M3 L6: anti-asthma drugs Flashcards
bronchial asthma
- resp syndrome
- characterized by decreased airflow thru airways
pathology:
- inflammation of the bronchial walls
- narrowing of airways
- increased resistance to airflow
clinical manifestation:
- cough, chest tightness, SOB, wheeze
Bronchi gets narrowing, and wall gets thicker bc of inflammatory action, and there is mucous inside
Bronchoconstriction, mucous secretion, and swelling
What receptor are on the bronchi
beta and beta-2
factors increase airway obstruction
- bronchoconstriction: contraction of bronchial smooth muscles
- mucosal edema: resulting from inflammation
- bronchiolar secretions: increase mucous secretion due to inflammati
treatment of asthma
control precipitating factors
anti-asthma agents
anti asthma agents
- bronchodilators
- anti-inflammatory agents
bronchodilators
- sympathomimetics:
- α and β adrenoreceptor agonists
- β2 adrenoreceptor agonists
- α adrenoreceptor agonists - anticholinergics
- xanthines (methylxanthines)
They act on beta-receptors
Epinephrine - stim alpha and beta and used more in children
Anticholinergics: inhibit parasympathetic
β2 adrenoreceptor agonists
mechanism:
- increased β2 adrenoreceptors on bronchial smooth muscles -> bronchodilation
- decrease mediators release from mast cells
pros:
- most effective bronchodilators
- minimal side effects
adverse effects: tachycardia, tremors, anxiety
Safer, less adverse effects
Very effective
β2 adrenoreceptor agonists
types:
- short acting (salbutamol (albuterol) and terbutaline)
- long acting (salmeterol, formoterol)
acute attacks:
- inhalation - aerosol or nebulised solution
- IV infusion (adrenaline - SC injection)
maintenance therapy:
- oral - tablets or syrup
- inhalation
Short acting: lifesaving ones! Used by inhalation, or injection - salbutamol** know - if u cross border and move south of the states the name changes
Long acting ones: can be used during or in between effects.
anticholinergics
mechanism:
- decrease muscarinic receptors -> block chlinergically-mediated bronchoconstriction
indications/route:
- usually adjunct therapy
- acute attacks plus or minus maintenance
- inhalation
ex: ipratropium bromide
xanthines
3 pharmacologically active compounds:
- caffeine
- theobromine
- theophylline* was highlighted
theophylline
- effective anti-asthma drug
- aminophylline: theophylline derivative
mechanism:
- decreases phosphodiesterases (PDEs) -> decreases cAMP hydrolysis -> accumulation of cAMP -> relaxation of bronchial smooth muscles -> bronchodilation
cons:
- narrow therapeutic range
- wide range of side effects
side effects:
- CVS: palpitation - dysrhythmias
- CNS: tremors - convulsions
- GIT: ab pain - nausea
Worst case, causes convulsions
routes of admission:
- oral
- IV (aminophylline only)
anti-inflammatory agents
- glucocorticoids (steroids)
- mast cell stabilizers
- leukotriene inhibitors (leukotriene receptor antagonists, leukotriene synthesis inhibitors)
- omalizumab
- methotrexate
glucocorticoids
mechanism:
- anti-inflammatory effect on bronchial mucosa
- decreased macrophages - eosinophils - lymphocytes
- decrease mucus secretion
routes of administration:
- inhalation (main)
- oral
- IV
ex: beclomethasone
mast cell stabilizers
- stabilize mast cells -> decrease release of chemical mediators (ex: histamine) that cause bronchoconstriction -> incidence of attacks
- indications: prophylaxis (not suitable during acute attacks)
Quite useful can’t use them on their own
Don’t use them in acute attacks
Used by inhalation
ex: cromolyn sodium and nedocromil
leukotriene receptor antagonists
- selective blocking of leukotrienes action on the resp tract: decreases mucus secretion, decreases bronchoconstriction
indications:
- adjunct therapy
- prophylaxis (not suitable during acute attacks)
route of administration:
- oral
ex: montelukast and zafirlukast
These meds compete w leukotrienes for their receptors, they stim inflammatory reaction, and this causes bronchoconstriction
Competitive inhibition
