vs Oral therapy for asthma (NC come back to)
Aerosol:
Slow absorption and rapid systemic clearance
Low dose to achieve appropriate conc. in lungs - rapid
Low systemic conc. of drug
Low incidence of adverse effects
Distribution of drug reduced in severe airway disease
Oral:
Good absorption and slow systemic clearance
Need high dose to achieve appropriate conc. in lungs
High systemic conc. of drug
High incidence of adverse effects (but depends on drug)
Distribution of drug uneffected in airway disease
Beta 2-agonists
- bronchodilators: relaxes smooth muscle in airways
- stimulate bronchial smooth muscle beta2 receptors: increase cAMP
- short acting: salbutamol
- long acting: salmeterol/formoterol (twice a day), indacaterol/vilanterol/olodaterol (once daily)
- combination inhalers - beclometasone/formoterol: MART (maintenance and reliever therapy)
- used in asthma [as ICS/LABA dual or ICS/LABA/LAMA triple] and COPD [as triple or LAMA/LABA dual]
- high therapeutic ratio when given inhaled route
- Beta 2 down regulation and tachyphylaxis with chronic LABA
- systemic beta 2 effects when given systemically or at high inhaled doses
- high nebulised doses given in acute attack
What’s the the 2 classes of B2 adrenoreceptor agonists?
Short acting (SABA) - salbutamol
Long acting (LABA) - salmetrol, formoterol
What is the first line treatment for mild, intermittent asthma? (NC)
SABAs e.g salbutamol
Usually admitted by inhalation via dry powder …
What treatment is useful for nocturnal asthma (act for approx. 8 hours)?
long acting B2 adrenoreceptor agonists (LABA) - salmeterol, formoterol
LABAs must ALWAYS be co-administered with a glucocorticoid - used alone may worsen asthma and can increase risk of death
Never use alone
What does cysteinyl leukotrine (CysLT1) receptor antagonists do? (Check over)
Block CysLT1 receptors as when these receptors are activated is causes smooth muscle contraction, mucus secretion and oedema
Methylxanthines
- Bronchodilator/anti-inflammatory
- Oral theophylline for maintenance therapy
- IV aminophylline for acute attacks
- add to inhaled steroid as a complimentary non steroidal anti-inflammatory
- non selective phosphodiesterase inhibitor (increase cAMP)
- also act as adenosine antagonist
- very narrow therapeutic window (therapeutic conc. can cause nausea, vomiting, abdominal discomfort)
- low therapeutic ratio - P450 drug interactions 9eg. Erythromycin)
- used in asthma
What type of drug is corticorticoids? What are the 2 major classes? (NC)
Anti-inflammatory
Glucocortocoids …
Mineralcorticoids - zona glomerusla ..
What do muscarinic (cholinergic) receptors do?
- M1 receptors enhance the cholinergic reflex (innate immune response to injury, pathogens, and tissue ischemia)
- M2 receptors inhibit acetylcholine release
- M3 receptors mediate bronchoconstriction and mucus secretion
What are effort dependent tests?
Forced expiratory volumes and Forced expiratory Flow rates - spirometry
What is spirometry? NC
Taking a forced exilation from full inspiration
Volume (L) expired within first second should be close to full capacity - we measure the volume from the 1st second
- Asthmatics get the same FVC as normal people but it just takes them longer - FVC conserved
- In people with COPD FVC is not conserved/ is impaired ~ residual volume is higher (air can get in but cant get out/is trapped) FEV1:FVC ratio impaired/decreased
- Restrictive curve is similar to normal pattern but is squashed down (people with interstitial lung disease) ratio of FEV1:FVC is not impaired, it is reduced but in proportion
Summary of lung function pattens - obstructive vs restrictive NC
MUST KNOW
Obstructive - asthma, COPD
FEV1 response to B2 antagonist >12%
<12% due to airway muscle hypertrophy so doesn’t react the same way to bronchodilators
Restrictive- interstitial lung disease
Bronchial challenge testing
Induce bronchoconstriction by excercise
- fall in FEV1 or PEF after exercise, also activated by cold air ~ asthma
- fall in SaO2 during exercise in interstitial lung disease (good for monitoring treatment response)
- full CArdiopulmoary exercise test (CPET) - differentiate cardiac vs resp dyspneo (rarely used and if so tends to be in athletes)
Induce bronchoconstriction by methacholine/histamine/mannitol
- Marker of Airway hyper-responsiveness - twitchiness (must have to have asthma)
- Conc. to produce a 20% fall in FEV1
Induce bronchoconstriction by allergen/chemicals
- early and late responses
- diagnose of occupational asthma
Transfer factor (differing capacity) NC come back to!!
DLCO always preserved in asthma
DLCO not preserved in COPD
DLCO also decreased in…
Used to measure how much emphysema a patient has got or monitor treatment response with patients with interstitial lung disease
Asthma: Type 2 high vs low
High
- early onset
- atopic (allergy)
- extrinsic
Low
- late onset
- non-atopic
- intrinsically
What is the asthma triad?
- reversible airflow obstruction
- T2 airway inflammation
- Airway hyperresponsiveness
What is the dynamic evolution of asthma?
Bronchoconstricton > T2 airway inflammation > airway remodeling
What are the hallmarks of airway remodelling on asthma?
- Basement membrane thickening
- submucosa collagen disposition
- smooth muscle hypertrophy