Asthma Flashcards
Asthma
Sense of breathlessness and tightness of chest
wheezing, dyspnea, cough
cause: immune-related airway inflammation
events leading to inflammation and bronchoconstriction
1) Allergen molecule binds to IgE on mast cells
2) Mast cells release mediatotors
–> bronchocontrictions
–> infiltration of inflammatory cells
3) inflammatory cells release more mediators
RESULT: airway inflammation characterized by edema, mucus plugging, smooth muscle hypertrophy = airflow obstruction
4) inflammation cause by bronchial hyperactivity
COPD symptoms result from 2 processes
1) Chronic bronchitis
- cough, excessive sputum
- hypertrophy of mucus-secreting glands in epithelium of large airways
2) Emphysema
- enlarged airspace within bronchioles and alveoli
- deterioration of walls of air spaces
Both caused by rxn to cigarette smoke
Major Drugs for Asthma and COPD: 2 classes
1) Antiinflammatory agents
Glucocorticoids: admin on fixed schedule
2) Bronchodilators
B2 aagonist: fixed schedule or as needed
- inhaled
Benefits of inhalation
direct to site of action
systemic effects minimized
rapid relief of acute attacks
Glucocorticoid drugs
Beclomethasone (inhaled)
Prednisone (PO prototype)
- most effective for long term control of airway inflammation
Beclomethasone (inhaled)
Prednisone (PO prototype)
Mechanism
decrease synthesis and release of inflammatory mediators (leukotrienes, histamines, prostaglandins)
Decreased infiltration and activity of inflammatory cells (eosinophils, leukocytes)
Decreased edema of airway mucosa
Beclomethasone (inhaled)
Prednisone (PO prototype)
Therapeutic use
control inflammation in both asthma and COPD
effective for asthma prophylaxis and management of COPD exacerbations
don’t alter course of conditions
- provide management of symptoms
inhalation use: very effective, fist line therapy
Prednisone (PO prototype) use
when symptoms cant be controlled with inhaled meds
moderate to severe asthma
high potential for toxicity
- treat brief as possible
Beclomethasone (inhaled)
Adverse effects
inhaled - devoid of serious toxicity
- high doses: oropharyngeal candidiasis (thrush), dysphonia (speaking difficulty)
- long-term high dose: adrenal suppression ( adrenal glands don’t make enough cortisol)
Prednisone (PO prototype) adverse effects
prolonged therapy: adreanal suppression, osteoporosis, immunosuppression
KEY: transferring from PO to inhaled requires several months for recovery of adrenocortical function
Beclomethasone (inhaled)
preparations
regular schedule
Prednisone (PO prototype) prepations dose and administration
methylprednisone, prednisone are preferred
adult dose 40-60 mg/day for 3-10 days
children: lower
Leukotriene receptor antagonists (LTRAs)
suppress leukotriene
- leukotriene involved in recruitment of eosinophils and other inflammatory cells
Types of LTRAs
Zileuton
- blocks leukotriene synthesis
Montelukast
- block leukotriene receptor
Leukotrienes
promote smooth muscle contraction, vessel permeability and inflammation
Zileuton mechanism
effects not immediate
inhibits enzyme that converts arachidonic acid into leukotrienes
Zileuton pharmacokinetics
PO, rapid absorption
Zileuton Adverse effects
Liver injury, possible hepatitis
Neuropsychiatric effects
montelukast: three indications
1) prophylaxis and maintenance in asthma
2) prevention of exercise-induced bronchospasm
3) relief of allergic rhinitis
montelukast mechanism
high affinity for leukotriene receptors
montelukast pharmacokinetics
PO rapidly absorbed
Metabolised in liver
Excreted in bile
Mast cell Stabilizer drug
Cromolyn
Cromolyn
Inhalation agent that suppresses bronchial inflammation
Prophylaxis in patients with mild to moderate asthma
Used when glucocorticoids cause problems
- not as effective as glucocorticoids
Mech of Cromolyn
Stabilizes mast cells
- prevent release of histamines
- inhibits eosinophils and macrophages
cromolyn pharmacokinetics
administrered by nebulizer
excreted unchanged in urine
Cromolyn therapeutic uses
Maximal effects take weeks to develop
prophylaxis for season allergy attacks
Administer 10-15 prior to exercise