Drugs in asthma and COPD

Question 1

clinical Sx of COPD

Answer 1

• chronic bronchitis (inflammation of bronchi)
• emphysema (destruction of alveolar structure - airway collapse during expiration)
• cough
• mucus hyper-secretion
• SOB

Question 2

What are causes of COPD?

Answer 2

• smoking
• air pollution
• occupational (ie firefighter)

Question 3

Why is emphysema debilitating?

Answer 3

• It is the breakdown of alveolar membranes
• normal membranes have a honeycomb structure that allows for efficient gas exchange
• when the membrane breaks down, gas exchange is impaired and CO2 will accumulate in our system, raising the blood pH

Question 4

Define/describe asthma

Answer 4

• Chronic inflammatory disorder of the airways

- characterized by recurring episodes of hyper-responsiveness to stimuli that causes bronchoconstriction

Question 5

Clinical Sx of asthma

Answer 5

• recurring episodes of cough
• wheezing
• tight chest
• dyspnea (SOB)

Question 6

Asthma is based on what type of triggers?

Answer 6

Stimuli can be characterized as either extrinsic (allergic) or intrinsic (non-allergic)

Question 7

List the b2-agonists we need to know for this course. Are they long-acting or short?

Answer 7

Short acting: Albuterol, Salbutamol, Terbutaline (can be given by SC injection) (is also b1 and b2 agonist)
LABA: Salmeterol

Question 8

MOA of b2-agonists

Answer 8

Stimulate adenylyl cyclase, thereby increasing the formation of cAMP which acts to relax the airway smooth muscle, leading to bronchodilation

Question 9

What is a problem associated with chronic drug use in patients with chronic asthma? How can we prevent this? Will be on exam

Answer 9

• Problem: development of desensitization to b2-agonists
• When someone is desensitized, you have to increase the dose to get a response. Increasing the dose of b2-agonists will allow them to also target b1-receptors on the heart.
• Solution: co-administration of b2-agonists and corticosteroids

Question 10

B2-agonists: adverse effects? drug interactions?

Answer 10

AE:
- b1 receptors on the heart may get stimulated, causing tachycardia
- skeletal muscle tremor
- tolerance may develop with frequent use
Interactions:
- propranolol (think - don’t give a b2-agonist to a patient on non-specific beta blockers)
- co-admin. with corticosteroids prevents desensitization (good interaction)

Question 11

Describe Methylxanthines (Theophylline) and their proposed MOA

Answer 11

• inhibits phosphodiesterase, resulting in an increase in cAMP. cAMP acts to relax the airway
• inhibits adenosine receptors for a systemic and CNS effect (adenosine causes the contraction of bronchial smooth muscle and histamine release)
• Can stimulate the contractility of diaphragmatic muscles

Question 12

Describe theophylline (indication, route of admin)

Answer 12

• Admin is safest when done by aerosol, as other routes can adversely affect heart and CNS
• Indication: for COPD; for steroid insensitivity.
  => used as a 2nd choice for the Tx of acute attacks

Question 13

Describe the narrow therapeutic window of theophylline

Answer 13

pharmacokinetics are slightly unpredictable; varies widely among similar patients. Should only be given under supervision

Question 14

adverse effects of theophylline

Answer 14

• increased CV effects if given with b2-agonists
• Common SE: headache, insomnia, tremors
• Serious SE: anaphylaxis, N&V, stimulates heart, fever, and seizures

Question 15

List two anticholinergic drugs and their MOA in asthma treatment

Answer 15

Drugs: Ipratropium (short acting), Tiotropium (long acting)

• MOA: blocks muscarinic receptors to prevent bronchial constriction and mucus secretion
• no effect on inflammation