Drugs for Pulmonary Disorders

1
Drugs for Pulmonary Disorders

• Chapter 25

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Respiratory System

• Brings oxygen in and removes carbon dioxide
  through respirations (exchange of gasses)
• Ventilation- process of moving air in and out of
  lungs
• Inspiration- diaphragm contracts/lowers, creating
  negative pressure that draws air into lungs
• Expiration- diaphragm relaxes, air leaves
  passively
• Respiratory rate is usually 12-20 times per
  minute but may change due to numerous factors

3
Respiratory System

• Air enters through nose/pharynx, passes through
  trachea into two bronchi, which divide into
  smaller bronchioles
• These branches of the bronchial tree terminate in
  air sacs called alveoli
• Rich in capillaries
• Site of gas exchange

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Bronchioles

• Lined with smooth muscle, which is controlled
  involuntarily by nervous system
• During fight or flight response, these muscles
  relax, causing bronchodilation
• During rest and relaxation response, these
  muscles constrict, causing bronchoconstriction

5
Inhalation as a drug administration route

• Allows almost instantaneous onset of action
• Drugs can be given locally for respiratory
  problems without causing systemic SE
• Devices for administration
• Nebulizers- vaporize a liquid drug
• Dry powder inhaler- delivers fine powder
• Metered-dose inhaler- at moment of inhalation,
  client squeezes device and a propellant delivers
  dose can be tricky to use

6
Asthma

• Characterized by bronchospasm (severe
  constriction of smooth muscle lining bronchi)
  superimposed on inflammation
• Bronchospasm- causes dyspnea (SOB) and cough
• Inflammation- causes mucus production and
  swelling
• Status asthmaticus- severe asthma that is
  unresponsive to therapy, can cause death

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Asthma Treatment

• ALL asthmatics should be on a least 2 meds
• Preventers- taken on a daily basis to inhibit
  inflammation
• Relievers- taken as needed for asthma symptoms
• Classes of anti-asthma meds
• Beta 2-adrenergic agonists
• Glucocorticoids
• Mast-cell inhibitors
• Antitussives/expectorants/mucolytics

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Beta 2-adrenergic agonists (albuterol)

• These are relievers
• Mimic fight-or-flight response by activating beta
  receptors in lungs
• Also called bronchodilators due to ability to
  relax smooth muscle in bronchi
• May be inhaled or taken orally
• These drugs work best if taken before a
  precipitating event
• SE fight-or-flight responses (more so with oral
  doses) such as nervousness, ? heart rate, tremor

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Glucocorticoids (beclomethasone)

• These are preventers and relievers through their
  ability to suppress inflammation
• Inhaled, they are excellent for prevention but do
  nothing to stop an acute asthma attack
• Orally, they can relieve bronchospasm
• SE may mask infection candidiasis of oral
  cavity (instruct clients to rinse their mouth
  after inhalation)

10
Mast Cell Inhibitors (cromolyn sodium)

• These are preventers
• Inhibit the release of histamine from mast cells
• More effective in children

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Antitussives/Expectorants/ Mucolytics

• Cough is normal reflex used to clear the airways
• Dry hacking cough can be irritating and can even
  produce bronchospasm
• Antitussives- suppress cough
• Narcotics (codeine)- very effective, even at low
  doses with little chance for dependancy
• OTC (dextromethorphan)- few SE, not as effective
• Expectorants (guaifenesin)- reduce thickness of
  bronchial secretions to facilitate removal by
  cough
• Mucolytics (acetylcysteine)- directly loosen
  thick secretions through inhalation

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Chronic Obstructive Pulmonary Disease

• Progressive inflammatory lung disease
  characterized by decreased ability to exhale
• 3 Types may be caused by genetics, air pollution
  and smoking. Most cases are related to smoking
• Asthma- bronchospasm superimposed on inflammation
• Chronic bronchitis- bronchial tree chronically
  produces excess mucus, leading to dyspnea
  (shortness of breath) and coughing
• Emphysema- alveoli dilate permanently to maximum
  size in order to get more air. This is final
  stage of COPD. Characterized by extreme
  shortness of breath
• Therapy includes bronchodilators, inhaled
  glucocorticoids, mucolytics, expectorants, oxygen
  therapy. Avoid respiratory depressants
• There is no cure