Medications That Affect the Respiratory System

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Medications That Affect the Respiratory System

• Unit 26

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Objectives

• Describe respiration
• Describe the causes of respiratory conditions
  and/or diseases
• Describe the various drug classifications that
  are used for respiratory system conditions and
  diseases
• Identify selected drugs according to each
  described classification

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Respiratory System

• Principal organs include the nose, pharynx,
  larynx, trachea, bronchi, and lungs
• The lungs contain no muscle tissue instead they
  rely on the movement of surrounding structures
  (ribs and diaphragm) in order to function

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Inspiration vs. Expiration

• Inspiration contraction of the rib muscles and
  the diaphragm expands the thoracic cavity and
  causes the intake of air into the lungs
• Expiration relaxation of rib muscles which
  decreases the volume of the cavity and forces air
  out of the lungs

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Conditions and Diseases

• Causes can include
• Allergies
• Pathogenic microorganisms
• Environmental conditions
• Hereditary factors

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Antihistamines

• Chemical agents related to histamine that block
  histamine (H1) receptors
• Effective in the treatment of allergic rhinitis,
  dermatitis, insect bites, plant poisons, and
  anaphylactic shock
• Adverse Reactions sleepiness, dizziness,
  disturbed coordination, increased bronchial
  secretions

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Decongestants

• Congestion may occur as a result of infection,
  allergies, inflammation, or emotional distress
• Stimulate the alpha-adrenergic receptors of
  vascular smooth muscle constricting the vessels
  in the nasal mucosa. This reduces blood flow to
  the affected area, slows mucus production, and
  opens nasal passages.

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Antitussives

• Coughing is a protective mechanism that clears
  the respiratory tract of secretions and foreign
  substances
• Act to ease respiratory discomfort, facilitate
  sleep, and reduce irritation
• Two types of antitussives
• Narcotic
• Non-narcotic

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Antitussives

• Narcotic act by depressing the cough center
  located in the medulla, raising its threshold for
  incoming cough impulse
• Non-narcotic anesthetize the stretch receptors
  located in the respiratory passages, lungs, and
  pleura, by dampening their activity and reducing
  the cough reflex

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Expectorants

• Agent that stimulates and decreases the thickness
  of respiratory tract secretions
• Act by enhancing the output of lower respiratory
  tract fluids and help make them less viscid
• Help to loosen mucus and make cough more
  productive

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Mucolytics

• Drugs that reduce the viscosity of respiratory
  tract fluids
• Break chemical bonds in mucus, lowering the
  viscosity
• Used in the treatment of chronic obstructive
  pulmonary disease (COPD), cystic fibrosis, and
  pneumonia

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Bronchodilators

• Used to improve pulmonary airflow in patients
  with COPD and asthma.
• Classified in four types
• 1. Sympathomimetics
• 2. Xanthines
• 3. Leukotrine receptor antagonists
• 4. Anticholinergic agents

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Sympathomimetics

• Relax smooth muscle cells by acting on beta-2
  adrenoreceptors. They produce a vasoconstriction
  response which reduces edema in the bronchial
  mucosa.
• Ex Isuprel, Adrenalin

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Xanthines

• Relax smooth muscle of the bronchial airways and
  pulmonary blood vessels by blocking
  phosphodiesterase, an enzyme that increases
  adenosine monophosphate (AMP).
• By preventing the breakdown of cyclic AMP, smooth
  muscles relax and bronchodilation occurs.

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Leukotriene Receptor Antagonists (Blockers)

• Used in the treatment and management of asthma
• Act by blocking cysteinyl leukotrienes, which are
  associated with asthma, airway edema, smooth
  muscle contraction, and inflammation
• Ex. Accolate, Zyflo, Singulair

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Anticholinergic Agents

• Act by inhibiting cholinergic receptors in
  bronchial smooth muscle, resulting in decreased
  concentrations of cyclic guanosine monophosphate
  (cGMP)
• This action causes localized bronchodilation
• Used to treat COPD, bronchitis, emphysema

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Glucocorticoids

• Anti-inflammatory agents that are chemically
  related to the hormone cortisone
• Used to treat bronchial asthma and hayfever
• Ex. Flonase, Rhinocort

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Tuberculosis

• Contagious disease caused by the bacterium
  Mycobacterium tuberculosis
• Spread by airborne transmission
• An estimated 10 million Americans are infected
  with TB
• Symptoms include chronic cough, low-grade fever,
  night sweats, wekaness, weight loss

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Tuberculosis

• Diagnosis TB skin test, chest X-ray
• Treatment requires long-term drug therapy (6-9
  months)
• Two weeks of treatment until enough bacteria are
  killed so people are no longer contagious
• Cure takes approximately nine months of full-time
  drug therapy