L13a Treatment of Asthma Flashcards
Goals of Asthma Treatment
Control chronic symptoms
Maintain normal activity levels and exercise
Maintain near-normal pulmonary function
Prevent exacerbation of asthma (especially during winter time)
Minimize emergency department (ED)
treatments visits and hospitalizations
Avoid adverse effects of (abuse of) asthma medications
Asthma Treatments: Relievers
drugs that provide relief from (Acute) asthma symptoms. Normally rapid onset but short duration, cause airway Smooth-muscle relaxation. Patients should keep relievers on hand and take it only when they need it - during an asthma attack, or (sometimes) before exercising.
-sometimes used as a preventer (keep handy for life threatening asthma)
Asthma Treatments: Preventers
do not provide relief for an acute asthma attack, they are *“long-term control medications“ which have *Anti-inflammatory effects to prevent the acute asthma attack.
Patients take preventer medicines daily, even if they have no symptoms.
Asthma Treatments
Relievers
Preventers
Others
Three Types of Bronchodilators
Three types of bronchodilators:
- Inhaled beta-adrenergic agonists
- Anticholinergicagents
- Xanthine drugs
Benefits of Inhaled Beta-agonists in the management of Asthma
- Relief of bronchoconstriction due to smooth-muscle relaxation
- Marked protection against all nonspecific constrictor stimuli, such as cold air, methacholine and exercise (prevent exercise induced asthma)
- Reduced vascular permeability and edema
- Increased mucociliary clearance due to increased ciliary beat frequency
- May (partially) reduce inflammation due to inhibition of mediator release from inflammatory cells and priming of glucocorticoid receptors
Mechanism of relaxation of bronchial smooth muscle
- B2 agonists diffuses and bonds with B2 transmembrane receptor
- Gs activated. activates AC (adenylate cyclase)
- AC converts ATP –> cAMP
- Increase cAMP = increase PKA (protein kinase A)
- a) Increase Ca2+ activated K+ channel –> K+ release
b) Increase Na+/K+ ATPase
c) decrease PI (phosphatidylinositol) hydrolysis
d) Increase Na+/Ca2+ exchange
e) Reduce MLCK (Myosin Light Chain kinase)
all causing 6.
a) Smooth muscle relaxation
b) inhibits mediator release
Aspects of Bronchodilators (relievers)
Pharmacodynamics of different bronchodilators
Adverse effects and limitations
Different delivery systems and devices
A century of Progress: B-Agonist History
1000Bc Ma Haung (2000 years later w/o much improvement except opiate causing smooth muscle relaxation w. side effect) 1900 Epinephrine (injection)1 = first smooth muscle relaxation modern drug 1960= B2 Selective Albuterol = first B2 agonist bronchodilater became available in the market = start of modern treatments 1960-2000= Long acting B2 Selective Albuterol available
Theophylline
Inhibits cAMP - (PDE)-> AMP
Theophylline can retain increasing/high cAMP concentration
Charybdotoxin
Stops K+ release
Selectivity of B2 Adrenergics
alots of B2 agonists are non selective
- when the B2 receptors are activated: will cause
1. Smooth muscle relaxation
2. Reduced edema
3. Inhibit mediator release
B2 subtype cells
Smooth muscle Epithelium (airway) Submucosal glands (B1/B2) Care cells Cholinergic nerves Sensory nerves (B2/B3) Bronchial vessels (B2) Inflammatory cells (B2) -mast cells -macrophages -eosinophils -T-lymphocytes
Smooth muscle subtype and function
B2 Subtype
Function:
-Relaxation
-Inhibition of Proliferation
Epithelium (airway) subtype and function
B2 Subtype Function: -Increase ion transport -Secretion of inhibitory factor? -Increased ciliary beating -Increased mucociliary clearance
Submucosal glands and Clare cells subtype and function
Submucosal glands Subtype: B1/B2
Clare cells Subtype: B2
Function: Increased secretion
Cholinergic nerves subtype and function
B2 Subtype
Reduced ACh release
Sensory nerves subtype and function
B2/B3 subtype
Function
-Reduced neuropeptide release
-Reduced activation?
Bronchial vessels subtype and function
B2 subtype
Function:
Vasodilation
Inflammatory cells subtype and function
Subtype all: B2 Mast cells: Reduced mediator release Macrophages: No effects? Eosinophils: Reduced mediator release T-lymphocytes: Reduced cytokine release
Non B2 subtype only Cells
Submucosal glands: B1/B2
Sensory nerves: B2/B3
Heart Receptors and Effect if Stimulated
Receptors: B1 and B2 Effect if stimulation: -Increased contractility -Increased conduction velocity --> Increased HR heart rate
Arteriole Receptors and Effect if Stimulated
a1 and a2 Receptor = vasoconstriction
B2 Receptor = Vasodilation
Lung Receptors and Effect if Stimulated
B2 receptor
Effect if stimulated: Bronchodilation