Chapter 7 Respiratory Drugs

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Chapter 7 Respiratory Drugs
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Ventilation

• Refers to the movement of air in and out of the
  lungs through a series of air passages.
• Nose
• Mouth
• Trachea
• Bronchial tree
• The upper portion of the respiratory system is
  mainly responsible for conditioning inhaled air
  from the environment.

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• To maintain normal ventilatory function, it is
  critical that the upper respiratory system adjust
  the temperature and humidify the inhaled air as
  well as provide filtration of the contaminants in
  the ambient air.

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• Filtration of inspired air occurs mainly as the
  inhaled air passes over the mucus lined
  epithelium of the trachea.
• The branches of the bronchial tree are lined with
  smooth muscle, which adjusts the constriction and
  dilation of the airways in response to the needs
  of the body.

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Respiratory System

• In the respiratory system, receptor specificity
  is a very important issue and has prompted a
  continued development in many of the agents
  discussed in this chapter.

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• One of the major systems regulating the
  respiratory system is the autonomic nervous
  system
• A main function of the autonomic nervous system
  is to regulate smooth muscle tone in the
  respiratory system and thereby maintain the
  balance between bronchoconstriction and
  bronchodilation.

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Asthma

• Millions of people in the United States have
  asthma and billions of dollars are spent annually
  on the care of these individuals.
• Asthma is a condition of the respiratory system
  involving narrowing (bronchoconstriction) and
  inflammation of the small air passages of the
  lower respiratory system.

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• Technically, asthma, exercise induced asthma
  (EIA), and exercise induced bronchoconstriction
  (EIB) are separate conditions and treated
  differently.
• True asthma is characterized by both
  bronchoconstriction and inflammation in the
  respiratory tract.

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• Exercise is a trigger for approximately 80 to
  90 of individuals with asthma.
• Individuals with EIA, must have excellent control
  of their underlying asthma in order to be able to
  prevent asthma exacerbations during physical
  activity

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• Exercise-induced bronchoconstriction without
  active inflammation is technically not exercise
  induced asthma.
• Exercise-induced bronchoconstriction occurs in
  approximately 11 of individuals without asthma
  and the rate may be as high as 50 for elite
  athletes.

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• In asthmatic reaction, inflammatory response
  increase in mucus production to protect body
• Excess coating can lead to air-flow restriction
• Another mechanism to protect body is
  bronchoconstriction

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• The classic signs of an acute asthma exacerbation
  are
• Shortness of breath
• Wheezing following exercise
• Other signs and symptoms include
• Cough
• Headache
• Stomach cramps
• Pain or tightness in the chest
• Nausea

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• These signs and symptoms typically start 6 to 8
  minutes after the onset of strenuous exercise but
  may not reach maximum severity until up to 15
  minutes after the cessation of exercise.
• Typically, spontaneous return to baseline
  respiratory function occurs within a 20- to
  60-minute period following onset of symptoms.

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Asthma Treatment Options

• Certified athletic trainers often interact with
  athletes who use an inhaler, or more formally
  known as metered dose inhalers (MDIs).
• Most true asthma exacerbations have both an
  inflammatory and bronchoconstriction component.
• The use of medications to control and treat
  asthma may address one or both of these problems.
  

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• Currently, the most widely accepted approach to
  asthma treatment is to initially control the
  inflammatory process associated with the trigger
  and thus prevent bronchoconstriction onset.
• This approach is reflected in the switch from
  heavy dependence on rescue inhalers to the
  increased use of controlling agents.

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• With respect to exercise-induced asthma, the
  athlete typically experiences little or no active
  inflammatory process and the primary complication
  is the bronchoconstriction associated with the
  exercise trigger.
• The treatment for asthma and EIA are different.

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• Asthma exacerbations are categorized based on the
  severity and the frequency of the symptoms.
• In general, asthma is broken down into four
  categories (Table 7-1, pg 95)
• mild intermittent
• mild persistent
• moderate persistent
• severe persistent

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Commonly Used Drugs for Asthma Control

• Numerous pharmacological approaches are used to
  treat asthma.
• Some factors that influence the choice of
  approach are severity and frequency of the
  exacerbations, as well as the convenience of
  using the drug.
• The drugs used to treat asthma can be classified
  into two groups
• bronchodilators and anti-inflammatory agents
  (steroids and non-steroids).

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• It is generally accepted that anyone with
  persistent asthma should utilize a controlling
  agent for the inflammatory component in
  conjunction with a rescue inhaler for the
  bronchoconstriction.
• The role of corticosteroids in asthma, and
  respiratory care in general, is to combat
  inflammation of the airways associated with
  certain respiratory conditions.

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• Corticosteroids indirectly prevent
  inflammation-mediated bronchoconstriction through
  the inhibition of prostaglandins and
  leukotrienes.
• In addition, corticosteroids reverse vascular
  permeability associated with the inflammation
  process.

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• Oral nonsteroidal asthma medications are an
  attractive alternative to the use of inhaled
  steroids in the control of asthma.
• In addition, there is no fluctuation in delivery
  of the medication due to improper use of the MDI.
• It is important to note that all individuals who
  use either steroids or nonsteroidals still need
  access to a rescue inhaler in the event of an
  asthma exacerbation

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• Rescue Inhalers
• Table 7-2, pg 96
• Exercise-induced Asthma
• Causes
• water loss
• heat exchange cooling the airways
• Increased sodium intake
• Must have formal diagnosis

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Adverse Effects of Asthma Medications

• MDIs have less serious adverse effects
• Localized delivery of the medication
• The adverse effects of beta-2 agonists are
  relatively minor.
• Common adverse effects include nervousness,
  restlessness, trembling, throat irritation, and
  potential airway hypersensitivity.

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• Inhaled steroids, have localized side effects,
  such as throat irritation and hoarseness.
• The inhaled steroid residue present in the mouth
  alters the bacterial environment, thus allowing
  for opportunistic yeast infections in the mouth.
• To limit this problem, users are encouraged to
  rinse their mouth and brush their teeth after
  each use of an inhaler.

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• Oral steroids short-term and long-term adverse
  effects.
• Short term increased appetite, acne, poor wound
  healing, fluid retention, and insomnia
• Long-term avascular necrosis, osteoporosis,
  glaucoma, and decreased muscle mass

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• Adverse effects of inhaled nonsteroidal asthma
  medications
• Bitter taste in mouth
• Throat irritation
• Dry mouth
• Headache
• Skin rash

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Allergies

• Are the result of some adverse environmental
  stimulus
• Two classes of drugs are used for the treatment
  of allergies
• Antihistamines
• Corticosteroids (nasal sprays).

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Histamines

• Histamine causes blood vessel dilation and
  subsequently an inflammatory response in the area
  affected.
• Results in an inflammatory response noted by the
  classic allergy symptoms, such as runny nose,
  itchy and watery eyes, and sneezing.

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Antihistamines

• Antihistamines produce three general effects on
  the body
• Alteration of histamine action
• Sedation
• Anticholinergic activity (decreased salivation,
  dry mouth, and constipation)

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• Currently there are first- and second-generation
  antihistamines
• The major differences between the two generations
  are
• The time they are active
• 1st generation 4 to 6 hrs
• 2nd generation up to 12 hrs
• The extent to which they promote drowsiness
• 2nd generation are less sedating

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• Antihistamine drugs
• Halt increased vascular permeability
• Decrease smooth muscle constriction of the
  airways
• First-generation antihistamines cross the blood
  brain barrier and cause sedation
• Use a first-generation antihistamine during the
  evening (less expensive) and nighttime
• Switch to a second-generation antihistamine
  during the daytime

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• Antihistamines result in decreased symptoms and
  increased patient comfort.
• Their use is sometimes questioned.
• Impeding these effects is not always a good
  thing.
• The body produces mucus in an effort to protect
  the respiratory system.
• Decreasing these functions may slow recovery.

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• Antihistamines may not be effective in decreasing
  nasal blockage.
• Second-generation antihistamines are available
  with a decongestant.
• Claritin-D and Allegra-D
• A decongestant will assist with the resolution of
  the runny nose and head congestion.

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• Adverse effects of antihistamines
• Mucous membrane dryness
• Cardiac stimulation
• Blurred vision
• Urinary retention

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Steroid Nasal Spray

• Nasal steroid medications are specifically used
  for allergic rhinitis.
• They are not for symptoms of the common cold.
• Drugs are delivered locally.
• Potential for nasal irritation, dryness, and
  epistaxis

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Coughs and Colds

• Runny nose, mild sore throat, and watery eyes are
  similar in both the common cold and allergic
  reactions.
• Common cold refers to a nonbacterial infection of
  the upper respiratory system.

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Cough and Cold Medications

• Decongestants
• vasoconstriction resulting in mucosal drying
• Antihistamines
• combat increased histamine nasal congestion and
  mucosal irritation
• Expectorants
• facilitate the removal of mucous from the
  respiratory system
• Antitussives
• work to suppress coughing

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• Medications may contain a combination of
  decongestant, antihistamine, expectorant, and
  antitussive agents
• Vicks NyQuil contains
• Acetaminophen
• Pseudoephedrine, a decongestant,
• Dextromethorphan, a cough suppressant
• Antihistamine

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Decongestants

• Prolonged use of decongestants
• Headache
• Nausea
• Dry mouth and nose
• Dizziness
• Nervousness
• Prolonged application of nasal spray (topical)
• Can cause a rebound effect vasodilatation after
  the initial vasoconstriction decreases

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• Common decongestants
• Pseudoephedrine (Sudafed)
• Tetrahydroziline (Visine)
• Oxymetazoline (Afrin)

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Expectorants

• Cough syrup to relieve the coughing linked to
  cold symptoms
• Cough syrups can contain
• Antitussive (cough suppressant)
• Expectorant (promotes mucus clearance)
• If the coughing linked with a cold is
  nonproductive, eliminate the nonproductive
  coughing

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• Mucus removal produced by the body during the
  common cold needs to be thin and mobile for the
  coughing to be productive.
• Expectorants are available in two forms
• Mucolytic
• Stimulant

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Antitussives

• Antitussives suppress the cough.
• Use a central or a local mechanism.
• Used for short periods of time.
• Used to inhibit a cough via a central mechanism.
  
• Cough center located in the medulla is targeted.
  

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• Dextromethorphan (DM) is the most common
  ingredient in OTC suppressing agents.
• Robitussin products, Tylenol cold products, and
  NyQuil medications.
• Physician can prescribe a narcotic antitussive.
• Codeine or hydrocodone.
• Addictive property of narcotics.
• Duration of the prescription does not exceed 1
  week.

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Adverse Effects

• OTC cold and allergy medications relatively show
  few serious adverse effects.
• Participating in a sport while in a state of
  drowsiness could be dangerous.
• Antihistamines (1st generation) can result in
  significant drowsiness even after the drugs
  half-life is complete.

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• Antihistamines may cause anticholinergic effects
  such as
• Mucus membrane dryness
• Cardiac stimulation
• Decreased gastrointestinal activity
• Urinary retention
• Decongestants can promote
• Excessive drying of the nose and throat
• Tachycardia and restlessness

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• Guaifenesin (cough syrups)
• Dizziness
• Headache
• Nausea
• Antitussives (Dextromethorphan)
• Mild dizziness
• Drowsiness
• Nausea
• Stomach cramps