Drugs For Treating Asthma

Question 1

Asthma

Answer 1

• Partial blockage of the bronchi/bronchioles,
  ~ Often some degree of blockage is
  present even when asymptomatic
• Triggers: Cause inflammatory response
  ~ Allergens
  ~ Infection
  ~ Air temperature
  ~ Emotional state
  ~ Exercise (exercise induced
  bronchospasm)

Question 2

Role of Inflammation on Asthma

Answer 2

• Both PG and LT are produced in the respiratory tract, but there are specialized LT receptors on the smooth muscle and lining of the bronchi.
  ~ PG and LT cause vasodilation and
  increased vessel permeability leading
  to swelling of the airway.
  ~ Activation of the LT receptors has
  additional effects:
  > Increases mucus production.
  > Bronchospasm

Question 3

General Guidelines for Treatment

Answer 3

• Everyone with Asthma should use a quick relief bronchodilator
• Those with persistent asthma should also use daily anti-inflammatory medication

Question 4

Persistent Asthma

Answer 4

• Grades: Mild, Moderate, Severe
  ~ Number of days per week with
  symptoms.
  ~ Number of night time awakenings per
  week.
  ~ Number of times quick relief
  bronchodilator used per week.
  ~ Level of diminished lung function.
• Pt. should always be taking an anti-inflammatory

Question 5

Quick Relief/Rescue Drugs

Answer 5

• Drugs used to treat an acute attack or prevent an imminent attack
• Types
  ~ Bronchodilators
  > Short acting Beta-2 Agonists
  > Anticholinergics
  ~ Systemic Corticosteroids

Question 6

Beta-2 Agonists

Answer 6

• Beta-2 receptors are a component of the sympathetic nervous system and found in many different tissues in the body.
  ~ Activated when bound to hormones
  associated with the sympathetic
  nervous system.
  > Epinephrine
  > Norepinephrine
  ~ When Beta-2 receptors in the
  respiratory tract are activated,
  smooth muscle is relaxed
  > Bronchodilation
• Mimics what the CNS would do

Question 7

Short Acting Beta-2 Agonists Drugs

Answer 7

• Albuterol/Proventil
• Levalbuterol/Xopenex
• Pirbuterol/Maxair

Question 8

Beta-2 Agonists Side Effects

Answer 8

• Also Beta-2 receptors in skeletal muscle and liver
  ~ Tremor
  ~ Hyperglycemia
• Can also exert effect on Beta-1 receptors in the cardiac muscle and kidneys
  ~ Tachycardia (increased HR)
  ~ Hypertension (increased BP)

Question 9

Anticholinergics

Answer 9

• In the respiratory tract the release of acetylcholine causes smooth muscle in the respiratory tract to contract.
  ~ Bronchoconstriction/Bronchospasm
• Anticholinergics inhibit the cholinergic receptors leading to less contraction
  ~ Bronchodilation

Question 10

Anticholinergics Side Effects

Answer 10

• Not widely used since there are many side effects associated with use.
  ~ Blurred Vision
  ~ Constipation
  ~ Decreased Sweating
  ~ Dry Mouth
  ~ Throat Irritation
  ~ Pupil Dilation
  ~ Urinary Hesitancy/Retention

Question 11

Anticholinergics for Asthma

Answer 11

• Few anticholinergic drugs used.
  ~ Iprotropium/Atrovent
  ~ Combivent: Iprotropium + Albuterol
  ~ Side effects of iprotropium are minor
  and include:
  > Dry Mouth
  > Throat Irritation
  > Bad Taste

Question 12

Quick Relief Systemic Corticosteroids

Answer 12

• Delivered by injection.
  ~ Control bronchospasm/inflammation/
  mucus by inhibiting the majority of the
  inflammatory process including the
  lipoxygenase pathway that produces
  LT.
  ~ Few side effects since the use is short
  term.
  ~ Examples
  > Methylprednisolone
  > Prednisolone
  > Prednisone

Question 13

Long Term Therapy

Answer 13

• Used to reduce the incidence of acute attacks
  ~ Not used for acute attacks
• Types
  ~ Inhaled Corticosteroids
  ~ Long Acting Beta Agonists
  ~ Leukotriene Modifiers
  ~ Mast Cell Stabilizers

Question 14

Inhaled Corticosteroids

Answer 14

• Mechanism: Bronchodilation
• Examples
  ~ Slower and longer lasting than rescue
  drugs.
  ~ Administered multiple times daily.
  > Beclomethasone/Vanceril
  > Fluticasone/Flovent

Question 15

Inhaled Corticosteroids: Adverse Effects

Answer 15

• Potentially the same as when using for other inflammatory conditions, but less likely due to low dosage
  ~ Some is swallowed or absorbed in the
  lungs so systemic effects are possible

Question 16

Long Acting Beta Agonists

Answer 16

• Mechanism: Bronchodilation
• Examples
  ~ Sometimes inhaled to limit side
  effects.
  > Albuterol/Proventil
  ~ Same drug used for quick relief, but
  given as a tablet.
  > Salmeterol/Serevent
  ~ Can be combined with corticosteroid
  to increase effectiveness and decrease
  number of inhalations per day.
  > Fluticasone + Salmeterol = Advair/
  Diskus
  > Budesonide + Formoterol =
  Symbicort

Question 17

Long Acting Beta Agonists: Adverse Effects

Answer 17

• Same potential as short acting beta agonists.
  ~ Especially when taken orally.
  ~ When inhaled, occurrence of side
  effects is decreased.
  ~ Some using these medications may
  have a fatal acute asthma attack.
  > Mechanism Unknown
  • If used alone causes
  Bronchodilation, but doesn’t
  effect inflammatory process,
  mistake or on purpose non
  administration?

Question 18

Leukotriene Modifiers

Answer 18

• Mechanisms/Examples
  ~ Leukotrienes Antagonists
  > Bind to LT receptors preventing LT
  binding
  • Examples - Administered
  orally.
  * Montelukast/Singulair
  * Zafirlukast/Accolate

  ~ Leukotriene Synthesis Inhibitors
         > Inhibit lipoxgenase activity   
         > Example: Zileuton/Zyflo

Question 19

Leukotriene Modifiers Adverse Effects

Answer 19

• Headache
• Hepatotoxicity
• Not a preferred drug because they’re less effective that corticosteroids

Question 20

Mast Cell Stabilizers

Answer 20

• Mechanism
  ~ Stabilizes the mast cells membrane to
  stop the release of HT when exposed
  to an allergen/pathogen or BK
• Examples: Inhaled
  ~ Cromolyn/Intal
  ~ Nedocromil/Tilade

Question 21

Mast Cell Stabilizers Adverse Effects

Answer 21

• None common
• Not a preferred drug because they’re less effective than corticosteroids and take a long period of time to have positive effects