Strategy?
- to return lung function to as near normal as possible.
- primary classes of drugs used to treat asthma : bronchodilator and anti-inflammatory agents
- alternative therapies : leukotrines modulators, cromolyn sodium nedocromil sodium
1) bronchodilator
- for maintenance therapy
- reliever : rapid symptomatic relief
Epinephrine

• both a and b
• subcutaneous route : acute and status asthmaticus
• therapeutic effects: increased HR, CO, SV, elevated systolic and decrease diastolic, decreased systemic vascular resistance.
• adverse effects: anxiety, tremor, palpitations, extreme HTN, Pulmonary oedema, angina, ventricular arrhythmias
  

B2-agonists

• Albuterol (Proventil/Ventolin) ,Terbutaline (Brethine) ,Salmeterol (Serevent)
• MoA : enhance production of cAMP
  

• Terbutaline and albuterol - either oral / inhalation ( rapid onset thus for acute symptoms)
  
• Salmeterol - inhalation only
• B2-agonist - tachycardia at large dose
• Salmeterol - longer half-life (prophylactic use) and short duration of action (not to be used to treat acute symptoms)
• Terbutaline - control premature labour (by abolished contraction of uterine smooth muscle)
• Adverse Effects: Orally --> muscle tremor, tachycardia, palpitations. IV for premature labour-->tachy cardia, pulmonary oedema (mother), hypoglycaemia (baby)
• inhalation - minor SE

Theophylline

• MoA : inhibits phosphodiesterase enzyme (enzyme that inactivates cAMP and cGMP)
• narrow therapeutic index
• slow metabolism in disease state (i.e heart failure, liver disease, respiratory obstruction)
• SE : nausea and vomiting (common in first time user), restlessness, diuresis, fever
• CI : used cautiously in MI, liver disease, myocardial disease
• half-life prolonged in CCF
• interaction with : cimetidine, zileuton

Anti-cholinergic

• Ipratropium bromide (Atrovent)
• slow onset
• suitable for prophylactic
• ipratropium + albuterol (Combivent) used in COPD
• devoid of CNS SE
• peripheral SE : dry mouth, headache, nervousness

2) Anti-inflammatory Agents
- inhaled corticosteroid, along with b2-agonist -> firstline therapy of CHRONIC ASTHMA.

Corticosteroid

• Oral : Prednisolone
  
• Parenteral : Hydrocortisone
  
• Inhalation : Beclometasone dipropionate

• Effects take hours to develop (can't be used for quick relief of acute)
• inhaled steroid not effective for relief of acute episodes of severe bronchospasm
• systemic corticosteroid (eg. Prednisolone) used for short-term treatment that does not respond to B2-agonist
• not to be used as maintenance unless other options failed (due to SE)
• SE of systemic admin > SE of inhalant admin
• SE : adrenal suppression, cushingoid changes, growth retardation, cataracts, osteoporosis, infection vulnerability

3) Alternative therapy
- not to be used as monotherapy
- for prophylactic

Leukotrine modulator

• Zafirlukast (accolate), montelukast(singulair), Zileuton (Zyflo)