Respiratory Medicine Flashcards
(45 cards)
what is the pathophysiology of Asthma ?
Type 1 hypersensitivity reaction leads to TH2/ Eosinophilic inflammation via degranulation .
Leads to airway remodelling via -
Mucosal oedema , Bronchoconstriction and mucus plugging
what specially do B2 agonists target in Asthma ?
what about steroids ?
SM dysfunction
Inflammation
why is Asthma difficult to manage ?
heterogeneous disease
pathologically can vary (Eosinophils and neutrophils)
Symptom paterns and triggers vary
response to treatment vary
how do you define asthma control ?
Minimal symptoms during day + night Minimal need for reliever No exacerbations no limitations of physical activity normal lung function
what should you check before starting therapy ?
Check compliance with existing therapy
inhaler technique
eliminate trigger factors
what is Step 1 on Management of Asthma ?
What drug ?
what do you need to be aware of ?
Short acting B2 agonists - Salbutamol, Terbutaline
Only for relief
if used regularly = reduce asthma control
what is site of action of B2 agonist if only for symptom relief ? what can happen on overuse?
Predominant action on SM in airway
also inhibit mast cell degranulation but if overuse happens this can reverse and sensitivity increases
how does B2 adrenorecpetor work in smooth muscle ?
Alpha s Subunit phosphorylates GDP to GTP and activates Adenyl cyclase to increase cAMP =
Inhibits Myosin light chain
activates PKA-
relaxation
name 1 fast onset long duration B2 agonist and its uses
Formoterol -
Reliever
reduce sever asthma Exacerbation
name 1 long onset long duration B2 agonist and its use
Salmeterol
prophylaxis
what are side effects of B2 Agonists ?
Tachy , palpitation and tremor
when should you use step 2 therapy ?
- using inhaler more than 3 times a wek
- symptoms 3 times a week
- waking up once a week
- Exacerbations requiring oral steroids in the last 2 yrs
(symptoms more than x2 a mnth)
what is step 2 therapy?
regular preventer via inhaled corticosteroids
how do steroids work ?
Attaches to transcription factor (GCS receptor) and chaperones disassociate allows gene transactivation of Anti-inflammaotries and also increase B2 receptor production
also Transrepression of inflammatory mediators
name 2 inhaled steroids
Beclomethasone dipropionate, Budesonide, Fluticasone,
What chemical changes were done to previous steroids and what changes therefore happened to new ones ?
Lipophilic side chain added
a higher affinity for GCS receptor . increased uptake and dwell time in tissue
inactivates hepatic metabolism
how does inhaled steroids enter circulation ?
Lung depsostion and absorption
Swallowed fraction and gut absorption and phase 1 met in liver
what asthma do you have to be aware of when giving steroids ?
Non - eosinophlic patients do not respond as well to inhaled steroids than eosinophilic
what is step 3 therapy?
when is it indicated ?
what drugs ?
add-on
long acting B2 Agonists
Over 400 mcg/day of ICS
Formoterol and salmeterol
which of the LABA is the most potent ?
Formoterol and then Salmeterol
how do you measure potency ?
the dose at causing half the max response
which of the LABA is the most efficacy ?
foametrol = 100% repsonse Salmeterol = 50%
how do you measure efficacy ?
the dose at which the max response is occurring
what are features of LABAs?
reduce asthma exacerbations , improve symptoms and lung functions
not anti-inflammatory
